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Note: This page contains sample records for the topic "gradients thermal conductivity" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


1

Phase-field modeling of temperature gradient driven pore migration coupling with thermal conduction  

SciTech Connect

Pore migration in a temperature gradient (Soret effect) is investigated by a phase-field model coupled with a heat transfer calculation. Pore migration is observed towards the high temperature domain with velocities that agree with analytical solution. Due to the low thermal conductivity of the pores, the temperature gradient across individual pores is increased, which in turn, accelerates the pore migration. In particular, for pores filled with xenon and helium, the pore velocities are increased by a factor of 2.2 and 2.1, respectively. A quantitative equation is then derived to predict the influence of the low thermal conductivity of pores.

Liangzhe Zhang; Michael R Tonks; Paul C Millett; Yongfeng Zhang; Karthikeyan Chockalingam; Bulent Biner

2012-04-01T23:59:59.000Z

2

Estimation of in-situ thermal conductivities from temperature gradient measurements  

Science Conference Proceedings (OSTI)

A mathematical model has been developed to study the effect of variable thermal conductivity of the formations, and the wellbore characteristics, on the fluid temperature behavior inside the wellbore during injection or production and after shut-in. During the injection or production period the wellbore fluid temperature is controlled mainly by the fluid flow rate and the heat lost from the fluid to the formation. During the shut-in period, the fluid temperature is strongly affected by differences in the formation thermal conductivities. Based on the results of the present analysis, two methods for estimating in-situ thermal conductivity were derived. First, the line source concept is extended to estimate values of the formation thermal conductivities utilizing the fluid temperature record during the transient period of injection or production and shut-in. The second method is applied when a well is under thermal equilibrium conditions. Values of the formation thermal conductivities can also be estimated by using a continuous temperature gradient log and by measuring the thermal conductivity of the formation at a few selected wellbore locations.

Hoang, V.T.

1980-12-01T23:59:59.000Z

3

The Stability of Dilute Plasmas with Thermal and Composition Gradients. I. The Slow Conduction Limit: Overstable Gravity Modes  

E-Print Network (OSTI)

We analyze the stability of a dilute plasma with thermal and composition gradients in the limit where conduction is slow compared to the dynamical timescale. We find necessary and sufficient conditions for stability when the background magnetic field is either parallel or perpendicular to the thermal and composition gradients that are parallel to the gravitational field. We provide approximate solutions for all the relevant modes involved, which are driven by gravity, conduction, and diffusion. We discuss the astrophysical implications of our findings for a representative galaxy cluster where helium has sedimented.

Pessah, Martin E

2011-01-01T23:59:59.000Z

4

Definition: Thermal Gradient Holes | Open Energy Information  

Open Energy Info (EERE)

Gradient Holes Jump to: navigation, search Dictionary.png Thermal Gradient Holes "A hole logged by a temperature probe to determine the thermal gradient. Usually involves a hole...

5

Thermally Conductive Graphite Foam  

oriented graphite planes, similar to high performance carbon fibers, which have been estimated to exhibit a thermal conductivity greater than 1700 ...

6

Cylindrical thermal contact conductance  

E-Print Network (OSTI)

Thermal contact conductance is highly important in a wide variety of applications, from the cooling of electronic chips to the thermal management of spacecraft. The demand for increased efficiency means that components need to withstand higher temperatures and heat transfer rates. Many situations call for contact heat transfer through nominally cylindrical interfaces, yet relatively few studies of contact conductance through cylindrical interfaces have been undertaken. This study presents a review of the experimental and theoretical investigations of the heat transfer characteristics of composite cylinders, presenting data available in open literature in comparison with relevant correlations. The present investigation presents a study of the thermal contact conductance of cylindrical interfaces. The experimental investigation of sixteen different material combinations offers an opportunity to develop predictive correlations of the contact conductance, in conjunction with an analysis of the interface pressure as a function of the thermal state of the individual cylindrical shells. Experimental results of the present study are compared with previously published conductance data and conductance models.

Ayers, George Harold

2003-08-01T23:59:59.000Z

7

Thermal conductivity of mass-graded graphene flakes  

E-Print Network (OSTI)

In this letter we investigate thermal conductions in mass-graded graphene flakes by nonequilibrium molecular dynamics simulations. It shows mass-graded graphene flakes reveal no thermal rectification effect in thermal conduction process. Dependences of thermal conductivity upon the heat fluxes and the mass gradients are studied. It is found that thermal conductivity would be dramatically decreased by increasing the mass gradients. We also discuss the influence of thermal curvatures and thermal expansions upon the thermal conduction process in mass-graded graphene flakes.

Cheh, Jigger

2011-01-01T23:59:59.000Z

8

Enhanced Thermal Conductivity Oxide Fuels  

SciTech Connect

the purpose of this project was to investigate the feasibility of increasing the thermal conductivity of oxide fuels by adding small fractions of a high conductivity solid phase.

Alvin Solomon; Shripad Revankar; J. Kevin McCoy

2006-01-17T23:59:59.000Z

9

Thermal conductivity of thermal-battery insulations  

DOE Green Energy (OSTI)

The thermal conductivities of a variety of insulating materials used in thermal batteries were measured in atmospheres of argon and helium using several techniques. (Helium was used to simulate the hydrogen atmosphere that results when a Li(Si)/FeS{sub 2} thermal battery ages.) The guarded-hot-plate method was used with the Min-K insulation because of its extremely low thermal conductivity. For comparison purposes, the thermal conductivity of the Min-K insulating board was also measured using the hot-probe method. The thermal-comparator method was used for the rigid Fiberfrax board and Fiberfrax paper. The thermal conductivity of the paper was measured under several levels of compression to simulate the conditions of the insulating wrap used on the stack in a thermal battery. The results of preliminary thermal-characterization tests with several silica aerogel materials are also presented.

Guidotti, R.A.; Moss, M.

1995-08-01T23:59:59.000Z

10

Thermal Gradient Holes | Open Energy Information  

Open Energy Info (EERE)

Thermal Gradient Holes Thermal Gradient Holes Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Thermal Gradient Holes Details Activities (50) Areas (39) Regions (4) NEPA(29) Exploration Technique Information Exploration Group: Drilling Techniques Exploration Sub Group: Exploration Drilling Parent Exploration Technique: Exploration Drilling Information Provided by Technique Lithology: Stratigraphic/Structural: Hydrological: Field wide fluid flow characteristics if an array of wells are drilled Thermal: Mapping and projecting thermal anomalies Cost Information Low-End Estimate (USD): 5.00500 centUSD 0.005 kUSD 5.0e-6 MUSD 5.0e-9 TUSD / foot Median Estimate (USD): 16.501,650 centUSD 0.0165 kUSD 1.65e-5 MUSD 1.65e-8 TUSD / foot High-End Estimate (USD): 50.005,000 centUSD

11

Thermal conductivity of aqueous foam  

Science Conference Proceedings (OSTI)

Thermal conductivity plays an important part in the response of aqueous foams used as geothermal drilling fluids. The thermal conductivity of these foams was measured at ambient conditions using the thermal conductivity probe technique. Foam densities studied were from 0.03 to 0.2 g/cm/sup 3/, corresponding to liquid volume fractions of the same magnitude. Microscopy of the foams indicated bubble sizes in the range 50 to 300 ..mu..m for nitrogen foams, and 30 to 150 ..mu..m for helium foams. Bubble shapes were observed to be polyhedral at low foam densities and spherical at the higher densities. The measured conductivity values ranged from 0.05 to 0.12 W/m-K for the foams studied. The predicted behavior in foam conductivity caused by a change in the conductivity of the discontinuous gas phase was observed using nitrogen or helium gas in the foams. Analysis of the probe response data required an interpretation using the full intergral solution to the heat conduction equation, since the thermal capacity of the foam was small relative to the thermal mass of the probe. The measurements of the thermal conductivity of the foams were influenced by experimental effects such as the probe input power, foam drainage, and the orientation of the probe and test cell. For nitrogen foams, the thermal conductivity vs liquid volume fraction was observed to fall between predictions based on the parallel ordering and Russell models for thermal conduction in heterogeneous materials.

Drotning, W.D.; Ortega, A.; Havey, P.E.

1982-05-01T23:59:59.000Z

12

Thermal conductivity Measurements of Kaolite  

Science Conference Proceedings (OSTI)

Testing was performed to determine the thermal conductivity of Kaolite 1600, which primarily consists of Portland cement and vermiculite. The material was made by Thermal Ceramics for refractory applications. Its combination of light weight, low density, low cost, and noncombustibility made it an attractive alternative to the materials currently used in ES-2 container for radioactive materials. Mechanical properties and energy absorption tests of the Kaolite have been conducted at the Y-12 complex. Heat transfer is also an important factor for the application of the material. The Kaolite samples are porous and trap moisture after extended storage. Thermal conductivity changes as a function of moisture content below 100 C. Thermal conductivity of the Kaolite at high temperatures (up to 700 C) are not available in the literature. There are no standard thermal conductivity values for Kaolite because each sample is somewhat different. Therefore, it is necessary to measure thermal conductivity of each type of Kaolite. Thermal conductivity measurements will help the modeling and calculation of temperatures of the ES-2 containers. This report focuses on the thermal conductivity testing effort at ORNL.

Wang, H

2003-02-21T23:59:59.000Z

13

Thermal Conduction in Graphene and Graphene Multilayers  

E-Print Network (OSTI)

1 1.2 Thermal transport atxv Introduction xii 1.1 Thermal conductivity and65 4.13 Thermal conductivity of graphene as a function of

Ghosh, Suchismita

2009-01-01T23:59:59.000Z

14

Thermal Gradient Holes At Blue Mountain Area (Fairbank & Neggemann...  

Open Energy Info (EERE)

Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Blue Mountain Area (Fairbank & Neggemann, 2004) Exploration...

15

Invert Effective Thermal Conductivity Calculation  

SciTech Connect

The objective of this calculation is to evaluate the temperature-dependent effective thermal conductivities of a repository-emplaced invert steel set and surrounding ballast material. The scope of this calculation analyzes a ballast-material thermal conductivity range of 0.10 to 0.70 W/m {center_dot} K, a transverse beam spacing range of 0.75 to 1.50 meters, and beam compositions of A 516 carbon steel and plain carbon steel. Results from this calculation are intended to support calculations that identify waste package and repository thermal characteristics for Site Recommendation (SR). This calculation was developed by Waste Package Department (WPD) under Office of Civilian Radioactive Waste Management (OCRWM) procedure AP-3.12Q, Revision 1, ICN 0, Calculations.

M.J. Anderson; H.M. Wade; T.L. Mitchell

2000-03-17T23:59:59.000Z

16

Thermal Gradient Holes At Coso Geothermal Area (1976) | Open Energy  

Open Energy Info (EERE)

Thermal Gradient Holes At Coso Geothermal Area (1976) Thermal Gradient Holes At Coso Geothermal Area (1976) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Coso Geothermal Area (1976) Exploration Activity Details Location Coso Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date 1976 Usefulness useful DOE-funding Unknown Notes Temperatures have been obtained to depths up to 133 m in 22 boreholes with measurements being made at least four times in each borehole. Geothermal gradients ranged from 240C/km to 450 0C/km. References Combs, J. (1 December 1976) Heat flow determinations and implied thermal regime of the Coso geothermal area, California Retrieved from "http://en.openei.org/w/index.php?title=Thermal_Gradient_Holes_At_Coso_Geothermal_Area_(1976)&oldid=511217"

17

High Thermal Gradient Directional Solidification with Liquid Metal ...  

Science Conference Proceedings (OSTI)

Presentation Title, High Thermal Gradient Directional Solidification with Liquid Metal Cooling and Its Application in the Processing of Nickel-Based Superalloys.

18

Thermal Gradient Holes At Breitenbush Hot Springs Area (Ingebritsen...  

Open Energy Info (EERE)

Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Breitenbush Hot Springs Area (Ingebritsen, Et Al., 1993)...

19

Thermal Gradient Holes At Mccoy Geothermal Area (DOE GTP) | Open...  

Open Energy Info (EERE)

Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Mccoy Geothermal Area (DOE GTP) Exploration Activity Details...

20

Thermal Gradient Holes At Pilgrim Hot Springs Area (DOE GTP)...  

Open Energy Info (EERE)

Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Pilgrim Hot Springs Area (DOE GTP) Exploration Activity Details...

Note: This page contains sample records for the topic "gradients thermal conductivity" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Thermal Gradient Holes At Lake City Hot Springs Area (Warpinski...  

Open Energy Info (EERE)

Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Lake City Hot Springs Area (Warpinski, Et Al., 2004) Exploration...

22

Thermal Gradient Holes At Long Valley Caldera Area (Sorey, Et...  

Open Energy Info (EERE)

Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Long Valley Caldera Area (Sorey, Et Al., 1991) Exploration Activity...

23

Thermal Gradient Holes At Upper Hot Creek Ranch Area (Benoit...  

Open Energy Info (EERE)

Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Upper Hot Creek Ranch Area (Benoit & Blackwell, 2006) Exploration...

24

Thermal Gradient Holes At Obsidian Cliff Area (Hulen, Et Al....  

Open Energy Info (EERE)

Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Obsidian Cliff Area (Hulen, Et Al., 2003) Exploration Activity...

25

Thermal Gradient Holes At Central Nevada Seismic Zone Region...  

Open Energy Info (EERE)

Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Central Nevada Seismic Zone Region (Pritchett, 2004) Exploration...

26

Thermal Gradient Holes At Newberry Caldera Area (DOE GTP) | Open...  

Open Energy Info (EERE)

Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Newberry Caldera Area (DOE GTP) Exploration Activity Details...

27

Thermal Gradient Holes At San Emidio Desert Area (DOE GTP) |...  

Open Energy Info (EERE)

Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At San Emidio Desert Area (DOE GTP) Exploration Activity Details...

28

Thermal Gradient Holes At Flint Geothermal Area (DOE GTP) | Open...  

Open Energy Info (EERE)

Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Flint Geothermal Area (DOE GTP) Exploration Activity Details...

29

Thermal Gradient Holes At Spencer Hot Springs Area (Shevenell...  

Open Energy Info (EERE)

Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Spencer Hot Springs Area (Shevenell, Et Al., 2008) Exploration...

30

Thermal Gradient Holes At Walker-Lane Transitional Zone Region...  

Open Energy Info (EERE)

Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Walker-Lane Transitional Zone Region (Pritchett, 2004) Exploration...

31

Thermal Gradient Holes At Mcgee Mountain Area (DOE GTP) | Open...  

Open Energy Info (EERE)

Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Mcgee Mountain Area (DOE GTP) Exploration Activity Details Location...

32

Pumpernickel Valley Geothermal Project Thermal Gradient Wells  

DOE Green Energy (OSTI)

The Pumpernickel Valley geothermal project area is located near the eastern edge of the Sonoma Range and is positioned within the structurally complex Winnemucca fold and thrust belt of north-central Nevada. A series of approximately north-northeast-striking faults related to the Basin and Range tectonics are superimposed on the earlier structures within the project area, and are responsible for the final overall geometry and distribution of the pre-existing structural features on the property. Two of these faults, the Pumpernickel Valley fault and Edna Mountain fault, are range-bounding and display numerous characteristics typical of strike-slip fault systems. These characteristics, when combined with geophysical data from Shore (2005), indicate the presence of a pull-apart basin, formed within the releasing bend of the Pumpernickel Valley – Edna Mountain fault system. A substantial body of evidence exists, in the form of available geothermal, geological and geophysical information, to suggest that the property and the pull-apart basin host a structurally controlled, extensive geothermal field. The most evident manifestations of the geothermal activity in the valley are two areas with hot springs, seepages, and wet ground/vegetation anomalies near the Pumpernickel Valley fault, which indicate that the fault focuses the fluid up-flow. There has not been any geothermal production from the Pumpernickel Valley area, but it was the focus of a limited exploration effort by Magma Power Company. In 1974, the company drilled one exploration/temperature gradient borehole east of the Pumpernickel Valley fault and recorded a thermal gradient of 160oC/km. The 1982 temperature data from five unrelated mineral exploration holes to the north of the Magma well indicated geothermal gradients in a range from 66 to 249oC/km for wells west of the fault, and ~283oC/km in a well next to the fault. In 2005, Nevada Geothermal Power Company drilled four geothermal gradient wells, PVTG-1, -2, -3, and -4, and all four encountered geothermal fluids. The holes provided valuable water geochemistry, supporting the geothermometry results obtained from the hot springs and Magma well. The temperature data gathered from all the wells clearly indicates the presence of a major plume of thermal water centered on the Pumpernickel Valley fault, and suggests that the main plume is controlled, at least in part, by flow from this fault system. The temperature data also defines the geothermal resource with gradients >100oC/km, which covers an area a minimum of 8 km2. Structural blocks, down dropped with respect to the Pumpernickel Valley fault, may define an immediate reservoir. The geothermal system almost certainly continues beyond the recently drilled holes and might be open to the east and south, whereas the heat source responsible for the temperatures associated with this plume has not been intersected and must be at a depth greater than 920 meters (depth of the deepest well – Magma well). The geological and structural setting and other characteristics of the Pumpernickel Valley geothermal project area are markedly similar to the portions of the nearby Dixie Valley geothermal field. These similarities include, among others, the numerous, unexposed en echelon faults and large-scale pull-apart structure, which in Dixie Valley may host part of the geothermal field. The Pumpernickel Valley project area, for the majority of which Nevada Geothermal Power Company has geothermal rights, represents a geothermal site with a potential for the discovery of a relatively high temperature reservoir suitable for electric power production. Among locations not previously identified as having high geothermal potential, Pumpernickel Valley has been ranked as one of four sites with the highest potential for electrical power production in Nevada (Shevenell and Garside, 2003). Richards and Blackwell (2002) estimated the total heat loss and the preliminary production capacity for the entire Pumpernickel Valley geothermal system to be at 35MW. A more conservative estimate, for

Z. Adam Szybinski

2006-01-01T23:59:59.000Z

33

THERMAL CONDUCTIVITY ANALYSIS OF GASES  

DOE Patents (OSTI)

This patent describes apparatus for the quantitative analysis of a gaseous mixture at subatmospheric pressure by measurement of its thermal conductivity. A heated wire forms one leg of a bridge circuit, while the gas under test is passed about the wire at a constant rate. The bridge unbalance will be a measure of the change in composition of the gas, if compensation is made for the effect due to gas pressure change. The apparatus provides a voltage varying with fluctuations of pressure in series with the indicating device placed across the bridge, to counterbalance the voltage change caused by fluctuations in the pressure of the gaseous mixture.

Clark, W.J.

1949-06-01T23:59:59.000Z

34

Thermal Gradient Holes At Coso Geothermal Area (1974) | Open Energy  

Open Energy Info (EERE)

Coso Geothermal Area (1974) Coso Geothermal Area (1974) Exploration Activity Details Location Coso Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date 1974 Usefulness useful DOE-funding Unknown Exploration Basis Use heat flow studies for the first time at Coso to indicate the presence or absence of abnormal heat Notes Located 10 sites for heat flow boreholes using available seismic ground noise and electrical resistivity data; data collected from 9 of 10; thermal conductivity measurements were completed using both the needle probe technique and the divided bar apparatus with a cell arrangement. In the upper few hundred meters of the subsurface heat is being transferred by a conductive heat transfer mechanism with a value of ~ 15 µcal/cm2sec; the background heat flow is ~ 3.5 HFU.

35

Thermal Gradient Holes At Salt Wells Area (Bureau of Land Management, 2009)  

Open Energy Info (EERE)

Thermal Gradient Holes At Salt Wells Area (Bureau of Land Management, 2009) Thermal Gradient Holes At Salt Wells Area (Bureau of Land Management, 2009) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Salt Wells Area (Bureau of Land Management, 2009) Exploration Activity Details Location Salt Wells Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date 2008 - 2008 Usefulness not indicated DOE-funding Unknown Exploration Basis Vulcan increased exploration efforts in the summer and fall of 2008, during which time the company drilled two temperature gradient holes (86-15 O on Pad 1 and 17-16 O on Pad 3); conducted seismic, gravity and magnetotelluric surveys; and drilled deep exploration wells at Pads 6 and 8 and binary wells at Pads 1, 2, 4, and 7. Notes

36

Thermal Gradient Holes At Central Nevada Seismic Zone Region (Pritchett,  

Open Energy Info (EERE)

Thermal Gradient Holes At Central Nevada Seismic Zone Region (Pritchett, Thermal Gradient Holes At Central Nevada Seismic Zone Region (Pritchett, 2004) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Central Nevada Seismic Zone Region (Pritchett, 2004) Exploration Activity Details Location Central Nevada Seismic Zone Geothermal Region Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes NOTE: These are theoretical/computer simulation tests of various methods on eight hypothetical 'model' basing-and-range geothermal systems. "The 300-meter heat flow holes are essentially useless for finding the "hidden" reservoirs. Clearly, the best results are obtained from the SP and MT surveys, with DC resistivity a close third. It is concluded that the best

37

High Thermal Gradient Directional Solidification and Its Application ...  

Science Conference Proceedings (OSTI)

By using zone-intensified overheating and liquid-metal cooling, high thermal gradients of up to 800 K/cm were achieved. Application of these methods in the ...

38

A New Horizontal Gradient, Continuous Flow, Ice Thermal Diffusion Chamber  

Science Conference Proceedings (OSTI)

A continuous-flow, horizontal gradient, ice thermal diffusion chamber has been developed and tested for heterogeneous ice nucleation of aerosol particles under accurately controlled supersaturations and supercooling in the absence of a substrate. ...

E. M. Tomlinson; N. Fukuta

1985-12-01T23:59:59.000Z

39

Correlation Between Thermal Conductivity and Microstructural ...  

Science Conference Proceedings (OSTI)

Characterization of MOX fuel pellets by Photothermal microscopy · Correlation Between Thermal Conductivity and Microstructural Evolutions in CeO2 Upon ...

40

Major transitions in evolution linked to thermal gradients above hydrothermal vents  

E-Print Network (OSTI)

The emergence of the main divisions of today's life: (1) unicellular prokaryotes, (2) unicellular eukaryotes, (3) multicellular eukaryotes, and (4) metazoans, are examples of the--still unexplained--major transitions in evolution. Regarding the origin of life, I have proposed that primordial life functioned as heat engine (thermosynthesis) while thermally cycled in convecting volcanic hot springs. Here I argue for a role of thermal gradients above submarine hydrothermal vents (SHV) in several major transitions. The last decade has witnessed the emergence of phononics, a novel discipline in physics based on controlled heat transport in thermal gradients. It builds thermal analogs to electronic devices: the thermal diode, the thermal transistor, the thermal switch, the thermal amplifier, the thermal memory--the thermal computer has been proposed. Encouraged by (1) the many similarities between microtubules (MT) and carbon nanotubes, which have a very high thermal conductivity, and (2) the recent discovery of a silk protein which also has a very high thermal conductivity, I combine and extend the mentioned ideas, and propose the general conjecture that several major transitions of evolution were effected by thermal processes, with four additional partial conjectures: (1) The first organisms used heat engines during thermosynthesis in convection cells; (2) The first eukaryotic cells used MT during thermosynthesis in the thermal gradient above SHV; (3) The first metazoans used transport of water or in water during thermosynthesis above SHV under an ice-covered ocean during the Gaskiers Snowball Earth; and (4) The first mammalian brain used a thermal machinery based on thermal gradients in or across the cortex. When experimentally proven these conjectures, which are testable by the methods of synthetic biology, would significantly enhance our understanding of life.

Anthonie W. J. Muller

2012-12-03T23:59:59.000Z

Note: This page contains sample records for the topic "gradients thermal conductivity" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Thermal Gradient Holes At Lightning Dock Area (Warpinski, Et Al., 2004) |  

Open Energy Info (EERE)

Thermal Gradient Holes At Lightning Dock Area Thermal Gradient Holes At Lightning Dock Area (Warpinski, Et Al., 2004) Exploration Activity Details Location Lightning Dock Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not indicated DOE-funding Unknown Notes The awardee conducted seismic, gravity, resistivity, and airborne magnetic surveys, drilled temperature-gradient wells, and selected a location for a test well (52-7). The test well was drilled to a total depth of 770 m during 2003. Maximum temperatures approached 140degrees C and a short flow test suggested that a production well could be drilled to 600 m and produce economic volumes of 130-140degrees C fluid. A final assessment of the resource is currently being performed. References N. R. Warpinski, A. R. Sattler, R. Fortuna, D. A. Sanchez, J.

42

Electron thermal conduction in LASNEX  

SciTech Connect

This report is a transcription of hand-written notes by DM dated 29 January 1986, transcribed by SW, with some clarifying comments added and details specific to running the LASNEX code deleted. Reference to the esoteric measurement units employed in LASNEX has also been deleted by SW (hopefully, without introducing errors in the numerical constants). The report describes the physics equations only, and only of electron conduction. That is, it does not describe the numerical method, which may be finite difference or finite element treatment in space, and (usually) implicit treatment in time. It does not touch on other electron transport packages which are available, and which include suprathermal electrons, nonlocal conduction, Krook model conduction, and modifications to electron conduction by magnetic fields. Nevertheless, this model is employed for the preponderance of LASNEX simulations.

Munro, D.; Weber, S.

1994-12-16T23:59:59.000Z

43

An Innovative High Thermal Conductivity Fuel Design  

SciTech Connect

Thermal conductivity of the fuel in today's Light Water Reactors, Uranium dioxide, can be improved by incorporating a uniformly distributed heat conducting network of a higher conductivity material, Silicon Carbide. The higher thermal conductivity of SiC along with its other prominent reactor-grade properties makes it a potential material to address some of the related issues when used in UO2 [97% TD]. This ongoing research, in collaboration with the University of Florida, aims to investigate the feasibility and develop a formal methodology of producing the resultant composite oxide fuel. Calculations of effective thermal conductivity of the new fuel as a function of %SiC for certain percentages and as a function of temperature are presented as a preliminary approach. The effective thermal conductivities are obtained at different temperatures from 600K to 1600K. The corresponding polynomial equations for the temperature-dependent thermal conductivities are given based on the simulation results. Heat transfer mechanism in this fuel is explained using a finite volume approach and validated against existing empirical models. FLUENT 6.1.22 was used for thermal conductivity calculations and to estimate reduction in centerline temperatures achievable within such a fuel rod. Later, computer codes COMBINE-PC and VENTURE-PC were deployed to estimate the fuel enrichment required, to maintain the same burnup levels, corresponding to a volume percent addition of SiC.

Jamil A. Khan

2009-11-21T23:59:59.000Z

44

Increased thermal conductivity monolithic zeolite structures  

SciTech Connect

A monolith comprises a zeolite, a thermally conductive carbon, and a binder. The zeolite is included in the form of beads, pellets, powders and mixtures thereof. The thermally conductive carbon can be carbon nano-fibers, diamond or graphite which provide thermal conductivities in excess of about 100 W/mK to more than 1,000 W/mK. A method of preparing a zeolite monolith includes the steps of mixing a zeolite dispersion in an aqueous colloidal silica binder with a dispersion of carbon nano-fibers in water followed by dehydration and curing of the binder is given.

Klett, James (Knoxville, TN); Klett, Lynn (Knoxville, TN); Kaufman, Jonathan (Leonardtown, MD)

2008-11-25T23:59:59.000Z

45

Pumpernickel Valley Geothermal Project Thermal Gradient Wells | Open Energy  

Open Energy Info (EERE)

Valley Geothermal Project Thermal Gradient Wells Valley Geothermal Project Thermal Gradient Wells Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Report: Pumpernickel Valley Geothermal Project Thermal Gradient Wells Details Activities (4) Areas (1) Regions (0) Abstract: The Pumpernickel Valley geothermal project area is located near the eastern edge of the Sonoma Range and is positioned within the structurally complex Winnemucca fold and thrust belt of north-central Nevada. A series of approximately north-northeast-striking faults related to the Basin and Range tectonics are superimposed on the earlier structures within the project area, and are responsible for the final overall geometry and distribution of the pre-existing structural features on the property. Two of these faults, the Pumpernickel Valley fault and Edna Mountain fault,

46

High Thermal Conductivity AlN Materials  

Science Conference Proceedings (OSTI)

AlN has replaced BeO as the high thermal conductivity ceramic of choice due to the adverse health effects associated with BeO. The development of high ...

47

Measurements of Electron Thermal Transport due to Electron Temperature Gradient Modes in a Basic Experiment  

Science Conference Proceedings (OSTI)

Production and identification of electron temperature gradient modes have already been reported [X. Wei, V. Sokolov, and A. K. Sen, Phys. Plasmas 17, 042108 (2010)]. Now a measurement of electron thermal conductivity via a unique high frequency triple probe yielded a value of {chi}{sub perpendiculare} ranging between 2 and 10 m{sup 2}/s, which is of the order of a several gyrobohm diffusion coefficient. This experimental result appears to agree with a value of nonlocal thermal conductivity obtained from a rough theoretical estimation and not inconsistent with gyrokinetic simulation results for tokamaks. The first experimental scaling of the thermal conductivity versus the amplitude of the electron temperature gradient fluctuation is also obtained. It is approximately linear, indicating a strong turbulence signature.

Sokolov, V.; Sen, A. K. [Plasma Research Laboratory, Columbia University, New York, New York 10027 (United States)

2011-10-07T23:59:59.000Z

48

Thermal conductivity modeling of building façade materials  

Science Conference Proceedings (OSTI)

An experimental research has been conducted to assess the thermo-physical properties of three building materials in both dry and moist state: beech wood, autoclaved aerated concrete and brick. The objectives of the paper envisage the measurement of the ... Keywords: building materials, contact temperature, determining method, finite element, numerical modeling, thermal conductivity

Monica Chereches; Nelu-Cristian Chereches; Catalin Popovici

2010-04-01T23:59:59.000Z

49

Two-Gradient Convection in a Vertical Slot with Maxwell-Cattaneo Heat Conduction  

SciTech Connect

We study the effect of the Maxwell-Cattaneo law of heat conduction (MCHC) on the 1D flow in a vertical slot subject to both vertical and horizontal temperature gradients. The gravitational acceleration is allowed to oscillate, which provides an opportunity to investigate the quantitative contribution of thermal inertia as epitomized by MCHC. The addition of the time derivative in MCHC increases the order of the system. We use a spectral expansion with Rayleigh's beam functions as the basis set, which is especially suited to fourth order boundary value problems (BVP). We show that the time derivative (relaxation of the thermal flux) has a dissipative nature and leads to the appearance of purely real negative eigenvalues. Yet it also increases the absolute value of the imaginary part and decreases the absolute value of the real part of the complex eigenvalues. Thus, the system has a somewhat more oscillatory behavior than the one based on Fourier's heat conduction law (FHC)

Papanicolaou, N. C. [Department of Computer Science, University of Nicosia, P.O. Box 24005, 1700 Nicosia (Cyprus); Christov, C. I. [Department of Mathematics, University of Louisiana at Lafayette, LA 70504-1010 (United States); Jordan, P. M. [Entropy Reversal Consultants (L.L.C), P. O. Box 691, Abita Springs, LA 70420 (United States); Code 7181, Naval Research Lab., Stennis Space Ctr., MS 39529 (United States)

2009-10-29T23:59:59.000Z

50

Nanoscale thermal transport and the thermal conductance of interfaces  

E-Print Network (OSTI)

absorption depends on temperature of the nanotube · Assume heat capacity is comparable to graphite · Cooling conductance · Pump probe apparatus · Transient absorption ­ Carbon nanotubes and thermal transport at hard optical absorption of nanoparticles and nanotubes in liquid suspensions. ­ Measure the thermal relaxation

Braun, Paul

51

Gas storage carbon with enhanced thermal conductivity  

DOE Patents (OSTI)

A carbon fiber carbon matrix hybrid adsorbent monolith with enhanced thermal conductivity for storing and releasing gas through adsorption and desorption is disclosed. The heat of adsorption of the gas species being adsorbed is sufficiently large to cause hybrid monolith heating during adsorption and hybrid monolith cooling during desorption which significantly reduces the storage capacity of the hybrid monolith, or efficiency and economics of a gas separation process. The extent of this phenomenon depends, to a large extent, on the thermal conductivity of the adsorbent hybrid monolith. This invention is a hybrid version of a carbon fiber monolith, which offers significant enhancements to thermal conductivity and potential for improved gas separation and storage systems.

Burchell, Timothy D. (Oak Ridge, TN); Rogers, Michael Ray (Knoxville, TN); Judkins, Roddie R. (Knoxville, TN)

2000-01-01T23:59:59.000Z

52

COSMOLOGICAL MAGNETOHYDRODYNAMIC SIMULATIONS OF CLUSTER FORMATION WITH ANISOTROPIC THERMAL CONDUCTION  

SciTech Connect

The intracluster medium (ICM) has been suggested to be buoyantly unstable in the presence of magnetic field and anisotropic thermal conduction. We perform first cosmological simulations of galaxy cluster formation that simultaneously include magnetic fields, radiative cooling, and anisotropic thermal conduction. In isolated and idealized cluster models, the magnetothermal instability (MTI) tends to reorient the magnetic fields radially whenever the temperature gradient points in the direction opposite to gravitational acceleration. Using cosmological simulations of cluster formation we detect radial bias in the velocity and magnetic fields. Such radial bias is consistent with either the inhomogeneous radial gas flows due to substructures or residual MTI-driven field rearrangements that are expected even in the presence of turbulence. Although disentangling the two scenarios is challenging, we do not detect excess bias in the runs that include anisotropic thermal conduction. The anisotropy effect is potentially detectable via radio polarization measurements with LOFAR and the Square Kilometer Array and future X-ray spectroscopic studies with the International X-ray Observatory. We demonstrate that radiative cooling boosts the amplification of the magnetic field by about two orders of magnitude beyond what is expected in the non-radiative cases. This effect is caused by the compression of the gas and frozen-in magnetic field as it accumulates in the cluster center. At z = 0 the field is amplified by a factor of about 10{sup 6} compared to the uniform magnetic field that evolved due to the universal expansion alone. Interestingly, the runs that include both radiative cooling and thermal conduction exhibit stronger magnetic field amplification than purely radiative runs. In these cases, buoyant restoring forces depend on the temperature gradients rather than the steeper entropy gradients. Thus, the ICM is more easily mixed and the winding up of the frozen-in magnetic field is more efficient, resulting in stronger magnetic field amplification. We also demonstrate that thermal conduction partially reduces the gas accretion driven by overcooling despite the fact that the effective conductivity is suppressed below the Spitzer-Braginskii value.

Ruszkowski, M. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Lee, D. [Department of Astronomy, ASC/Flash Center, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Brueggen, M. [School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen 05233 (Germany); Parrish, I. [Astronomy Department and Theoretical Astrophysics Center, 601 Campbell Hall, University of California, Berkeley, CA 94720 (United States); Oh, S. Peng, E-mail: mateuszr@umich.edu, E-mail: dongwook@flash.uchicago.edu, E-mail: m.brueggen@jacobs-university.de, E-mail: iparrish@astro.berkeley.edu, E-mail: peng@physics.ucsb.edu [Department of Physics, University of California, Santa Barbara, CA 93106 (United States)

2011-10-20T23:59:59.000Z

53

Thermal Conductivity of Cubic and Hexagonal Mesoporous Silica Thin Films  

E-Print Network (OSTI)

K.L. Fang, “Anisotropic thermal conductivity of nanoporousmesoporous silica as a thermal isolation layer”, Ceramicsand V. Wittwer, “Some thermal and optical properties of a

Coquil, Thomas; Richman, Eric K.; Hutchinson, Neal J.; Tolbert, S H; Pilon, Laurent

2009-01-01T23:59:59.000Z

54

Microstructure and Thermal Conductivity of Hydrated Calcium ...  

Science Conference Proceedings (OSTI)

... the above-mentioned temperature gradients, the effect of the 150 °C temperature gradient is not ... Journal of Volcanology and Geothermal Research. ...

2007-05-02T23:59:59.000Z

55

Thermal conduction in cosmological SPH simulations  

E-Print Network (OSTI)

Thermal conduction in the intracluster medium has been proposed as a possible heating mechanism for offsetting central cooling losses in rich clusters of galaxies. In this study, we introduce a new formalism to model conduction in a diffuse ionised plasma using smoothed particle hydrodynamics (SPH), and we implement it in the parallel TreePM/SPH-code GADGET-2. We consider only isotropic conduction and assume that magnetic suppression can be described in terms of an effective conductivity, taken as a fixed fraction of the temperature-dependent Spitzer rate. We also account for saturation effects in low-density gas. Our formulation manifestly conserves thermal energy even for individual and adaptive timesteps, and is stable in the presence of small-scale temperature noise. This allows us to evolve the thermal diffusion equation with an explicit time integration scheme along with the ordinary hydrodynamics. We use a series of simple test problems to demonstrate the robustness and accuracy of our method. We then ...

Jubelgas, M; Dolag, K

2004-01-01T23:59:59.000Z

56

Thermal lens elimination by gradient-reduced zone coupling of optical beams  

DOE Patents (OSTI)

A thermal gradient-reduced-zone laser includes a laser medium and an optically transparent plate with an index of refraction that is less than the index of refraction of the laser medium. The pump face of the laser medium is bonded to a surface of the optically transparent member. Pump light is directed through the transparent plate to optically pump the solid state laser medium. Heat conduction is mainly through the surface of the laser medium where the heat is introduced by the pump light. Heat flows in a direction opposite to that of the pump light because the side of the laser medium that is opposite to that of the pump face is not in thermal contact with a conductor and thus there is no heat flux (and hence, no temperature gradient), thus producing a thermal gradient-reduced zone. A laser cavity is formed around the laser medium such that laser light oscillating within the laser cavity reflects by total-internal-reflection from the interface between the pump face and the optically transparent plate and enters and exits through a thermal gradient-reduced zone.

Page, Ralph H. (San Ramon, CA); Beach, Raymond J. (Livermore, CA)

2000-01-01T23:59:59.000Z

57

Method for determining thermal conductivity and thermal capacity per unit volume of earth in situ  

DOE Patents (OSTI)

A method for determining the thermal conductivity of the earth in situ is based upon a cylindrical probe (10) having a thermopile (16) for measuring the temperature gradient between sets of thermocouple junctions (18 and 20) of the probe after it has been positioned in a borehole and has reached thermal equilibrium with its surroundings, and having means (14) for heating one set of thermocouple junctions (20) of the probe at a constant rate while the temperature gradient of the probe is recorded as a rise in temperature over several hours (more than about 3 hours). A fluid annulus thermally couples the probe to the surrounding earth. The recorded temperature curves are related to the earth's thermal conductivity, k.sub..infin., and to the thermal capacity per unit volume, (.gamma.c.sub.p).sub..infin., by comparison with calculated curves using estimates of k.sub..infin. and (.gamma.c.sub.p).sub..infin. in an equation which relates these parameters to a rise in the earth's temperature for a known and constant heating rate.

Poppendiek, Heinz F. (LaJolla, CA)

1982-01-01T23:59:59.000Z

58

Enhancing Thermal Conductivity and Reducing Friction  

NLE Websites -- All DOE Office Websites (Extended Search)

Laboratory currently has several projects underway to develop advanced fluids, films, coatings, and Laboratory currently has several projects underway to develop advanced fluids, films, coatings, and processes to improve thermal conductivity and reduce friction. These measures are helping to increase energy efficiency for next-generation transportation applications. Superhard and Slick Coating (SSC) Opportunity: Friction, wear, and lubrication strongly affect the energy efficiency, durability, and environmental compatibility of

59

Effects of air infiltration on the effective thermal conductivity...  

NLE Websites -- All DOE Office Websites (Extended Search)

Effects of air infiltration on the effective thermal conductivity of internal fiberglass insulation and on the delivery of thermal capacity via ducts Title Effects of air...

60

The thermal conductivity of rock under hydrothermal conditions: measurements and applications  

SciTech Connect

The thermal conductivities of most major rock-forming minerals vary with both temperature and confining pressure, leading to substantial changes in the thermal properties of some rocks at the high temperatures characteristic of geothermal systems. In areas with large geothermal gradients, the successful use of near-surface heat flow measurements to predict temperatures at depth depends upon accurate corrections for varying thermal conductivity. Previous measurements of the thermal conductivity of dry rock samples as a function of temperature were inadequate for porous rocks and susceptible to thermal cracking effects in nonporous rocks. We have developed an instrument for measuring the thermal conductivity of water-saturated rocks at temperatures from 20 to 350 °C and confining pressures up to 100 MPa. A transient line-source of heat is applied through a needle probe centered within the rock sample, which in turn is enclosed within a heated pressure vessel with independent controls on pore and confining pressure. Application of this technique to samples of Franciscan graywacke from The Geysers reveals a significant change in thermal conductivity with temperature. At reservoir-equivalent temperatures of 250 °C, the conductivity of the graywacke decreases by approximately 25% relative to the room temperature value. Where heat flow is constant with depth within the caprock overlying the reservoir, this reduction in conductivity with temperature leads to a corresponding increase in the geothermal gradient. Consequently, reservoir temperature are encountered at depths significantly shallower than those predicted by assuming a constant temperature gradient with depth. We have derived general equations for estimating the thermal conductivity of most metamorphic and igneous rocks and some sedimentary rocks at elevated temperature from knowledge of the room temperature thermal conductivity. Application of these equations to geothermal exploration should improve estimates of subsurface temperatures derived from heat flow measurements.

Williams, Colin F.; Sass, John H.

1996-01-24T23:59:59.000Z

Note: This page contains sample records for the topic "gradients thermal conductivity" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

Heat conductance in nonlinear lattices at small temperature gradients  

E-Print Network (OSTI)

This paper proposes a new methodological framework within which the heat conductance in 1D lattices can be studied. The total process of heat conductance is separated into two parts where the first one is the equilibrium process at equal temperatures $T$ of both ends and the second one -- non-equilibrium with the temperature $\\Delta T$ of one end and zero temperature of the other. This approach allows significant decrease of computational time at $\\Delta T \\to 0$. The threshold temperature $T_{\\rm thr}$ is found which scales $T_{\\rm thr}(N) \\sim N^{-3}$ with the lattice size $N$ and by convention separates two mechanisms of heat conductance: phonon mechanism dominates at $T T_{\\rm thr}$. Solitons and breathers are directly visualized in numerical experiments. The problem of heat conductance in non-linear lattices in the limit $\\Delta T \\to 0$ can be reduced to the heat conductance of harmonic lattice with time-dependent stochastic rigidities determined by the equilibrium process at temperature $T$. The detailed analysis is done for the $\\beta$-FPU lattice though main results are valid for one-dimensional lattices with arbitrary potentials.

T. Yu. Astakhova; V. N. Likhachev; G. A. Vinogradov

2010-06-09T23:59:59.000Z

62

Regulation of thermal conductivity in hot galaxy clusters by MHD turbulence  

E-Print Network (OSTI)

The role of thermal conduction in regulating the thermal behavior of cooling flows in galaxy clusters is reexamined. Recent investigations have shown that the anisotropic Coulomb heat flux caused by a magnetic field in a dilute plasma drives a dynamical instability. A long standing problem of cooling flow theory has been to understand how thermal conduction can offset radiative core losses without completely preventing them. In this Letter we propose that magnetohydrodynamic turbulence driven by the heat flux instability regulates field-line insulation and drives a reverse convective thermal flux, both of which may mediate the stabilization of the cooling cores of hot clusters. This model suggests that turbulent mixing should accompany strong thermal gradients in cooling flows. This prediction seems to be supported by the spatial distribution of metals in the central galaxies of clusters, which shows a much stronger correlation with the ambient hot gas temperature gradient than with the parent stellar population.

Steven A. Balbus; Christopher S. Reynolds

2008-06-05T23:59:59.000Z

63

ENERGY SCAVENGING BASED ON TRANSIENT THERMAL GRADIENTS: APPLICATION TO STRUCTURAL HEALTH MONITORING OF AIRCRAFTS  

E-Print Network (OSTI)

ENERGY SCAVENGING BASED ON TRANSIENT THERMAL GRADIENTS: APPLICATION TO STRUCTURAL HEALTH MONITORING from its environment [2]. A possible source of energy could be thermal gradients. This paper the upper limit for the thermal energy that could be captured, let us consider a sealed tank containing 1 g

Paris-Sud XI, Université de

64

Thermal Gradient Holes At Socorro Mountain Area (Owens, Et Al., 2005) |  

Open Energy Info (EERE)

Thermal Gradient Holes At Socorro Mountain Area (Owens, Et Al., 2005) Thermal Gradient Holes At Socorro Mountain Area (Owens, Et Al., 2005) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Socorro Mountain Area (Owens, Et Al., 2005) Exploration Activity Details Location Socorro Mountain Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not indicated DOE-funding Unknown Notes Pre-existing evidence includes heat gradients of upwards of 490mW/m2 from thermal-gradient wells, tepid spring waters (32oC) and silica geochemistry indicating thermal waters with a minimum of 82 degrees C at depth References Lara Owens, Richard Baars, David Norman, Harold Tobin (2005) New Methods In Exploration At The Socorro Peak Kgra- A Gred Iii Project Retrieved from

65

Reduced Thermal Conductivity of Compacted Silicon Nanowires  

E-Print Network (OSTI)

alpha1=k1/(density1*cp1); %Thermal diffusivity of PMMA B1=Simon R. Phillpot, “Nanoscale Thermal Transport”, Journal of9] E.T. Swartz, R.O. Pohl, “Thermal Boundary Resistance”,

Yuen, Taylor S.

66

Thermal Gradient Holes At Hualalai Northwest Rift Area (Thomas, 1986) |  

Open Energy Info (EERE)

Hualalai Northwest Rift Hualalai Northwest Rift Area (Thomas, 1986) Exploration Activity Details Location Hualalai Northwest Rift Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not useful DOE-funding Unknown Notes Although not part of the current effort, two deep (approximately 2000 m) exploratory wells were drilled on the north flank of Hualalai near Puu Waawaa cinder cone. The geophysical data used for siting these wells were proprietary and hence unavailable for publication; however, the temperatures measured at the bottoms of the wells were reported to be below 20degrees C. Chemical analysis of water samples taken from these wells did not provide useful geothermal data due to contamination of the well water with drilling muds References Donald M. Thomas (1 January 1986) Geothermal Resources Assessment In

67

Effect of heat treatment temperature on binder thermal conductivities  

SciTech Connect

The effect of heat treatment on the thermal conductivities of a pitch and a polyfurfuryl alcohol binder residue was investigated. Graphites specially prepared with these two binders were used for the experiments. Measured thermal conductivities were treated in terms of a two-component system, and the binder thermal conductivities were calculated. Both binder residues showed increased thermal conductivity with increased heat treatment temperature. (auth)

Wagner, P.

1975-12-01T23:59:59.000Z

68

Ab-Initio Thermal Conductivity for Thermoelectric Nanostructured ...  

Science Conference Proceedings (OSTI)

About this Abstract. Meeting, 2012 TMS Annual Meeting & Exhibition. Symposium , Energy Nanomaterials. Presentation Title, Ab-Initio Thermal Conductivity for ...

69

Conductive Thermal Interaction in Evaporative Cooling Process  

E-Print Network (OSTI)

It has long been recognized that evaporative cooling is an effective and logical substitute for mechanical cooling in hot-arid climates. This paper explores the application of evaporative coolers to the hot-humid climates using a controlled temperature of the incoming water. With exploitation of the effect of the thermal conduction between cool underground water and entering air, the performance of an evaporative cooler can be enhanced and its use in hot and moderately humid climates should also be considered. Usually the dry-bulb depression performed by an evaporative cooler depends solely on the ambient wet-bulb temperature. The cool underground water in an evaporative cooler can cause not only adiabatic evaporation but also sensible heat transfer between water and entering air for thermal comfort. This hybrid system outperforms the two-stage evaporative cooler without employing a complicated heat exchanger (indirect system), if the temperature of underground water is lower than the ambient wet-bulb temperature. Several areas in the southern hot-humid parts of the U.S. meet this condition.

Kim, B. S.; Degelman, L. O.

1990-01-01T23:59:59.000Z

70

Thermal Gradient Holes At Silver Peak Area (DOE GTP) | Open Energy...  

Open Energy Info (EERE)

Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Silver Peak Area (DOE GTP) Exploration Activity Details Location...

71

Thermal Gradient Holes At Alum Area (DOE GTP) | Open Energy Informatio...  

Open Energy Info (EERE)

Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Alum Geothermal Area (DOE GTP) Exploration Activity Details...

72

Thermal Gradient Holes At Fort Bliss Area (DOE GTP) | Open Energy...  

Open Energy Info (EERE)

Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Fort Bliss Area (DOE GTP) Exploration Activity Details Location...

73

Thermal Gradient Holes At Hot Pot Area (DOE GTP) | Open Energy...  

Open Energy Info (EERE)

Hot Pot Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Hot Pot Area (DOE GTP) Exploration Activity...

74

Thermal Conduction in Graphene and Graphene Multilayers  

E-Print Network (OSTI)

E. , and Ju, Y. S. , “ Heat conduction in novel electronicBalandin, A. A. , “Heat conduction in graphene: experimentalD. , “Simulation of heat conduction in suspended graphene

Ghosh, Suchismita

2009-01-01T23:59:59.000Z

75

Reduced Thermal Conductivity of Compacted Silicon Nanowires  

E-Print Network (OSTI)

Chen, “Coherent Phonon Heat Conduction in Superlattices,”1 Chapter 1: Heat Conduction in Nanostructured Materialsfindings. Chapter 1: Heat Conduction in Nanostructured

Yuen, Taylor S.

76

Thermal Gradient Holes At Hot Springs Ranch Area (Szybinski, 2006) | Open  

Open Energy Info (EERE)

Thermal Gradient Holes At Hot Springs Ranch Area (Szybinski, 2006) Thermal Gradient Holes At Hot Springs Ranch Area (Szybinski, 2006) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Hot Springs Ranch Area (Szybinski, 2006) Exploration Activity Details Location Hot Springs Ranch Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes In 2005, Nevada Geothermal Power Company drilled four geothermal gradient wells, PVTG-1, -2, -3, and -4, and all four encountered geothermal fluids. The holes provided valuable water geochemistry, supporting the geothermometry results obtained from the hot springs and Magma well. The temperature data gathered from all the wells clearly indicates the presence of a major plume of thermal water centered on the Pumpernickel Valley

77

Anisotropic Thermal Conduction and the Cooling Flow Problem in Galaxy Clusters  

E-Print Network (OSTI)

We examine the long-standing cooling flow problem in galaxy clusters with 3D MHD simulations of isolated clusters including radiative cooling and anisotropic thermal conduction along magnetic field lines. The central regions of the intracluster medium (ICM) can have cooling timescales of ~200 Myr or shorter--in order to prevent a cooling catastrophe the ICM must be heated by some mechanism such as AGN feedback or thermal conduction from the thermal reservoir at large radii. The cores of galaxy clusters are linearly unstable to the heat-flux-driven buoyancy instability (HBI), which significantly changes the thermodynamics of the cluster core. The HBI is a convective, buoyancy-driven instability that rearranges the magnetic field to be preferentially perpendicular to the temperature gradient. For a wide range of parameters, our simulations demonstrate that in the presence of the HBI, the effective radial thermal conductivity is reduced to less than 10% of the full Spitzer conductivity. With this suppression of ...

Parrish, Ian J; Sharma, Prateek

2009-01-01T23:59:59.000Z

78

Thermal Conductivity Measurements of Thermoelectric Films  

Science Conference Proceedings (OSTI)

... which allow solid-state conversion of thermal to electrical energy, have a ... and exhaust system, which can run either an electric motor or accessories ...

2013-03-15T23:59:59.000Z

79

Breaking the Thermal Conductivity Glass Limit  

Science Conference Proceedings (OSTI)

High Thermal Energy Storage Density LiNO3-KNO3-NaNO2-KNO2 Quaternary Molten Salt System for Parabolic Trough Concentrating Solar Power Generation.

80

Chandra constraints on the thermal conduction in the intracluster plasma of A2142  

E-Print Network (OSTI)

In this Letter, we use the recent Chandra observation of A2142 reported by Markevitch et al. to put constraints on thermal conduction in the intracluster plasma. We show that the observed sharp temperature gradient requires that classical conductivity has to be reduced at least by a factor of between 250 and 2500. The result provides a direct constraint on an important physical process relevant to the gas in the cores of clusters of galaxies.

S. Ettori; A. C. Fabian

2000-07-26T23:59:59.000Z

Note: This page contains sample records for the topic "gradients thermal conductivity" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Effects of Composition and Granulometry on Thermal Conductivity of ...  

Science Conference Proceedings (OSTI)

It has been observed that thermal conductivity of cover material is strongly ... Experimental Investigation of Single Bubble Characteristics in a Cold Model of a ... Creep on Potroom Busbars and Electrical Insulation: Thermal-Electrical Aspects.

82

Thermal Conductivity Prediction of Nano Fluid Using ANN/GA  

Science Conference Proceedings (OSTI)

Abstract Scope, Thermal conductivities of nano fluid in a two-phase having different compositions of both base fluid as well as nano particles in a closed ...

83

Measuring Thermal Conductivity of Powder Insulation at Cryogenic Temperatures.  

E-Print Network (OSTI)

?? A device to measure bulk effective thermal conductivity of powder insulation at cryogenic temperatures has been designed and tested. The design consists of two… (more)

Barrios, Matthew Nicklas

2006-01-01T23:59:59.000Z

84

Thermal Gradient Holes At Lightning Dock Area (Cunniff & Bowers, 2005) |  

Open Energy Info (EERE)

Thermal Gradient Holes At Lightning Dock Area Thermal Gradient Holes At Lightning Dock Area (Cunniff & Bowers, 2005) Exploration Activity Details Location Lightning Dock Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not indicated DOE-funding Unknown Notes The two gradient holes were sited on federal geothermal leases owned by Lightning Dock Geothermal, Inc. and both were drilled into lakebed sediments some distance from the intense shallow geothermal anomaly located in the eastern half of Section 7, Township 25 South, Range 19 West. References Roy A. Cunniff, Roger L. Bowers (2005) Final Technical Report, Geothermal Resource Evaluation And Definitioni (Gred) Program-Phases I, Ii, And Iii For The Animas Valley, Nm Geothermal Resource Retrieved from "http://en.openei.org/w/index.php?title=Thermal_Gradient_Holes_At_Lightning_Dock_Area_(Cunniff_%26_Bowers,_2005)&oldid=387460"

85

Law for Thermal Conductivity of Crystalline Nanoporous Silicon Using Molecular Dynamic Simulations  

E-Print Network (OSTI)

G. A. , 2007. “Lattice thermal conductivity of nanoporousPore-size dependence of the thermal conductivity of porousand Chen, G. , 2004. “Thermal conductivity of nanoporous

Fang, Jin; Pilon, Laurent

2011-01-01T23:59:59.000Z

86

Clackamas 4800-foot thermal gradient hole: Cascade geothermal drilling: Final technical report  

Science Conference Proceedings (OSTI)

Thermal Power Company (Thermal) completed a thermal gradient hole to about 5000 feet (1524 m) total depth in Section 28, Township 8 South, Range 8 East, Willamette Meridian, Marion County, Oregon. The objective was to obtain data for the characterization of the deep hydrothermal regime in the Cascades volcanic region in order to better define its geothermal resource potential. The depth and location of the thermal gradient hole were designed by Thermal to test the basis of the Clackamas geothermal system exploration model developed by Chevron Resources Company.

Iovenitti, J.L.; D'Olier, W.L.

1987-09-30T23:59:59.000Z

87

Thermal Gradient Holes At Blue Mountain Area (Fairbank & Neggemann, 2004) |  

Open Energy Info (EERE)

Blue Mountain Area (Fairbank & Neggemann, 2004) Blue Mountain Area (Fairbank & Neggemann, 2004) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Blue Mountain Area (Fairbank & Neggemann, 2004) Exploration Activity Details Location Blue Mountain Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown References Brian D. Fairbank, Kim V. Niggemann (2004) Deep Blue No 1- A Slimhole Geothermal Discovery At Blue Mountain, Humboldt County, Nevada Retrieved from "http://en.openei.org/w/index.php?title=Thermal_Gradient_Holes_At_Blue_Mountain_Area_(Fairbank_%26_Neggemann,_2004)&oldid=386709" Category: Exploration Activities What links here Related changes Special pages Printable version Permanent link

88

Thermal conductivity and other properties of cementitious grouts  

DOE Green Energy (OSTI)

The thermal conductivity and other properties cementitious grouts have been investigated in order to determine suitability of these materials for grouting vertical boreholes used with geothermal heat pumps. The roles of mix variables such as water/cement ratio, sand/cement ratio and superplasticizer dosage were measured. In addition to thermal conductivity, the cementitious grouts were also tested for bleeding, permeability, bond to HDPE pipe, shrinkage, coefficient of thermal expansion, exotherm, durability and environmental impact. This paper summarizes the results for selected grout mixes. Relatively high thermal conductivities were obtained and this leads to reduction in predicted bore length and installation costs. Improvements in shrinkage resistance and bonding were achieved.

Allan, M.

1998-08-01T23:59:59.000Z

89

THERMAL CONDUCTIVITY AND OTHER PROPERTIES OF CEMENTITIOUS GROUTS  

DOE Green Energy (OSTI)

The thermal conductivity and other properties cementitious grouts have been investigated in order to determine suitability of these materials for grouting vertical boreholes used with geothermal heat pumps. The roles of mix variables such as water/cement ratio, sand/cement ratio and superplasticizer dosage were measured. In addition to thermal conductivity, the cementitious grouts were also tested for bleeding, permeability, bond to HDPE pipe, shrinkage, coefficient of thermal expansion, exotherm, durability and environmental impact. This paper summarizes the results for selected grout mixes. Relatively high thermal conductivities were obtained and this leads to reduction in predicted bore length and installation costs. Improvements in shrinkage resistance and bonding were achieved.

ALLAN,M.

1998-05-01T23:59:59.000Z

90

3 omega method for specific heat and thermal conductivity measurements  

E-Print Network (OSTI)

We present a 3 omega method for simultaneously measuring the specific heat and thermal conductivity of a rod- or filament-like specimen using a way similar to a four-probe resistance measurement. The specimen in this method needs to be electrically conductive and with a temperature-dependent resistance, for acting both as a heater to create a temperature fluctuation and as a sensor to measure its thermal response. With this method we have successfully measured the specific heat and thermal conductivity of platinum wire specimens at cryogenic temperatures, and measured those thermal quantities of tiny carbon nanotube bundles some of which are only 10^-9 g in mass.

L. Lu; W. Yi; D. L. Zhang

2002-02-06T23:59:59.000Z

91

Thermal Conduction and Multiphase Gas in Cluster Cores  

E-Print Network (OSTI)

We examine the role of thermal conduction and magnetic fields in cores of galaxy clusters through global simulations of the intracluster medium (ICM). In particular, we study the influence of thermal conduction, both isotropic and anisotropic, on the condensation of multiphase gas in cluster cores. Previous hydrodynamic simulations have shown that cold gas condenses out of the hot ICM in thermal balance only when the ratio of the cooling time ($t_{\\rm cool}$) and the free-fall time ($t_{\\rm ff}$) is less than $\\approx 10$. Since thermal conduction is significant in the ICM and it suppresses local cooling at small scales, it is imperative to include thermal conduction in such studies. We find that anisotropic (along local magnetic field lines) thermal conduction does not influence the condensation criterion for a general magnetic geometry, even if thermal conductivity is large. However, with isotropic thermal conduction cold gas condenses only if conduction is suppressed (by a factor $\\lesssim 0.3$) with respe...

Wagh, Baban; McCourt, Michael

2013-01-01T23:59:59.000Z

92

Quantitative analysis of damage in PBX 9501 subjected to a linear thermal gradient  

SciTech Connect

We have conducted a series of experiments in which a cylinder of PBX 9501 is placed in a specially designed fixture with each end fixed at a different temperature. This arrangement sets up a thermal gradient in the explosive that is carefully controlled and maintained for a specified amount of time. This configuration has a number of advantages over thermally damaging separate pieces at a series of different temperatures, the principal one being that damage in this experiment is a continuous function of position. This makes analysis and distinction of regions easier and more straightforward. For the experiments reported in this paper, the explosive samples have been subjected to a series of different analysis techniques. We have used polarized light microscopy, physical adsorption, Raman spectroscopy, and small angle neutron and x-ray scattering in an attempt to characterize the particle morphology, porosity distribution, crack and void formation, and chemical state as a function of thermal treatment. While not all of the efforts were informative, the data clearly show trends and form a basis for understanding the effects of thermal damage on explosive behavior.

Asay, B. W. (Blaine W.); Henson, B. F. (Bryan F.); Peterson, P. D. (Paul D.); Mang, J. T. (Joseph T.); Smilowitz, L. B. (Laura B.); Dickson, P. M. (Peter M.)

2002-01-01T23:59:59.000Z

93

Theoretical investigation of the impact of grain boundaries and fission gases on UO2 thermal conductivity  

SciTech Connect

Thermal conductivity is one of the most important metrics of nuclear fuel performance. Therefore, it is crucial to understand the impact of microstructure features on thermal conductivity, especially since the microstructure evolves with burn-up or time in the reactor. For example, UO{sub 2} fuels are polycrystalline and for high-burnup fuels the outer parts of the pellet experience grain sub-division leading to a very fine grain structure. This is known to impact important physical properties such as thermal conductivity as fission gas release. In a previous study, we calculated the effect of different types of {Sigma}5 grain boundaries on UO{sub 2} thermal conductivity and predicted the corresponding Kapitza resistances, i.e. the resistance of the grain boundary in relation to the bulk thermal resistance. There have been reports of pseudoanisotropic effects for the thermal conductivity in cubic polycrystalline materials, as obtained from molecular dynamics simulations, which means that the conductivity appears to be a function of the crystallographic direction of the temperature gradient. However, materials with cubic symmetry should have isotropic thermal conductivity. For this reason it is necessary to determine the cause of this apparent anisotropy and in this report we investigate this effect in context of our earlier simulations of UO{sub 2} Kapitza resistances. Another source of thermal resistance comes from fission products and fission gases. Xe is the main fission gas and when generated in sufficient quantity it dissolves from the lattice and forms gas bubbles inside the crystalline structure. We have performed studies of how Xe atoms dissolved in the UO{sub 2} matrix or precipitated as bubbles impact thermal conductivity, both in bulk UO{sub 2} and in the presence of grain boundaries.

Du, Shiyu [Los Alamos National Laboratory; Andersson, Anders D. [Los Alamos National Laboratory; Germann, Timothy C. [Los Alamos National Laboratory; Stanek, Christopher R. [Los Alamos National Laboratory

2012-05-02T23:59:59.000Z

94

Thermal Gradient Holes At Kilauea East Rift Area (Thomas, 1986) | Open  

Open Energy Info (EERE)

Thermal Gradient Holes At Kilauea East Rift Area (Thomas, 1986) Thermal Gradient Holes At Kilauea East Rift Area (Thomas, 1986) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Kilauea East Rift Area (Thomas, 1986) Exploration Activity Details Location Kilauea East Rift Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes Two separate phases of geothermal exploratory drilling have occurred on the lower East Rift. The first was essentially a wildcat venture with relatively little surface exploratory data having been gathered, whereas the second was initiated after somewhat more geoscience information had been acquired under the Hawaii Geothermal Project. The results of the successful exploratory drilling program on the Kilauea

95

Thermal Gradient Holes At Kilauea Summit Area (Keller, Et Al., 1979) | Open  

Open Energy Info (EERE)

Thermal Gradient Holes At Kilauea Summit Area (Keller, Et Al., 1979) Thermal Gradient Holes At Kilauea Summit Area (Keller, Et Al., 1979) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Kilauea Summit Area (Keller, Et Al., 1979) Exploration Activity Details Location Kilauea Summit Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes A deep borehole was drilled at the summit of Kilauea volcano, Hawaii, between April 6 and July 9, 1973. The hole is located approximately 1 km south of the edge of Halemaumau crater (Figs. 1 and 2), a crater within the summit caldera of the volcano. The total depth of the hole is 1262 m (4141 ft) measured from the derrick floor at an altitude of 1102 m (3616 ft). A description of the drilling program and some of the results obtained have

96

Thermal Gradient Holes At Crump's Hot Springs Area (DOE GTP) | Open Energy  

Open Energy Info (EERE)

source source History View New Pages Recent Changes All Special Pages Semantic Search/Querying Get Involved Help Apps Datasets Community Login | Sign Up Search Page Edit History Facebook icon Twitter icon » Thermal Gradient Holes At Crump's Hot Springs Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Crump's Hot Springs Area (DOE GTP) Exploration Activity Details Location Crump's Hot Springs Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not indicated DOE-funding Unknown Notes 8 wells References (1 January 2011) GTP ARRA Spreadsheet Retrieved from "http://en.openei.org/w/index.php?title=Thermal_Gradient_Holes_At_Crump%27s_Hot_Springs_Area_(DOE_GTP)&oldid=402699"

97

Thermal Gradient Holes At Twenty-Nine Palms Area (Sabin, Et Al., 2010) |  

Open Energy Info (EERE)

Thermal Gradient Holes At Twenty-Nine Palms Area (Sabin, Et Al., 2010) Thermal Gradient Holes At Twenty-Nine Palms Area (Sabin, Et Al., 2010) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Twenty-Nine Palms Geothermal Area (Sabin, Et Al., 2010) Exploration Activity Details Location Twenty-Nine Palms Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes The first and only Seabee drilling project was the installation of five TGHs at the Camp Wilson region of the MCAGCC Marine base near Twenty-Nine Palms, CA. While the program was a success and GPO identified an anomaly where a deep, slim hole is to be drilled in June, 2010, the Seabee rig was sent oversees soon after drilling was completed. If/when another rig

98

Thermal Gradient Holes At Fish Lake Valley Area (DOE GTP) | Open Energy  

Open Energy Info (EERE)

source source History View New Pages Recent Changes All Special Pages Semantic Search/Querying Get Involved Help Apps Datasets Community Login | Sign Up Search Page Edit History Facebook icon Twitter icon » Thermal Gradient Holes At Fish Lake Valley Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Fish Lake Valley Area (DOE GTP) Exploration Activity Details Location Fish Lake Valley Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not indicated DOE-funding Unknown Notes 2 wells References (1 January 2011) GTP ARRA Spreadsheet Retrieved from "http://en.openei.org/w/index.php?title=Thermal_Gradient_Holes_At_Fish_Lake_Valley_Area_(DOE_GTP)&oldid=511222" Categories:

99

Thermal Gradient Holes At Nw Basin & Range Region (Pritchett, 2004) | Open  

Open Energy Info (EERE)

Thermal Gradient Holes At Nw Basin & Range Region (Pritchett, 2004) Thermal Gradient Holes At Nw Basin & Range Region (Pritchett, 2004) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Nw Basin & Range Region (Pritchett, 2004) Exploration Activity Details Location Northwest Basin and Range Geothermal Region Exploration Technique Thermal Gradient Holes Activity Date Usefulness not useful DOE-funding Unknown Notes NOTE: These are theoretical/computer simulation tests of various methods on eight hypothetical 'model' basing-and-range geothermal systems. "The 300-meter heat flow holes are essentially useless for finding the "hidden" reservoirs. Clearly, the best results are obtained from the SP and MT surveys, with DC resistivity a close third. It is concluded that the best

100

ANISOTROPIC THERMAL CONDUCTION AND THE COOLING FLOW PROBLEM IN GALAXY CLUSTERS  

SciTech Connect

We examine the long-standing cooling flow problem in galaxy clusters with three-dimensional magnetohydrodynamics simulations of isolated clusters including radiative cooling and anisotropic thermal conduction along magnetic field lines. The central regions of the intracluster medium (ICM) can have cooling timescales of {approx}200 Myr or shorter-in order to prevent a cooling catastrophe the ICM must be heated by some mechanism such as active galactic nucleus feedback or thermal conduction from the thermal reservoir at large radii. The cores of galaxy clusters are linearly unstable to the heat-flux-driven buoyancy instability (HBI), which significantly changes the thermodynamics of the cluster core. The HBI is a convective, buoyancy-driven instability that rearranges the magnetic field to be preferentially perpendicular to the temperature gradient. For a wide range of parameters, our simulations demonstrate that in the presence of the HBI, the effective radial thermal conductivity is reduced to {approx}<10% of the full Spitzer conductivity. With this suppression of conductive heating, the cooling catastrophe occurs on a timescale comparable to the central cooling time of the cluster. Thermal conduction alone is thus unlikely to stabilize clusters with low central entropies and short central cooling timescales. High central entropy clusters have sufficiently long cooling times that conduction can help stave off the cooling catastrophe for cosmologically interesting timescales.

Parrish, Ian J.; Sharma, Prateek; Quataert, Eliot, E-mail: iparrish@astro.berkeley.ed [Astronomy Department and Theoretical Astrophysics Center, 601 Campbell Hall, University of California, Berkeley, CA 94720 (United States)

2009-09-20T23:59:59.000Z

Note: This page contains sample records for the topic "gradients thermal conductivity" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Three Modes of Heat Transferâ??Thermal Conduction, Thermal Convection,  

Science Conference Proceedings (OSTI)

...).46, 44, 43, 42, 41, 40, 39, 38, 37, Ref 1In induction heating, all three modes of heat transferâ??conduction,

102

Thermal Gradient Holes At Chocolate Mountains Area (Alm, Et Al., 2010) |  

Open Energy Info (EERE)

Chocolate Mountains Area (Alm, Et Al., 2010) Chocolate Mountains Area (Alm, Et Al., 2010) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Chocolate Mountains Area (Alm, Et Al., 2010) Exploration Activity Details Location Chocolate Mountains Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes "Shallow temperature gradient drilling began at the CMAGR in January of 2010. 13 temperature gradient holes were completed to a depth of 500' below ground surface. Sites were selected based on the compilation of previous exploration and resulting data is being integrated into the most recent geologic model. This model will form the basis for the selection of a deeper (2000'-4000') temperature gradient drilling campaign at the CMAGR in

103

Thermal Gradient Holes At Twenty-Nine Palms Area (Page, Et Al., 2010) |  

Open Energy Info (EERE)

Thermal Gradient Holes At Twenty-Nine Palms Thermal Gradient Holes At Twenty-Nine Palms Geothermal Area (Page, Et Al., 2010) Exploration Activity Details Location Twenty-Nine Palms Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes From November 2008 to March 2009, Seabees from the Naval Construction Division (NCD) successfully completed fivetemperature gradient holes for the GPO. Samples taken from each hole were similar in nature; mixtures of sand and conglomerates with the occasional granite sections were typically encountered. Each hole varied slightly in depth, ranging from 600ft to 1,000ft; however, each hole has been completed to acceptable standards of the GPO. Upon completion of drilling, 3" metal tubing was inserted to

104

Thermal Gradient Holes At Hawthorne Area (Lazaro, Et Al., 2010) | Open  

Open Energy Info (EERE)

source source History View New Pages Recent Changes All Special Pages Semantic Search/Querying Get Involved Help Apps Datasets Community Login | Sign Up Search Page Edit History Facebook icon Twitter icon » Thermal Gradient Holes At Hawthorne Area (Lazaro, Et Al., 2010) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Hawthorne Area (Lazaro, Et Al., 2010) Exploration Activity Details Location Hawthorne Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes The Navy recently completed a temperature gradient hole (TGH) drilling campaign. Results suggest multiple resources may exist on HAD lands. To further define the shallow resource, the Navy will drill one or two

105

Fiber/Matrix Interfacial Thermal Conductance Effect on the Thermal Conductivity of SiC/SiC Composites  

SciTech Connect

SiC/SiC composites used in fusion reactor applications are subjected to high heat fluxes and require knowledge and tailoring of their in-service thermal conductivity. Accurately predicting the thermal conductivity of SiC/SiC composites as a function of temperature will guide the design of these materials for their intended use, which will eventually include the effects of 14-MeV neutron irradiations. This paper applies an Eshelby-Mori-Tanaka approach (EMTA) to compute the thermal conductivity of unirradiated SiC/SiC composites. The homogenization procedure includes three steps. In the first step EMTA computes the homogenized thermal conductivity of the unidirectional (UD) SiC fiber embraced by its coating layer. The second step computes the thermal conductivity of the UD composite formed by the equivalent SiC fibers embedded in a SiC matrix, and finally the thermal conductivity of the as-formed SiC/SiC composite is obtained by averaging the solution for the UD composite over all possible fiber orientations using the second-order fiber orientation tensor. The EMTA predictions for the transverse thermal conductivity of several types of SiC/SiC composites with different fiber types and interfaces are compared to the predicted and experimental results by Youngblood et al.

Nguyen, Ba Nghiep; Henager, Charles H.

2013-04-20T23:59:59.000Z

106

Thermal Conductivity Database of Various Structural Carbon-Carbon  

Science Conference Proceedings (OSTI)

Advanced thermal protection materials envisioned for use on future hypersonic vehicles will likely be subjected to temperatures in excess of 1811 K (2800F) and, therefore, will require the rapid conduction of heat away from the stagnation regions of ...

Ohlhorst Craig W.; Vaughn Wallace L.; Ransone Philip O.; Tsou Hwa-Tsu

1997-11-01T23:59:59.000Z

107

Investigation on thermal conductivity and AC impedance of graphite suspension  

E-Print Network (OSTI)

Over the past decade, some groups have reported that nanofluids, which are liquids containing suspensions of nanoparticles, have substantially higher thermal conductivity than that of the base fluids. However, the reported ...

Wang, Jianjian, S.M. Massachusetts Institute of Technology

2011-01-01T23:59:59.000Z

108

Experimental investigations of solid-solid thermal interface conductance  

E-Print Network (OSTI)

Understanding thermal interface conductance is important for nanoscale systems where interfaces can play a critical role in heat transport. In this thesis, pump and probe transient thermoreflectance methods are used to ...

Collins, Kimberlee C. (Kimberlee Chiyoko)

2010-01-01T23:59:59.000Z

109

Raman Spectroscopy of High Thermal Conductivity AlN Ceramics ...  

Science Conference Proceedings (OSTI)

Thermal conductivity of AlN ceramics was measured by laser flash method. Raman spectroscopy was used to characterize oxygen related defects of AlN ... Transport in Co-Based Materials for Fuel Cells and Oxygen Separation Membranes.

110

A benchmark study on the thermal conductivity of nanofluids  

E-Print Network (OSTI)

This article reports on the International Nanofluid Property Benchmark Exercise, or INPBE, in which the thermal conductivity of identical samples of colloidally stable dispersions of nanoparticles or “nanofluids,” was ...

Buongiorno, Jacopo

111

Thermal Gradient Holes At Upper Hot Creek Ranch Area (Benoit & Blackwell,  

Open Energy Info (EERE)

Hot Creek Ranch Area (Benoit & Blackwell, Hot Creek Ranch Area (Benoit & Blackwell, 2006) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Upper Hot Creek Ranch Area (Benoit & Blackwell, 2006) Exploration Activity Details Location Upper Hot Creek Ranch Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not useful DOE-funding Unknown Notes Ten temperature gradient holes up to 500' deep were initially planned but higher than anticipated drilling and permitting costs within a fixed budget reduced the number of holes to five. Four of the five holes drilled to depths of 300 to 400' encountered temperatures close to the expected regional thermal background conditions. These four holes failed to find any evidence of a large thermal anomaly surrounding the UHCR hot springs. The

112

An Empirical Model of UO2 Thermal Conductivity Based on Laser Flash Measurements of Thermal Diffusivity  

Science Conference Proceedings (OSTI)

Thermal conductivity of irradiated fuel materials, which can be derived from measured thermal diffusivity (TD), is a key consideration in thermal performance and design of a fuel rod. However, without interpretation, the measured TD data cannot be used directly to calculate fuel temperatures during irradiation. This report provides such interpretation and presents an empirical model for the degradation of UO2 thermal conductivity with burn-up.

1998-10-07T23:59:59.000Z

113

Thermal Gradient Holes At Salt Wells Area (Bureau of Land Management...  

Open Energy Info (EERE)

temperature gradient holes (86-15 O on Pad 1 and 17-16 O on Pad 3); conducted seismic, gravity and magnetotelluric surveys; and drilled deep exploration wells at Pads 6 and 8 and...

114

Thermal Gradient Holes At Northern Basin & Range Region (Pritchett, 2004) |  

Open Energy Info (EERE)

Gradient Holes At Northern Basin & Range Region (Pritchett, 2004) Gradient Holes At Northern Basin & Range Region (Pritchett, 2004) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Northern Basin & Range Region (Pritchett, 2004) Exploration Activity Details Location Northern Basin and Range Geothermal Region Exploration Technique Thermal Gradient Holes Activity Date Usefulness not useful DOE-funding Unknown Notes NOTE: These are theoretical/computer simulation tests of various methods on eight hypothetical 'model' basing-and-range geothermal systems. "The 300-meter heat flow holes are essentially useless for finding the "hidden" reservoirs. Clearly, the best results are obtained from the SP and MT surveys, with DC resistivity a close third. It is concluded that the best

115

Thermal Gradient Holes At Chocolate Mountains Area (Sabin, Et Al., 2010) |  

Open Energy Info (EERE)

Thermal Gradient Holes At Chocolate Mountains Area Thermal Gradient Holes At Chocolate Mountains Area (Sabin, Et Al., 2010) Exploration Activity Details Location Chocolate Mountains Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not indicated DOE-funding Unknown Notes In lieu of Seabee TGH drilling, GPO awarded a large IDIQ TGH drilling contract in December, 2009. Over the next two years, 90 500-ft TGHs will be installed at select sites in California and Nevada. Interim data from this campaign are already available for the Chocolate Mountains and Hawthorne. Results of these programs can be found in the Chocolate Mountains and Hawthorne papers also available in this volume. References Andrew Sabin, S. Bjornstad, M. Lazaro, D. Meade, C. Page, S. Alm, A. Tiedeman, W. C. Huang (2010) Navy's Geothermal Program Office: Overview

116

Thermal Gradient Holes At Lake City Hot Springs Area (Warpinski, Et Al.,  

Open Energy Info (EERE)

2004) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Lake City Hot Springs Area (Warpinski, Et Al., 2004) Exploration Activity Details Location Lake City Hot Springs Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not indicated DOE-funding Unknown Notes The Lake City site, which is located in far northeastern California, consists of a previously identified geothermal site that has been explored with both geophysics and drilling (Hedel, 1981), but has not been characterized adequately to allow accurate siting or drilling of production wells. Some deep wells, several seismic lines, limited gravity surveys, and geochemical and geological studies have suggested that the geothermal

117

Thermally conductive cementitious grout for geothermal heat pump systems  

DOE Patents (OSTI)

A thermally conductive cement-sand grout for use with a geothermal heat pump system. The cement sand grout contains cement, silica sand, a superplasticizer, water and optionally bentonite. The present invention also includes a method of filling boreholes used for geothermal heat pump systems with the thermally conductive cement-sand grout. The cement-sand grout has improved thermal conductivity over neat cement and bentonite grouts, which allows shallower bore holes to be used to provide an equivalent heat transfer capacity. In addition, the cement-sand grouts of the present invention also provide improved bond strengths and decreased permeabilities. The cement-sand grouts can also contain blast furnace slag, fly ash, a thermoplastic air entraining agent, latex, a shrinkage reducing admixture, calcium oxide and combinations thereof.

Allan, Marita (Old Field, NY)

2001-01-01T23:59:59.000Z

118

Thermal conductivity of dense quark matter and cooling of stars  

E-Print Network (OSTI)

The thermal conductivity of the color-flavor locked phase of dense quark matter is calculated. The dominant contribution to the conductivity comes from photons and Nambu-Goldstone bosons associated with breaking of baryon number which are trapped in the quark core. Because of their very large mean free path the conductivity is also very large. The cooling of the quark core arises mostly from the heat flux across the surface of direct contact with the nuclear matter. As the thermal conductivity of the neighboring layer is also high, the whole interior of the star should be nearly isothermal. Our results imply that the cooling time of compact stars with color-flavor locked quark cores is similar to that of ordinary neutron stars.

Igor A. Shovkovy; Paul J. Ellis

2002-04-11T23:59:59.000Z

119

Pretest Caluculations of Temperature Changes for Field Thermal Conductivity Tests  

Science Conference Proceedings (OSTI)

A large volume fraction of the potential monitored geologic repository at Yucca Mountain may reside in the Tptpll (Tertiary, Paintbrush Group, Topopah Spring Tuff, crystal poor, lower lithophysal) lithostratigraphic unit. This unit is characterized by voids, or lithophysae, which range in size from centimeters to meters. A series of thermal conductivity field tests are planned in the Enhanced Characterization of the Repository Block (ECRB) Cross Drift. The objective of the pretest calculation described in this document is to predict changes in temperatures in the surrounding rock for these tests for a given heater power and a set of thermal transport properties. The calculation can be extended, as described in this document, to obtain thermal conductivity, thermal capacitance (density x heat capacity, J {center_dot} m{sup -3} {center_dot} K{sup -1}), and thermal diffusivity from the field data. The work has been conducted under the ''Technical Work Plan For: Testing and Monitoring'' (BSC 2001). One of the outcomes of this analysis is to determine the initial output of the heater. This heater output must be sufficiently high that it will provide results in a reasonably short period of time (within several weeks or a month) and be sufficiently high that the heat increase is detectable by the instruments employed in the test. The test will be conducted in stages and heater output will be step increased as the test progresses. If the initial temperature is set too high, the experiment will not have as many steps and thus fewer thermal conductivity data points will result.

N.S. Brodsky

2002-07-17T23:59:59.000Z

120

Thermal Conductivity and Shear Strength of K Basin Sludge  

DOE Green Energy (OSTI)

Hanford K Basin sludge contains metallic uranium and uranium oxides that will corrode, hydrate, and, consequently, generate heat and hydrogen gas during storage. Heat is generated within the K Basin sludge by radiolytic decay and the reaction of uranium metal with water. To maintain thermal stability, the sludge must be retrieved, staged, transported, and stored in systems designed to provide a rate of heat removal that prevents the temperature in the sludge from increasing beyond acceptable limits. To support the dispositioning of the sludge to T Plant, modeling and testing and analyses are being performed to predict the behavior of sludge when placed into the storage containers. Two physical properties of the sludge that are critical to the modeling and analyses efforts are thermal conductivity and the sludge shear strength (yield stress). This report provides the results of thermal conductivity and shear strength measurements performed on representative sludge samples from the K East Basin.

Poloski, Adam P. (BATTELLE (PACIFIC NW LAB)); Bredt, Paul R. (BATTELLE (PACIFIC NW LAB)); Schmidt, Andrew J. (BATTELLE (PACIFIC NW LAB)); Swoboda, Robert G. (BATTELLE (PACIFIC NW LAB)); Chenault, Jeffrey W. (BATTELLE (PACIFIC NW LAB)); Gano, Sue (BATTELLE (PACIFIC NW LAB))

2002-05-17T23:59:59.000Z

Note: This page contains sample records for the topic "gradients thermal conductivity" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

The effect of thermal aging on the thermal conductivity of plasma sprayed and EB-PVD thermal barrier coatings  

DOE Green Energy (OSTI)

Thermal barrier coatings (TBCs) applied to the hot gas components of turbine engines lead to enhanced fuel efficiency and component reliability. Understanding the mechanisms which control the thermal transport behavior of the TBCs is of primary importance. Electron beam-physical vapor deposition (EV-PVD) and air plasma spraying (APS) are the two most commonly used coating techniques. These techniques produce coatings with unique microstructures which control their performance and stability. The density of the APS coatings was controlled by varying the spray parameters. The low density APS yttria-partially stabilized zirconia (yttria-PSZ) coatings yielded a thermal conductivity that is lower than both the high density APS coatings and the EB-PVD coatings. The thermal aging of both fully and partially stabilized zirconia are compared. The thermal conductivity of the coatings permanently increases upon exposure to high temperatures. These increases are attributed to microstructural changes within the coatings. This increase in thermal conductivity can be modeled using a relationship which depends on both the temperature and time of exposure. Although the EB-PVD coatings are less susceptible to thermal aging effects, results suggest that they typically have a higher thermal conductivity than APS coatings before thermal aging. The increases in thermal conductivity due to thermal aging for plasma sprayed partially stabilized zirconia have been found to be less than for plasma sprayed fully stabilized zirconia coatings.

Dinwiddie, R.B.; Beecher, S.C.; Porter, W.D. [Oak Ridge National Lab., TN (United States); Nagaraj, B.A. [General Electric Co., Cincinnati, OH (United States). Aircraft Engine Group

1996-05-01T23:59:59.000Z

122

SIMULATIONS OF MAGNETOHYDRODYNAMICS INSTABILITIES IN INTRACLUSTER MEDIUM INCLUDING ANISOTROPIC THERMAL CONDUCTION  

SciTech Connect

We perform a suite of simulations of cooling cores in clusters of galaxies in order to investigate the effect of the recently discovered heat flux buoyancy instability (HBI) on the evolution of cores. Our models follow the three-dimensional magnetohydrodynamics of cooling cluster cores and capture the effects of anisotropic heat conduction along the lines of magnetic field, but do not account for the cosmological setting of clusters or the presence of active galactic nuclei (AGNs). Our model clusters can be divided into three groups according to their final thermodynamical state: catastrophically collapsing cores, isothermal cores, and an intermediate group whose final state is determined by the initial configuration of magnetic field. Modeled cores that are reminiscent of real cluster cores show evolution toward thermal collapse on a timescale which is prolonged by a factor of approx2-10 compared with the zero-conduction cases. The principal effect of the HBI is to re-orient field lines to be perpendicular to the temperature gradient. Once the field has been wrapped up onto spherical surfaces surrounding the core, the core is insulated from further conductive heating (with the effective thermal conduction suppressed to less than 10{sup -2} of the Spitzer value) and proceeds to collapse. We speculate that, in real clusters, the central AGN and possibly mergers play the role of 'stirrers', periodically disrupting the azimuthal field structure and allowing thermal conduction to sporadically heat the core.

Bogdanovic, Tamara; Reynolds, Christopher S. [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Balbus, Steven A. [Ecole Normale Superieure, Laboratoire de Radioastronomie, 24 rue Lhomond, 75231 Paris CEDEX 05 (France); Parrish, Ian J., E-mail: tamarab@astro.umd.ed, E-mail: chris@astro.umd.ed, E-mail: steven.balbus@lra.ens.f, E-mail: iparrish@astro.berkeley.ed [Astronomy Department and Theoretical Astrophysics Center, 601 Campbell Hall, University of California, Berkeley, CA 94720 (United States)

2009-10-10T23:59:59.000Z

123

Thermal Crosslinking of Organic Semiconducting Polythiophene Improves Transverse Hole Conductivity  

Science Conference Proceedings (OSTI)

Thermal crosslinking using a suitable radical initiator simultaneously improves electrical conductivity in the semiconducting polymer poly(3-hexylthiophene) and makes the material insoluble. Crosslinked polythiophene shows as much as a fivefold increase in hole conductivity across the film thickness without any shift in spectral light absorption. Grazing incidence x-ray diffraction reveals more in-plane polymer lamellae stacking with only a small decrease in film crystallinity. Improved transverse conductivity increases the performance of model planar solar cells by threefold, from 0.07% to 0.2%. The ability to render polythiophene insoluble without disrupting film structural order enables fabrication pathways to more complex device architectures.

Gearba, I.R.; Nam, C.-Y.; Pindak, R.; Black, C.T.

2009-10-26T23:59:59.000Z

124

VALIDATION OF A THERMAL CONDUCTIVITY MEASUREMENT SYSTEM FOR FUEL COMPACTS  

SciTech Connect

A high temperature guarded-comparative-longitudinal heat flow measurement system has been built to measure the thermal conductivity of a composite nuclear fuel compact. It is a steady-state measurement device designed to operate over a temperature range of 300 K to 1200 K. No existing apparatus is currently available for obtaining the thermal conductivity of the composite fuel in a non-destructive manner due to the compact’s unique geometry and composite nature. The current system design has been adapted from ASTM E 1225. As a way to simplify the design and operation of the system, it uses a unique radiative heat sink to conduct heat away from the sample column. A finite element analysis was performed on the measurement system to analyze the associated error for various operating conditions. Optimal operational conditions have been discovered through this analysis and results are presented. Several materials have been measured by the system and results are presented for stainless steel 304, inconel 625, and 99.95% pure iron covering a range of thermal conductivities of 10 W/m*K to 70 W/m*K. A comparison of the results has been made to data from existing literature.

Jeff Phillips; Colby Jensen; Changhu Xing; Heng Ban

2011-03-01T23:59:59.000Z

125

HYDROGEN REDISTRIBUTION IN THIN PLATES OF ZIRCONIUM UNDER LARGE THERMAL GRADIENTS  

DOE Green Energy (OSTI)

By using experimental data, the quantities determimng the extent of dissolved H redistribution under a thermal gradient in Zircaloy were calculated. It is concluded that the phenomenon of hydride precipitation by means of thermaI gradient diffusion of dissolved H in Zircaloy fuel plates and cladding places much more severe restrictions on the allowable pre-operation H content of such elements than was hitherto suspected. The specific effects of operating conditions on H content of plates and cladding are presented in detail. (M. H.R.)

Markowitz, J.M.

1958-01-01T23:59:59.000Z

126

Simultaneous measurement of the thermal conductivity and thermal diffusivity of unconsolidated materials by the transient hot wire method  

Science Conference Proceedings (OSTI)

This paper describes a new design for the transient hot wire method that can obtain the thermal conductivity and thermal diffusivity of unconsolidated materials. In this method

Greg C. Glatzmaier; W. Fred Ramirez

1985-01-01T23:59:59.000Z

127

Effective Thermal Conductivity of High Temperature Insulations for Reusable Launch Vehicles  

E-Print Network (OSTI)

An experimental apparatus was designed to measure the effective thermal conductivity of various high temperature insulations subject to large temperature gradients representative of typical launch vehicle reentry aerodynamic heating conditions. The insulation sample cold side was maintained around room temperature, while the hot side was heated to temperatures as high as 1800°F. The environmental pressure was varied from 1 x 10 -4 to 760 torr. All the measurements were performed in a dry gaseous nitrogen environment. The effective thermal conductivity of the following insulation samples were measured: Saffilä at 1.5, 3, 6 lb/ft 3 , Q-Fiberä felt at 3, 6 lb/ft 3 , Cerachromeä at 6, 12 lb/ft 3 , and three multi-layer insulation configurations at 1.5 and 3 lb/ft 3 .. Introduction Metallic and refractory-composite thermal protection systems are being considered for a new generation of reusable launch vehicles (RLV). The main function of the thermal protection system (TPS) is to...

Kamran Daryabeigi

1999-01-01T23:59:59.000Z

128

Effective Thermal Conductivity of High Temperature Insulations for Reusable Launch Vehicles  

E-Print Network (OSTI)

An experimental apparatus was designed to measure the effective thermal conductivity of various high temperature insulations subject to large temperature gradients representative of typical launch vehicle reentry aerodynamic heating conditions. The insulation sample cold side was maintained around room temperature, while the hot side was heated to temperatures as high as 1800F. The environmental pressure was varied from 1 x 10 -4 to 760 torr. All the measurements were performed in a dry gaseous nitrogen environment. The effective thermal conductivity of the following insulation samples were measured: Saffil at 1.5, 3, 6 lb/ft 3 , Q-Fiber felt at 3, 6 lb/ft 3 , Cerachrome at 6, 12 lb/ft 3 , and three multi-layer insulation configurations at 1.5 and 3 lb/ft 3 .. Introduction Metallic and refractory-composite thermal protection systems are being considered for a new generation of reusable launch vehicles (RLV). The main function of the thermal protection system (TPS) is to mai...

Kamran Daryabeigi Langley

1999-01-01T23:59:59.000Z

129

THERMAL CONDUCTIVITY AND VISCOSITY OF GAS MIXTURES (thesis)  

SciTech Connect

Correlations based upon empirical modified equations derived from kinetic theory were developed for the thermal conductivity and viscosity of gas mixtures. The conductivity equation was compared to 226 binary mixture conductivities in temperatures from 0 to 774 deg C from the literature and this work. The average deviation is 2.1%. In correlating conductivity data of mixtures of polyatomic molecules, the energy transport is considered in two parts, i.e., one protion transferred by collision and the other by diffusion. The proposed viscosity equation reproduces 103 binary data points with an average deviation of 1.3%. These equations are more consistent with experiment than existing correlations in the literature. the relation of the conductivity or viscosity to composition and temperature are discussed in the light of the proposed equations. It has been demonstrated that, at a given composition, the ratio of the measured conductivity to that calculated on the molar average basis for mixtures of most simple molecules and the ratio of the measured viscosity to that calculated on the molar average basis for mixtures of most gases should be nearly constant over a temperature range of 200 to 300 deg C. The thermal conductivity of ten gases and selected binary and ternary mixtures of them were measured in a concentric silver cylinder cell in the temperature range of 100 to 540 deg C The gases are He, A, N/sub 2/, O/sub 2/, CO/sub 2/, CH/sub 4/, C/sub 2/ H/sub 4/, C/sub 3/H/sub 8/, methyl ether , and methyl formats. (auth)

Cheung, H.

1958-04-01T23:59:59.000Z

130

Thermal Gradient Holes At Hawthorne Area (Sabin, Et Al., 2010) | Open  

Open Energy Info (EERE)

Sabin, Et Al., 2010) Sabin, Et Al., 2010) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Hawthorne Area (Sabin, Et Al., 2010) Exploration Activity Details Location Hawthorne Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not indicated DOE-funding Unknown Notes In lieu of Seabee TGH drilling, GPO awarded a large IDIQ TGH drilling contract in December, 2009. Over the next two years, 90 500-ft TGHs will be installed at select sites in California and Nevada. Interim data from this campaign are already available for the Chocolate Mountains and Hawthorne. Results of these programs can be found in the Chocolate Mountains and Hawthorne papers also available in this volume. References Andrew Sabin, S. Bjornstad, M. Lazaro, D. Meade, C. Page, S. Alm, A.

131

Thermal Gradient Holes At Walker-Lane Transitional Zone Region (Pritchett,  

Open Energy Info (EERE)

Walker-Lane Transitional Zone Region (Pritchett, Walker-Lane Transitional Zone Region (Pritchett, 2004) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Walker-Lane Transitional Zone Region (Pritchett, 2004) Exploration Activity Details Location Walker-Lane Transition Zone Geothermal Region Exploration Technique Thermal Gradient Holes Activity Date Usefulness not useful DOE-funding Unknown Notes NOTE: These are theoretical/computer simulation tests of various methods on eight hypothetical 'model' basing-and-range geothermal systems. "The 300-meter heat flow holes are essentially useless for finding the "hidden" reservoirs. Clearly, the best results are obtained from the SP and MT surveys, with DC resistivity a close third. It is concluded that the best

132

Thermal Gradient Holes At Cove Fort Area (Warpinski, Et Al., 2002) | Open  

Open Energy Info (EERE)

Et Al., 2002) Et Al., 2002) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Cove Fort Area (Warpinski, Et Al., 2002) Exploration Activity Details Location Cove Fort Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not indicated DOE-funding Unknown Notes The project at Cove Fort/Sulphurdale in Utah, T26S R6/7W, is concerned with locating and drilling a 900-meter well to explore the western extension of the Cove Fort-Sulphurdale geothermal area. The geophysical exploration consisted of resistivity, ground magnetic, and microgravity surveys that were made to site the well in an optimum location. Drilling of the test well was completed in the fall of 2001 and results are currently being evaluated. The total depth of the well is 598 m with a

133

Thermal Gradient Holes At Spencer Hot Springs Area (Shevenell, Et Al.,  

Open Energy Info (EERE)

Hot Springs Area (Shevenell, Et Al., Hot Springs Area (Shevenell, Et Al., 2008) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Spencer Hot Springs Area (Shevenell, Et Al., 2008) Exploration Activity Details Location Spencer Hot Springs Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes Collaboration with the gold mining industry has brought two new geothermal discoveries to the attention of the geothermal community. Exploration holes at Tungsten Mountain and McGuiness Hills (Spencer Hot Springs?) in 2004 and 2005 encountered hot water and steam at depths of meters with fluid geothermometry indicating reservoir temperatures of 170 to 200oC. More information can be obtained from the Nevada Bureau of Mines and Geology web

134

Thermal Gradient Holes At Fort Bidwell Area (Lafleur, Et Al., 2010) | Open  

Open Energy Info (EERE)

Bidwell Area (Lafleur, Et Al., 2010) Bidwell Area (Lafleur, Et Al., 2010) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Fort Bidwell Area (Lafleur, Et Al., 2010) Exploration Activity Details Location Fort Bidwell Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes "Four wells have been successfully drilled into this resource since the early 1980s using a combination of funds provided by the California Energy Commission (CEC) and the United State Department of Energy (USDOE). The first three wells, FB-1, -2 and -3 have been discussed in a previous paper (Barker et al., 2005). The current status of the FBIC project to evaluate the potential geothermal resource under the reservation is that a deep

135

Geothermal potential of West-Central New Mexico from geochemical and thermal gradient data  

DOE Green Energy (OSTI)

To study the low temperature and Hot Dry Rock (HDR) geothermal potential of west-central New Mexico, 46 water samples were collected and geothermal gradient measurements were made in 29 wells. Water chemistry data indicate that all the samples collected are meteoric waters. High temperatures of samples taken from wells between Gallup and Tohatchi indicate these wells may derive water from a warm aquifer below the depth of the wells. The chemistries of the samples farther south on the Zuni Indian reservation suggest these waters are not circulating below 600 m of the surface. Geothermometry calculations support the conclusion that the waters sampled are meteoric. The geothermometry also indicates that the deep reservoir between Gallup and Tohatchi may be greater than 60/sup 0/C. Thermal gradient data indicate an area of high gradient on the Zuni Indian Reservation with a measured maximum of 67/sup 0/C/km between 181 m and 284 m. This high probably is not hydrologically controlled. The maximum gradients in the study area are 76/sup 0/C/km and 138/sup 0/C/km, measured just east of Springerville, Arizona. These gradients are undoubtedly controlled by circulating water, possibly heated by a magmatic source at depth and circulating back to the surface.

Levitte, D.; Gambill, D.T.

1980-11-01T23:59:59.000Z

136

Experimental and numerical study of the effective thermal conductivity of silica nanocomposites with thermal boundary resistance  

SciTech Connect

The thermal interface resistance at the macro scale is mainly described by the physical gap between two interfaces and constriction resistance due to this gap. The small gaps between the two material faces makes up the majority of thermal interface resistance at the macro scale. So, most of the studies have been focused on characterizing effect of surface geometry and material properties to thermal interface resistance. This resistance is more widely known as thermal contact resistance, represented with Rc. There are various models to predict thermal contact resistance at macro scale. These models predict thermal resistance Rc for given two materials by utilizing their bulk thermomechanical properties. Although, Rc represents thermal resistance accurately for macro size contacts between two metals, it is not suitable to describe interface resistance of particles in modern TIMs, aka particulate composites. The particles inside recently available TIMs are micron size and with effort to further increase surface area this particle size is approaching nano scale. At this small scale, Rc does not accurately predict thermal interface, as it is very difficult to characterize the surface topography. The thermal discontinuity at perfectly bonded interface of two dissimilar materials is termed as thermal boundary resistance (Rb) or Kapitza resistance. The macroscopic assumptions that thermal discontinuity only exists due to gaps and surface geometry leads to substantial error in determining interface thermal properties at micron and nano scale. The phenomenon of thermal boundary resistance is an inherent material property and arises due to fundamental mechanism of thermal transport. For metal-matrix particulate composites, Rb plays more important role than Rc. The free flowing nature of the polymer would eliminate most of the gaps between the two materials at their interface. This means almost all of the thermal resistance at particle/matrix interface would occur due to Rb. The current study presents experimental study of thermal boundary resistance for silica nano particles embedded inside epoxy resin. The bulk conductivity of the sample is measured and Rc is back calculated using Hasselman-Johnson s (H-J) equation. The numerical validation of the equation is also presented, including extrapolation study to predict effective conductivity of the nanocomposite TIM.

Kothari, Rushabh M [ORNL; Dinwiddie, Ralph Barton [ORNL; Wang, Hsin [ORNL

2013-01-01T23:59:59.000Z

137

Electrical conductivity and thermal dilepton rate from quenched lattice QCD  

E-Print Network (OSTI)

We report on a continuum extrapolation of the vector current correlation function for light valence quarks in the deconfined phase of quenched QCD. This is achieved by performing a systematic analysis of the influence of cut-off effects on light quark meson correlators at $T\\simeq 1.45 T_c$ using clover improved Wilson fermions. We discuss resulting constraints on the electrical conductivity and the thermal dilepton rate in a quark gluon plasma. In addition new results at 1.2 and 3.0 $T_c$ will be presented.

Olaf Kaczmarek; Anthony Francis

2011-09-19T23:59:59.000Z

138

Electrical conductivity and thermal dilepton rate from quenched lattice QCD  

E-Print Network (OSTI)

We report on a continuum extrapolation of the vector current correlation function for light valence quarks in the deconfined phase of quenched QCD. This is achieved by performing a systematic analysis of the influence of cut-off effects on light quark meson correlators at $T\\simeq 1.45 T_c$ using clover improved Wilson fermions. We discuss resulting constraints on the electrical conductivity and the thermal dilepton rate in a quark gluon plasma. In addition new results at 1.2 and 3.0 $T_c$ will be presented.

Kaczmarek, Olaf

2011-01-01T23:59:59.000Z

139

Role of Brownian Motion Hydrodynamics on Nanofluid Thermal Conductivity  

Science Conference Proceedings (OSTI)

We use a simple kinetic theory based analysis of heat flow in fluid suspensions of solid nanoparticles (nanofluids) to demonstrate that the hydrodynamics effects associated with Brownian motion have a minor effect on the thermal conductivity of the nanofluid. Our conjecture is supported by the results of molecular dynamics simulations of heat flow in a model nanofluid with well-dispersed particles. Our findings are consistent with the predictions of the effective medium theory as well as with recent experimental results on well dispersed metal nanoparticle suspensions.

W Evans, J Fish, P Keblinski

2005-11-14T23:59:59.000Z

140

Study of thermal-gradient-induced migration of brine inclusions in salt. Final report  

Science Conference Proceedings (OSTI)

Natural salt deposits, which are being considered for high-level waste disposal, contain a small volume fraction of water in the form of brine inclusions distributed throughout the salt. Radioactive decay heating of the nuclear wastes will impose a temperature gradient on the surrounding salt which mobilizes the brine inclusions. Inclusions filled completely with brine (the all-liquid inclusions) migrate up the temperature gradient and eventually accumulate brine near the buried waste forms. The brine may slowly corrode or degrade the waste forms, which is undesirable. Therefore it is important to consider the migration of brine inclusions in salt under imposed temperature gradients to properly evaluate the performance of a future salt repository for nuclear wastes. The migration velocities of the inclusions were found to be dependent on temperature, temperature gradient, and inclusion shape and size. The velocities were also dictated by the interfacial mass transfer resistance at brine/solid interface. This interfacial resistance depends on the dislocation density in the crystal, which in turn, depends on the axial compressive loading of the crystal. At low axial loads, the dependence between the velocity and temperature gradient is nonlinear. At high axial loads, the interfacial resistance is reduced and the migration velocity depends linearly on the temperature gradient. All-liquid inclusions filled with mixed brines were also studied. For gas-liquid inclusions, helium, air and argon were compared. Migration studies were also conducted on single crystallites of natural salt as well as in polycrystalline natural salt samples. The behavior of the inclusions at large-ange grain boundaries was observed.

Olander, D.R.

1984-08-01T23:59:59.000Z

Note: This page contains sample records for the topic "gradients thermal conductivity" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Light beam dynamics in materials with radially-inhomogeneous thermal conductivity  

E-Print Network (OSTI)

We study the properties of bright and vortex solitons in thermal media with nonuniform thermal conductivity and homogeneous refractive index, whereby the local modulation of the thermal conductivity strongly affects the entire refractive index distribution. While regions where the thermal conductivity is increased effectively expel light, self-trapping may occur in the regions with reduced thermal conductivity, even if such regions are located close to the material boundary. As a result, strongly asymmetric self-trapped beams may form inside a ring with reduced thermal conductivity and perform persistent rotary motion. Also, such rings are shown to support stable vortex solitons, which may feature strongly non-canonical shapes.

Kartashov, Yaroslav V; Torner, Lluis

2013-01-01T23:59:59.000Z

142

Experimental Investigation of Size Effects on the Thermal Conductivity of Silicon-Germanium Alloy Thin Films  

E-Print Network (OSTI)

We experimentally investigate the role of size effects and boundary scattering on the thermal conductivity of silicon-germanium alloys. The thermal conductivities of a series of epitaxially grown Si[subscript 1-x] Ge[subscript ...

Cheaito, Ramez

143

Thermal interface conductance in Si/Ge superlattices by equilibrium molecular dynamics  

E-Print Network (OSTI)

We provide a derivation allowing the calculation of thermal conductance at interfaces by equilibrium molecular dynamics simulations and illustrate our approach by studying thermal conduction mechanisms in Si/Ge superlattices. ...

Esfarjani, Keivan

144

Role of thermal conduction in an advective accretion with bipolar outflows  

E-Print Network (OSTI)

Steady-state advective accretion flows in the presence of thermal conduction are studied. All three components of velocity in a spherical coordinates are considered and the flow displays both inflowing and outflowing regions according to our similarity solutions. Thermal conductivity provides latitudinal energy transport and so, the flow rotates more slowly and becomes hotter with increasing thermal conductivity coefficient. We also show that opening angle of the outflow region decreases as thermal conduction becomes stronger.

Khajenabi, Fazeleh

2013-01-01T23:59:59.000Z

145

T I ENHANCING THERMAL CONDUCTIVITY OF FLUIDS WITH NANOPARTICLES*  

Office of Scientific and Technical Information (OSTI)

JAM 1 1 1935 JAM 1 1 1935 b T I ENHANCING THERMAL CONDUCTIVITY OF FLUIDS WITH NANOPARTICLES* Stephen U. S. Choi 1 and J. A. Eastman 2 1 Energy Technology Division and ^Materials Science Division Argonne National Laboratory, Argonne, IL 60439 October 1995 The submitted manuscript has been authored by a contractor of the U.S. Government under contract No. W-31-109-ENG-38. Accordingly, the U.S. Government retains a nonexclusive, royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for U.S. Government purposes. DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsi-

146

Universal properties of thermal and electrical conductivity of gauge theory plasmas from holography  

E-Print Network (OSTI)

We show that for CFT's admitting gravity duals, thermal conductivity is fixed by central charges in a universal manner. We also discuss possible bound on thermal conductivity. Using this universality relation exhibited by thermal conductivity, we show how to express electrical conductivity in terms of thermodynamical quantities even in the presence of chemical potential i.e. electrical conductivity can be calculated without writing down perturbation equations and solving them even at nonvanishing chemical potential.

Jain, Sachin

2009-01-01T23:59:59.000Z

147

Spatially localized measurement of thermal conductivity using a hybrid photothermal technique  

SciTech Connect

A photothermal technique capable of measuring thermal conductivity with micrometer lateral resolution is presented. This technique involves measuring separately the thermal diffusivity, D, and thermal effusivity, e, to extract the thermal conductivity, k=(e2/D)1/2. To generalize this approach, sensitivity analysis was conducted for materials having a range of thermal conductivities. Experimental validation was sought using two substrate materials, SiO2 and CaF2, both coated with thin titanium films. The measured conductivities compare favorably with literature values.

David H Hurley; Marat Khafizov; Zilong Hua; Rory Kennedy; Heng Ban

2012-05-01T23:59:59.000Z

148

Thermal conductivity of $sup 238$PuO$sub 2$ powder, intermediates, and dense fuel forms  

SciTech Connect

The thermal conductivities of porous $sup 238$PuO$sub 2$ powder (calcined oxalate), milled powder, and high-density granules were calculated from direct measurements of steady-state temperature profiles resulting from self- heating. Thermal conductivities varied with density, temperature, and gas content of the pores. Errors caused by thermocouple heat conduction were less than 5 percent when the dimensions of the thermal conductivity cell and the thermocouple were properly selected. (auth)

Bickford, D.F.; Crain, B. Jr.

1975-10-01T23:59:59.000Z

149

Thermal conductance and rectification of asymmetric tilt grain boundary in graphene  

E-Print Network (OSTI)

We have investigated the lattice thermal transport across the asymmetry tilt grain boundary between armchair and zigzag grains by using nonequilibrium molecular dynamics (NEMD). We have observed significant temperature drop and ultralow temperature-dependent thermal boundary resistance. Importantly, we find an unexpected thermal rectification phenomenon, i.e, the thermal conductivity and Kapitza conductance is asymmetric with respect to the thermal transport direction. And the effect of thermal rectification could be amplified by increasing the difference of temperature imposed on two sides. Our results propose a new promising kind of thermal rectifier and phonon diodes from polycrystalline graphene without delicate manupulation of the atomic structures.

Cao, Hai-Yuan; Gong, Xin-Gao

2011-01-01T23:59:59.000Z

150

Thermal Gradient Holes At Chena Area (Erkan, Et. Al., 2008) | Open Energy  

Open Energy Info (EERE)

Chena Area (Erkan, Et. Al., Chena Area (Erkan, Et. Al., 2008) Exploration Activity Details Location Chena Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes MULTI-STAGE DRILLING Once a hole is drilled the natural-state pressure distribution with depth is essentially unrecoverable (Grant et al., 1982). One of the best ways to mitigate this effect is to use multi-stage drilling (White et al., 1975; Grant et al., 1982). This type of drilling was applied at Chena and its usefulness in understanding the natural flow regimes is demonstrated. Here, we illustrate how high-quality equilibrium temperature logs can often be used to identify permeable fractures. The independent interpretations of flow regimes based on temperature-depth curves and the

151

Thermal Gradient Holes At Tungsten Mountain Area (Shevenell, Et Al., 2008)  

Open Energy Info (EERE)

Shevenell, Et Al., 2008) Shevenell, Et Al., 2008) Exploration Activity Details Location Tungsten Mountain Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes Collaboration with the gold mining industry has brought two new geothermal discoveries to the attention of the geothermal community. Exploration holes at Tungsten Mountain and McGuiness Hills (Figure 1) in 2004 and 2005 encountered hot water and steam at depths of meters with fluid geothermometry indicating reservoir temperatures of 170 to 200oC. More information can be obtained from the Nevada Bureau of Mines and Geology web site (www.nbmg.unr.edu/geothermal/gtmap.pdf), and from a PowerPoint presentation titled 'Geothermal Exploration Short Stories' posted on the Geothermal Resources Council web site

152

Thermal Gradient Holes At Cove Fort Area - Vapor (Warpinski, Et Al., 2002)  

Open Energy Info (EERE)

2) 2) Exploration Activity Details Location Cove Fort Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not indicated DOE-funding Unknown Notes The project at Cove Fort/Sulphurdale in Utah, T26S R6/7W, is concerned with locating and drilling a 900-meter well to explore the western extension of the Cove Fort-Sulphurdale geothermal area. The geophysical exploration consisted of resistivity, ground magnetic, and microgravity surveys that were made to site the well in an optimum location. Drilling of the test well was completed in the fall of 2001 and results are currently being evaluated. The total depth of the well is 598 m with a non-equilibrated maximum temperature probably in the range of 157degrees C and a very complicated geologic structure.

153

Thermal Gradient Holes At Tungsten Mountain Area (Kratt, Et Al., 2008) |  

Open Energy Info (EERE)

Kratt, Et Al., 2008) Kratt, Et Al., 2008) Exploration Activity Details Location Tungsten Mountain Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes twenty-three gold exploration holes were drilled by Newcrest Resources, Inc. during 2005 and 2006 along the range front. These holes approached or exceeded 300 m in depth and all holes encountered hot water and/or steam. Despite the high temperatures encountered at relatively shallow depths, there are no active geothermal features such as hot springs or steam vents at the surface. The presence of small outcrops of argillic alteration containing anomalous gold attracted the interest of exploration geologists. References Christopher Kratt, Mark Coolbaugh, Chris Sladek, Rick Zehner, Robin

154

Reversible temperature regulation of electrical and thermal conductivity using liquid–solid phase transitions  

E-Print Network (OSTI)

Reversible temperature tuning of electrical and thermal conductivities of materials is of interest for many applications, including seasonal regulation of building temperature, thermal storage and sensors. Here we introduce ...

Zheng, Ruiting

155

Thermal conductivity from first-principles in bulk, disordered, and nanostructured materials  

E-Print Network (OSTI)

Thermal conductivity is an important transport property that plays a vital role in applications such as high efficiency thermoelectric devices as well as in thermal management of electronics. We present a first-principles ...

Garg, Jivtesh

2011-01-01T23:59:59.000Z

156

High thermal conductivity connector having high electrical isolation  

DOE Patents (OSTI)

A method and article for providing a low-thermal-resistance, high-electrical-isolation heat intercept connection. The connection method involves clamping, by thermal interference fit, an electrically isolating cylinder between an outer metallic ring and an inner metallic disk. The connection provides durable coupling of a heat sink and a heat source.

Nieman, Ralph C. (Downers Grove, IL); Gonczy, John D. (Oak Lawn, IL); Nicol, Thomas H. (St. Charles, IL)

1995-01-01T23:59:59.000Z

157

Thermal conduction and particle transport in strong MHD turbulence, with application to galaxy-cluster plasmas  

E-Print Network (OSTI)

We investigate field-line separation in strong MHD turbulence analytically and with direct numerical simulations. We find that in the static-magnetic-field approximation the thermal conductivity in galaxy clusters is reduced by a factor of about 5-10 relative to the Spitzer thermal conductivity of a non-magnetized plasma. We also estimate how the thermal conductivity would be affected by efficient turbulent resistivity.

Benjamin D. G. Chandran; Jason L. Maron

2003-03-11T23:59:59.000Z

158

Temperature, thermal-conductivity, and heat-flux data,Raft River...  

Open Energy Info (EERE)

Temperature, thermal-conductivity, and heat-flux data,Raft River area, Cassia County, Idaho (1974-1976) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Report:...

159

Finite - difference modeling of the Yucca Mountain, Nevada Area: a study of the regional water table gradients based on hydraulic conductivity contrasts  

E-Print Network (OSTI)

The Nevada Yucca Mountain site is being investigated to determine if it is a suitable site for the construction of a high-level nuclear waste repository. A feature of concern north of the selected site is an abrupt rise in the water table. This high gradient of 0.15 is flanked to the north by a moderate gradient of 0.015 and to the south by a very small gradient of 0.0001. Since the mechanisms creating this feature have the potential to cause changes in the position and configuration of the water table, they must be understood so risk analysis of the site may be performed. The three distinct gradient regions found at the site may be related to the Cenozoic volcanics, the Paleozoic clastic aquitard, and the Paleozoic carbonates. The large hydraulic gradient regionally corresponds with the northern limit of the Paleozoic carbonates, at the contact of the Eleana Formation, a Paleozoic aquitard. This study investigates, using finite difference modeling, the relationship between the steep hydraulic gradient and hydraulic conductivity contrasts. The site was modeled with flow boundaries to investigate the effects of variable gradient input to the flow balance calculation. A model was run with differential volcanic hydraulic conductivity zones with regulated flow into the carbonates. Constant head boundaries were implemented in models to investigate the effect of both a confined and open carbonate zone and with vertical barriers above the argillite/carbonate contact. The results of the study found that vertical and horizontal hydraulic conductivity contrasts do not fully account for the steep gradients, although the vertical contrasts marginally increase the gradient from horizontal contrasts. The confined carbonate zone model produced results that do not correlate with field data. The vertical barrier model did successfully reproduce steep gradients with gradient steepness related to flow restriction. Through the use of flow boundaries the steep gradient was reproduced successfully with a contrast of 0.8 orders of magnitude by allowing flow into the carbonate zone.

Davidson, Timothy Ross

1994-01-01T23:59:59.000Z

160

Experimental measurements of the thermal conductivity of ash deposits: Part 1. Measurement technique  

Science Conference Proceedings (OSTI)

This paper describes a technique developed to make in situ, time-resolved measurements of the effective thermal conductivity of ash deposits formed under conditions that closely replicate those found in the convective pass of a commercial boiler. Since ash deposit thermal conductivity is thought to be strongly dependent on deposit microstructure, the technique is designed to minimize the disturbance of the natural deposit microstructure. Traditional techniques for measuring deposit thermal conductivity generally do not preserve the sample microstructure. Experiments are described that demonstrate the technique, quantify experimental uncertainty, and determine the thermal conductivity of highly porous, unsintered deposits. The average measured conductivity of loose, unsintered deposits is 0.14 {+-} 0.03 W/(m K), approximately midway between rational theoretical limits for deposit thermal conductivity.

A. L. Robinson; S. G. Buckley; N. Yang; L. L. Baxter

2000-04-01T23:59:59.000Z

Note: This page contains sample records for the topic "gradients thermal conductivity" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Acoustic emission from thermal-gradient cracks in UO$sub 2$  

SciTech Connect

A feasibility study has been conducted to evaluate the potential use of acoustic emission to monitor thermal-shock damage in direct electrical heating of UO$sub 2$ pellets. In the apparatus used for the present tests, two acoustic- emission sensors were placed on extensions of the upper and lower electrical feedthroughs. Commercially available equipment was used to accumulate acoustic- emission data. The accumulation of events displayed on a cathode-ray-tube screen indicates the total number of acoustic-emission events at a particular location within the pellet stack. These tests have indicated that acoustic emission can be used to monitor thermal-shock damage in UO$sub 2$ pellets subjected to direct- electrical heating. 8 references. (auth)

Kennedy, C.R.; Kupperman, D.S.; Wrona, B.J.

1975-01-01T23:59:59.000Z

162

Experimental investigation of plastic finned-tube heat exchangers, with emphasis on material thermal conductivity  

Science Conference Proceedings (OSTI)

In this paper, two modified types of polypropylene (PP) with high thermal conductivity up to 2.3 W/m K and 16.5 W/m K are used to manufacture the finned-tube heat exchangers, which are prospected to be used in liquid desiccant air conditioning, heat recovery, water source heat pump, sea water desalination, etc. A third plastic heat exchanger is also manufactured with ordinary PP for validation and comparison. Experiments are carried out to determine the thermal performance of the plastic heat exchangers. It is found that the plastic finned-tube heat exchanger with thermal conductivity of 16.5 W/m K can achieve overall heat transfer coefficient of 34 W/m{sup 2} K. The experimental results are compared with calculation and they agree well with each other. Finally, the effect of material thermal conductivity on heat exchanger thermal performance is studied in detail. The results show that there is a threshold value of material thermal conductivity. Below this value improving thermal conductivity can considerably improve the heat exchanger performance while over this value improving thermal conductivity contributes very little to performance enhancement. For the finned-tube heat exchanger designed in this paper, when the plastic thermal conductivity can reach over 15 W/m K, it can achieve more than 95% of the titanium heat exchanger performance and 84% of the aluminum or copper heat exchanger performance with the same dimension. (author)

Chen, Lin; Li, Zhen; Guo, Zeng-Yuan [Department of Engineering Mechanics, Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Tsinghua University, Beijing 100084 (China)

2009-07-15T23:59:59.000Z

163

Ion thermal conductivity for a pure tokamak plasma  

DOE Green Energy (OSTI)

The neoclassical and Pfirsch-Schlueter component of the ion heat conduction for a pure hydrogen Tokamak plasma are recalculated without assuming large aspect ratio and without neglecting energy scattering collisions. Using a model collision operator the conductivity is determined numerically for various collision frequencies and aspect ratios. An approximate algebraic expression is fitted to the results. Even for comparatively large aspect ratios(approx. 10) energy scattering increases the conductivity in the banana regime by about 50% and for small aspect ratios(approx. 3.3) the Pfirsch-Schlueter contribution causes a further increase of approximately 60%.

Bolton, C.; Ware, A.

1981-10-01T23:59:59.000Z

164

Thermal Conductivity Spectroscopy Technique to Measure Phonon Mean Free Paths  

E-Print Network (OSTI)

Size effects in heat conduction, which occur when phonon mean free paths (MFPs) are comparable to characteristic lengths, are being extensively explored in many nanoscale systems for energy applications. Knowledge of MFPs ...

Schmidt, A. J.

165

Technical Project Plan for The Enhanced Thermal Conductivity of Oxide Fuels Through the Addition of High Thermal Conductivity Fibers and Microstructural Engineering  

SciTech Connect

The commercial nuclear power industry is investing heavily in advanced fuels that can produce higher power levels with a higher safety margin and be produced at low cost. Although chemically stable and inexpensive to manufacture, the in-core performance of UO{sub 2} fuel is limited by its low thermal conductivity. There will be enormous financial benefits to any utility that can exploit a new type of fuel that is chemically stable, has a high thermal conductivity, and is inexpensive to manufacture. At reactor operating temperatures, UO{sub 2} has a very low thermal conductivity (<5 W/m {center_dot}K), which decreases with temperature and fuel burnup. This low thermal conductivity limits the rate at which energy can be removed from the fuel, thus limiting the total integrated reactor power. If the fuel thermal conductivity could be increased, nuclear reactors would be able to operate at higher powers and larger safety margins thus decreasing the overall cost of electricity by increasing the power output from existing reactors and decreasing the number of new electrical generating plants needed to meet base load demand. The objective of the work defined herein is to produce an advanced nuclear fuel based on the current UO{sub 2} fuel with superior thermal conductivity and structural integrity that is suitable for current and future nuclear reactors, using the existing fuel fabrication infrastructure with minimal modifications. There are two separate components to the research: (1) Enhanced Thermal Conductivity (ETC) - adding high conductivity fibers to the UO{sub 2} prior to sintering, which act as conduits for moving the heat energy generated within the pellet to the outer surface, (2) Microstructural Engineering (ME) - adding second phase particulates to UO{sub 2} bodies to retard grain growth and to increase thermal conductivity, as well as improve fracture and creep resistance. Different groups will perform the laboratory work for each of these research components with some overlap in personnel. The overlapping areas primarily involve computer simulations and final testing of the fuel in a reactor. The estimated cost and duration of this project is $5,000,000 over three years.

Hollenbach, Daniel F [ORNL; Ott, Larry J [ORNL; Besmann, Theodore M [ORNL; Armstrong, Beth L [ORNL; Wereszczak, Andrew A [ORNL; Lin, Hua-Tay [ORNL; Ellis, Ronald James [ORNL; Becher, Paul F [ORNL; Jubin, Robert Thomas [ORNL; Voit, Stewart L [ORNL

2010-09-01T23:59:59.000Z

166

Computational Efficient Upscaling Methodology for Predicting Thermal Conductivity of Nuclear Waste forms  

SciTech Connect

This study evaluated different upscaling methods to predict thermal conductivity in loaded nuclear waste form, a heterogeneous material system. The efficiency and accuracy of these methods were compared. Thermal conductivity in loaded nuclear waste form is an important property specific to scientific researchers, in waste form Integrated performance and safety code (IPSC). The effective thermal conductivity obtained from microstructure information and local thermal conductivity of different components is critical in predicting the life and performance of waste form during storage. How the heat generated during storage is directly related to thermal conductivity, which in turn determining the mechanical deformation behavior, corrosion resistance and aging performance. Several methods, including the Taylor model, Sachs model, self-consistent model, and statistical upscaling models were developed and implemented. Due to the absence of experimental data, prediction results from finite element method (FEM) were used as reference to determine the accuracy of different upscaling models. Micrographs from different loading of nuclear waste were used in the prediction of thermal conductivity. Prediction results demonstrated that in term of efficiency, boundary models (Taylor and Sachs model) are better than self consistent model, statistical upscaling method and FEM. Balancing the computation resource and accuracy, statistical upscaling is a computational efficient method in predicting effective thermal conductivity for nuclear waste form.

Li, Dongsheng; Sun, Xin; Khaleel, Mohammad A.

2011-09-28T23:59:59.000Z

167

Serpentine Thermal Coupling Between a Stream and a Conducting Body  

Science Conference Proceedings (OSTI)

Here we document the effect of flow configuration on the heat transfer performance of a serpentine shaped stream embedded in a conducting solid. Several configurations with fixed volume of fluid are considered: U-shaped with varying spacing between the parallel portions of the U, serpentine shapes with three elbows, and conducting soil with several parallelepipedal shapes. We show that the spacing must be greater than a critical value in order for the heat transfer density of the stream-solid configuration to be the highest that it can be. Spacings larger than this critical value do not yield improvements in heat transfer density. We also show that even though the heat transfer is time dependent, the stream-solid configuration has an effective number of heat transfer units Ntu that is nearly constant in time. The larger Ntu values correspond to the configurations with greater heat transfer density.

Kobayashi, H.; Lorente, S.; Anderson, R.; Bejan, A.

2012-02-15T23:59:59.000Z

168

Preliminary study on improvement of cementitious grout thermal conductivity for geothermal heat pump applications  

DOE Green Energy (OSTI)

Preliminary studies were preformed to determine whether thermal conductivity of cementitious grouts used to backfill heat exchanger loops for geothermal heat pumps could be improved, thus improving efficiency. Grouts containing selected additives were compares with conventional bentonite and cement grouts. Significant enhancement of grout alumina grit, steel fibers, and silicon carbide increased the thermal conductivity when compared to unfilled, high solids bentonite grouts and conventional cement grouts. Furthermore, the developed grouts retained high thermal conductivity in the dry state, where as conventional bentonite and cement grouts tend to act as insulators if moisture is lost. The cementitious grouts studied can be mixed and placed using conventional grouting equipment.

Allan, M.L.

1996-06-01T23:59:59.000Z

169

EVALUATION OF THERMAL CONDUCTIVITY OF INSTALLED-IN-PLACE POLYURETHANE FOAM INSULATION BY EXPERIMENT AND ANALYSIS  

SciTech Connect

In the thermal analysis of the 9977 package, it was found that calculated temperatures, determined using a typical thermal analysis code, did not match those measured in the experimental apparatus. The analysis indicated that the thermal resistance of the overpack in the experimental apparatus was less than that expected, based on manufacturer's reported value of thermal conductivity. To resolve this question, the thermal conductivity of the installed foam was evaluated from the experimental results, using a simplified analysis. This study confirmed that the thermal resistance of the experimental apparatus was lower than that which would result from the manufacturer's published values for thermal conductivity of the foam insulation. The test package was sectioned to obtain samples for measurement of material properties. In the course of the destructive examination a large uninsulated region was found at the bottom of the package, which accounted for the anomalous results. Subsequent measurement of thermal conductivity confirmed the manufacturer's published values. The study provides useful insight into the use of simplified, scoping calculations for evaluation of thermal performance of packages.

Smith, A; Bruce Hardy, B; Kurt Eberl, K; Nick Gupta, N

2007-12-05T23:59:59.000Z

170

ESTIMATION OF IN-SITU THERMAL CONDUCTIVITIES FROM TEMPERATURE GRADIENT MEASUREMENTS  

E-Print Network (OSTI)

where: pc v • phonon heat capacity, c• phonon velocity,fluid density, the specific heat capacity of the fluid. Thean l8cm Values of heat capacities diameter casing for three

Hoang, V.T.

2010-01-01T23:59:59.000Z

171

ESTIMATION OF IN-SITU THERMAL CONDUCTIVITIES FROM TEMPERATURE GRADIENT MEASUREMENTS  

E-Print Network (OSTI)

in a Cir- culating Drilling Fluid," Journal of Petroleumtemperature after drilling, or injecting fluid. Bullard [14

Hoang, V.T.

2010-01-01T23:59:59.000Z

172

ESTIMATION OF IN-SITU THERMAL CONDUCTIVITIES FROM TEMPERATURE GRADIENT MEASUREMENTS  

E-Print Network (OSTI)

By analyzing the heat transfer process inside the tubing andnatural convection heat transfer process, three equationsis the dominant heat transfer process during shut-in, the

Hoang, V.T.

2010-01-01T23:59:59.000Z

173

Thermal desorption treatability test conducted with VAC*TRAX Unit  

SciTech Connect

In 1992, Congress passed the Federal Facilities Compliance Act, requiring the U.S. Department of Energy (DOE) to treat and dispose of its mixed waste in accordance with Resource Conservation and Recovery Act (RCRA) treatment standards. In response to the need for mixed-waste treatment capacity, where off-site commercial treatment facilities do not exist or cannot be used, the DOE Albuquerque Operations Office (DOE-AL) organized a Treatment Selection Team to match mixed waste with treatment options and develop a strategy for treatment of mixed waste. DOE-AL manages nine sites with mixed-waste inventories. The Treatment Selection Team determined a need to develop mobile treatment units (MTUs) to treat waste at the sites where the wastes are generated. Treatment processes used for mixed wastes must remove the hazardous component (i.e., meet RCRA treatment standards) and contain the radioactive component in a form that will protect the worker, public, and environment. On the basis of the recommendations of the Treatment Selection Team, DOE-AL assigned projects to the sites to bring mixed-waste treatment capacity on-line. The three technologies assigned to the DOE Grand Junction Projects Office (DOE-GJPO) include thermal desorption (TD), evaporative oxidation, and waste water evaporation.

1996-01-01T23:59:59.000Z

174

Cluster expansion and optimization of thermal conductivity in SiGe nanowires  

E-Print Network (OSTI)

We investigate the parametrization and optimization of thermal conductivity in silicon-germanium alloy nanowires by the cluster-expansion technique. Si1?xGex nanowires are of interest for thermoelectric applications and ...

Chan, Maria K.

175

Temperature, thermal-conductivity, and heat-flux data,Raft River area,  

Open Energy Info (EERE)

Temperature, thermal-conductivity, and heat-flux data,Raft River area, Temperature, thermal-conductivity, and heat-flux data,Raft River area, Cassia County, Idaho (1974-1976) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Report: Temperature, thermal-conductivity, and heat-flux data,Raft River area, Cassia County, Idaho (1974-1976) Details Activities (1) Areas (1) Regions (0) Abstract: Basin and Range Province; Cassia County Idaho; economic geology; exploration; geophysical surveys; geothermal energy; heat flow; heat flux; Idaho; North America; Raft River basin; south-central Idaho; surveys; temperature; thermal conductivity; United States; USGS Author(s): Urban, T.C.; Diment, W.H.; Nathenson, M.; Smith, E.P.; Ziagos, J.P.; Shaeffer, M.H. Published: Open-File Report - U. S. Geological Survey, 1/1/1986 Document Number: Unavailable

176

Thermal conductivity of self-assembled nano-structured ZnO bulk ceramics  

Science Conference Proceedings (OSTI)

In this study, we describe the changes in thermal conductivity behavior of ZnO-Al micro- and nano-two-phase self-assembled composites with varying grain sizes. The reduction in thermal conductivity values of micro-composites was limited to {approx}15% for ZnO-4% Al. However, nano-composites exhibited large reduction, by a factor of about three, due to uniform distribution of nano-precipitates (ZnAl2O4) and large grain boundary area. Interestingly, the micro-composites revealed continuous decrease in thermal conductivity with increase in Al substitution while the nano-composites exhibited the lowest magnitudes for 2% Al concentration. Raman spectra indicated that phonon confinement in ZnO-Al nano-composites causes drastic decrease in the value of thermal conductivity.

Zhao, Yu [Bio-Inspired Materials and Devices Laboraory (BMDL); Yan, Yongke [Bio-Inspired Materials and Devices Laboraory (BMDL); Kumar, Ashok [Bio-Inspired Materials and Devices Laboraory (BMDL); Wang, Hsin [ORNL; Porter, Wallace D [ORNL

2012-01-01T23:59:59.000Z

177

Effective thermal conductivity measurements relevant to deep borehole nuclear waste disposal  

E-Print Network (OSTI)

The objective of this work was to measure the effective thermal conductivity of a number of materials (particle beds, and fluids) proposed for use in and around canisters for disposal of high level nuclear waste in deep ...

Shaikh, Samina

2007-01-01T23:59:59.000Z

178

Thermal conductivity of fluids containing suspension of nanometer-sized particles  

E-Print Network (OSTI)

Nanofluids, which are fluids containing suspension of nanometer-sized particles, have been reported to possess substantially higher thermal conductivity than their respective base fluids. This thesis reports on an experimental ...

Ma, Jack Jeinhao

2006-01-01T23:59:59.000Z

179

Thermal Conduction in Aligned Carbon Nanotube–Polymer Nanocomposites with High Packing Density  

E-Print Network (OSTI)

Nanostructured composites containing aligned carbon nanotubes (CNTs) are very promising as interface materials for electronic systems and thermoelectric power generators. We report the first data for the thermal conductivity ...

Marconnet, Amy M.

180

The Effect of Soil Thermal Conductivity Parameterization on Surface Energy Fluxes and Temperatures  

Science Conference Proceedings (OSTI)

The sensitivity of sensible and latent heat fluxes and surface temperatures to the parameterization of the soil thermal conductivity is demonstrated using a soil vegetation atmosphere transfer scheme (SVATS) applied to intensive field campaigns (...

C. D. Peters-Lidard; E. Blackburn; X. Liang; E. F. Wood

1998-04-01T23:59:59.000Z

Note: This page contains sample records for the topic "gradients thermal conductivity" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Enhancing thermal conductivity of fluids with graphite nanoparticles and carbon nanotube  

DOE Patents (OSTI)

A fluid media such as oil or water, and a selected effective amount of carbon nanomaterials necessary to enhance the thermal conductivity of the fluid. One of the preferred carbon nanomaterials is a high thermal conductivity graphite, exceeding that of the neat fluid to be dispersed therein in thermal conductivity, and ground, milled, or naturally prepared with mean particle size less than 500 nm, and preferably less than 200 nm, and most preferably less than 100 nm. The graphite is dispersed in the fluid by one or more of various methods, including ultrasonication, milling, and chemical dispersion. Carbon nanotubes with graphitic structure is another preferred source of carbon nanomaterial, although other carbon nanomaterials are acceptable. To confer long term stability, the use of one or more chemical dispersants is preferred. The thermal conductivity enhancement, compared to the fluid without carbon nanomaterial, is proportional to the amount of carbon nanomaterials (carbon nanotubes and/or graphite) added.

Zhang, Zhiqiang (Lexington, KY); Lockwood, Frances E. (Georgetown, KY)

2008-03-25T23:59:59.000Z

182

LARGE SCALE PERMEABILITY TEST OF THE GRANITE IN THE STRIPA MINE AND THERMAL CONDUCTIVITY TEST  

E-Print Network (OSTI)

No.2 LARGE SCALE PERMEABILITY TEST OF THE GRANITE' IN THEMINE AND, THERMAL CONDUCTIVITY TEST Lars Lundstrom and HakanSUMMARY REPORT Background TEST SITE Layout of test places

Lundstrom, L.

2011-01-01T23:59:59.000Z

183

Thermal Conductivity of Wood-Derived Graphite and Copper-Graphite  

SciTech Connect

The thermal conductivity of wood-derived graphite and graphite/copper composites was studied both experimentally and using finite element analysis. The unique, naturally-derived, anisotropic porosity inherent to wood-derived carbon makes standard porosity-based approximations for thermal conductivity poor estimators. For this reason, a finite element technique which uses sample microstructure as model input was utilized to determine the conductivity of the carbon phase independent of porosity. Similar modeling techniques were also applied to carbon/copper composite microstructures and predicted conductivities were compared to those determined via experiment.

Johnson, M. T. [Northwestern University, Evanston; Childers, Amanda [Northwestern University, Evanston; Ramírez-Rico, J. [Universidad de Sevilla-CSIC, Spain; Wang, Hsin [ORNL; Faber, K. T. [Northwestern University, Evanston

2013-01-01T23:59:59.000Z

184

Influence of the temperature dependence of thermal parameters of heat conduction models on the reconstruction of thermal history of igneous-intrusion-bearing basins  

Science Conference Proceedings (OSTI)

Heat conduction models are important tools for reconstructing the thermal history of sedimentary basins affected by magmatic intrusions. Accurate thermal properties of the intrusion and its wall rocks are crucial for accurate predictions of thermal history. ... Keywords: Igneous intrusion, Peak temperature, Specific heat, Thermal conductivity, Vitrinite reflectance

Dayong Wang; Xiancai Lu; Yongchen Song; Rong Shao; Tian Qi

2010-10-01T23:59:59.000Z

185

Particle Swarm Optimization and Gradient Descent Methods for Optimization of PI Controller for AGC of Multi-area Thermal-Wind-Hydro Power Plants  

Science Conference Proceedings (OSTI)

The automatic generation control (AGC) of three unequal interconnected Thermal, Wind and Hydro power plant has been designed with PI controller. Further computational intelligent technique Particle Swarm Optimization and conventional Gradient Descent ... Keywords: Automatic generation control, Particle swarm optimization, Gradient Descent method, Generation rate constraint, Area control error, Wind energy conversion system

Naresh Kumari, A N. Jha

2013-04-01T23:59:59.000Z

186

FAST STATIC AND DYNAMIC GRID LEVEL THERMAL SIMULATION CONSIDERING TEMPERATURE DEPENDENT THERMAL CONDUCTIVITY OF SILICON  

E-Print Network (OSTI)

heat diffusion equation has been conventionally handled by grid-grids and an approximate delta function simulating a point heatgrid size of 64×64. To obtain transient thermal mask an impulse heat

Ziabari, Amirkoushyar

2012-01-01T23:59:59.000Z

187

Novel Charging Station and Computational Modeling for High Thermal Conductivity Heat Pipe Thermal Ground Planes.  

E-Print Network (OSTI)

??Thermal ground planes (TGPs) are planar, thin (thickness of 3 mm or less) heat pipes which use two-phase heat transfer. TGPs are innovative high-performance, integrated… (more)

Ababneh, Mohammed

2012-01-01T23:59:59.000Z

188

Universal properties of thermal and electrical conductivity of gauge theory plasmas from holography  

E-Print Network (OSTI)

We propose that for conformal field theories admitting gravity duals, the thermal conductivity is fixed by the central charges in a universal manner. Though we do not have a proof as yet, we have checked our proposal against several examples. This proposal, if correct, allows us to express electrical conductivity in terms of thermodynamical quantities even in the presence of chemical potential.

Sachin Jain

2009-12-14T23:59:59.000Z

189

Determination of Thermal Contact Conductance of Metal Tabs for Battery Ultrasonic Welding Process  

SciTech Connect

A new experimental apparatus and data analysis algorithm were used to determine the thermal contact conductance between 0.2-mm-thick pure aluminum battery tabs as a function of contact pressure from 3.6 to 14.4 MPa. Specimens were sandwiched between one optically transparent and one infrared (IR) transparent glass windows, and heated up from one side by an intense short pulse of flash light. The temperature transient on the other side was measured by an IR camera. In order to determine the thermal contact conductance, two experiment configurations having different number of Al specimen layers were used. Numerical heat conduction simulations showed that the thermal contact conductance strongly depended on the ratio of the maximum temperature rise between the two configurations. Moreover, this ratio was not sensitive to the uncertainties of other thermal properties. Through the simulation results, a simple correlation between the gap conductance and the ratio was established. Therefore, once the ratio of the temperature rise between two configurations was experimentally measured, the thermal contact conductance could be readily determined from the correlation. The new method was fast and robust. Most importantly, the data analysis algorithm improved the measurement accuracy by considerably reducing the uncertainties associated with the thermophysical properties of materials and measurement system.

Chen, Jian [ORNL; Zhang, Wei [ORNL; Yu, Zhenzhen [ORNL; Feng, Zhili [ORNL

2012-01-01T23:59:59.000Z

190

Geothermal Resource/Reservoir Investigations Based on Heat Flow and Thermal Gradient Data for the United States  

Science Conference Proceedings (OSTI)

Several activities related to geothermal resources in the western United States are described in this report. A database of geothermal site-specific thermal gradient and heat flow results from individual exploration wells in the western US has been assembled. Extensive temperature gradient and heat flow exploration data from the active exploration of the 1970's and 1980's were collected, compiled, and synthesized, emphasizing previously unavailable company data. Examples of the use and applications of the database are described. The database and results are available on the world wide web. In this report numerical models are used to establish basic qualitative relationships between structure, heat input, and permeability distribution, and the resulting geothermal system. A series of steady state, two-dimensional numerical models evaluate the effect of permeability and structural variations on an idealized, generic Basin and Range geothermal system and the results are described.

D. D. Blackwell; K. W. Wisian; M. C. Richards; J. L. Steele

2000-04-01T23:59:59.000Z

191

Holographic electrical and thermal conductivity in strongly coupled gauge theory with multiple chemical potentials  

E-Print Network (OSTI)

We study transport coefficients of strongly coupled gauge theory in the presence of multiple chemical potential which are dual to rotating D3, M2 and M5 brane. Using the general form of the perturbation equations, we compute DC-electrical conductivity at finite temperature as well as at zero temperature. We also study thermal conductivity for the same class of black holes and show that thermal conductivity and viscosity obeys Wiedemann-Franz like law even in the presence of multiple chemical potential.

Sachin Jain

2009-12-11T23:59:59.000Z

192

An Analytical Study Of A 2-Layer Transient Thermal Conduction Problem As  

Open Energy Info (EERE)

Analytical Study Of A 2-Layer Transient Thermal Conduction Problem As Analytical Study Of A 2-Layer Transient Thermal Conduction Problem As Applied To Soil-Temperature Surveys Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: An Analytical Study Of A 2-Layer Transient Thermal Conduction Problem As Applied To Soil-Temperature Surveys Details Activities (0) Areas (0) Regions (0) Abstract: The soil temperature survey is an inexpensive exploration method in groundwater and geothermal resource investigations. In its simplest form, temperatures measured in shallow holes are analyzed to deduce variations in material properties. Typical interpretation schemes are based on simple, one-layer solutions to the Fourier conduction equation using the annual solar cycle as a surface heat source. We present a solution to the

193

Stratigraphy and alteration, 15 shallow thermal gradient holes, Roosevelt Hot Springs KGRA and vicinity, Millard and Beaver Counties, Utah  

DOE Green Energy (OSTI)

Fifteen shallow thermal gradient drill holes were recently completed by Geothermal Power Corporation (GPCR) in the vicinity of the Roosevelt Hot Springs KGRA. Five holes penetrated Tertiary granitic rocks and Precambrian gneiss east of the KGRA. Seven holes completed entirely in alluvium near the southwestern corner of the KGRA encountered a near-surface marker horizon of Pleistocene pumice and perlite. Maximum calculated alluvial sedimentation rates since initial deposition of this pumice and perlite range from 1 foot in 12,500 years to 1 foot in 2,300 years. Three holes east of the Mineral Mountains penetrated late Cenozoic basaltic andesite beneath a thin veneer of alluvium. All 15 GPCR drill holes appear to be peripheral to a central zone of anomalously high thermal gradient and low resisitivity delineated by previous investigations. GPCR-8 and -14, however, are characterized by high heat flow and relatively abundant manganese oxide mineralization, which may reflect a favorable hydrologic system controlling thermal fluid flow at depth. These holes thus seem most encouraging for discovery of a deeper high-temperature geothermal resource.

Hulen, J.B.

1978-09-01T23:59:59.000Z

194

SELF-SIMILAR STRUCTURE OF A HOT MAGNETIZED FLOW WITH THERMAL CONDUCTION  

Science Conference Proceedings (OSTI)

We have explored the structure of a hot magnetized accretion flow with thermal conduction. The importance of thermal conduction in hot accretion flows has been confirmed by observations of the hot gas surrounding Sgr A* and a few other nearby galactic nuclei. For a steady state structure of such accretion flows, a set of self-similar solutions is presented. In this paper, we have actually tried to re-check the solution presented by Abbassi et al. using a physical constraint. In this study, we find that Equation (29) places a new constraint that limits answers presented by Abbassi et al. In that paper, the parameter space, which is established in the new constraint, was plotted. However, the new requirement makes up only a small parameter space with physically acceptable solutions. And now in this paper, we have followed the idea with more effort and tried to find out how thermal conduction influences the structure of the disks in a physical parameter space. We have found that the existence of thermal conduction will lead to the reduction of accretion and radial and azimuthal velocities as well as the vertical thickness of the disk, which is slightly reduced. Moreover, the surface density of the disk will increase when thermal conduction becomes important in hot magnetized flow.

Ghasemnezhad, M.; Khajavi, M. [Department of Physics, School of Sciences, Ferdowsi University of Mashhad, Mashhad, 91775-1436 (Iran, Islamic Republic of); Abbassi, S., E-mail: abbassi@ipm.ir [School of Physics, Damghan University, P.O. Box 36715-364, Damghan (Iran, Islamic Republic of)

2012-05-01T23:59:59.000Z

195

Thermal conductivity of cementitious grouts for geothermal heat pumps. Progress report FY 1997  

DOE Green Energy (OSTI)

Grout is used to seal the annulus between the borehole and heat exchanger loops in vertical geothermal (ground coupled, ground source, GeoExchange) heat pump systems. The grout provides a heat transfer medium between the heat exchanger and surrounding formation, controls groundwater movement and prevents contamination of water supply. Enhanced heat pump coefficient of performance (COP) and reduced up-front loop installation costs can be achieved through optimization of the grout thermal conductivity. The objective of the work reported was to characterize thermal conductivity and other pertinent properties of conventional and filled cementitious grouts. Cost analysis and calculations of the reduction in heat exchanger length that could be achieved with such grouts were performed by the University of Alabama. Two strategies to enhance the thermal conductivity of cementitious grouts were used simultaneously. The first of these was to incorporate high thermal conductivity filler in the grout formulations. Based on previous tests (Allan and Kavanaugh, in preparation), silica sand was selected as a suitable filler. The second strategy was to reduce the water content of the grout mix. By lowering the water/cement ratio, the porosity of the hardened grout is decreased. This results in higher thermal conductivity. Lowering the water/cement ratio also improves such properties as permeability, strength, and durability. The addition of a liquid superplasticizer (high range water reducer) to the grout mixes enabled reduction of water/cement ratio while retaining pumpability. Superplasticizers are commonly used in the concrete and grouting industry to improve rheological properties.

Allan, M.L.

1997-11-01T23:59:59.000Z

196

Impacts of Soil and Pipe Thermal Conductivity on Performance of Horizontal Pipe in a Ground-source Heat Pump  

E-Print Network (OSTI)

In this paper the composition and thermal property of soil are discussed. The main factors that impact the soil thermal conductivity and several commonly-used pipe materials are studied. A model of heat exchanger with horizontal pipes of ground-source heat pump is developed. The impact of soil thermal conductivity and pipe thermal conductivity on the soil temperature field around the buried pipe, and the thermal performance of the heat exchanger are simulated. The simulation results show that with the increase of soil thermal conductivity, heat transfer quantity obviously increases, and the temperature of soil around pipe decrease under winter conditions. The temperature field varies relatively faster with thermal conductivity in the site nearer to the buried pipe. With the increase of pipe thermal conductivity, heat transfer quantity and the mean temperature of the buried pipe's outside surface all increase.

Song, Y.; Yao, Y.; Na, W.

2006-01-01T23:59:59.000Z

197

Low-Conductivity Thermal Barrier Coating for Gas Turbines: Material Testing Status  

Science Conference Proceedings (OSTI)

Advanced gas turbines rely on air-cooled components protected by ceramic thermal barrier coatings to survive increasingly high operating temperatures. A new generation of coatings offers lower thermal conductivity, potentially further reducing component heat loading, which can improve durability, lower life cycle cost, and enable longer range efficiency gains. Testing improved coatings is a necessary step towards field demonstration.BackgroundAs gas turbine ...

2012-12-31T23:59:59.000Z

198

Thermal conductivity of rocks associated with energy extraction from hot dry rock geothermal systems  

DOE Green Energy (OSTI)

Results of thermal conductivity measurements are given for 14 drill core rock samples taken from two exploratory HDR geothermal wellbores (maximum depth of 2929 m (9608 ft) drilled into Precambrian granitic rock in the Jemez Mountains of northern New Mexico. These samples have been petrographically characterized and in general represent fresh competent Precambrian material of deep origin. Thermal conductivities, modal analyses, and densities are given for all core samples studied under dry and water-saturated conditions. Additional measurements are reported for several sedimentary rocks encountered in the upper 760 m (2500 ft) of that same region. A cut-bar thermal conductivity comparator and a transient needle probe were used for the determinations with fused quartz and Pyroceram 9606 as the standards. The maximum temperature range of the measurements was from the ice point to 250/sup 0/C. The measurements on wet, water-saturated rock were limited to the temperature range below room temperature. Conductivity values of the dense core rock samples were generally within the range from 2 to 2.9 W/mK at 200/sup 0/C. Excellent agreement was achieved between these laboratory measurements of thermal conductivity and those obtained by in situ measurements used in the HDR wellbores. By using samples of sufficient thickness to provide a statistically representative heat flow path, no difference between conductivity values and their temperature coefficients for orthogonal directions (heat flow parallel or perpendicular to core axis) was observed. This isotropic behavior was even found for highly foliated gneissic specimens. Estimates of thermal conductivity based on a composite dispersion analysis utilizing pure minerallic phase conductivities and detailed modal analyses usually agreed to within 9 percent of the experimental values.

Sibbitt, W.L.; Dodson, J.G.; Tester, J.W.

1978-01-01T23:59:59.000Z

199

Thermal management of batteries using a Variable-Conductance Insulation (VCI) enclosure  

DOE Green Energy (OSTI)

Proper thermal management is important for optimum performance and durability of most electric-vehicle batteries. For high-temperature cells such as sodium/sulphur, a very efficient and responsive thermal control system is essential. Heat must be removed during exothermic periods and retained when the batteries are not in use. Current thermal management approaches rely on passive insulation enclosures with active cooling loops that penetrate the enclosure. This paper presents the design, analysis, and testing of an enclosure with variable conductance insulation (VCI). VCI uses a hydride with an integral electric resistance heater to expel and retrieve a small amount of hydrogen gas into a vacuum space. By controlling the amount of hydrogen gas, the thermal conductance can be varied by more than 100:1, enabling the cooling loop (cold plate) to be mounted on the enclosure exterior. By not penetrating the battery enclosure, the cooling system is simpler and more reliable. Also, heat can be retained more effectively when desired. For high temperatures, radiation shields within the vacuum space are required. Ceramic spacers are used to maintain separation of the steel enclosure materials against atmospheric loading. Ceramic-to-ceramic thermal contact resistance within the spacer assembly minimizes thermal conductance. Two full-scale (0.8-m {times} 0.9-m {times} 0.3-m) prototypes were designed, built, and tested under high-temperature 200{degrees}-350{degrees}C battery conditions. With an internal temperature of 330{degrees}C (and 20{degrees}C ambient), the measured total-enclosure minimum heat loss was 80 watts (excluding wire pass-through losses). The maximum heat rejection was 4100 watts. The insulation can be switched from minimum to maximum conductance (hydrogen pressure from 2.0 {times} 10{sup -3} to 8 torr) in 3 minutes. Switching from maximum to minimum conductance was longer (16 minutes), but still satisfactory because of the large thermal mass of the battery.

Burch, S.D.; Parish, R.C.; Keyser, M.A.

1995-05-01T23:59:59.000Z

200

Thermal Conductivity of Thermally-Isolating Polymeric and Composite Structural Support Materials Between 0.3 and 4 K  

E-Print Network (OSTI)

We present measurements of the low-temperature thermal conductivity of a number of polymeric and composite materials from 0.3 to 4 K. The materials measured are Vespel SP-1, Vespel SP-22, unfilled PEEK, 30% carbon fiber-filled PEEK, 30% glass-filled PEEK, carbon fiber Graphlite composite rod, Torlon 4301, G-10/FR-4 fiberglass, pultruded fiberglass composite, Macor ceramic, and graphite rod. These materials have moderate to high elastic moduli making them useful for thermally-isolating structural supports.

Runyan, M C

2008-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "gradients thermal conductivity" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Thermal Conductivity of Thermally-Isolating Polymeric and Composite Structural Support Materials Between 0.3 and 4 K  

E-Print Network (OSTI)

We present measurements of the low-temperature thermal conductivity of a number of polymeric and composite materials from 0.3 to 4 K. The materials measured are Vespel SP-1, Vespel SP-22, unfilled PEEK, 30% carbon fiber-filled PEEK, 30% glass-filled PEEK, carbon fiber Graphlite composite rod, Torlon 4301, G-10/FR-4 fiberglass, pultruded fiberglass composite, Macor ceramic, and graphite rod. These materials have moderate to high elastic moduli making them useful for thermally-isolating structural supports.

M. C. Runyan; W. C. Jones

2008-06-11T23:59:59.000Z

202

Predicting Thermal Conductivity Evolution of Polycrystalline Materials Under Irradiation Using Multiscale Approach  

SciTech Connect

A multiscale methodology was developed to predict the evolution of thermal conductivity of polycrystalline fuel under irradiation. In the mesoscale level, phase field model was used to predict the evolution of gas bubble microstructure. Generation of gas atoms and vacancies were taken into consideration. In the macroscopic scale, a statistical continuum mechanics model was applied to predict the anisotropic thermal conductivity evolution during irradiation. Microstructure predicted by phase field model was fed into statistical continuum mechanics model to predict properties and behavior. Influence of irradiation intensity, exposition time and morphology were investigated. This approach provides a deep understanding on microstructure evolution and property prediction from a basic scientific viewpoint.

Li, Dongsheng; Li, Yulan; Hu, Shenyang Y.; Sun, Xin; Khaleel, Mohammad A.

2012-03-01T23:59:59.000Z

203

THE EFFECT OF ANISOTROPIC CONDUCTION ON THE THERMAL INSTABILITY IN THE INTERSTELLAR MEDIUM  

SciTech Connect

Thermal instability (TI) can strongly affect the structure and dynamics of the interstellar medium (ISM) in the Milky Way and other disk galaxies. Thermal conduction plays an important role in the TI by stabilizing small scales and limiting the size of the smallest condensates. In the magnetized ISM, however, heat is conducted anisotropically (primarily along magnetic field lines). We investigate the effects of anisotropic thermal conduction on the nonlinear regime of the TI by performing two-dimensional magnetohydrodynamic simulations. We present models with magnetic fields of different initial geometries and strengths, and compare them to hydrodynamic models with isotropic conduction. We find that anisotropic conduction does not significantly alter the overall density and temperature statistics in the saturated state of the TI. However, it can strongly affect the shapes and sizes of cold clouds formed by the TI. For example, for uniform initial fields long filaments of cold gas are produced that are reminiscent of some observed H I clouds. For initially tangled fields, such filaments are not produced. We also show that anisotropic conduction suppresses turbulence generated by evaporative flows from the surfaces of cold blobs, which may have implications for mechanisms for driving turbulence in the ISM.

Choi, Ena; Stone, James M. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

2012-03-10T23:59:59.000Z

204

The Dynamics of Rayleigh-Taylor Stable and Unstable Contact Discontinuities with Anisotropic Thermal Conduction  

E-Print Network (OSTI)

We study the effects of anisotropic thermal conduction along magnetic field lines on an accelerated contact discontinuity in a weakly collisional plasma. We first perform a linear stability analysis similar to that used to derive the Rayleigh-Taylor instability (RTI) dispersion relation. We find that anisotropic conduction is only important for compressible modes, as incompressible modes are isothermal. Modes grow faster in the presence of anisotropic conduction, but growth rates do not change by more than a factor of order unity. We next run fully non-linear numerical simulations of a contact discontinuity with anisotropic conduction. The non-linear evolution can be thought of as a superposition of three physical effects: temperature diffusion due to vertical conduction, the RTI, and the heat flux driven buoyancy instability (HBI). In simulations with RTI-stable contact discontinuities, the temperature discontinuity spreads due to vertical heat conduction. This occurs even for initially horizontal magnetic f...

Lecoanet, Daniel; Quataert, Eliot

2012-01-01T23:59:59.000Z

205

Thermal conductivity of silicic tuffs: predictive formalism and comparison with preliminary experimental results  

Science Conference Proceedings (OSTI)

Performance of both near- and far-field thermomechanical calculations to assess the feasibility of waste disposal in silicic tuffs requires a formalism for predicting thermal conductivity of a broad range of tuffs. This report summarizes the available thermal conductivity data for silicate phases that occur in tuffs and describes several grain-density and conductivity trends which may be expected to result from post-emplacement alteration. A bounding curve is drawn that predicts the minimum theoretical matrix (zero-porosity) conductivity for most tuffs as a function of grain density. Comparison of experimental results with this curve shows that experimental conductivities are consistently lower at any given grain density. Use of the lowered bounding curve and an effective gas conductivity of 0.12 W/m{sup 0}C allows conservative prediction of conductivity for a broad range of tuff types. For the samples measured here, use of the predictive curve allows estimation of conductivity to within 15% or better, with one exception. Application and possible improvement of the formalism are also discussed.

Lappin, A. R.

1980-07-01T23:59:59.000Z

206

Atomistic calculation of the thermal conductance of large scale bulk-nanowire junctions  

SciTech Connect

We have developed a stable and efficient kernel method to compute thermal transport in open systems, based on the scattering-matrix approach. This method is applied to compute the thermal conductance of a junction between bulk silicon and silicon nanowires with diameter up to 10 nm. We have found that beyond a threshold diameter of 7 nm, transmission spectra and contact conductances scale with the cross section of the contact surface, whereas deviations from this general trend are observed in thinner wires. This result allows us to predict the thermal resistance of bulk-nanowire interfaces with larger cross sections than those tractable with atomistic simulations, and indicate the characteristic size beyond which atomistic systems can in principle be treated accurately by mean-field theories. Our calculations also elucidate how dimensionality reduction and shape affect interfacial heat transport.

Duchemin, Ivan; Donadio, Davide [Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz (Germany)

2011-09-15T23:59:59.000Z

207

Enhanced thermal conductivity of ethylene glycol with single-walled carbon nanotube inclusions  

E-Print Network (OSTI)

with the Hamilton-Crosser model, the Lu-Lin model, Nan`s effective medium theory and the Hashin-Strikman model to rest of the models. Networking of nanotubes to form a tri-dimensional structure was considered #12;models. Therefore, more studies need to be performed to measure the effective thermal conductivity

Maruyama, Shigeo

208

Temperature dependent thermal conductivity increase of aqueous nanofluid with single walled carbon nanotube inclusions  

E-Print Network (OSTI)

the thermal conductivity at higher temperatures up to 6%. Computational modeling of SWCNTs in water using of water seeded with single-walled carbon nanotubes (SWCNT) synthesized using the alcohol catalytic this fluid for practical applications. We compare experimental results with existing analytical models

Maruyama, Shigeo

209

Thermal Inertia of Conductivity Cells: Observations with a Sea-Bird Cell  

Science Conference Proceedings (OSTI)

We have examined the magnitude and relaxation time of the thermal anomaly of the fluid flowing through the conductivity cell manufactured by Sea-Bird Electronics (SBE) that is induced by the heat stored in the wall of this cell using oceanic data ...

Rolf G. Lueck; James J. Picklo

1990-10-01T23:59:59.000Z

210

Thermal battery. [solid metal halide electrolytes with enhanced electrical conductance after a phase transition  

DOE Patents (OSTI)

The patent describes an improved thermal battery whose novel design eliminates various disadvantages of previous such devices. Its major features include a halide cathode, a solid metal halide electrolyte which has a substantially greater electrical conductance after a phase transition at some temperature, and a means for heating its electrochemical cells to activation temperature.

Carlsten, R.W.; Nissen, D.A.

1973-03-06T23:59:59.000Z

211

Functionally gradient materials for thermal barrier coatings in advanced gas turbine systems  

DOE Green Energy (OSTI)

New designs for advanced gas turbine engines for power production are required to have higher operating temperatures in order to increase efficiency. However, elevated temperatures will increase the magnitude and severity of environmental degradation of critical turbine components (e.g. combustor parts, turbine blades, etc.). To offset this problem, the usage of thermal barrier coatings (TBCs) has become popular by allowing an increase in maximum inlet temperatures for an operating engine. Although thermal barrier technology is over thirty years old, the principle failure mechanism is the spallation of the ceramic coating at or near the ceramic/bond coat interface. Therefore, it is desirable to develop a coating that combines the thermal barrier qualities of the ceramic layer and the corrosion protection by the metallic bond coat without the detrimental effects associated with the localization of the ceramic/metal interface to a single plane.

Banovic, S.W.; Chan, H.M.; Marder, A.R. [Lehigh Univ., Bethlehem, PA (United States)] [and others

1995-12-31T23:59:59.000Z

212

Low Thermal Conductivity of RE4Si2O7N2 (RE=Y, Lu): A Systematic ...  

Science Conference Proceedings (OSTI)

The present work shows that identifying new low thermal conductivity ceramics can be realized by a combination approach of first-principles calculation and ...

213

Structure, thermal expansion and electrical conductivity of Nb-substituted LaCoO{sub 3}  

Science Conference Proceedings (OSTI)

The effect of Nb-substitution in LaCoO{sub 3} has been examined by evaluating the electrical conductivity, thermal expansion and crystal structure of the solid solutions LaCo{sub 1-x}Nb{sub x}O{sub 3} (x=0 to 1/3). It was demonstrated that Nb-substitution in LaCoO{sub 3} was mainly compensated by reduction of Co{sup 3+} to Co{sup 2+}, and that oxidation of Co{sup 2+} could destabilise the solid solution. The ambient crystal structure was shown to transform from rhombohedral R3{sup Macron }c perovskite (x=0) to orthorhombic Pbnm (x=0.15, 0.20) and finally to B-site ordered perovskite P2{sub 1}/n (x=0.25, 1/3) perovskite with increasing Nb-substitution. The thermal expansion of LaCo{sub 1-x}Nb{sub x}O{sub 3} was shown to be strongly depressed with increasing Nb-content, and significantly lower thermal expansion was observed for LaCo{sub 2/3}Nb{sub 1/3}O{sub 3} relative to LaCoO{sub 3}. The electrical conductivity was reduced with increasing Nb-content, and semi-conducting properties was demonstrated for LaCo{sub 1-x}Nb{sub x}O{sub 3} in contrast to the metallic behaviour of pure LaCoO{sub 3} at elevated temperature. The thermal expansion, electrical conductivity and the stability of the materials were discussed with emphasis on Co/Nb ordering, the oxidation state and spin transitions of Co. - Graphical abstract: Substitution of Nb in LaCoO{sub 3} increases the unit cell volume, reduces the symmetry of the unit cell and introduces cation ordering. The chemical substitution leads to suppression of the electronic conductivity and reduces the thermal expansion of the lattice. Highlights: Black-Right-Pointing-Pointer Cation ordering and crystal structure is reported for LaCo{sub x}Nb{sub 1-x}O{sub 3}. Black-Right-Pointing-Pointer Substitution of Nb in LaCoO{sub 3} is compensated by reduction of Co{sup 3+} to Co{sup 2+}. Black-Right-Pointing-Pointer Thermal expansion of LaCoO{sub 3} is reduced by Nb-substitution. Black-Right-Pointing-Pointer Electrical conductivity of LaCoO{sub 3} is reduced by Nb-substitution.

Oygarden, Vegar; Lein, Hilde L. [Department of Materials Science and Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim (Norway); Grande, Tor, E-mail: grande@ntnu.no [Department of Materials Science and Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim (Norway)

2012-08-15T23:59:59.000Z

214

Development of a Test Technique to Determine the Thermal Conductivity of Large Refractory Ceramic Test Specimens  

SciTech Connect

A method has been developed to utilize the High Intensity Infrared lamp located at Oak Ridge National Laboratory for the measurement of thermal conductivity of bulk refractory materials at elevated temperatures. The applicability of standardized test methods to determine the thermal conductivity of refractory materials at elevated temperatures is limited to small sample sizes (laser flash) or older test methods (hot wire, guarded hot plate), which have their own inherent problems. A new method, based on the principle of the laser flash method, but capable of evaluating test specimens on the order of 200 x 250 x 50 mm has been developed. Tests have been performed to validate the method and preliminary results are presented in this paper.

Hemrick, James Gordon [ORNL; Dinwiddie, Ralph Barton [ORNL; Loveland, Erick R [ORNL; Prigmore, Andre L [ORNL

2012-01-01T23:59:59.000Z

215

Dissipative instability of MHD tangential discontinuity in magnetized plasmas with anisotropic viscosity and thermal conductivity.  

E-Print Network (OSTI)

The stability of the MHD tangential discontinuity is studied in compressible plasmas in the presence of anisotropic viscosity and thermal conductivity. The general dispersion equation is derived and solutions to this dispersion equation and stability criteria are obtained for the limiting cases of incompressible and cold plasmas. In these two limiting cases the effect of thermal conductivity vanishes and the solutions are only influenced by viscosity. The stability criteria for viscous plasmas are compared with those for ideal plasmas where stability is determined by the Kelvin-Helmholtz velocity VKH as a threshold for the difference in the equilibrium velocities. Viscosity turns out to have a destabilizing influence when the viscosity coefficient takes different values at the two sides of the discontinuity. Viscosity lowers the threshold velocity V c below the ideal KelvinHelmholtz velocity VKH , so that there is a range of velocities between V c and VKH where the overstability is of ...

Michael Ruderman; Erwin Verwichte; Robertus Erdelyi; Marcel Goossens; Elyiyy

1996-01-01T23:59:59.000Z

216

Unglazed transpired solar collector having a low thermal-conductance absorber  

DOE Patents (OSTI)

An unglazed transpired solar collector using solar radiation to heat incoming air for distribution, comprises an unglazed absorber formed of low thermal-conductance material having a front surface for receiving the solar radiation and openings in the unglazed absorber for passage of the incoming air such that the incoming air is heated as it passes towards the front surface of the absorber and the heated air passes through the openings in the absorber for distribution. 3 figs.

Christensen, C.B.; Kutscher, C.F.; Gawlik, K.M.

1997-12-02T23:59:59.000Z

217

Unglazed transpired solar collector having a low thermal-conductance absorber  

DOE Patents (OSTI)

An unglazed transpired solar collector using solar radiation to heat incoming air for distribution, comprising an unglazed absorber formed of low thermal-conductance material having a front surface for receiving the solar radiation and openings in the unglazed absorber for passage of the incoming air such that the incoming air is heated as it passes towards the front surface of the absorber and the heated air passes through the openings in the absorber for distribution.

Christensen, Craig B. (Boulder, CO); Kutscher, Charles F. (Golden, CO); Gawlik, Keith M. (Boulder, CO)

1997-01-01T23:59:59.000Z

218

Measurement of effective thermal conductivity of wheat as a function of moisture content  

Science Conference Proceedings (OSTI)

Grain drying and storage are one of the main activities of agricultural industry. Increasing energy costs have stressed the importance of calculation of heat and mass transfer in a grain bulk in order to be able to optimize drying facilities. Another limitation during drying is the preservation of grain structure and its nutritional values, Muehlbauer and Christ have shown that damage to the grain structure and grain nutritional value is dependent upon grain temperature and drying time. Therefore, proper conditions during drying and storage of cereal grains require the knowledge of the thermophysical properties of the grains. The effective thermal conductivity of two varieties of Triticum durum wheat and a wheat product, bulgur, is determined at different moisture contents and at ambient temperature by the transient lime heat source method. The moisture contents of the samples ranged from 9.17 to 38.65% wet basis and the bulk densities ranged from 675 to 827 kg/m{sup 3}. Under those conditions, the measured effective thermal conductivities ranged from 0.159 to 0.201 W/m.K. The effective thermal conductivity is found to be linearly increasing with moisture content. The results are also in good agreement with literature values.

Tavman, S. [Ege Univ., Izmir (Turkey). Food Engineering Dept.] [Ege Univ., Izmir (Turkey). Food Engineering Dept.; Tavman, I.H. [Dokuz Eyluel Univ., Izmir (Turkey). Mechanical Engineering Dept.] [Dokuz Eyluel Univ., Izmir (Turkey). Mechanical Engineering Dept.

1998-07-01T23:59:59.000Z

219

Thermal conductivity of diamond-loaded glues for the ATLAS particle physics detector  

E-Print Network (OSTI)

The ATLAS experiment is one of two large general-purpose particle detectors at the Large Hadron Collider (LHC) at the CERN laboratory in Geneva, Switzerland. ATLAS has been collecting data from the collisions of protons since December 2009, in order to investigate the conditions that existed during the early Universe and the origins of mass, and other topics in fundamental particle physics. The innermost layers of the ATLAS detector will be exposed to the most radiation over the first few years of operation at the LHC. In particular, the layer closest to the beam pipe, the B-layer, will degrade over time due to the added radiation. To compensate for its degradation, it will be replaced with an Insertable B-Layer (IBL) around 2016. The design of and R&D for the IBL is ongoing, as the hope is to use the most current technologies in the building of this new sub-detector layer. One topic of interest is the use of more thermally conductive glues in the construction of the IBL, in order to facilitate in the dissipation of heat from the detector. In this paper the measurement and use of highly thermally conductive glues, in particular those that are diamond-loaded, will be discussed. The modified transient plane source technique for thermal conductivity is applied in characterizing the glues across a wide temperature range.

E. A. Ouellette; A. Harris

2010-08-04T23:59:59.000Z

220

Thermal diffusivity and thermal conductivity of sintered UO2 and UO2-Gd2O3. Technical report  

SciTech Connect

The thermal diffusivity was measured using the laser flash method on sintered uranium dioxide (O/U=2.003, density=10.48X10 kg/m, from 300 to 2773 K), and urania and gadolinia mixed fuel (2,4 and 6 Wt% Gd2O3 content, from 600 to 1850 K). An equation was suggested for near-stoichiometric uranium dioxide over the temperature range 500-3100 K: K=(1-aP)(1/(A+BT)+DTxexp(-E/kT)x(1+H(E/kT+2)(sup 2))), where K in W/(m)(K), P is the fraction of porosity, a=2.74-5.8X10(sup 4-)T, A=3.68X10(sup 2-)(m)(K)/W, B=2.25X10(sup 4-)m/W, D=5.31X10(sup 3-)W/mXK2, H=0.264, E=1.15 ev, k is the Boltzmann constant. The thermal conductivity of UO2-Gd2O3 samples as a function of temperature and Gd2O3 content, X, could be expressed by phonon conduction; K=1/(A+BT) in the temperature range from 600 to 1700 K, where A=2.50 X+0.044(m)(K)/W.

Ying, S.; Ji, Z.

1988-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "gradients thermal conductivity" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Fabrication of high thermal conductivity arrays of carbon nanotubes and their composites  

DOE Patents (OSTI)

Methods and apparatus are described for fabrication of high thermal conductivity arrays of carbon nanotubes and their composites. A composition includes a vertically aligned nanotube array including a plurality of nanotubes characterized by a property across substantially all of the vertically aligned nanotube array. A method includes depositing a vertically aligned nanotube array that includes a plurality of nanotubes; and controlling a deposition rate of the vertically aligned nanotubes array as a function of an in situ monitored property of the plurality of nanotubes.

Geohegan, David B. (Knoxville, TN); Ivanov, Ilya N. (Knoxville, TN); Puretzky,; Alexander A. (Knoxville, TN)

2010-07-27T23:59:59.000Z

222

Experimental investigation of size effect on thermal conductivity for ultra-thin amorphous poly(methyl methacrylate) (PMMA) films  

E-Print Network (OSTI)

An investigation was conducted to determine whether a “size effect” phenomenon for one particular thermophysical property, thermal conductivity, actually exists for amorphous poly(methyl methacrylate) (PMMA) films with thicknesses ranging from 40 nm to 2 ?m. This was done by using a non-contact, non-invasive, in-situ Transient Thermo-Reflectance (TTR) laser based technique. The results demonstrated that the intrinsic thermal conductivity of a 40 nm PMMA film deposited on native oxide of silicon increases by a factor of three over bulk PMMA values, and a distinct increase in the thermal conductivity of PMMA film was observed in ultra-thin (sub 100 nm) films. This confirmed the importance of film thickness for the through-plane thermal conductivity value of PMMA film on native oxide of silicon.

Kim, Ick Chan

2007-05-01T23:59:59.000Z

223

Preparation of silica aerogels with improved mechanical properties and extremely low thermal conductivities through modified sol-gel process  

E-Print Network (OSTI)

Reported silica aerogels have a thermal conductivity as low as 15 mW/mK. The fragility of silica aerogels, however, makes them impractical for structural applications. The purpose of the study is to improve the ductility ...

Zuo, Yanjia

2010-01-01T23:59:59.000Z

224

PROBLEM 13.94 KNOWN: Diameter, temperature and emissivity of boiler tube. Thermal conductivity and emissivity of  

E-Print Network (OSTI)

PROBLEM 13.94 KNOWN: Diameter, temperature and emissivity of boiler tube. Thermal conductivity of 0.5 mm), Td = 773 K nd the ash provides a significant resistance to heat transfer.a COMMENTS: Boiler

Rothstein, Jonathan

225

Experimental Determination of the Effect of Reactor Radiation on the Thermal Conductivity of Uranium-Impregnated Graphite  

SciTech Connect

Experiments are described in which the change in thermal conductivity of U-impregnated graphite under neutron irradiation was measured. Thermal resistivities relative to the thermal resistivity of undamaged impregnated graphite are reorted as functions of exposure. From applications of the expermental results to the North American Aviation low-power research reactor the peak tem. of the core is determined for a given reactor power and time of operation.

Hetrick, D.L.; McCarty, W.K.; Steele, G.N.; Brown, M.S.; Clark, E.V.; Holmes, F.R.; Howard, D.F.; McElroy, W.N.; Shields, B.L.

1953-01-06T23:59:59.000Z

226

Ground surface temperature reconstructions: Using in situ estimates for thermal conductivity acquired with a fiber-optic distributed thermal perturbation sensor  

Science Conference Proceedings (OSTI)

We have developed a borehole methodology to estimate formation thermal conductivity in situ with a spatial resolution of one meter. In parallel with a fiber-optic distributed temperature sensor (DTS), a resistance heater is deployed to create a controlled thermal perturbation. The transient thermal data is inverted to estimate the formation's thermal conductivity. We refer to this instrumentation as a Distributed Thermal Perturbation Sensor (DTPS), given the distributed nature of the DTS measurement technology. The DTPS was deployed in permafrost at the High Lake Project Site (67 degrees 22 minutes N, 110 degrees 50 minutes W), Nunavut, Canada. Based on DTPS data, a thermal conductivity profile was estimated along the length of a wellbore. Using the thermal conductivity profile, the baseline geothermal profile was then inverted to estimate a ground surface temperature history (GSTH) for the High Lake region. The GSTH exhibits a 100-year long warming trend, with a present-day ground surface temperature increase of 3.0 {+-} 0.8 C over the long-term average.

Freifeld, B.M.; Finsterle, S.; Onstott, T.C.; Toole, P.; Pratt, L.M.

2008-10-10T23:59:59.000Z

227

Cross-plane lattice and electronic thermal conductivities of ErAs : InGaAs/InGaAlAs superlattices  

E-Print Network (OSTI)

should be noted that the lattice thermal conductivity should88, 242107 ?2006? Cross-plane lattice and electronic thermalWe studied the cross-plane lattice and electronic thermal

2006-01-01T23:59:59.000Z

228

Thermally conductive cementitious grouts for geothermal heat pumps. Progress report FY 1998  

DOE Green Energy (OSTI)

Research commenced in FY 97 to determine the suitability of superplasticized cement-sand grouts for backfilling vertical boreholes used with geothermal heat pump (GHP) systems. The overall objectives were to develop, evaluate and demonstrate cementitious grouts that could reduce the required bore length and improve the performance of GHPs. This report summarizes the accomplishments in FY 98. The developed thermally conductive grout consists of cement, water, a particular grade of silica sand, superplasticizer and a small amount of bentonite. While the primary function of the grout is to facilitate heat transfer between the U-loop and surrounding formation, it is also essential that the grout act as an effective borehole sealant. Two types of permeability (hydraulic conductivity) tests was conducted to evaluate the sealing performance of the cement-sand grout. Additional properties of the proposed grout that were investigated include bleeding, shrinkage, bond strength, freeze-thaw durability, compressive, flexural and tensile strengths, elastic modulus, Poisson`s ratio and ultrasonic pulse velocity.

Allan, M.L.; Philippacopoulos, A.J.

1998-11-01T23:59:59.000Z

229

Method of making improved gas storage carbon with enhanced thermal conductivity  

DOE Patents (OSTI)

A method of making an adsorbent carbon fiber based monolith having improved methane gas storage capabilities is disclosed. Additionally, the monolithic nature of the storage carbon allows it to exhibit greater thermal conductivity than conventional granular activated carbon or powdered activated carbon storage beds. The storage of methane gas is achieved through the process of physical adsorption in the micropores that are developed in the structure of the adsorbent monolith. The disclosed monolith is capable of storing greater than 150 V/V of methane [i.e., >150 STP (101.325 KPa, 298K) volumes of methane per unit volume of storage vessel internal volume] at a pressure of 3.5 MPa (500 psi).

Burchell, Timothy D [Oak Ridge, TN; Rogers, Michael R [Knoxville, TN

2002-11-05T23:59:59.000Z

230

Method of making improved gas storage carbon with enhanced thermal conductivity  

SciTech Connect

A method of making an adsorbent carbon fiber based monolith having improved methane gas storage capabilities is disclosed. Additionally, the monolithic nature of the storage carbon allows it to exhibit greater thermal conductivity than conventional granular activated carbon or powdered activated carbon storage beds. The storage of methane gas is achieved through the process of physical adsorption in the micropores that are developed in the structure of the adsorbent monolith. The disclosed monolith is capable of storing greater than 150 V/V of methane [i.e., >150 STP (101.325 KPa, 298K) volumes of methane per unit volume of storage vessel internal volume] at a pressure of 3.5 MPa (500 psi).

Burchell, Timothy D. (Oak Ridge, TN); Rogers, Michael R. (Knoxville, TN)

2002-01-01T23:59:59.000Z

231

Characterization of Min-K TE-1400 Thermal Insulation (Two-Year Gradient Stress Relaxation Testing Update)  

Science Conference Proceedings (OSTI)

Min-K 1400TE insulation material was characterized at Oak Ridge National Laboratory for use in structural applications under gradient temperature conditions. A previous report (ORNL/TM-2008/089) discusses the testing and results from the original three year duration of the project. This testing included compression testing to determine the effect of sample size and test specimen geometry on the compressive strength of Min-K, subsequent compression testing on cylindrical specimens to determine loading rates for stress relaxation testing, isothermal stress relaxation testing, and gradient stress relaxation testing. This report presents the results from the continuation of the gradient temperature stress relaxation testing and the resulting updated modeling.

Hemrick, James Gordon [ORNL; Lara-Curzio, Edgar [ORNL; King, James [ORNL

2009-09-01T23:59:59.000Z

232

Evaluation of the Thermal Performance for a Wire Mesh/Hollow Glass Microsphere Composite Structure as a Conduction Barrier  

E-Print Network (OSTI)

An experimental investigation exploring the use of wire mesh/hollow glass microsphere combination for use as thermal insulation was conducted with the aim to conclude whether or not it represents a superior insulation technology to those on the market. Three primary variables, including number of wire mesh layers, filler material, and temperature dependence were studied using an apparatus that was part of L.I.C.H.E.N (LabVIEW Integrated Conduction Heat Experiment Network), a setup whose basic components allow three vertically stacked samples to be thermally and mechanically controlled. Knowing the temperature profile in the upper and lower samples allows for determination of thermal conductivity of the middle material through the use of Fourier?s law. The numbers of layers investigated were two, four, six, and eight, with each separated by a metallic liner. The filler materials included air, s15, s35 and s60HS 3MTM hollow glass microspheres. The experiments were conducted at four temperatures of 300, 330, 366, and 400K with an interface pressure of 20 Psi. The experimental results indicated the ?number of layers? used was the primary factor in determining the effective thermal conductivity value. The addition of hollow glass microspheres as filler material resulted in statistically insignificant changes in effective thermal conductivity. Increasing the number of wire mesh layers resulted in a corresponding increase in effective thermal conductivity of the insulation. Changes in temperature had little to no effect on thermal conductivity. The effective thermal conductivity values for the proposed insulation structure ranged from 0.22 to 0.65 W/m-K, the lowest of which came from the two layer case having air as filler material. The uncertainties associated with the experimental results fell between 10 to 20 percent in all but a few cases. In the best performing cases, when compared with existing insulation technologies, thermal conductivity was approximately 3 to 10 times higher than these methods of insulation. Thus, the proposed insulation scheme with hollow glass-sphere filler material does not represent superior technology, and would be deemed uncompetitive with those readily available in the insulation market.

Mckenna, Sean

2008-12-01T23:59:59.000Z

233

Comparison of Different Upscaling Methods for Predicting Thermal Conductivity of Complex Heterogeneous Materials System: Application on Nuclear Waste Forms  

SciTech Connect

To develop a strategy in thermal conductivity prediction of a complex heterogeneous materials system, loaded nuclear waste forms, the computational efficiency and accuracy of different upscaling methods have been evaluated. The effective thermal conductivity, obtained from microstructure information and local thermal conductivity of different components, is critical in predicting the life and performance of waste form during storage. Several methods, including the Taylor model, Sachs model, self-consistent model, and statistical upscaling method, were developed and implemented. Microstructure based finite element method (FEM) prediction results were used to as benchmark to determine the accuracy of the different upscaling methods. Micrographs from waste forms with varying waste loadings were used in the prediction of thermal conductivity in FEM and homogenization methods. Prediction results demonstrated that in term of efficiency, boundary models (e.g., Taylor model and Sachs model) are stronger than the self-consistent model, statistical upscaling method, and finite element method. However, when balancing computational efficiency and accuracy, statistical upscaling is a useful method in predicting effective thermal conductivity for nuclear waste forms.

Li, Dongsheng; Sun, Xin; Khaleel, Mohammad A.

2013-01-01T23:59:59.000Z

234

Design of a steady state thermal conductivity measurement device for CNT RET polymer composites  

E-Print Network (OSTI)

fall within ~ 10%. Heat conduction through the TCs coulda 6% difference. To eliminate heat conduction effects, otherlaw formulation of heat conduction in materials. BASIC

Louie, Brian Ming

2011-01-01T23:59:59.000Z

235

Conduction Effect of Thermal Radiation in a Metal Shield Pipe in a Cryostat for a Cryogenic Interferometric Gravitational Wave Detector  

E-Print Network (OSTI)

A large heat load caused by thermal radiation through a metal shield pipe was observed in a cooling test of a cryostat for a prototype of a cryogenic interferometric gravitational wave detector. The heat load was approximately 1000 times larger than the value calculated by the Stefan-Boltzmann law. We studied this phenomenon by simulation and experiment and found that it was caused by the conduction of thermal radiation in a metal shield pipe.

Takayuki Tomaru; Masao Tokunari; Kazuaki Kuroda; Takashi Uchiyama; Akira Okutomi; Masatake Ohashi; Hiroyuki Kirihara; Nobuhiro Kimura; Yoshio Saito; Nobuaki Sato; Takakazu Shintomi; Toshikazu Suzuki; Tomiyoshi Haruyama; Shinji Miyoki; Kazuhiro Yamamoto; Akira Yamamoto

2007-11-06T23:59:59.000Z

236

A method for the thermal characterization, visualization, and integrity evaluation of conducting material samples or complex structures  

DOE Patents (OSTI)

This invention is useful in thermal imaging of conducting materials, and is particularly useful in measuring thermal conductivity and thermal boundary conditions in composite anisotropic materials, in materials of irregular shape, and in materials for high-temperature applications. It also has utility in visualizing the integrity of complex structures such as a machine, power plant, or chemical plant. The method is for modeling a conducting material sample or structure (system) as an electrical network of resistances, for measuring electric resistance between selected leads attached to the surface of the system, and, using basic circuit theory, for translating measured resistances into temperatures or indications of integrity in corresponding regions of the system. 10 figs.

Ortiz, M.G.

1991-12-31T23:59:59.000Z

237

Salt concentration gradient solar ponds: modeling and optimization  

DOE Green Energy (OSTI)

A computer simulation design tool has been developed to simulate dynamic thermal performance for salinity gradient solar ponds. This program will be available to the public through the SERI Solar Analysis Methods Center. Dynamic programming techniques are applied to allow significant user flexibility in analyzing pond performance under realistic load and weather conditions. Finite element techniques describe conduction heat transfer through the pond, earth, and edges. Results are presented that illustrate typical thermal performance of salinity gradient ponds. Sensitivity studies of salty pond thermal performance with respect to geometry, load, and optical transmission are included.

Jayadev, T. S.; Henderson, J.

1979-01-01T23:59:59.000Z

238

Anomalously low thermal conductivity and thermoelectric properties of new cationic clathrates in the Sn-In-As-I system  

Science Conference Proceedings (OSTI)

Single-crystal samples of cationic clathrates in the Sn-In-As-I system with different indium contents have been synthesized. Their crystal structure has been analyzed and their thermoelectric properties have been measured. These compounds are found to be n-type semiconductors with high absolute values of the Seebeck coefficient (S = 400-600 {mu}V/K) and anomalously low thermal conductivity ({kappa} {materials. The reasons for the anomalously low thermal conductivity of these semiconductors are discussed and ways for optimizing their thermoelectric properties are shown.

Shevelkov, A. V.; Kelm, E. A.; Olenev, A. V. [Moscow State University, Faculty of Chemistry (Russian Federation); Kulbachinskii, V. A., E-mail: kulb@mig.phys.msu.ru; Kytin, V. G. [Moscow State University, Faculty of Physics (Russian Federation)

2011-11-15T23:59:59.000Z

239

Thermal conductivity depth-profile reconstruction of multilayered cylindrical solids using the thermal-wave Green function method  

Science Conference Proceedings (OSTI)

In this paper, a theoretical model for characterizing solid multi-layered cylindrical samples illuminated by a modulated uniform incident beam is developed by means of the Green function method. The specific Green function for the multi-layered cylindrical structure is derived and an analytical expression for the thermal-wave field in such a cylindrical sample is presented. The thermal-wave field of an inhomogeneous cylindrical sample irradiated with incident light of arbitrary angular and/or radial intensity distribution was obtained using this theoretical model. Furthermore, experimental validation is also presented in the form of experimental results with steel cylinders of various diameters.

Xie Guangxi [Key Lab of Modern Optical Technologies of Jiangsu Province, Institute of Modern Optical Technologies, Soochow University, Suzhou, Jiangsu, 215006 (China); Department of Physics, Jiangnan University, Wuxi, Jiangsu, 214122 (China); Zhang Jie; Liu Liwang; Wang Chinhua [Key Lab of Modern Optical Technologies of Jiangsu Province, Institute of Modern Optical Technologies, Soochow University, Suzhou, Jiangsu, 215006 (China); Mandelis, Andreas [Center for Advanced Diffusion-Wave Technologies (CADIFT), Department of Mechanical and Industrial Engineering, University of Toronto M5S 3G8, Ontario (Canada)

2011-06-01T23:59:59.000Z

240

Heat Conduction  

Science Conference Proceedings (OSTI)

Table 2   Differential equations for heat conduction in solids...conduction in solids General form with variable thermal properties General form with constant thermal properties General form, constant properties, without heat

Note: This page contains sample records for the topic "gradients thermal conductivity" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
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241

The Effect of Silicon on the Thermal Conductivity of Al-Si Alloys  

Science Conference Proceedings (OSTI)

In order to develop new die-cast aluminum alloys with adequate thermal ... Frequency Modulation Effect on the Solidification of Alloy 718 Fusion Zone.

242

Fabrication of nano-hole array patterns on transparent conducting oxide layer using thermally curable nanoimprint lithography  

Science Conference Proceedings (OSTI)

A two-dimensional, periodic array of nano-sized holes was fabricated in an indium tin oxide (ITO) layer, deposited onto a glass substrate with nanoimprint lithography. As a result of a thermally curing imprint process, hole array patterns with a diameter ... Keywords: Indium tin oxide (ITO), Nanoimprint lithography (NIL), Patterned transparent electrode, Photonic crystals, Transparent conducting oxide (TCO) layer

Kyeong-Jae Byeon; Seon-Yong Hwang; Heon Lee

2008-05-01T23:59:59.000Z

243

Hyper-resistivity and electron thermal conductivity due to destroyed magnetic surfaces in axisymmetric plasma equilibria  

Science Conference Proceedings (OSTI)

In order to model the effects of small-scale current-driven magnetic fluctuations in a mean-field theoretical description of a large-scale plasma magnetic field B(x,t), a space and time dependent hyper-resistivity {Lambda}(x,t) can be incorporated into the Ohm's law for the parallel electric field E Dot-Operator B. Using Boozer coordinates, a theoretical method is presented that allows for a determination of the hyper-resistivity {Lambda}({psi}) functional dependence on the toroidal magnetic flux {psi} for arbitrary experimental steady-state Grad-Shafranov axisymmetric plasma equilibria, if values are given for the parallel plasma resistivity {eta}({psi}) and the local distribution of any auxiliary plasma current. Heat transport in regions of plasma magnetic surfaces destroyed by resistive tearing modes can then be modeled by an electron thermal conductivity k{sub e}({psi})=({epsilon}{sub 0}{sup 2}m{sub e}/e{sup 2}){Lambda}({psi}), where e and m{sub e} are the electron charge and mass, respectively, while {epsilon}{sub 0} is the permittivity of free space. An important result obtained for axisymmetric plasma equilibria is that the {psi}{psi}-component of the metric tensor of Boozer coordinates is given by the relation g{sup {psi}{psi}}({psi}){identical_to}{nabla}{psi} Dot-Operator {nabla}{psi}=[{mu}{sub 0}G({psi})][{mu}{sub 0}I({psi})]/{iota}({psi}), with {mu}{sub 0} the permeability of free space, G({psi}) the poloidal current outside a magnetic surface, I({psi}) the toroidal current inside a magnetic surface, and {iota}({psi}) the rotational transform.

Weening, R. H. [Department of Radiologic Sciences, Thomas Jefferson University, 901 Walnut Street, Philadelphia, Pennsylvania 19107-5233 (United States)

2012-06-15T23:59:59.000Z

244

IMPACT OF TEMPERATURE-DEPENDENT RESISTIVITY AND THERMAL CONDUCTION ON PLASMOID INSTABILITIES IN CURRENT SHEETS IN THE SOLAR CORONA  

SciTech Connect

In this paper, we investigate, by means of two-dimensional magnetohydrodynamic simulations, the impact of temperature-dependent resistivity and thermal conduction on the development of plasmoid instabilities in reconnecting current sheets in the solar corona. We find that the plasma temperature in the current-sheet region increases with time and it becomes greater than that in the inflow region. As secondary magnetic islands appear, the highest temperature is not always found at the reconnection X-points, but also inside the secondary islands. One of the effects of anisotropic thermal conduction is to decrease the temperature of the reconnecting X-points and transfer the heat into the O-points, the plasmoids, where it gets trapped. In the cases with temperature-dependent magnetic diffusivity, {eta} {approx} T {sup -3/2}, the decrease in plasma temperature at the X-points leads to (1) an increase in the magnetic diffusivity until the characteristic time for magnetic diffusion becomes comparable to that of thermal conduction, (2) an increase in the reconnection rate, and (3) more efficient conversion of magnetic energy into thermal energy and kinetic energy of bulk motions. These results provide further explanation of the rapid release of magnetic energy into heat and kinetic energy seen during flares and coronal mass ejections. In this work, we demonstrate that the consideration of anisotropic thermal conduction and Spitzer-type, temperature-dependent magnetic diffusivity, as in the real solar corona, are crucially important for explaining the occurrence of fast reconnection during solar eruptions.

Ni Lei; Roussev, Ilia I.; Lin Jun [Yunnan Astronomical Observatory, CAS, P.O. Box 110, Kunming 650011, Yunnan (China); Ziegler, Udo, E-mail: leini@ynao.ac.cn, E-mail: iroussev@ifa.hawaii.edu, E-mail: uziegler@aip.de [Leibniz-Institut fuer Astrophysik Potsdam, D-14482 Potsdam (Germany)

2012-10-10T23:59:59.000Z

245

Modeling Simulation Of Pyrolysis Of Biomass: Effect Of Thermal Conductivity, Reactor Temperature And Particle Size On Product Concentrations  

E-Print Network (OSTI)

The simultaneous chemical kinetics and heat transfer model is used to predict the effects of the most important physical and thermal properties (thermal conductivity, reactor temperature and particle size) of the feedstock on the convective-radiant pyrolysis of biomass fuels. The effects of these parameters have been analyzed for different geometries such as slab, cylinder and sphere. Finite difference method is employed for solving heat transfer model equation while Runge-Kutta 4 th order method is used for solving chemical kinetics model equations. Simulations are carried out for equivalent radius ranging from 0.0000125 m to 0.02 m, and temperature ranging from 303 K to 2100 K.

Chaurasia And Babu; A. S. Chaurasia; B. V. Babu

2003-01-01T23:59:59.000Z

246

Lattice Boltzmann modeling of the effective thermal conductivity for fibrous materials  

E-Print Network (OSTI)

J. , M. Wang, and Z. Li, A lattice Boltzmann algorithm forA novel thermal model for the lattice Boltzmann method inS. and Doolen G.D. , Lattice Boltzmann method for fluid

Wang, Moran; He, Jihuan; Yu, Jianyong; Pan, Ning

2007-01-01T23:59:59.000Z

247

EE5, Growth and Thermal Conductivity of Polycrystalline GaAs ...  

Science Conference Proceedings (OSTI)

A simple yet extensively used configuration for thermal management in high .... Microstructure and Properties of Colloidal ITO Films and Cold-Sputtered ITO Films .... Hybrid Inorganic-Organic Molecular Magnets on an Ultrathin Insulating Film.

248

Three-dimensional effect on the effective thermal conductivity of porous media  

E-Print Network (OSTI)

conductivity of multiphase random porous media. The energymorphology of multiphase random porous media. Wang’sfor multiphase conjugate heat transfer through a porous

Wang, Moran R Dr.; Wang, J K; Pan, N; Chen, S Y; He, J H

2007-01-01T23:59:59.000Z

249

Thermal stability of proton conducting acid doped polybenzimidazole in simulated fuel cell environments  

Science Conference Proceedings (OSTI)

Recently, polybenzimidazole membrane doped with phosphoric acid (PBI) was found to have promising properties for use as a polymer electrolyte in a high temperature (ca. 150 to 200 C) proton exchange membrane direct methanol fuel cell. However, operation at 200 C in strongly reducing and oxidizing environments introduces concerns of the thermal stability of the polymer electrolyte. To simulate the conditions in a high temperature fuel cell, PBI samples were loaded with fuel cell grade platinum black, doped with ca. 480 mole percent phosphoric acid (i.e., 4.8 H{sub 3}PO{sub 4} molecules per PBI repeat unit) and heated under atmospheres of either nitrogen, 5% hydrogen, or air in a thermal gravimetric analyzer. The products of decomposition were taken directly into a mass spectrometer for identification. In all cases weight loss below 400 C was found to be due to loss of water. Judging from the results of these tests, the thermal stability of PBI is more than adequate for use as a polymer electrolyte in a high temperature fuel cell.

Samms, S.R.; Wasmus, S.; Savinell, R.F. [Case Western Reserve Univ., Cleveland, OH (United States)

1996-04-01T23:59:59.000Z

250

Ground surface temperature reconstructions: Using in situ estimates for thermal conductivity acquired with a fiber-optic distributed thermal perturbation sensor  

E-Print Network (OSTI)

with homogeneous thermal properties, to invert cooling data.thermal simulations of DTPS testing showing modeled coolingand cooling. The match between measured and modeled thermal

Freifeld, B.M.

2009-01-01T23:59:59.000Z

251

Simulated evolution of fractures and fracture networks subject to thermal cooling: A coupled discrete element and heat conduction model  

SciTech Connect

Advancement of EGS requires improved prediction of fracture development and growth during reservoir stimulation and long-term operation. This, in turn, requires better understanding of the dynamics of the strongly coupled thermo-hydro-mechanical (THM) processes within fractured rocks. We have developed a physically based rock deformation and fracture propagation simulator by using a quasi-static discrete element model (DEM) to model mechanical rock deformation and fracture propagation induced by thermal stress and fluid pressure changes. We also developed a network model to simulate fluid flow and heat transport in both fractures and porous rock. In this paper, we describe results of simulations in which the DEM model and network flow & heat transport model are coupled together to provide realistic simulation of the changes of apertures and permeability of fractures and fracture networks induced by thermal cooling and fluid pressure changes within fractures. Various processes, such as Stokes flow in low velocity pores, convection-dominated heat transport in fractures, heat exchange between fluid-filled fractures and solid rock, heat conduction through low-permeability matrices and associated mechanical deformations are all incorporated into the coupled model. The effects of confining stresses, developing thermal stress and injection pressure on the permeability evolution of fracture and fracture networks are systematically investigated. Results are summarized in terms of implications for the development and evolution of fracture distribution during hydrofracturing and thermal stimulation for EGS.

Huang, Hai; Plummer, Mitchell; Podgorney, Robert

2013-02-01T23:59:59.000Z

252

Structure formation in the presence of relativistic heat conduction: corrections to the Jeans wave number with a stable first order in the gradients formalism  

E-Print Network (OSTI)

The problem of structure formation in relativistic dissipative fluids was analyzed in a previous work within Eckart's framework, in which the heat flux is coupled to the hydrodynamic acceleration, additional to the usual temperature gradient term. It was shown that in such case, the pathological behavior of fluctuations leads to the disapperance of the gravitational instability responsible for structure formation. In the present work the problem is revisited now using a constitutive equation derived from relativistic kinetic theory. The new relation, in which the heat flux is not coupled to the hydrodynamic acceleration, leads to a consistent first order in the gradients formalism. In this case the gravitational instability remains, and only relativistic corrections to the Jeans wave number are obtained. In the calculation here shown the non-relativistc limit is recovered, opposite to what happens in Eckart's case.

J. H. Mondragon-Suarez; A. Sandoval-Villalbazo; A. L. Garcia-Perciante

2012-01-21T23:59:59.000Z

253

Effects of axial heat conduction and material properties on the performance characteristics of a thermal transient anemometer probe  

Science Conference Proceedings (OSTI)

This paper describes an investigation of the axial heat transfer within a thermal transient anemometer probe. A previous study, evaluated the performance characteristics of a thermal transient anemometer system. The study revealed discrepancies between a simplified theory and test results in the development of a universal calibration curve for probes of varying diameters. Although the cause of these discrepancies were left uncertain due to an inadequate theoretical model, the study suggested that axial conduction within the probe could account for the deviations. In this paper, computer simulations are used to further investigate axial heat conduction within the probes. The effect on calibration of axial variations of material properties along the probes is also discussed. Results from the computer simulation are used in lieu of the theoretical model used in the previous study to develop a satisfactory universal calibration curve. The computer simulations provide evidence that there is significant axial heat conduction within the probes, and that this was the cause of the discrepancies noted in the previous study.

Bailey, J.L.; Page, R.J. [Argonne National Lab., IL (United States); Acharya, M. [Illinois Inst. of Technology, Chicago, IL (United States). Fluid Dynamics Research Center

1995-07-01T23:59:59.000Z

254

Thermal conductance of solid-liquid interfaces Scott Huxtable, Zhenbin Ge, David G. Cahill  

E-Print Network (OSTI)

-liquid interfaces: Two approaches · Transient optical absorption of nanoparticles and nanotubes in liquid substrate. #12;Nanotubes in surfactant in water: Transient absorption · Optical absorption depends · Cooling rate (RC time constant) gives interface conductance G = 12 MW m-2 K-1G = 12 MW m K #12;Application

Braun, Paul

255

Reactive and internal contributions to the thermal conductivity of local thermodynamic equilibrium nitrogen plasma: The effect of electronically excited states  

Science Conference Proceedings (OSTI)

Internal and reactive contributions to the thermal conductivity of a local thermodynamic equilibrium nitrogen plasma have been calculated using the Chapman-Enskog method. Low-lying (LL) electronically excited states (i.e., states with the same principal quantum number of the ground state) and high-lying (HL) ones (i.e., states with principal quantum number n> 2) have been considered. Several models have been developed, the most accurate being a model that treats the LL states as separate species while disregarding the presence of HL states, on account of their enormous transport cross sections.

Bruno, D.; Colonna, G.; Laricchiuta, A. [CNR IMIP Bari, Bari (Italy); Capitelli, M. [CNR IMIP Bari, Bari (Italy); Department of Chemistry, University of Bari, Bari, Italy and CNR IMIP Bari, Bari (Italy)

2012-12-15T23:59:59.000Z

256

Spatial and temporal variations in streambed hydraulic conductivity quantified with time-series thermal methods  

E-Print Network (OSTI)

conductivity Streambed seepage Heat as a tracer Surface water­ground water interaction Pajaro River s u m m a r was 62 m3 s�1 , with most of the loss occurring along the lower part of the experimental reach. Point and with time, with greater seepage occurring along the lower part of the reach and during the summer and fall

Fisher, Andrew

257

Conduction and Moisture Diffusion  

Science Conference Proceedings (OSTI)

Table 2   Equivalent physical quantities...conduction Temperature Temperature gradient Heat flux Heat conductivities Resistivities Electric conduction Electric potential Electric field intensity Current density Electric conductivities Resistivities Electrostatics Electric potential Electric field intensity Electric induction, electric...

258

Method for the thermal characterization, visualization, and integrity evaluation of conducting material samples or complex structures  

DOE Patents (OSTI)

Disclosed is a method for modeling a conducting material sample or structure (herein called a system) as at least two regions which comprise an electrical network of resistances, for measuring electric resistance between at least two selected pairs of external leads attached to the surface of the system, wherein at least one external lead is attached to the surface of each of the regions, and, using basic circuit theory, for translating measured resistances into temperatures or thermophysical properties in corresponding regions of the system. 16 figs.

Ortiz, M.G.

1992-11-24T23:59:59.000Z

259

Thermal dilepton rate and electrical conductivity: An analysis of vector current correlation functions in quenched lattice QCD  

E-Print Network (OSTI)

We calculate the vector current correlation function for light valence quarks in the deconfined phase of QCD. The calculations have been performed in quenched lattice QCD at T=1.45 Tc for four values of the lattice cut-off on lattices up to size 128^3x48. This allows to perform a continuum extrapolation of the correlation function in the Euclidean time interval tau*T -in [0.2, 0.5], which extends to the largest temporal separations possible at finite temperature, to better than 1% accuracy. In this interval, at the value of the temperature investigated, we find that the vector correlation function never deviates from the free correlator for massless quarks by more than 9%. We also determine the first two non-vanishing thermal moments of the vector meson spectral function. The second thermal moment deviates by less than 7% from the free value. With these constraints, we then proceed to extract information on the spectral representation of the vector correlator and discuss resulting consequences for the electrical conductivity and the thermal dilepton rate in the plasma phase.

H. -T. Ding; A. Francis; O. Kaczmarek; F. Karsch; E. Laermann; W. Soeldner

2010-12-22T23:59:59.000Z

260

Thermal Conductivity Measurement of Xe-Implanted Uranium Dioxide Thick Films using Multilayer Laser Flash Analysis  

SciTech Connect

The Fuel Cycle Research and Development program's Advanced Fuels campaign is currently pursuing use of ion beam assisted deposition to produce uranium dioxide thick films containing xenon in various morphologies. To date, this technique has provided materials of interest for validation of predictive fuel performance codes and to provide insight into the behavior of xenon and other fission gasses under extreme conditions. In addition to the structural data provided by such thick films, it may be possible to couple these materials with multilayer laser flash analysis in order to measure the impact of xenon on thermal transport in uranium dioxide. A number of substrate materials (single crystal silicon carbide, molybdenum, and quartz) containing uranium dioxide films ranging from one to eight microns in thickness were evaluated using multilayer laser flash analysis in order to provide recommendations on the most promising substrates and geometries for further investigation. In general, the uranium dioxide films grown to date using ion beam assisted deposition were all found too thin for accurate measurement. Of the substrates tested, molybdenum performed the best and looks to be the best candidate for further development. Results obtained within this study suggest that the technique does possess the necessary resolution for measurement of uranium dioxide thick films, provided the films are grown in excess of fifty microns. This requirement is congruent with the material needs when viewed from a fundamental standpoint, as this length scale of material is required to adequately sample grain boundaries and possible second phases present in ceramic nuclear fuel.

Nelson, Andrew T. [Los Alamos National Laboratory

2012-08-30T23:59:59.000Z

Note: This page contains sample records for the topic "gradients thermal conductivity" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

High temperature thermal conductivity measurements of UO/sub 2/ by Direct Electrical Heating. Final report. [MANTRA-III  

SciTech Connect

High temperature properties of reactor type UO/sub 2/ pellets were measured using a Direct Electrical Heating (DEH) Facility. Modifications to the experimental apparatus have been made so that successful and reproducible DEH runs may be carried out while protecting the pellets from oxidation at high temperature. X-ray diffraction measurements on the UO/sub 2/ pellets have been made before and after runs to assure that sample oxidation has not occurred. A computer code has been developed that will model the experiment using equations that describe physical properties of the material. This code allows these equations to be checked by comparing the model results to collected data. The thermal conductivity equation for UO/sub 2/ proposed by Weilbacher has been used for this analysis. By adjusting the empirical parameters in Weilbacher's equation, experimental data can be matched by the code. From the several runs analyzed, the resulting thermal conductivity equation is lambda = 1/4.79 + 0.0247T/ + 1.06 x 10/sup -3/ exp(-1.62/kT/) - 4410. exp(-3.71/kT/) where lambda is in w/cm K, k is the Boltzman constant, and T is the temperature in Kelvin.

Bassett, B

1980-10-01T23:59:59.000Z

262

Simulated biomass and soil carbon of loblolly pine and cottonwood plantations across a thermal gradient in southeastern United States  

Science Conference Proceedings (OSTI)

Changes in biomass and soil carbon with nitrogen fertilization were simulated for a 25-year loblolly pine (Pinus taeda) plantation and for three consecutive 7-year short-rotation cottonwood (Populus deltoides) stands. Simulations were conducted for 17 locations in the southeastern United States with mean annual temperatures ranging from 13.1 to 19.4 C. The LINKAGES stand growth model, modified to include the "RothC" soil C and soil N model, simulated tree growth and soil C status. Nitrogen fertilization significantly increased cumulative cottonwood aboveground biomass in the three rotations from a site average of 106 to 272 Mg/ha in 21 years, whereas the equivalent site averages for loblolly pine were unchanged at 176 and 184 Mg/ha in 25 years. Location results, compared on the annual sum of daily mean air temperatures above 5.5 C (growing-degree-days), showed contrasts. Loblolly pine biomass increased whereas cottonwood decreased with increasing growing-degree-days, particularly in cottonwood stands receiving N fertilization. The increment of biomass due to N addition per unit of control biomass (relative response) declined in both plantations with increase in growing-degree-days. Average soil C in loblolly pine stands increased from 24.3 to 40.4 Mg/ha in 25 years and in cottonwood soil C decreased from 14.7 to 13.7 Mg/ha after three 7-year rotations. Soil C did not decrease with increasing growing-degree-days in either plantation type suggesting that global warming may not initially affect soil C. Nitrogen fertilizer increased soil C slightly in cottonwood plantations and had no significant effect on the soil C of loblolly stands.

Luxmoore, Robert J [ORNL; Tharp, M Lynn [ORNL; Post, Wilfred M [ORNL

2008-01-01T23:59:59.000Z

263

Improved 3-omega measurement of thermal conductivity in liquid, gases, and powders using a metal-coated optical fiber  

Science Conference Proceedings (OSTI)

A novel 3?thermal conductivitymeasurement technique called metal-coated 3? is introduced for use with liquids

Scott N. Schiffres; Jonathan A. Malen

2011-01-01T23:59:59.000Z

264

One-dimensional heat conductivity exponent from a random collision model J. M. Deutsch and Onuttom Narayan  

E-Print Network (OSTI)

One-dimensional heat conductivity exponent from a random collision model J. M. Deutsch and Onuttom to conductivity would predict that if the temperature gradient "T in a material is small, the heat current flowing January 2003; published 18 July 2003 We obtain numerically the thermal conductivity of a quasi

California at Santa Cruz, University of

265

The Braginskii model of the Rayleigh-Taylor instability. I. Effects of self-generated magnetic fields and thermal conduction in two dimensions  

E-Print Network (OSTI)

(abridged) There exists a substantial disagreement between computer simulation results and high-energy density laboratory experiments of the Rayleigh-Taylor instability Kuranz et al. (2010). We adopt the Braginskii formulation for transport in hot, dense plasma, implement and verify the additional physics modules, and conduct a computational study of a single-mode RTI in two dimensions with various combinations of the newly implemented modules. We find that magnetic fields reach levels on the order of 11 MG in the absence of thermal conduction. We observe denting of the RT spike tip and generation of additional higher order modes as a result of these fields. Contrary to interpretation presented in earlier work Nishiguchi (2002), the additional mode is not generated due to modified anisotropic heat transport effects but due to dynamical effect of self-generated magnetic fields. The main effects of thermal conduction are a reduction of the RT instability growth rate (by about 20% for conditions considered here)...

Modica, Frank; Zhiglo, Andrey

2013-01-01T23:59:59.000Z

266

Thermal and Electrical Transport in Oxide Heterostructures  

E-Print Network (OSTI)

of thermal conductivity . . . . . . . . . . . . . . . .4.4 Thermal transport in2.3.2 Thermal transport . . . . . . . . . . . . . . . .

Ravichandran, Jayakanth

2011-01-01T23:59:59.000Z

267

[Geothermal resource/reservoir investigations based on heat flow and thermal gradient data for the US]. 6. quarterly technical progress report  

Science Conference Proceedings (OSTI)

During the second quarter of the second year of the contract activity has focused on the task of implementing the exploration well data base. In addition the author has continued to work on the tasks of the maintenance of the WWW site with the heat flow and gradient data base, and development of a modeling capability for analysis of the geothermal system exploration data. He is implementing the data base template for geothermal system temperature-depth/gradient/heat flow data to be used in conjunction with the regional temperature-depth/gradient/heat flow data base that he had already developed. The implementation this quarter has focused on the state of Nevada as the most number of wells are there and few of the wells have been previously available in a data base. A map is enclosed that updates the state of Nevada from the preliminary map in the first quarterly report. They presently are entering data into the geothermal data base. They now have over 1,000 sites in Nevada with data from the sources that they have access to at this time. The breakdown based on the data now entered into the data base is shown in a table.

Blackwell, D.D.

1998-08-18T23:59:59.000Z

268

[Geothermal resource/reservoir investigations based on heat flow and thermal gradient data for the US]. 7. quarterly technical progress report  

Science Conference Proceedings (OSTI)

During the report period, activity has continued to focus on the task of implementing the exploration well data base. In addition the author has continued to work on the tasks of the maintenance of the WWW site with the heat flow and gradient data base, and development of a modeling capability for analysis of the geothermal system exploration data. He is implementing the data base template for geothermal system temperature-depth/gradient/heat flow data to be used in conjunction with the regional temperature-depth/gradient/heat flow data base that he had already developed. Some results of the implementation are included with this report in the form of graphic summaries of the data prepared from the assembled data base. He has continued to enter data into the geothermal data base. The implementation this quarter has continued to focus on the state of Nevada as the most number of wells are there and few of the wells have been previously available in a data base. During this quarter he has maintained the Internet home page illustrating and having available for distribution the regional data base and maps. The address of the page is http://www.smu.edu/{approximately}geothermal/.

Blackwell, D.D.

1998-10-29T23:59:59.000Z

269

Effects of Irradiation and Post-Irradiation Annealing on the Thermal Conductivity/ Diffusivity of Monolithic SIC and SIC/SIC Composites  

Science Conference Proceedings (OSTI)

Laser flash thermal diffusivity measurements were made on high-purity monolithic CVD-SiC (impurity concentration layup made by the isothermal chemical vapor infiltration process and with either a “thick” 1.0 µm or a “thin” 0.11 µm PyC fiber coating) before and after irradiation in the HFIR reactor (250 to 800°C, 4-8 dpa-SiC) and after post-irradiation annealing composite samples to 1200°C. Thermal conductivity in SiC is controlled by phonon transport. Point defects introduced into SiC during neutron irradiation are effective scattering centers for phonons, and as a consequence the thermal conductivity is sharply reduced. For irradiation temperatures below ~800°C, the accumulation of point defects (in SiC mostly single or small clusters of interstitials and isolated vacancies) saturates when the interstitial-vacancy recombination rate equals the defect production rate. For saturation conditions, the relative reduction in the SiC thermal conductivity decreases in a manner similar to its swelling reduction with increasing irradiation temperature. Examination of SiC swelling data at various irradiation temperatures and doses indicates that saturation occurs for ~2 dpa-SiC at 200°C and decreases continuously to ~0.4 dpa-SiC at 800°C. Based on a model that assumes a uniform distribution of the phonon scattering defects, the calculated defect concentration for unirradiated CVD-SiC was less than 1 appm, which is consistent with the manufacturer’s value of <5 wppm impurities. The defect concentrations estimated for the irradiated CVD-SiC samples decreased continuously from ~25,000 to 940 appm as the irradiation temperature increased from 252 to 800°C. The small intrinsic defect concentration in comparison to the rather large extrinsic irradiation-induced defect concentrations illustrates why CVD-SiC makes an ideal irradiation damage monitor.

Youngblood, Gerald E.; Senor, David J.; Jones, Russell H.

2004-08-01T23:59:59.000Z

270

Preliminary measurements of the thermal conductivity of rocks from LASL geothermal test holes GT-1 and GT-2  

DOE Green Energy (OSTI)

The conductivities on a number of dry rocks have been measured in an air environment. These experimental values are probably about 10 percent lower than the in situ values. Initial attempts to prepare ''wet'' rock samples (rocks saturated with water) have so far resulted in only ''damp'' rocks. Considerable effort will be required to characterize the crack system in ''solid'' rocks and to predict the probable conductivity values for in situ conditions.

Sibbitt, W.L.

1975-12-01T23:59:59.000Z

271

Thermal Management of Solar Cells  

E-Print Network (OSTI)

phonon transmission and interface thermal conductance acrossF. Miao, et al. , "Superior Thermal Conductivity of Single-Advanced Materials for Thermal Management of Electronic

Saadah, Mohammed Ahmed

2013-01-01T23:59:59.000Z

272

Numerical analysis of heat transfer by conduction and natural convection in loose-fill fiberglass insulation--effects of convection on thermal performance  

SciTech Connect

A two-dimensional code for solving equations of convective heat transfer in porous media is used to analyze heat transfer by conduction and convection in the attic insulation configuration. The particular cases treated correspond to loose-fill fiberglass insulation, which is characterized by high porosity and air permeability. The effects of natural convection on the thermal performance of the insulation are analyzed for various densities, permeabilities, and thicknesses of insulation. With convection increasing the total heat transfer through the insulation, the thermal resistance was found to decrease as the temperature difference across the insulating material increases. The predicted results for the thermal resistance are compared with data obtained in the large-scale climate simulator at the Roof Research Center using the attic test module, where the same phenomenon has already been observed. The way the wood joists within the insulation influence the start of convection is studied for differing thermophysical and dynamic properties of the insulating material. The presence of wood joists induces convection at a lower temperature difference.

Delmas, A.A.; Wilkes, K.E.

1992-04-01T23:59:59.000Z

273

Hamilton-Jacobi and quantum theory formulations of thermal-wave propagation under the dual-phase lagging model of heat conduction  

SciTech Connect

Dual-phase lagging model is one of the most promising approaches to generalize the Fourier heat conduction equation, and it can be reduced in the appropriate limits to the hyperbolic Cattaneo-Vernotte and to the parabolic equations. In this paper it is shown that the Hamilton-Jacobi and quantum theory formulations that have been developed to study the thermal-wave propagation in the Fourier framework can be extended to include the more general approach based on dual-phase lagging. It is shown that the problem of solving the heat conduction equation can be treated as a thermal harmonic oscillator. In the classical approach a formulation in canonical variables is presented. This formalism is used to introduce a quantum mechanical approach from which the expectation values of observables such as the temperature and heat flux are obtained. These formalisms permit to use a methodology that could provide a deeper insight into the phenomena of heat transport at different time scales in media with inhomogeneous thermophysical properties.

Ordonez-Miranda, J.; Alvarado-Gil, J. J. [Department of Applied Physics, Cinvestav-Unidad Merida, Carretera Antigua a Progreso km. 6, A.P. Postal 73 'Cordemex', Merida, Yucatan 97310 (Mexico); Zambrano-Arjona, Miguel A. [Facultad de Ingenieria, Universidad Autonoma de Yucatan, A.P. 150 Cordemex, Merida, Yucatan 97310 (Mexico)

2010-02-15T23:59:59.000Z

274

Nickel gradient electrode  

SciTech Connect

This invention relates generally to rechargeable batteries, and, in particular, relates to batteries that use nickel electrodes. It provides an improved nickel electrode with a selected gradient of additive materials. The concentration of additives in the impregnating solution are controlled during impregnation such that an additive gradient is generated. In the situation where the highest ionic conductivity is needed at the current collector boundary with the active material, the electrochemical impregnating solution is initially high in additive, and at the end of impregnation has been adjusted to significantly lower additive concentration. For chemical impregnation, the electrodes are similarly dipped in solutions that are initially high in additive. This invention is suitable for conventional additives such as cobalt, cadmium, barium, manganese, and zinc. It is therefore one objective of the invention to provide an improved nickel electrode of a battery cell with an additive in the active material to increase the life of the battery cell. Another objective is to provide for an improved nickel electrode having a greater concentration of additive near the current collector of nickel.

Zimmerman, A.H.

1988-03-31T23:59:59.000Z

275

Measuring the Impact of Experimental Parameters upon the Estimated Thermal Conductivity of Closed-Cell Foam Insulation Subjected to an Accelerated Aging Protocol ? Two Year Results  

SciTech Connect

The thermal conductivity of many closed-cell foam insulation products changes over time as production gases diffuse out of the cell matrix and atmospheric gases diffuse into the cells. Thin slicing has been shown to be an effective means of accelerating this process in such a way as to produce meaningful results. Efforts to produce a more prescriptive version of the ASTM C 1303 standard test method have led to a broad ruggedness test. This test includes the aging of full size insulation specimens for time periods up to five years for later comparison to the predicted results. Experimental parameters under investigation include: slice thickness, slice origin (at the surface or from the core of the slab), thin slice stack composition, product facings, original product thickness, product density, and product type. This paper will compare the results after two years of full-thickness aging.

Stovall, Therese K [ORNL

2009-01-01T23:59:59.000Z

276

The evolution of interstellar clouds in a streaming hot plasma including heat conduction  

E-Print Network (OSTI)

To examine the evolution of giant molecular clouds in the stream of a hot plasma we performed two-dimensional hydrodynamical simulations that take full account of self-gravity, heating and cooling effects and heat conduction by electrons. We use the thermal conductivity of a fully ionized hydrogen plasma proposed by Spitzer and a saturated heat flux according to Cowie & McKee in regions where the mean free path of the electrons is large compared to the temperature scaleheight. Significant structural and evolutionary differences occur between simulations with and without heat conduction. Dense clouds in pure dynamical models experience dynamical destruction by Kelvin-Helmholtz (KH) instability. In static models heat conduction leads to evaporation of such clouds. Heat conduction acting on clouds in a gas stream smooths out steep temperature and density gradients at the edge of the cloud because the conduction timescale is shorter than the cooling timescale. This diminishes the velocity gradient between the...

Vieser, W

2007-01-01T23:59:59.000Z

277

Comparative studies of geothermal surveys in 3-meter and temperature-gradient holes  

Science Conference Proceedings (OSTI)

The reliability of conducting temperature surveys within the upper 3 meters of the surface to map geothermal anomalies is demonstrated in experiments at two prospects in which deeper gradient hole data were obtained. The 3m temperatures faithfully outlined the thermal anomaly at McCoy, Nevada; and in Dixie Valley, NV 3m surveys reproduced and detailed patterns derived from 40m data. These encouraging results led to the development of multi-thermistor strings for logging the seasonal wave within the upper 3 meters. From many such logs, diffusivity variations can be detected, which might otherwise be misconstrued as thermal anomalies. The technique is demonstrated by a typical Basin-Range reconnaissance project. As many as 10 or more 3m holes can be emplaced in the time required for a conventional gradient well, and with considerably less impact on the environment.

Lang, A.L.; Deymonaz, J.; Pilkington, H.D.

1982-10-01T23:59:59.000Z

278

Temperature-gradient and heat flow data, Grass Valley, Nevada  

DOE Green Energy (OSTI)

A series of 16 shallow and intermediate-depth temperature-gradient holes were drilled for Sunoco Energy Development Co. in Grass Valley, Pershing County, Nevada, on leases held by Aminoil USA, Inc., under the cost-sharing industry-linked program of the Department of Energy. Thirteen shallow (85-152 m) and 3 intermediate-depth (360-457 m) holes were completed and logged during the period June through September, 1979. The locations of these holes and of pre-existing temperature-gradient holes are shown on plate 1. This report constitutes a final data transmittal and disclosure of results. The drilling subcontractor was Southwest Drilling and Exploration, Inc. of Central, Utah. They provided a Gardner-Denver 15W rig, a 3-man crew, and supporting equipment. A l l holes were drilled with mud as the circulating medium. Drilling histories for each hole are summarized in table 1. GeothermEx, Inc. performed on-site geological descriptions of the cuttings; obtained several temperature profiles for each hole, including an equilibrium profile taken 23 days or more after cessation of drilling; selected samples for thermal conductivity measurements; integrated temperature, temperature-gradient, and heat-flow data obtained in this project with published values; and prepared this report.

Koenig, James B.; Gardner, Murray C.

1979-11-01T23:59:59.000Z

279

Thermal Transport in Graphene Multilayers and Nanoribbons  

E-Print Network (OSTI)

1 CHAPTER 2 Thermal transport atvalues of graphene’s thermal conductivity and different1 Thermal conductivity : metals and non - metallic

Subrina, Samia

2011-01-01T23:59:59.000Z

280

Transitioning water to an enhanced heat-conducting phase  

E-Print Network (OSTI)

Water can be transitioned to an enhanced heat-conducting phase by supercooling only the water at the bottom of a container. The temperature gradient across the 4 cm in the center of an 8 cm long column of water with a 397 mW heat source at the top was lowered from 32oC to 0.75oC when the temperature at the bottom of the column was lowered from 1.2 oC to -5.6oC. The effective thermal conductivity of the water was increased from ~0.607 W/mK to ~24 W/mK. This result demonstrates that water has a high effective thermal conducting phase that has not been previously reported.

Brownridge, James D

2011-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "gradients thermal conductivity" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
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281

Thermal regimes of Malaysian sedimentary basins  

Science Conference Proceedings (OSTI)

Properly corrected and calibrated thermal data are important in estimating source-rock maturation, diagenetics, evolution of reservoirs, pressure regimes, and hydrodynamics. Geothermal gradient, thermal conductivity, and heat flow have been determined for the sedimentary succession penetrated by exploratory wells in Malaysia. Geothermal gradient and heat-flow maps show that the highest average values are in the Malay Basin. The values in the Sarawak basin are intermediate between those of the Malay basin and the Sabah Basin, which contains the lowest average values. Temperature data were analyzed from more than 400 wells. An important parameter that was studied in detail is the circulation time. The correct circulation time is essential in determining the correct geothermal gradient of a well. It was found that the most suitable circulation time for the Sabah Basin is 20 hr, 30 hr for the Sarawak Basin and 40 hr for the Malay Basin. Values of thermal conductivity, determined from measurement and calibrated calculations, were grouped according to depositional units and cycles in each basin.

Abdul Halim, M.F. (Petronas Research and Scientific Services, Selangor (Malaysia))

1994-07-01T23:59:59.000Z

282

Joining of Tungsten Armor Using Functional Gradients  

SciTech Connect

The joining of low thermal expansion armor materials such as tungsten to high thermal expansion heat sink materials has been a major problem in plasma facing component (PFC) development. Conventional planar bonding techniques have been unable to withstand the high thermal induced stresses resulting from fabrication and high heat flux testing. During this investigation, innovative functional gradient joints produced using vacuum plasma spray forming techniques have been developed for joining tungsten armor to copper alloy heat sinks. A model was developed to select the optimum gradient architecture. Based on the modeling effort, a 2mm copper rich gradient was selected. Vacuum plasma pray parameters and procedures were then developed to produce the functional gradient joint. Using these techniques, dual cooling channel, medium scale mockups (32mm wide x 400mm length) were produced with vacuum plasma spray formed tungsten armor. The thickness of the tungsten armor was up to 5mm thick. No evidence of debonding at the interface between the heat sink and the vacuum plasma sprayed material was observed.

John Scott O'Dell

2006-12-31T23:59:59.000Z

283

Determination of thermal parameters of one-dimensional nanostructures through a thermal transient method  

E-Print Network (OSTI)

of heat capacity and thermal conductivity measurements bythe heat pulse method for thermal transport measurements ofG. Speci?c heat and thermal conductivity measurements on

Arriagada, A.; Yu, E. T.; Bandaru, P. R.

2009-01-01T23:59:59.000Z

284

Short wavelength ion temperature gradient turbulence  

Science Conference Proceedings (OSTI)

The ion temperature gradient (ITG) mode in the high wavenumber regime (k{sub y}{rho}{sub s}>1), referred to as short wavelength ion temperature gradient mode (SWITG) is studied using the nonlinear gyrokinetic electromagnetic code GENE. It is shown that, although the SWITG mode may be linearly more unstable than the standard long wavelength (k{sub y}{rho}{sub s}<1) ITG mode, nonlinearly its contribution to the total thermal ion heat transport is found to be low. We interpret this as resulting from an increased zonal flow shearing effect on the SWITG mode suppression.

Chowdhury, J.; Ganesh, R. [Institute for Plasma Research, Bhat, Gandhinagar (India); Brunner, S.; Lapillonne, X.; Villard, L. [CRPP, Association EURATOM-Confederation Suisse, EPFL, 1015 Lausanne (Switzerland); Jenko, F. [Max-Planck-Institut fuer Plasmaphysik Boltzmannstr. 2, D-85748 Garching (Germany)

2012-10-15T23:59:59.000Z

285

Assembly and testing of a composite heat pipe thermal intercept for HTS current leads  

SciTech Connect

We are building high temperature superconducting (HTS) current leads for a demonstration HTS-high gradient magnetic separation (HGMS) system cooled by a cryocooler. The current leads are entirely conductively cooled. A composite nitrogen heat pipe provides efficient thermal communication, and simultaneously electrical isolation, between the lead and an intermediate temperature heat sink. Data on the thermal and electrical performance of the heat pipe thermal intercept are presented. The electrical isolation of the heat pipe was measured as a function of applied voltage with and without a thermal load across the heat pipe. The results show the electrical isolation with evaporation, condensation and internal circulation taking place in the heat pipe.

Daugherty, M.A.; Daney, D.E.; Prenger, F.C.; Hill, D.D.; Williams, P.M.; Boenig, H.J.

1995-09-01T23:59:59.000Z

286

Retrieving Horizontal Temperature Gradients and Advections from Single-Station Wind Profiler Observations  

Science Conference Proceedings (OSTI)

Vertical wind shears measured by the Plattevilie, Colorado wind profiler were used in conjunction with the geostrophic thermal wind equation to retrieve the horizontal thermal gradients and associated advections for a case involving an upper-...

Paul J. Neiman; M. A. Shapiro

1989-06-01T23:59:59.000Z

287

Steep Gradient Flume | Open Energy Information  

Open Energy Info (EERE)

Steep Gradient Flume Steep Gradient Flume Jump to: navigation, search Basic Specifications Facility Name Steep Gradient Flume Overseeing Organization University of Iowa Hydrodynamic Testing Facility Type Flume Length(m) 20.1 Beam(m) 0.9 Depth(m) 0.5 Cost(per day) Contact POC Special Physical Features Tilting flume from -1.5 to +16% slope; <3mm sedimentation recirculation capabilities; instrumentation rails Towing Capabilities Towing Capabilities None Wavemaking Capabilities Wavemaking Capabilities None Channel/Tunnel/Flume Channel/Tunnel/Flume Yes Recirculating Yes Wind Capabilities Wind Capabilities None Control and Data Acquisition Cameras Yes Number of Color Cameras 1 Available Sensors Acoustics, Flow, Thermal, Turbulence, Velocity Data Generation Capability Real-Time Yes

288

Design of a novel conduction heating based stress-thermal cycling apparatus for composite materials and its utilization to characterize composite microcrack damage thresholds  

E-Print Network (OSTI)

The objective of this research was to determine the effect of thermal cycling combined with mechanical loading on the development of microcracks in M40J/PMR-II- 50, the second generation aerospace application material. The objective was pursued by finding the critical controlling parameters for microcrack formation from mechanical stress-thermal cycling test. Three different in-plane strains (0%, 0.175~0.350%, and 0.325~0.650%) were applied to the composites by clamping composite specimens (M40J/PMR-II-50, [0,90]s, a unitape cross-ply) on the radial sides of half cylinders having two different radii (78.74mm and 37.96mm). Three different thermal loading experiments, 1) 23oC to �196oC to 250oC, 2) 23oC to 250oC, and 3) 23oC to -196oC, were performed as a function of mechanical inplane strain levels, heating rates, and number of thermal cycles. The apparatus generated cracks related to the in-plane stresses (or strains) on plies. The design and analysis concept of the synergistic stress-thermal cycling experiment was simplified to obtain main and interaction factors by applying 2k factorial design from the various factors affecting microcrack density of M40J/PMR-II-50. Observations indicate that the higher temperature portion of the cycle under load causes fiber/matrix interface failure. Subsequent exposure to higher stresses in the cryogenic temperature region results in composite matrix microcracking due to the additional stresses associated with the fiber-matrix thermal expansion mismatch.

Ju, Jaehyung

2005-08-01T23:59:59.000Z

289

Results of geothermal gradient core hole TCB-1, Tecuamburro volcano geothermal site, Guatemala, Central America  

DOE Green Energy (OSTI)

Results of geological, volcanological, hydrogeochemical, and geophysical field studies conducted in 1988 and 1989 at the Tecuamburro volcano geothermal site in Guatemala indicated that there is a substantial shallow heat source beneath the area of youngest volcanism. To obtain information on subsurface temperatures and temperature gradients, stratigraphy, hydrothermal alteration, fracturing, and possible inflows of hydrothermal fluids, a geothermal gradient core hole (TCB-1) was drilled to 808 m low on the northern flank of the Tecuamburro volcano Complex, 300 km south of a 300-m-diameter phreatic crater, Laguna Ixpaco, dated at 2,910 years. Gases from acid-sulfate springs near Laguna Ixpaco consistently yield maximum estimated subsurface temperatures of 250--300{degrees}C. The temperature versus depth curve from TCB-1 does not show isothermal conditions and the calculated thermal gradients from 500--800 m is 230{degrees}C/km. Bottom hole temperature is 238{degrees}C. Calculated heat flow values are nearly 9 heat flow units (HFU). The integration of results from the TCB-1 gradient core hole with results from field studies provides strong evidence that the Tecuamburro area holds great promise for containing a commercial geothermal resource.

Adams, A.I.; Chipera, S.; Counce, D.; Gardner, J.; Goff, S.; Goff, F.; Heiken, G.; Laughlin, A.W.; Musgrave, J.; Trujillo, P.E. Jr. (Los Alamos National Lab., NM (United States)); Aycinena, S.; Martinelli, L. (Swissboring Overseas Corp. Ltd., Guatemala City (Guatemala)); Castaneda, O.; Revolorio, M.; Roldan, A. (Unidad de Desarrollo Geotermico, Guatemala City (Guatemala). Inst. Nacional de Electrificacion); D

1992-02-01T23:59:59.000Z

290

Thermal Characterization of Nanostructures and Advanced Engineered Materials  

E-Print Network (OSTI)

A. and McEuen, P. L. , “Thermal Transport Measurements ofTomanek, D. , “Unusually High Thermal Conductivity of Carbonand Lau, C. N. , “Superior thermal conductivity of single-

Goyal, Vivek Kumar

2011-01-01T23:59:59.000Z

291

Electrochemical-thermal modeling and microscale phase change for passive internal thermal management of lithium ion batteries.  

SciTech Connect

A fully coupled electrochemical and thermal model for lithium-ion batteries is developed to investigate the impact of different thermal management strategies on battery performance. In contrast to previous modeling efforts focused either exclusively on particle electrochemistry on the one hand or overall vehicle simulations on the other, the present work predicts local electrochemical reaction rates using temperature-dependent data on commercially available batteries designed for high rates (C/LiFePO{sub 4}) in a computationally efficient manner. Simulation results show that conventional external cooling systems for these batteries, which have a low composite thermal conductivity ({approx}1 W/m-K), cause either large temperature rises or internal temperature gradients. Thus, a novel, passive internal cooling system that uses heat removal through liquid-vapor phase change is developed. Although there have been prior investigations of phase change at the microscales, fluid flow at the conditions expected here is not well understood. A first-principles based cooling system performance model is developed and validated experimentally, and is integrated into the coupled electrochemical-thermal model for assessment of performance improvement relative to conventional thermal management strategies. The proposed cooling system passively removes heat almost isothermally with negligible thermal resistances between the heat source and cooling fluid. Thus, the minimization of peak temperatures and gradients within batteries allow increased power and energy densities unencumbered by thermal limitations.

Fuller, Thomas F. (Georgia Institute of Technology, Atlanta, GA); Bandhauer, Todd (Georgia Institute of Technology, Atlanta, GA); Garimella, Srinivas (Georgia Institute of Technology, Atlanta, GA)

2012-01-01T23:59:59.000Z

292

Thermal Transport in Graphene Multilayers and Nanoribbons  

E-Print Network (OSTI)

80 CHAPTER 5 Heat Conduction in Few Layerto Fourier's Law of heat conduction, thermal conductivity isnext experiments on heat conduction in graphene structures

Subrina, Samia

2011-01-01T23:59:59.000Z

293

Thermal insulations using vacuum panels  

DOE Patents (OSTI)

Thermal insulation vacuum panels are formed of an inner core of compressed low thermal conductivity powders enclosed by a ceramic/glass envelope evaluated to a low pressure.

Glicksman, Leon R. (Lynnfield, MA); Burke, Melissa S. (Pittsburgh, PA)

1991-07-16T23:59:59.000Z

294

The evolution of interstellar clouds in a streaming hot plasma including heat conduction  

E-Print Network (OSTI)

To examine the evolution of giant molecular clouds in the stream of a hot plasma we performed two-dimensional hydrodynamical simulations that take full account of self-gravity, heating and cooling effects and heat conduction by electrons. We use the thermal conductivity of a fully ionized hydrogen plasma proposed by Spitzer and a saturated heat flux according to Cowie & McKee in regions where the mean free path of the electrons is large compared to the temperature scaleheight. Significant structural and evolutionary differences occur between simulations with and without heat conduction. Dense clouds in pure dynamical models experience dynamical destruction by Kelvin-Helmholtz (KH) instability. In static models heat conduction leads to evaporation of such clouds. Heat conduction acting on clouds in a gas stream smooths out steep temperature and density gradients at the edge of the cloud because the conduction timescale is shorter than the cooling timescale. This diminishes the velocity gradient between the streaming plasma and the cloud, so that the timescale for the onset of KH instabilities increases, and the surface of the cloud becomes less susceptible to KH instabilities. The stabilisation effect of heat conduction against KH instability is more pronounced for smaller and less massive clouds. As in the static case more realistic cloud conditions allow heat conduction to transfer hot material onto the cloud's surface and to mix the accreted gas deeper into the cloud.

W. Vieser; G. Hensler

2007-04-26T23:59:59.000Z

295

Normal Conducting CLIC Technology  

Science Conference Proceedings (OSTI)

The CLIC (Compact Linear Collider) multi?lateral study group based at CERN is studying the technology for an electron?positron linear collider with a centre?of?mass energy up to 5 TeV. In contrast to the International Linear Collider (ILC) study which has chosen to use super?conducting cavities with accelerating gradients in the range of 30–40 MV/m to obtain centre?of?mass collision energies of 0.5–1 TeV

Erk Jensen; CLIC Study Team

2006-01-01T23:59:59.000Z

296

Implicit continuum mechanics approach to heat conduction in granular materials  

SciTech Connect

In this paper, we derive a properly frame-invariant implicit constitutive relationship for the heat flux vector for a granular medium (or a density-gradient-type fluid). The heat flux vector is commonly modeled by Fourier’s law of heat conduction, and for complex materials such as nonlinear fluids, porous media, or granular materials, the coefficient of thermal conductivity is generalized by assuming that it would depend on a host of material and kinematic parameters such as temperature, shear rate, porosity, concentration, etc. In this paper, we extend the approach of Massoudi [Massoudi, M. Math. Methods Appl. Sci. 2006, 29, 1585; Massoudi, M. Math. Methods Appl. Sci. 2006, 29, 1599], who provided explicit constitutive relations for the heat flux vector for flowing granular materials; in order to do so, we use the implicit scheme suggested by Fox [Fox, N. Int. J. Eng. Sci. 1969, 7, 437], who obtained implicit relations in thermoelasticity.

Massoudi, M.; Mehrabadi, M.

2010-01-01T23:59:59.000Z

297

Generalized Stochastic Gradient Learning  

E-Print Network (OSTI)

#1;#2;#3;#2;#4;#5;#6;#7;#8;#2; #11;#12; #14;#15;#5;#16;#12;#7;#14; #1;#4;#5; #7;#2;#3;#12; #17;#2;#5;#4;#3;#7;#3;#18; George W. Evans, Seppo Honkapohja and Noah Willams #19;#14;#12; #20;#2;#4; #21;#22;#22;#23; #24;#25;#26;#27; #22;#23;#28;#23; #1... ;#2;#3;#4;#3;#2;#4;#5;#6;#4;#7;#8;#2;#3;#6; #4; #11;#3;#12;#2;#8;#3;#4; #6;#14;#15;#11;#16;#16;#11;#2;#17; Generalized Stochastic Gradient Learning? George W. Evans University of Oregon Seppo Honkapohja University of Cambridge Noah Williams Princeton...

Evans, George W; Honkapohja, Seppo; Williams, Noah

2006-03-14T23:59:59.000Z

298

Gradient Resources | Open Energy Information  

Open Energy Info (EERE)

Resources Resources Jump to: navigation, search Logo: Gradient Resources Name Gradient Resources Address 9670 Gateway Drive, Suite 200 Place Reno, Nevada Zip 89521 Sector Geothermal energy Year founded 1991 Company Type For Profit Phone number (775) 284-8842 Website http://www.gradient.com/ Region Rockies Area References Gradient Resources Website[1] LinkedIn Connections CrunchBase Profile No CrunchBase profile. Create one now! Gradient Resources is a company based in Reno, Nevada. Gradient Resources is engaged in the exploration and development of geothermal resources as well as the construction, ownership and operation of geothermal power plants. The Company is headquartered in Reno, Nevada with a regional office, drilling operations center, and well-cementing

299

Improved Thermal Properties of In Situ Formed Al/AlN Composites ...  

Science Conference Proceedings (OSTI)

Abstract Scope, Thermal conduction and thermal expansion behaviors of heat sink materials are critical for microelectronic packaging because high thermal ...

300

High-gradient compact linear accelerator  

DOE Patents (OSTI)

A high-gradient linear accelerator comprises a solid-state stack in a vacuum of five sets of disc-shaped Blumlein modules each having a center hole through which particles are sequentially accelerated. Each Blumlein module is a sandwich of two outer conductive plates that bracket an inner conductive plate positioned between two dielectric plates with different thicknesses and dielectric constants. A third dielectric core in the shape of a hollow cylinder forms a casing down the series of center holes, and it has a dielectric constant different that the two dielectric plates that sandwich the inner conductive plate. In operation, all the inner conductive plates are charged to the same DC potential relative to the outer conductive plates. Next, all the inner conductive plates are simultaneously shorted to the outer conductive plates at the outer diameters. The signal short will propagate to the inner diameters at two different rates in each Blumlein module. A faster wave propagates quicker to the third dielectric core across the dielectric plates with the closer spacing and lower dielectric constant. When the faster wave reaches the inner extents of the outer and inner conductive plates, it reflects back outward and reverses the field in that segment of the dielectric core. All the field segments in the dielectric core are then in unipolar agreement until the slower wave finally propagates to the third dielectric core across the dielectric plates with the wider spacing and higher dielectric constant. During such unipolar agreement, particles in the core are accelerated with gradients that exceed twenty megavolts per meter.

Carder, B.M.

1995-12-31T23:59:59.000Z

Note: This page contains sample records for the topic "gradients thermal conductivity" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Multilayer Nanoscale Thermal Barrier Coatings  

Science Conference Proceedings (OSTI)

Advanced high-efficiency gas turbines require thermal barrier coatings (TBCs) with low thermal conductivity and excellent thermal-cycling resistance. The multilayer TBC developed in this project has a thermal conductivity about half that of conventional TBCs and also rejects up to 70 percent of incoming radiant energy.

1999-05-26T23:59:59.000Z

302

The Influence of High Pressure Thermal Behavior on Friction-induced material transfer During Dry Machining of Titanium  

SciTech Connect

In this paper we study failure of coated carbide tools due to thermal loading. The study emphasizes the role assumed by the thermo-physical properties of the tool material in enhancing or preventing mass attrition of the cutting elements within the tool. It is shown that within a comprehensive view of the nature of conduction in the tool zone, thermal conduction is not solely affected by temperature. Rather it is a function of the so called thermodynamic forces. These are the stress, the strain, strain rate, rate of temperature rise, and the temperature gradient. Although that within such consideration description of thermal conduction is non-linear, it is beneficial to employ such a form because it facilitates a full mechanistic understanding of thermal activation of tool wear.

Abdel-Aal, H. A. [Laboratoire de Mecanique et Procedes de Fabrication (LMPF), ENSAM CER Chalons-en-Champagne, Rue Saint Dominique BP 508, 51006 Chalons-en-Champagne (France); El Mansori, M. [Ecole Nationale Superieure d'Arts et Metiers, 2, cours des Arts et Metiers-13617 Aix en Provence cedex 1 (France)

2011-05-04T23:59:59.000Z

303

Thermal Properties  

Science Conference Proceedings (OSTI)

Table 12   Thermal conductivities of polymers and other materials...40,000 2.8 Aluminum 24,000 1.7 Steel 5000 0.35 Granite 350 0.02 Crown glass (75 wt% silica) 90 0.006 Source: Ref 4...

304

Variable pressure thermal insulating jacket  

DOE Patents (OSTI)

A device for controlled insulation of a thermal device. The device includes a thermal jacket with a closed volume able to be evacuated to form an insulating jacket around the thermal source. A getter material is in communcation with the closed volume of the thermal jacket. The getter material can absorb and desorb a control gas to control gas pressure in the volume of the thermal jacket to control thermal conductivity in the thermal jacket.

Nelson, Paul A. (Wheaton, IL); Malecha, Richard F. (Naperville, IL); Chilenskas, Albert A. (Chicago, IL)

1994-01-01T23:59:59.000Z

305

Variable pressure thermal insulating jacket  

DOE Patents (OSTI)

A device for controlled insulation of a thermal device is disclosed. The device includes a thermal jacket with a closed volume able to be evacuated to form an insulating jacket around the thermal source. A getter material is in communication with the closed volume of the thermal jacket. The getter material can absorb and desorb a control gas to control gas pressure in the volume of the thermal jacket to control thermal conductivity in the thermal jacket. 10 figs.

Nelson, P.A.; Malecha, R.F.; Chilenskas, A.A.

1994-09-20T23:59:59.000Z

306

Conduction cooled tube supports  

DOE Patents (OSTI)

In boilers, process tubes are suspended by means of support studs that are in thermal contact with and attached to the metal roof casing of the boiler and the upper bend portions of the process tubes. The support studs are sufficiently short that when the boiler is in use, the support studs are cooled by conduction of heat to the process tubes and the roof casing thereby maintaining the temperature of the stud so that it does not exceed 1400.degree. F.

Worley, Arthur C. (Mt. Tabor, NJ); Becht, IV, Charles (Morristown, NJ)

1984-01-01T23:59:59.000Z

307

Interpreting Conductivity Microstructure: Estimating the Temperature Variance Dissipation Rate  

Science Conference Proceedings (OSTI)

A simple model of the conductivity gradient spectrum is developed and used to interpret oceanic conductivity microstructure observations. A principal goal is to estimate the correction factor E for inferring the temperature variance dissipation ...

Libe Washburn; Timothy F. Duda; David C. Jacobs

1996-12-01T23:59:59.000Z

308

Gradient zone boundary control in salt gradient solar ponds  

SciTech Connect

A method and apparatus for suppressing zone boundary migration in a salt gradient solar pond includes extending perforated membranes across the pond at the boundaries, between the convective and non-convective zones, the perforations being small enough in size to prevent individual turbulence disturbances from penetrating the hole, but being large enough to allow easy molecular diffusion of salt thereby preventing the formation of convective zones in the gradient layer. The total area of the perforations is a sizable fraction of the membrane area to allow sufficient salt diffusion while preventing turbulent entrainment into the gradient zone.

Hull, John R. (Downers Grove, IL)

1984-01-01T23:59:59.000Z

309

Conduction cooling: multicrate fastbus hardware  

SciTech Connect

Described is a new and novel approach for cooling nuclear instrumentation modules via heat conduction. The simplicity of liquid cooled crates and ease of thermal management with conduction cooled modules are described. While this system was developed primarily for the higher power levels expected with Fastbus electronics, it has many general applications.

Makowiecki, D.; Sims, W.; Larsen, R.

1980-11-01T23:59:59.000Z

310

Dielectric-Lined High-Gradient Accelerator Structure  

Science Conference Proceedings (OSTI)

Rectangular particle accelerator structures with internal planar dielectric elements have been studied, with a view towards devising structures with lower surface fields for a given accelerating field, as compared with structures without dielectrics. Success with this concept is expected to allow operation at higher accelerating gradients than otherwise on account of reduced breakdown probabilities. The project involves studies of RF breakdown on amorphous dielectrics in test cavities that could enable high-gradient structures to be built for a future multi-TeV collider. The aim is to determine what the limits are for RF fields at the surfaces of selected dielectrics, and the resulting acceleration gradient that could be achieved in a working structure. The dielectric of principal interest in this study is artificial CVD diamond, on account of its advertised high breakdown field ({approx}2 GV/m for dc), low loss tangent, and high thermal conductivity. Experimental studies at mm-wavelengths on materials and structures for achieving high acceleration gradient were based on the availability of the 34.3 GHz third-harmonic magnicon amplifier developed by Omega-P, and installed at the Yale University Beam Physics Laboratory. Peak power from the magnicon was measured to be about 20 MW in 0.5 {micro}s pulses, with a gain of 54 dB. Experiments for studying RF high-field effects on CVD diamond samples failed to show any evidence after more than 10{sup 5} RF pulses of RF breakdown up to a tangential surface field strength of 153 MV/m; studies at higher fields were not possible due to a degradation in magnicon performance. A rebuild of the tube is underway at this writing. Computed performance for a dielectric-loaded rectangular accelerator structure (DLA) shows highly competitive properties, as compared with an existing all-metal structure. For example, comparisons were made of a DLA structure having two planar CVD diamond elements with a all-metal CERN structure HDS operating at 30 GHz. It was shown that the ratio of maximum surface electric field to accelerating field at the metal wall is only 0.35-0.4 for DLA, much smaller than the value 2.2 for HDS; and the ratio of surface magnetic field to accelerating field is 3.0 mA/V for DLA, compared with 3.45 mA/V for HDS. These values bode well for DLA in helping to avoid breakdown and to reducing pulsed surface heating and fatigue. The shunt impedance is found to be 160-175 M{Omega}/m for DLA, as compared to 99 M{Omega}/m for HDS. Conclusions are reached from this project that CVD diamond appears promising as a dielectric with a high threshold for RF breakdown, and that rectangular accelerator structures can be devised using planar CVD diamond elements that could be operated at higher acceleration gradients with low probability of RF breakdown, as compared with corresponding all-metallic structures.

Jay L. Hirshfield

2012-04-24T23:59:59.000Z

311

Thermal Conductivity of Liquids and Gases  

Science Conference Proceedings (OSTI)

... JCED Supporting Information: Propane.(ASCII)(pdf)(Postscript). JCED Supporting Information: Butane.(ASCII)(pdf)(Postscript). ...

2006-10-31T23:59:59.000Z

312

Thermal Conductivity of Polycrystalline Semiconductors and Ceramics  

E-Print Network (OSTI)

industries, polycrystalline semiconductors and ceramics havelaser industry, people are also seeking good ceramic laser

Wang, Zhaojie

2012-01-01T23:59:59.000Z

313

Thermal Inertia of Conductivity Cells: Theory  

Science Conference Proceedings (OSTI)

The temperature anomaly of a fluid moving through circular and rectangular cylinders induced by the heat stored in the walls of these hollow cylinders is derived under the assumption of quasi-steady heat transfer. These geometries correspond ...

Rolf G. Lueck

1990-10-01T23:59:59.000Z

314

Viscosity and Thermal Conductivity Equations for Nitrogen ...  

Science Conference Proceedings (OSTI)

... that both could be used as reference equations for ... the National Institute of Standards and Technology (NIST). ... of state for air as a pseudo-pure fluid. ...

2004-04-05T23:59:59.000Z

315

Thermal Conductivity for a Linear Anharmonic System  

SciTech Connect

A model has been proposed wherein self consistent phonon theory together with the thermodynamic perturbation theory is employed to determine a trial Hamiltonian is employed to determine thermodynamic parameters based on pining as well as nearest neighbor quadratic-quartic interactions.

Pasrija, Ritu [Department of Physics, DAV College, Abohar-152116 (India); Kanika [Dasmesh Girls College, Badal (Muktsar)-152113 (India); Srivastava, Sunita [Deparment of Physics, Panjab University Chandigarh-160014 (India)

2011-07-15T23:59:59.000Z

316

Reduced Thermal Conductivity of Compacted Silicon Nanowires  

E-Print Network (OSTI)

Nanoscale Heat Transfer Processes …. ………………………………. 7 1.4:1.3 – Nanoscale Heat Transfer Processes When studying heat

Yuen, Taylor S.

317

Computational Design of Low Thermal Conductivity TBC ...  

Science Conference Proceedings (OSTI)

Page 1. Edwin R. Fuller, Jr., National Institute of Standards and Technology Gaithersburg, MD 20899 Yougen Yang, Derek D. Hass, and Haydn NG ...

2004-05-17T23:59:59.000Z

318

Can conduction induce convection? The non-linear saturation of buoyancy instabilities in dilute plasmas  

E-Print Network (OSTI)

We study the effects of anisotropic thermal conduction on low-collisionality, astrophysical plasmas using two and three-dimensional magnetohydrodynamic simulations. For weak magnetic fields, dilute plasmas are buoyantly unstable for either sign of the temperature gradient: the heat-flux-driven buoyancy instability (HBI) operates when the temperature increases with radius while the magnetothermal instability (MTI) operates in the opposite limit. In contrast to previous results, we show that, in the presence of a sustained temperature gradient, the MTI drives strong turbulence and operates as an efficient magnetic dynamo (akin to standard, adiabatic convection). Together, the turbulent and magnetic energies contribute up to ~10% of the pressure support in the plasma. In addition, the MTI drives a large convective heat flux, ~1.5% of rho c_s^3. These findings are robust even in the presence of an external source of strong turbulence. Our results on the nonlinear saturation of the HBI are consistent with previous...

McCourt, Michael; Sharma, Prateek; Quataert, Eliot

2010-01-01T23:59:59.000Z

319

Scaling of Macroscopic Properties of Porous Sediments Experiencing Compaction: Implications for Geothermal Gradient and Methane Inventory  

E-Print Network (OSTI)

Porous sediments in geological systems experience stress by the above-laying mass and consequent compaction, which may be significantly nonuniform across the massif. We derive scaling laws for the compaction of sediments of similar geological origin. With these laws, we evaluate the dependence of the transport properties of a fluid-saturated porous medium (permeability, effective molecular diffusivity, hydrodynamic dispersion, and thermal conductivity) on its porosity. In particular, we demonstrate irrelevance of the assumption of a uniform geothermal gradient for systems with nonuniform compaction and importance of the derived scaling laws for mathematical modelling of methane hydrate deposits, which are believed to have potential for impact on global climate change and Glacial-Interglacial cycles.

Goldobin, Denis S

2011-01-01T23:59:59.000Z

320

Conductive Polymers  

DOE Green Energy (OSTI)

Electroluminescent devices such as light-emitting diodes (LED) and high-energy density batteries. These new polymers offer cost savings, weight reduction, ease of processing, and inherent rugged design compared to conventional semiconductor materials. The photovoltaic industry has grown more than 30% during the past three years. Lightweight, flexible solar modules are being used by the U.S. Army and Marine Corps for field power units. LEDs historically used for indicator lights are now being investigated for general lighting to replace fluorescent and incandescent lights. These so-called solid-state lights are becoming more prevalent across the country since they produce efficient lighting with little heat generation. Conductive polymers are being sought for battery development as well. Considerable weight savings over conventional cathode materials used in secondary storage batteries make portable devices easier to carry and electric cars more efficient and nimble. Secondary battery sales represent an $8 billion industry annually. The purpose of the project was to synthesize and characterize conductive polymers. TRACE Photonics Inc. has researched critical issues which affect conductivity. Much of their work has focused on production of substituted poly(phenylenevinylene) compounds. These compounds exhibit greater solubility over the parent polyphenylenevinylene, making them easier to process. Alkoxy substituted groups evaluated during this study included: methoxy, propoxy, and heptyloxy. Synthesis routes for production of alkoxy-substituted poly phenylenevinylene were developed. Considerable emphasis was placed on final product yield and purity.

Bohnert, G.W.

2002-11-22T23:59:59.000Z

Note: This page contains sample records for the topic "gradients thermal conductivity" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Incremental criticality and yield gradients  

Science Conference Proceedings (OSTI)

Criticality and yield gradients are two crucial diagnostic metrics obtained from Statistical Static Timing Analysis (SSTA). They provide valuable information to guide timing optimization and timing-driven physical synthesis. Existing work in the literature, ...

Jinjun Xiong; Vladimir Zolotov; Chandu Visweswariah

2008-03-01T23:59:59.000Z

322

First Look at Gradient Crystals  

NLE Websites -- All DOE Office Websites (Extended Search)

Beamline 7.3.3. When current is applied to the block copolymer, as in charging a battery, a new structure emerges. balsara-gradient cystals (a) "Sundial" x-ray scattering...

323

Field Investigations And Temperature-Gradient Drilling At Marine Corps  

Open Energy Info (EERE)

Investigations And Temperature-Gradient Drilling At Marine Corps Investigations And Temperature-Gradient Drilling At Marine Corps Air-Ground Combat Center (Mcagcc), Twenty-Nine Palms, Ca Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Paper: Field Investigations And Temperature-Gradient Drilling At Marine Corps Air-Ground Combat Center (Mcagcc), Twenty-Nine Palms, Ca Details Activities (4) Areas (1) Regions (0) Abstract: The U.S. Navy's Geothermal Program Office (GPO) has been conducting geothermal exploration activities in the Camp Wilson area of Marine Corps Air-Ground Combat Center (MCAGCC), Twenty-nine Palms, CA, for almost two years. Work has included self-potential (SP) surveys, fault structure analyses using LiDAR surveys, and drilling and assessment of five (5) temperature-gradient holes. For several decades the GPO has worked

324

Geothermal gradient drilling, north-central Cascades of Oregon, 1979  

DOE Green Energy (OSTI)

A geothermal gradient drilling program was conducted on the western flank of the north-central Cascade Mountains in Oregon. Six wells were drilled during this program, although in effect seven were drilled, as two wells were drilled at site 3, the second well, however, actually going to a lesser depth than the first. Three of the wells (3, 4, and 5) were drilled in areas which topographically are subject to strong throughflows of ground water. None of these wells reached the regional water table, and all showed essentially isothermal geothermal gradients. The single well which was started essentially at the water table (well 6) shows a linear temperature rise with depth essentially from the top of the well bore. Well No. 2 shows an isothermal gradient down to the level of the regional water table and then shows a linear gradient of about 70/sup 0/C/km from the regional water table to total depth.

Youngquist, W.

1980-01-01T23:59:59.000Z

325

Recycling of wasted energy : thermal to electrical energy conversion.  

E-Print Network (OSTI)

??Harvesting useful electric energy from ambient thermal gradients and/or temperature fluctuations is immensely important. For many years, a number of direct and indirect thermal-to-electrical energy… (more)

Lim, Hyuck

2011-01-01T23:59:59.000Z

326

Quantification of Texture and Microstructure Gradients in ...  

Science Conference Proceedings (OSTI)

Strain Gradient and Degradation in Magnetic Properties: Focus Transformer Steel · Strain Gradient Crystal Plasticity Finite Element Modeling of Alpha-Iron.

327

Hybrid Dynamic Energy and Thermal Management in Heterogeneous Embedded Multiprocessor SoCs  

E-Print Network (OSTI)

Hybrid Dynamic Energy and Thermal Management in Heterogeneous Embedded Multiprocessor SoCs Shervin propose a joint thermal and energy management technique specifically designed for heterogeneous MPSo technique simultaneously reduces the thermal hot spots, temperature gradients, and energy consumption

Simunic, Tajana

328

Device for thermal transfer and power generation  

SciTech Connect

A system is provided. The system includes a device that includes top and bottom thermally conductive substrates positioned opposite to one another, wherein a top surface of the bottom thermally conductive substrate is substantially atomically flat and a thermal blocking layer disposed between the top and bottom thermally conductive substrates. The device also includes top and bottom electrodes separated from one another between the top and bottom thermally conductive substrates to define a tunneling path, wherein the top electrode is disposed on the thermal blocking layer and the bottom electrode is disposed on the bottom thermally conductive substrate.

Weaver, Stanton Earl (Northville, NY); Arik, Mehmet (Niskayuna, NY)

2011-04-19T23:59:59.000Z

329

Thermal Diffusivity and Thermal Conductivity of HLW and LAW ...  

Science Conference Proceedings (OSTI)

In the present work, such data were collected for four waste glasses representative of those currently projected for treatment of Hanford HLW and LAW streams.

330

Definition: Hydraulic Conductivity | Open Energy Information  

Open Energy Info (EERE)

Conductivity Conductivity Jump to: navigation, search Dictionary.png Hydraulic Conductivity Hydraulic conductivity is a physical property which measures the ability of the material to transmit fluid through pore spaces and fractures in the presence of an applied hydraulic gradient. Darcy's Law defines the hydraulic conductivity as the ratio of the average velocity of a fluid through a cross-sectional area (Darcy's velocity) to the applied hydraulic gradient.[1] View on Wikipedia Wikipedia Definition Hydraulic conductivity, symbolically represented as, is a property of vascular plants, soil or rock, that describes the ease with which a fluid (usually water) can move through pore spaces or fractures. It depends on the intrinsic permeability of the material and on the degree of

331

Evaluating the effects of temperature gradients and currents nonuniformity in on-chip interconnects  

Science Conference Proceedings (OSTI)

The paper provides a compact but accurate electro-thermal model of a long wiring on-chip interconnect embedded in the complex layout of a ULSI digital circuit. The proposed technique takes into account both the effect of temperature gradients over the ... Keywords: Current nonuniformity, Electro-thermal model, On-chip interconnect, Propagation delay

N. Spennagallo; L. Codecasa; D. D'Amore; P. Maffezzoni

2009-07-01T23:59:59.000Z

332

Scaffold Gradients: Finding the Right Environment for ...  

Science Conference Proceedings (OSTI)

Scaffold Gradients: Finding the Right Environment for Developing Cells. For Immediate Release: May 25, 2010. ...

2013-05-14T23:59:59.000Z

333

Gradient Combinatorial Libraries via Modulated Light ...  

Science Conference Proceedings (OSTI)

... Libraries via Modulated Light Exposure. Bookmark and Share Gradient Combinatorial Libraries via Modulated Light Exposure. ...

334

Downward continuation of temperature gradients at MacFarlane's Hot Spring, Northern Nevada  

SciTech Connect

MacFarlane's Hot Spring is located on the eastern margin of the Black Rock Desert of northwest Nevada. Detailed temperature logs from thirty-eight shallow boreholes (500 feet) and six intermediate depth boreholes (1500-2000 feet) have been used to construct a temperature gradient contour map covering approximately 144 square miles, both within and adjacent to the geothermal area. These temperature gradients were then continued downward through a detailed conductivity model to complete the threedimensional thermal picture. The principal results are as follows: The maximum measured temperature is 178/sup 0/F at 2,000 feet, and the maximum projected temperatures at greater depths are not likely to exceed the 250-350/sup 0/F range. The area of hydrothermal activity is confined to the western front of a structural platform bounded by two roughly parallel normal faults. The anomaly is best explained in terms of a simple groundwater flow model. The groundwater flows west through the structural platform and ascends when it intersects the conduit provided by the fault. The faults on the eastern side of the platform permit recharge to the system.

Swanberg, C.A.; Bowers, R.L.

1982-10-01T23:59:59.000Z

335

On Thermally Direct Circulations in Moist Atmospheres  

Science Conference Proceedings (OSTI)

An expression is derived for the critical horizontal gradient of subcloud-layer ?e in radiative-convective equilibrium, sufficient for the onset of thermally direct, zonally symmetric circulations. This corresponds to zero absolute vorticity at ...

Kerry A. Emanuel

1995-05-01T23:59:59.000Z

336

Thermal Stability of the World Ocean Thermoclines  

Science Conference Proceedings (OSTI)

Because of the strong variation with temperature of the thermal expansion coefficient of seawater, both horizontal and vertical mixing that perturb the gradients produce changes of volume, usually a decrease, that shift mass relative to the earth'...

N. P. Fofonoff

2001-08-01T23:59:59.000Z

337

251 Thermal Gradient Cycling with Simultaneous Silicate Particle ...  

Science Conference Proceedings (OSTI)

... of LiMnxFe1-xPO4 Glass and Glass-Ceramics for Lithium Ion Battery .... and Comparing the Inhibition Effect of Chromate, Bromate and Molybdate on the ...

338

Effects of Composition and Thermal Gradients on Rapid ...  

Science Conference Proceedings (OSTI)

Differential Characterization of Ikperejere Iron shale and Iron Sandstone Deposit · Direct Precipitation of Sr-doped LaP3O9 Thin Film Electrolytes for ...

339

Thermal Gradient Holes At Cove Fort Area (Warpinski, Et Al.,...  

Open Energy Info (EERE)

not indicated DOE-funding Unknown Notes Update to Warpinski, et al., 2002 References N. R. Warpinski, A. R. Sattler, R. Fortuna, D. A. Sanchez, J. Nathwani (2004) Geothermal...

340

Thermal Gradient Holes At Cove Fort Area - Vapor (Warpinski,...  

Open Energy Info (EERE)

not indicated DOE-funding Unknown Notes Update to Warpinski, et al., 2002 References N. R. Warpinski, A. R. Sattler, R. Fortuna, D. A. Sanchez, J. Nathwani (2004) Geothermal...

Note: This page contains sample records for the topic "gradients thermal conductivity" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Thermal Gradient Holes At Northern Basin & Range Region (Pritchett...  

Open Energy Info (EERE)

Date Usefulness not useful DOE-funding Unknown Notes NOTE: These are theoreticalcomputer simulation tests of various methods on eight hypothetical 'model' basing-and-range...

342

Article for thermal energy storage  

DOE Patents (OSTI)

A thermal energy storage composition is provided which is in the form of a gel. The composition includes a phase change material and silica particles, where the phase change material may comprise a linear alkyl hydrocarbon, water/urea, or water. The thermal energy storage composition has a high thermal conductivity, high thermal energy storage, and may be used in a variety of applications such as in thermal shipping containers and gel packs.

Salyer, Ival O. (Dayton, OH)

2000-06-27T23:59:59.000Z

343

Experimental and theoretical investigation of high gradient acceleration  

Science Conference Proceedings (OSTI)

This report contains a technical progress summary of the research conducted under the auspices of DOE Grant No. DE-FG0291ER-40648. Experimental and Theoretical Investigations of High Gradient Acceleration.'' This grant supports three research tasks: Task A consists of the design and fabrication of a 17GHz of photocathode gun, Task B supports the testing of high gradient acceleration using a 33GHz structure, and Task C comprises theoretical investigations, both in support of the experimental tasks and on critical physics issues for the development of high energy linear colliders. This report is organized as follows. The development of an rf gun design and research progress on the picosecond laser system is summarized in Sec. 2, the status of the studies of the LBL/Haimson high gradient structure, using a 50 MW free-electron laser is summarized in Sec. 3, and theoretical research progress is described in Sec. 4. Supporting material is contained in Appendices A-G.

Bekefi, G.; Chen, C.; Chen, S.; Danly, B.; Temkin, R.J.; Wurtele, J.S.

1992-02-01T23:59:59.000Z

344

Thermally activated miniaturized cooling system.  

E-Print Network (OSTI)

??A comprehensive study of a miniaturized thermally activated cooling system was conducted. This study represents the first work to conceptualize, design, fabricate and successfully test… (more)

Determan, Matthew Delos

2008-01-01T23:59:59.000Z

345

Thermal protection apparatus  

DOE Patents (OSTI)

An apparatus which thermally protects sensitive components in tools used in a geothermal borehole. The apparatus comprises a Dewar within a housing. The Dewar contains heat pipes such as brass heat pipes for thermally conducting heat from heat sensitive components to a heat sink such as ice.

Bennett, Gloria A. (Los Alamos, NM); Elder, Michael G. (Los Alamos, NM); Kemme, Joseph E. (Albuquerque, NM)

1985-01-01T23:59:59.000Z

346

Thermal protection apparatus  

DOE Patents (OSTI)

The disclosure is directed to an apparatus for thermally protecting sensitive components in tools used in a geothermal borehole. The apparatus comprises a Dewar within a housing. The Dewar contains heat pipes such as brass heat pipes for thermally conducting heat from heat sensitive components such as electronics to a heat sink such as ice.

Bennett, G.A.; Elder, M.G.; Kemme, J.E.

1984-03-20T23:59:59.000Z

347

Design, construction, and initial operation of the Los Alamos National Laboratory salt-gradient solar pond  

DOE Green Energy (OSTI)

A 232 m/sup 2/ solar pond was constructed at Los Alamos National Laboratory for the purpose of studying pond hydrodynamics on a large scale and to complement the flow visualization and one-dimensional pond simulator experiments that are ongoing at the Laboratory. Design methods and construction techniques, some of which are unique to this pond, are described in detail. The pond was excavated from a soft volcanic rock known as tuff; such rock forms a large fraction of the Los Alamos area surface geology. Because tuff has a small thermal conductivity, little insulation was required to reduce perimeter energy losses. In addition, the strength of tuff permitted the pond to be built with vertical side walls; this design eliminated local side wall convection in the gradient zone that is possible with sloping side walls. Instrumentation in the pond consists of traversing and fixed rakes of thermometers and salinity probes, an underwater pyranometer, and a weather station. The traversing rake is a wheeled trolley driven vertically on a rectangular rail. Installed on the trolley are coplanar platinum RTDs, a point conductivity probe, and an induction salinometer. The stationary rake supports 28 thermocouples and 28 sample-fluid withdrawal taps located every 10 cm. About 127 T of sodium chloride has been introduced and is nearly dissolved. A 120-cm-thick salinity gradient was established and the pond is heating. Preliminary results indicate a lower-convective-zone heating rate of 1.2/sup 0/C/day during the pond's first month of operation. Recommendations on pond design, construction, and instrumentation are presented.

Jones, G.F.; Meyer, K.A.; Hedstrom, J.C.; Dreicer, J.S.; Grimmer, D.P.

1983-01-01T23:59:59.000Z

348

Finite Heat conduction in 2D Lattices  

E-Print Network (OSTI)

This paper gives a 2D hamonic lattices model with missing bond defects, when the capacity ratio of defects is enough large, the temperature gradient can be formed and the finite heat conduction is found in the model. The defects in the 2D harmonic lattices impede the energy carriers free propagation, by another words, the mean free paths of the energy carrier are relatively short. The microscopic dynamics leads to the finite conduction in the model.

Lei Yang; Yang Kongqing

2001-07-30T23:59:59.000Z

349

Revisiting an Old Concept: The Gradient Wind  

Science Conference Proceedings (OSTI)

The gradient wind is defined as a horizontal wind having the same direction as the geostrophic wind but with a magnitude consistent with a balance of three forces: the pressure gradient force, the Coriolis force, and the centrifugal force arising ...

Keith F. Brill

350

A method for filtering hot spring noise from shallow temperature gradient data  

Science Conference Proceedings (OSTI)

A technique for separating shallow heat source effects from temperature gradient data is presented. The technique makes use of the depth dependent information available in the wave number spectrum of the gradient data. The effectiveness of the technique is demonstrated on a two-dimensional numerical model of a geothermal system containing a deep geothermal reservoir which is masked by a warm, shallow aquifer and a thermal spring. This geothermal system is representative of those found throughout the Basin and Range province. The resulting filtered gradients produce an excellent prediction of the temperatures in the modeled geothermal reservoir.

Li, T.M.C.; Chandler, C.A.; Ferguson, J.F.

1982-10-01T23:59:59.000Z

351

Ion temperature gradient instability and anomalous transport  

SciTech Connect

This report discusses experiments in ion temperature gradient instability and anomalous transport in the CLM steady state device. (LSP).

Sen, A.K.

1991-08-01T23:59:59.000Z

352

Near Boundary Gradient Zone: An Overview  

Science Conference Proceedings (OSTI)

Analyzing Upper Tails of Grain Size Distributions Using Extreme Value ... Strain Gradient and Degradation in Magnetic Properties: Focus Transformer Steel.

353

A Multiscale Model for Coupled Heat Conduction and Deformations of Viscoelastic Composites  

E-Print Network (OSTI)

This study introduces a multiscale model for analyzing nonlinear thermo-viscoelastic responses of particulate composites. A simplified micromechanical model consisting of four sub-cells, i.e., one particle and three matrix sub-cells is formulated to obtain the effective thermal and mechanical properties and time-dependent response of the composites. The particle and matrix constituents are made of isotropic homogeneous viscoelastic bodies undergoing small deformation gradients. Perfect bonds are assumed along the sub-cell???s interfaces. The coupling between the thermal and mechanical response is attributed to the dissipation of energy due to the viscoelastic deformation and temperature dependent material parameters in the viscoelastic constitutive model. The micromechanical relations are formulated in terms of incremental average field quantities, i.e., stress, strain, heat flux and temperature gradient, in the sub-cells. The effective mechanical properties and coefficient of thermal expansion are derived by satisfying displacement- and traction continuities at the interfaces during the thermo-viscoelastic deformations. The effective thermal conductivity is formulated by imposing heat flux- and temperature continuities at the subcells??? interfaces. The expression of the effective specific heat at a constant stress is also established. A time integration algorithm for simultaneously solving the equations that govern heat conduction and thermoviscoelastic deformations of isotropic materials is developed. The algorithm is then incorporated within each sub-cell of the micromechanical model together with the macroscopic energy equation to determine the effective coupled thermoviscoelastic response of the particulate composite. The numerical formulation is implemented within the ABAQUS, general purpose displacement based FE software, allowing for analyzing coupled heat conduction and deformations of composite structures. Experimental data on the effective thermal properties and time dependent responses of particulate composites available in the literature are used to verify the micromechanical model formulation. The multiscale model capability is also examined by comparing the field variables, i.e., temperature, displacement, stresses and strains, obtained from heterogeneous and homogeneous composite structures, during the transient heat conduction and deformations. Examples of coupled thermoviscoelastic analyses of particulate composites and functionally graded structures are also presented. The present micromechanical modeling approach is found to be computationally efficient and shows good agreement with experiments in predicting the effective thermo-mechanical response of particulate composites and functionally graded materials. Our analyses forecast a better design for creep resistant and less dissipative structures using particulate composites and functionally graded materials.

Khan, Kamran Ahmed

2011-05-01T23:59:59.000Z

354

Locally exact modifications of discrete gradient schemes  

E-Print Network (OSTI)

Locally exact integrators preserve linearization of the original system at every point. We construct energy-preserving locally exact discrete gradient schemes for arbitrary multidimensional canonical Hamiltonian systems by modifying classical discrete gradient schemes. Modifications of this kind are found for any discrete gradient.

Cie?li?ski, Jan L

2013-01-01T23:59:59.000Z

355

High-temperature thermal storage systems for advanced solar receivers materials selections  

DOE Green Energy (OSTI)

Advanced space power systems that use solar energy and Brayton or Stirling heat engines require thermal energy storage (TES) systems to operate continuously through periods of shade. The receiver storage units, key elements in both Brayton and Stirling systems, are designed to use the latent heat of fusion of phase-change materials (PCMs). The power systems under current consideration for near-future National Aeronautics and Space Administration space missions require working fluid temperatures in the 1100 to 1400 K range. The PCMs under current investigation that gave liquidus temperatures within this range are the fluoride family of salts. However, these salts have low thermal conductivity, which causes large temperature gradients in the storage systems. Improvements can be obtained, however, with the use of thermal conductivity enhancements or metallic PCMs. In fact, if suitable containment materials can be found, the use of metallic PCMs would virtually eliminate the orbit associated temperature variations in TES systems. The high thermal conductivity and generally low volume change on melting of germanium and alloys based on silicon make them attractive for storage of thermal energy in space power systems. An approach to solving the containment problem, involving both chemical and physical compatibility, preparation of NiSi/NiSi{sub 2}, and initial results for containment of germanium and NiSi/NiSi{sub 2}, are presented. 7 refs., 10 figs., 4 tabs.

Wilson, D.F.; DeVan, J.H.; Howell, M.

1990-09-01T23:59:59.000Z

356

Modeling of grain growth in UO2 under a temperature gradient  

Science Conference Proceedings (OSTI)

Characterization of MOX fuel pellets by Photothermal microscopy · Correlation Between Thermal Conductivity and Microstructural Evolutions in CeO2 Upon ...

357

Ocean Thermal Energy Conversion: Potential Environmental Impacts and Fisheries  

E-Print Network (OSTI)

Ocean Thermal Energy Conversion: Potential Environmental Impacts and Fisheries Christina M Comfort Institute #12;Ocean Thermal Energy Conversion (OTEC) · Renewable energy ­ ocean thermal gradient · Large, M.Sc. Candidate University of Hawaii at Manoa Department of Oceanography Hawaii Natural Energy

Hawai'i at Manoa, University of

358

Aluminum/TPG Metal Matrix Composite with Improved Thermal ...  

Science Conference Proceedings (OSTI)

It was found that A356/TPG interface was optimal for the examined MMC's high thermal conductivity. Low cooling rates assisted in reducing thermal stresses at ...

359

Solution Processing of Polymer Nanotube Thermal Interface Materials  

Science Conference Proceedings (OSTI)

Ideal TIMs should exhibit high thermal conductivity and maintain mechanical ... bulk polymers exhibit phonon scattering and are poor conductors of thermal ...

360

Gradient Projection Methods for Quadratic Programs and ...  

E-Print Network (OSTI)

Jul 30, 2003 ... Gradient Projection Methods for Quadratic Programs and Applications in Training Support Vector Machines. Thomas Serafini (serafini.thomas ...

Note: This page contains sample records for the topic "gradients thermal conductivity" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

A Mean-Gradient Model of the Dry Convective Boundary Layer  

Science Conference Proceedings (OSTI)

A mean-gradient model of the dry convective boundary layer is developed using a convective mass flux representation of the turbulent fluxes. A top-hat model of thermals is used to represent the average characteristics of updrafts and downdrafts ...

Shouping Wang; Bruce A. Albrecht

1990-01-01T23:59:59.000Z

362

Concrete Electrical Conductivity Test  

Science Conference Proceedings (OSTI)

Concrete Electrical Conductivity Test. Description/Summary: ... Details. Type of software: Virtual concrete electrical conductivity test. Authors: ...

2013-06-11T23:59:59.000Z

363

THERMAL RECOVERY  

NLE Websites -- All DOE Office Websites (Extended Search)

THERMAL RECOVERY Thermal recovery comprises the techniques of steamflooding, cyclic steam stimulation, and in situ combustion. In steamflooding, high-temperature steam is injected...

364

Results of temperature gradient and heat flow in Santiam Pass Area, Oregon, Volume 1  

DOE Green Energy (OSTI)

The conclusions of this report are: (1) There is a weakly defined thermal anomaly within the area examined by temperature-gradient holes in the Santiam Pass area. This is a relict anomaly showing differences in permeability between the High Cascades and Western Cascades areas, more than a fundamental difference in shallow crustal temperatures. (2) The anomaly as defined by the 60 F isotherms at 400 feet follows a north-south trend immediately westward of the Cascade axis in the boundary region. It is clear that all holes spudded into High Cascades rocks result in isothermal and reversal gradients. Holes spudded in Western Cascades rocks result in positive gradients. (3) Cold groundwater flow influences and masks temperature gradients in the High Cascades to a depth of at least 700 feet, especially eastward from the major north-south trending faults. Pleistocene and Holocene rocks are very permeable aquifers. (4) Shallow gradient drilling in the lowlands westward of the faults provides more interpretable information than shallow drilling in the cold-water recharge zones. Topographic and climatological effects can be filtered out of the temperature gradient results. (5) The thermal anomaly seems to have 2 centers: one in the Belknap-Foley area, and one northward in the Sand Mountain area. The anomalies may or may not be connected along a north-south trend. (6) A geothermal effect is seen in holes downslope of the Western-High Cascade boundary. Mixing with cold waters is a powerful influence on temperature gradient data. (7) The temperature-gradient program has not yet examined and defined the geothermal resources potential of the area eastward of the Western Cascades-High Cascades boundary. Holes to 1500-2000 feet in depth are required to penetrate the high permeability-cold groundwater regime. (8) Drilling conditions are unfavorable. There are very few accessible level drill sites. Seasonal access problems and environmental restrictions together with frequent lost circulation results in very high costs per foot drilled.

Cox, B.L.; Gardner, M.C.; Koenig, J.B.

1981-08-01T23:59:59.000Z

365

Proton conducting ceramic membranes for hydrogen separation  

Science Conference Proceedings (OSTI)

A multi-phase proton conducting material comprising a proton-conducting ceramic phase and a stabilizing ceramic phase. Under the presence of a partial pressure gradient of hydrogen across the membrane or under the influence of an electrical potential, a membrane fabricated with this material selectively transports hydrogen ions through the proton conducting phase, which results in ultrahigh purity hydrogen permeation through the membrane. The stabilizing ceramic phase may be substantially structurally and chemically identical to at least one product of a reaction between the proton conducting phase and at least one expected gas under operating conditions of a membrane fabricated using the material. In a barium cerate-based proton conducting membrane, one stabilizing phase is ceria.

Elangovan, S. (South Jordan, UT); Nair, Balakrishnan G. (Sandy, UT); Small, Troy (Midvale, UT); Heck, Brian (Salt Lake City, UT)

2011-09-06T23:59:59.000Z

366

Geothermal gradient map of the United States  

Science Conference Proceedings (OSTI)

A geothermal gradient map is needed in order to determine the hot dry rock (HDR) geothermal resource of the United States. Based on published and unpublished data (including new measurements) the HDR program will produce updated gradient maps annually, to be used as a tool for resource evaluation and exploration. The 1980 version of this map is presented.

Kron, A.; Heiken, G.

1980-01-01T23:59:59.000Z

367

Scrape-off Layer Flows With Pressure Gradient Scale Length ~ {rho}{sub p}  

SciTech Connect

A heuristic model for the plasma scrape-off width balances magnetic drifts against parallel loss at c{sub s} /2, resulting in a SOL width ~ {rho}{sub p}. T{sub sep} is calculated from Spitzer–Härm parallel thermal conduction. This results in a prediction for the power scrape-off width in quantitative agreement both in magnitude and scaling with recent experimental data. To achieve the ~ c{sub s} /2 flow assumed in this model and measured experimentally sets requirements on the ratio of upstream to total SOL particle sources, relative to the square-root of the ratio of target to upstream temperature. The Pfisch-Schlüter model for equilibrium flows has been modified to allow near-sonic flows, appropriate for gradient scale lengths of order {rho}{sub p}, resulting in a new quadrupole radial flow pattern. The strong parallel flows and plasma charging implied by this model suggest a mechanism for H-mode transition, consistent with many observations

Robert J. Goldston

2013-03-08T23:59:59.000Z

368

Thermal ignition combustion system  

DOE Patents (OSTI)

The thermal ignition combustion system comprises means for providing walls defining an ignition chamber, the walls being made of a material having a thermal conductivity greater than 20 W/m C and a specific heat greater than 480 J/kg C with the ignition chamber being in constant communication with the main combustion chamber, means for maintaining the temperature of the walls above a threshold temperature capable of causing ignition of a fuel, and means for conducting fuel to the ignition chamber. 8 figs.

Kamo, R.; Kakwani, R.M.; Valdmanis, E.; Woods, M.E.

1988-04-19T23:59:59.000Z

369

High-Efficiency Thermal Energy Storage System for CSP  

NLE Websites -- All DOE Office Websites (Extended Search)

June 15, 2013 | Singh * Thermal modeling will be conducted to establish the benefits of using a high thermal conducting graphite foams in conjunction with PCM and to develop a...

370

Thermal Management Using Carbon Nanotubes - Energy Innovation ...  

Patent 7,763,353: Fabrication of high thermal conductivity arrays of carbon nanotubes and their composites Methods and apparatus are described for ...

371

Definition: Thermal Rating | Open Energy Information  

Open Energy Info (EERE)

Rating Jump to: navigation, search Dictionary.png Thermal Rating The maximum amount of electrical current that a transmission line or electrical facility can conduct over a...

372

Fractography of Thermally Shocked Glass Cookware  

Science Conference Proceedings (OSTI)

Fractography of fractured glass cookware can be a time consuming process of putting ... to Conduct Thermal Shock Test on Refractories Using Steel Blocks.

373

Universal Gradient Methods for Convex Optimization Problems  

E-Print Network (OSTI)

Apr 18, 2013 ... methods (e.g. [9], [10], [1]), which increase the rate of convergence of the gradient schemes much above the limits of Black-Box Complexity ...

374

Continuous spray forming of functionally gradient materials  

SciTech Connect

Researchers at Plasma Processes Inc. have produced a Functional Gradient Material (FGM) through advanced vacuum plasma spray processing for high heat flux applications. Outlined in this paper are the manufacturing methods used to develop a four component functional gradient material of copper, tungsten, boron, and boron nitride. The FGM was formed with continuous gradients and integral cooling channels eliminating bondlines and providing direct heat transfer from the high temperature exposed surface to a cooling medium. Metallurgical and x-ray diffraction analyses of the materials formed through innovative VPS (vacuum plasma spray) processing are also presented. Applications for this functional gradient structural material range from fusion reactor plasma facing components to missile nose cones to boilers.

McKechnie, T.N.; Richardson, E.H.

1995-12-01T23:59:59.000Z

375

Separation of carbon nanotubes in density gradients  

DOE Patents (OSTI)

The separation of single-walled carbon nanotubes (SWNTs), by chirality and/or diameter, using centrifugation of compositions of SWNTs in and surface active components in density gradient media.

Hersam, Mark C. (Evanston, IL); Stupp, Samuel I. (Chicago, IL); Arnold, Michael S. (Northbrook, IL)

2012-02-07T23:59:59.000Z

376

Separation of carbon nanotubes in density gradients  

DOE Patents (OSTI)

The separation of single-walled carbon nanotubes (SWNTs), by chirality and/or diameter, using centrifugation of compositions of SWNTs in and surface active components in density gradient media.

Hersam, Mark C. (Evanston, IL); Stupp, Samuel I. (Chicago, IL); Arnold, Michael S. (Northbrook, IL)

2010-02-16T23:59:59.000Z

377

Thermal-Instability-Driven Turbulent Mixing in Galactic Disks: I. Effective Mixing of Metals  

E-Print Network (OSTI)

Observations show that radial metallicity gradients in disk galaxies are relatively shallow, if not flat, especially at large galactocentric distances and for galaxies in the high-redshift universe. Given that star formation and metal production are centrally concentrated, this requires a mechanism to redistribute metals. However, the nature of this mechanism is poorly understood, let alone quantified. To address this problem, we conduct magnetohydrodynamical simulations of a local shearing sheet of a thin, thermally unstable, gaseous disk driven by a background stellar spiral potential, including metals modeled as passive scalar fields. Contrary to what a simple \\alpha\\ prescription for the gas disk would suggest, we find that turbulence driven by thermal instability is very efficient at mixing metals, regardless of the presence or absence of stellar spiral potentials or magnetic fields. The timescale for homogenizing randomly distributed metals is comparable to or less than the local orbital time in the dis...

Yang, Chao-Chin

2012-01-01T23:59:59.000Z

378

The gradient flow in a twisted box  

E-Print Network (OSTI)

We study the perturbative behavior of the gradient flow in a twisted box. We apply this information to define a running coupling using the energy density of the flow field. We study the step-scaling function and the size of cutoff effects in SU(2) pure gauge theory. We conclude that the twisted gradient flow running coupling scheme is a valid strategy for step-scaling purposes due to the relatively mild cutoff effects and high precision.

Ramos, A

2013-01-01T23:59:59.000Z

379

Diversity, Body Mass, and Latitudinal Gradients in Primates  

E-Print Network (OSTI)

gradients in regional diversity of New World birds. GlobalT. (2003). Assessment of the diversity of African primates.of the latitudinal diversity gradient. American Naturalist,

Harcourt, A. H.; Schreier, B. M.

2009-01-01T23:59:59.000Z

380

Gradient effects on the fracture of inhomogeneous materials  

SciTech Connect

Functionally Graded Materials (FGMs) have a spatial variation in physical properties that can be tailored to meet the needs of a specific application and/or to minimize internal stresses arising from thermal and elastic mismatch. Modeling these materials as inhomogeneous continua allows assessment of the role of the gradient without requiring detailed knowledge of the microstructure. Motivated by the relative difficulty of obtaining analytical solutions to boundary value problems for FGMs, an accurate finite-element code is developed for obtaining numerical planar and axisymmetric linear thermoelastic solutions. In addition an approximate analytical technique for mapping homogeneous-modulus solutions to those for FGMs is assessed and classes of problems to which it applies accurately are identified. The fracture mechanics analysis of FGMs can be characterized by the classic stress intensities, KI and KII, but there has been scarce progress in understanding the role of the modulus gradient in determining fracture initiation and propagation. To address this question, a statistical fracture model is used to correlate near-tip stresses with brittle fracture initiation behavior. This describes the behavior of a material experiencing fracture initiation away from the crack tip. Widely dispersed zones of fracture initiation sites are expected. Finite-length kinks are analyzed to describe the crack path for continuous crack growth. For kink lengths much shorter than the gradient dimension, a parallel stress term describes the deviation of the kinking angle from that for homogeneous materials. For longer kinks there is a divergence of the kink angle predicted by the maximum energy release rate and the pure opening mode criteria.

Becker, T.L.

2000-05-01T23:59:59.000Z

Note: This page contains sample records for the topic "gradients thermal conductivity" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Salinity gradient solar pond technology applied to potash solution mining  

DOE Green Energy (OSTI)

A solution mining facility at the Eddy Potash Mine, Eddy County, New Mexico has been proposed that will utilize salinity gradient solar pond (SGSP) technology to supply industrial process thermal energy. The process will include underground dissolution of potassium chloride (KCl) from pillars and other reserves remaining after completion of primary room and pillar mining using recirculating solutions heated in the SGSP. Production of KCl will involve cold crystallization followed by a cooling pond stage, with the spent brine being recirculated in a closed loop back to the SGSP for reheating. This research uses SGSP as a renewable, clean energy source to optimize the entire mining process, minimize environmental wastes, provide a safe, more economical extraction process and reduce the need for conventional processing by crushing, grinding and flotation. The applications of SGSP technology will not only save energy in the extraction and beneficiation processes, but also will produce excess energy available for power generation, desalination, and auxiliary structure heating.

Martell, J.A.; Aimone-Martin, C.T.

2000-06-12T23:59:59.000Z

382

Code of Conduct  

NLE Websites -- All DOE Office Websites (Extended Search)

Governance » Governance » Ethics, Accountability » Code of Conduct Code of Conduct Helping employees recognize and resolve the ethics and compliance issues that may arise in their daily work. Contact Code of Conduct (505) 667-7506 Code of Conduct LANL is committed to operating in accordance with the highest standards of ethics and compliance and with its core values of service to our nation, ethical conduct and personal accountability, excellence in our work, and mutual respect and teamwork. LANL must demonstrate to customers and the public that the Laboratory is accountable for its actions and that it conducts business in a trustworthy manner. What is LANL's Code of Conduct? Charlie McMillan 1:46 Laboratory Director Charlie McMillan introduces the code LANL's Code of Conduct is designed to help employees recognize and

383

Control of Test Conduct  

NLE Websites -- All DOE Office Websites (Extended Search)

2 Revision 1 Effective June 2008 Control of Test Conduct Prepared by Electric Transportation Applications Prepared by: Date: Garrett P....

384

Laser window with annular grooves for thermal isolation  

DOE Patents (OSTI)

A laser window or other optical element which is thermally loaded, heats up and causes optical distortions because of temperature gradients between the center and the edge. A number of annular grooves, one to three or more, are formed in the element between a central portion and edge portion, producing a web portion which concentrates the thermal gradient and thermally isolates the central portion from the edge portion, producing a uniform temperature profile across the central portion and therefore reduce the optical distortions. The grooves are narrow and closely spaced with respect to the thickness of the element, and successive grooves are formed from alternate sides of the element.

Warner, B.E.; Horton, J.A.; Alger, T.W.

1983-07-13T23:59:59.000Z

385

CONDUCT OF OPERATIONS (CO)  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

CONDUCT OF OPERATIONS (CO) CONDUCT OF OPERATIONS (CO) OBJECTIVE TA-55 SST Facility NNSA ORR Implementation Plan 1 1 CO.1 The formality and discipline of operations is adequate to conduct work safely and programs are inplace to maintain this formality and discipline. (Core Requirement 13) Criteria 1. Programmatic elements of conduct of operations are in place for TA-55 SST operations. 2. The TA-55 SST operations personnel adequately demonstrate the principles of conduct ofoperations requirements during the shift performance period. Approach Record Reviews: Review procedures and other facility documents to verify compliance with conduct of operations principles. Interviews: Interview a sampling of the TA-55 SST associated personnel to validate their understanding of the conduct of operations principles (e.g., procedure usage,

386

METALLICITY GRADIENTS OF THICK DISK DWARF STARS  

Science Conference Proceedings (OSTI)

We examine the metallicity distribution of the Galactic thick disk using F, G, and K dwarf stars selected from the Sloan Digital Sky Survey, Data Release 8. Using the large sample of dwarf stars with proper motions and spectroscopically determined stellar parameters, metallicity gradients in the radial direction for various heights above the Galactic plane and in the vertical direction for various radial distances from the Galaxy center have been found. In particular, we find a vertical metallicity gradient of -0.113 {+-} 0.010 (-0.125 {+-} 0.008) dex kpc{sup -1} using an isochrone (photometric) distance determination in the range 1 kpc solar neighborhood. Metallicity gradients in the thin and thick disks are important probes into possible formation scenarios for our Galaxy and a consistent picture is beginning to emerge from results using large spectroscopic surveys, such as the ones presented here.

Carrell, Kenneth; Chen Yuqin; Zhao Gang, E-mail: carrell@nao.cas.cn [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

2012-12-01T23:59:59.000Z

387

1D-to-3D transition of phonon heat conduction in polyethylene using molecular dynamics simulations  

E-Print Network (OSTI)

The thermal conductivity of nanostructures generally decreases with decreasing size because of classical size effects. The axial thermal conductivity of polymer chain lattices, however, can exhibit the opposite trend, ...

Henry, Asegun

388

Umklapp Scattering and Heat Conductivity of Superlattices  

E-Print Network (OSTI)

The mean free path of phonons in superlattices is estimated. It is shown to be strongly dependent on the superlattice period due to the Umklapp scattering in subbands. It first falls with increasing the superlattice period until it becomes comparable with the latter after what it rises back to the bulk value. Similar behavior is expected of heat conductivity, which is proportional to the mean free path. Superlattices offer an opportunity to control physical properties in unprecedented ways. Their thermal conductivity is of interest both for a fundamental understanding of these systems as well as in applications. Recently there has been a resurgence of interest in finding materials with improved thermoelectric transport properties for cooling and power generation. The quality of a material for such applications is given by the thermoelectric figure of merit, which is inversely proportional to the thermal conductivity ?. In materials of interest, such as semiconductors, the lattice contribution to ? dominates. Experimental and theoretical work suggests that the thermal conductivity of superlattices is quite low, both for transport along the planes [1, 2, 10], or perpendicular to the planes [3, 4, 5, 6, 7, 8, 11]. The lattice heat conductivity ? is given approximately by an equation [12]:

M. V. Simkin; G. D. Mahan

2000-01-01T23:59:59.000Z

389

Recent Studies of RF Breakdown Physics in Normal Conducting Cavities  

SciTech Connect

The operating accelerating gradient in normal conducting accelerating structures is often limited by rf breakdown. The behavior of the rf breakdown depends on multiple parameters, including the input rf power, rf circuit, cavity shape and material. Here we discuss recent experimental data and theoretical studies of rf breakdown physics.

Dolgashev, Valery; /SLAC

2012-06-11T23:59:59.000Z

390

High-pressure liquid chromatographic gradient mixer  

DOE Patents (OSTI)

A gradient mixer effects the continuous mixing of any two miscible solvents without excessive decay or dispersion of the resultant isocratic effluent or of a linear or exponential gradient. The two solvents are fed under low or high pressure by means of two high performance liquid chromatographic pumps. The mixer comprises a series of ultra-low dead volume stainless steel tubes and low dead volume chambers. The two solvent streams impinge head-on at high fluxes. This initial nonhomogeneous mixture is then passed through a chamber packed with spirally-wound wires which cause turbulent mixing thereby homogenizing the mixture with minimum band-broadening.

Daughton, C.G.; Sakaji, R.H.

1982-09-08T23:59:59.000Z

391

The long range migration of hydrogen through Zircaloy in response to tensile and compressive stress gradients  

DOE Green Energy (OSTI)

Zircaloy-4, which is used widely as a core structural material in pressurized water reactors (PWRs), picks up hydrogen during service. Hydrogen solubility in Zircaloy-4 is low and zirconium hydride phases precipitate after the Zircaloy-4 lattice becomes supersaturated with hydrogen. These hydrides embrittle the Zircaloy-4, degrading its mechanical performance as a structural material. Because hydrogen can move rapidly through the Zircaloy-4 lattice, the potential exists for large concentrations of hydride to accumulate in local regions of a Zircaloy component remote from its point of entry into the component. Much has been reported in the literature regarding the long range migration of hydrogen through Zircaloy under concentration gradients and temperature gradients. Relatively little has been reported, however, regarding the long range migration of hydrogen under stress gradients. This paper presents experimental results regarding the long range migration of hydrogen through Zircaloy in response to both tensile and compressive stress gradients. The importance of this driving force for hydrogen migration relative to concentration and thermal gradients is discussed.

Kammenzind, B.F.; Berquist, B.M.; Bajaj, R.; Kreyns, P.H.; Franklin, D.G.

1998-11-01T23:59:59.000Z

392

Heat conduction in 2D strongly-coupled dusty plasmas  

E-Print Network (OSTI)

We perform non-equilibrium simulations to study heat conduction in two-dimensional strongly coupled dusty plasmas. Temperature gradients are established by heating one part of the otherwise equilibrium system to a higher temperature. Heat conductivity is measured directly from the stationary temperature profile and heat flux. Particular attention is paid to the influence of damping effect on the heat conduction. It is found that the heat conductivity increases with the decrease of the damping rate, while its magnitude confirms previous experimental measurement.

Hou, Lu-Jing

2008-01-01T23:59:59.000Z

393

High conductance surge cable  

DOE Patents (OSTI)

An electrical cable for connecting transient voltage surge suppressors to electrical power panels. A strip of electrically conductive foil defines a longitudinal axis, with a length of an electrical conductor electrically attached to the metallic foil along the longitudinal axis. The strip of electrically conductive foil and the length of an electrical conductor are covered by an insulating material. For impedance matching purposes, triangular sections can be removed from the ends of the electrically conductive foil at the time of installation. 6 figs.

Murray, M.M.; Wilfong, D.H.; Lomax, R.E.

1998-12-08T23:59:59.000Z

394

Thermal and non-thermal energies in solar flares  

E-Print Network (OSTI)

The energy of the thermal flare plasma and the kinetic energy of the non-thermal electrons in 14 hard X-ray peaks from 9 medium-sized solar flares have been determined from RHESSI observations. The emissions have been carefully separated in the spectrum. The turnover or cutoff in the low-energy distribution of electrons has been studied by simulation and fitting, yielding a reliable lower limit to the non-thermal energy. It remains the largest contribution to the error budget. Other effects, such as albedo, non-uniform target ionization, hot target, and cross-sections on the spectrum have been studied. The errors of the thermal energy are about equally as large. They are due to the estimate of the flare volume, the assumption of the filling factor, and energy losses. Within a flare, the non-thermal/thermal ratio increases with accumulation time, as expected from loss of thermal energy due to radiative cooling or heat conduction. Our analysis suggests that the thermal and non-thermal energies are of the same magnitude. This surprising result may be interpreted by an efficient conversion of non-thermal energy to hot flare plasma.

Pascal Saint-Hilaire; Arnold O. Benz

2005-03-03T23:59:59.000Z

395

Research Conduct Policies  

Office of Science (SC) Website

Research Conduct Policies Basic Energy Sciences (BES) BES Home About Research Materials Sciences & Engineering (MSE) Chemical Sciences, Geosciences, and Biosciences (CSGB)...

396

Multi-gradient drilling method and system  

DOE Patents (OSTI)

A multi-gradient system for drilling a well bore from a surface location into a seabed includes an injector for injecting buoyant substantially incompressible articles into a column of drilling fluid associated with the well bore. Preferably, the substantially incompressible articles comprises hollow substantially spherical bodies.

Maurer, William C. (Houston, TX); Medley, Jr., George H. (Spring, TX); McDonald, William J. (Houston, TX)

2003-01-01T23:59:59.000Z

397

Thermal insulated glazing unit  

SciTech Connect

An improved insulated glazing unit is provided which can attain about R5 to about R10 thermal performance at the center of the glass while having dimensions about the same as those of a conventional double glazed insulated glazing unit. An outer glazing and inner glazing are sealed to a spacer to form a gas impermeable space. One or more rigid, non-structural glazings are attached to the inside of the spacer to divide the space between the inner and outer glazings to provide insulating gaps between glazings of from about 0.20 inches to about 0.40 inches. One or more glazing surfaces facing each thermal gap are coated with a low emissivity coating. Finally, the thermal gaps are filled with a low conductance gas such as krypton gas.

Selkowitz, Stephen E. (Piedmont, CA); Arasteh, Dariush K. (Oakland, CA); Hartmann, John L. (Seattle, WA)

1991-01-01T23:59:59.000Z

398

Thermal insulated glazing unit  

DOE Patents (OSTI)

An improved insulated glazing unit is provided which can attain about R5 to about R10 thermal performance at the center of the glass while having dimensions about the same as those of a conventional double glazed insulated glazing unit. An outer glazing and inner glazing are sealed to a spacer to form a gas impermeable space. One or more rigid, non-structural glazings are attached to the inside of the spacer to divide the space between the inner and outer glazings to provide insulating gaps between glazings of from about 0.20 inches to about 0.40 inches. One or more glazing surfaces facing each thermal gap are coated with a low emissivity coating. Finally, the thermal gaps are filled with a low conductance gas such as krypton gas. 2 figs.

Selkowitz, S.E.; Arasteh, D.K.; Hartmann, J.L.

1988-04-05T23:59:59.000Z

399

Gradient zone-boundary control in salt-gradient solar ponds  

DOE Patents (OSTI)

A method and apparatus for suppressing zone boundary migration in a salt gradient solar pond includes extending perforated membranes across the pond at the boundaries, between the convective and non-convective zones, the perforations being small enough in size to prevent individual turbulence disturbances from penetrating the hole, but being large enough to allow easy molecular diffusion of salt thereby preventing the formation of convective zones in the gradient layer. The total area of the perforations is a sizeable fraction of the membrane area to allow sufficient salt diffusion while preventing turbulent entrainment into the gradient zone.

Hull, J.R.

1982-09-29T23:59:59.000Z

400

Electrically conductive diamond electrodes  

DOE Patents (OSTI)

An electrically conductive diamond electrode and process for preparation thereof is described. The electrode comprises diamond particles coated with electrically conductive doped diamond preferably by chemical vapor deposition which are held together with a binder. The electrodes are useful for oxidation reduction in gas, such as hydrogen generation by electrolysis.

Swain, Greg (East Lansing, MI); Fischer, Anne (Arlington, VA),; Bennett, Jason (Lansing, MI); Lowe, Michael (Holt, MI)

2009-05-19T23:59:59.000Z

Note: This page contains sample records for the topic "gradients thermal conductivity" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Temperatures and interval geothermal-gradient determinations from wells in National Petroleum Reserve in Alaska  

SciTech Connect

Temperature and related records from 28 wells in the National Petroleum Reserve in Alaska (NPRA) although somewhat constrained from accuracy by data gathering methods, extrapolate to undisturbed formation temperatures at specific depths below permafrost, and lead to calculated geothermal graidents between these depths. Tabulation of the results show that extrapolated undisturbed temperatures range from a minimum of 98/sup 0/F (37/sup 0/C) at 4000 feet (1220 m) to a maximum of 420/sup 0/F (216/sup 0/C) at 20,260 feet (6177 m) and that geothermal gradients range from 0.34/sup 0/F/100' (6/sup 0/C/km) between 4470 feet to 7975 feet (Lisburne No. 1) and 3.15/sup 0/F/100' (57/sup 0/C/km) between 6830 feet to 7940 feet (Drew Point No. 1). Essential information needed for extrapolations consists of: time-sequential bottom-hole temperatures during wire-line logging of intermediate and deep intervals of the borehole; the times that circulating drilling fluids had disturbed the formations; and the subsequent times that non-circulating drilling fluids had been in contact with the formation. In several wells presumed near direct measures of rock temperatures recorded from formation fluids recovered by drill stem tests (DST) across thin (approx. 10-20 foot) intervals are made available. We believe that the results approach actual values close enough to serve as approximations of the thermal regimes in appropriate future investigations. Continuous temperature logs obtained at the start and end of final logging operations, conductivity measurements, and relatively long-term measurements of the recovery from disturbance at shallow depths in many of the wells will permit refinements of our values and provide determination of temperatures at other depths. 4 references, 6 figures, 3 tables.

Blanchard, D.C.; Tailleur, I.L.

1983-12-15T23:59:59.000Z

402

Measurement of Thermal Diffusity and Flow Resistance for TCAP Materials  

DOE Green Energy (OSTI)

SRS uses the Thermal Cycling Absorption Process (TCAP) to separate isotopes of hydrogen. The frequency of thermal cycles is a limit of the productivity of the process and that frequency is largely determined by the thermal diffusivity of the absorbent material. For a given tube diameter, a larger thermal diffusivity decreases the time required for each cycle. In 1998, the Engineering Development Laboratory measured thermal diffusivity and thermal conductivity for three TCAP materials in helium.

STEIMKE, JOHN

2004-11-11T23:59:59.000Z

403

Measurement of Thermal Dependencies of PBG Fiber Properties  

SciTech Connect

Photonic crystal fibers (PCFs) represent a class of optical fibers which have a wide spectrum of applications in the telecom and sensing industries. Currently, the Advanced Accelerator Research Department at SLAC is developing photonic bandgap particle accelerators, which are photonic crystal structures with a central defect used to accelerate electrons and achieve high longitudinal electric fields. Extremely compact and less costly than the traditional accelerators, these structures can support higher accelerating gradients and will open a new era in high energy physics as well as other fields of science. Based on direct laser acceleration in dielectric materials, the so called photonic band gap accelerators will benefit from mature laser and semiconductor industries. One of the key elements to direct laser acceleration in hollow core PCFs, is maintaining thermal and structural stability. Previous simulations demonstrate that accelerating modes are sensitive to the geometry of the defect region and the variations in the effective index. Unlike the telecom modes (for which over 95% of the energy propagates in the hollow core) most of the power of these modes is located in the glass at the periphery of the central hole which has a higher thermal constant than air ({gamma}{sub SiO{sub 2}} = 1.19 x 10{sup -6} 1/K, {gamma}{sub air} = -9 x 10{sup -7} 1/K with {gamma} = dn/dT). To fully control laser driven acceleration, we need to evaluate the thermal and structural consequences of such modes on the PCFs. We are conducting series of interferometric tests to quantify the dependencies of the HC-633-02 (NKT Photonics) propagation constant (k{sub z}) on temperature, vibration amplitude, stress and electric field strength. In this paper we will present the theoretical principles characterizing the thermal behavior of a PCF, the measurements realized for the fundamental telecom mode (TE{sub 00}), and the experimental demonstration of TM-like mode propagation in the HC-633-02 fiber.

Laouar, Rachik

2011-07-06T23:59:59.000Z

404

Thermal analysis of heat storage canisters for a solar dynamic, space power system  

DOE Green Energy (OSTI)

A thermal analysis was performed of a thermal energy storage canister of a type suggested for use in a solar receiver for an orbiting Brayton cycle power system. Energy storage for the eclipse portion of the cycle is provided by the latent heat of a eutectic mixture of LiF and CaF/sub 2/ contained in the canister. The chief motivation for the study is the prediction of vapor void effects on temperature profiles and the identification of possible differences between ground test data and projected behavior in microgravity. The first phase of this study is based on a two-dimensional, cylindrical coordinates model using an interim procedure for describing void behavior in 1/minus/g and microgravity. The thermal anaylsis includes the effects of solidification front behavior, conduction in liquid/solid salt and canister materials, void growth and shrinkage, radiant heat transfer across the void, and convection in the melt due to Marangoni-induced flow and, in 1/minus/g, flow due to density gradients. A number of significant differences between 1/minus/g and 0/minus/g behavior were found. These resulted from differences in void location relative to the maximum heat flux and a significantly smaller effective conductance in 0/minus/g due to the absence of gravity-induced convection.

Wichner, R.P.; Solomon, A.D.; Drake, J.B.; Williams, P.T.

1988-04-01T23:59:59.000Z

405

THERMAL NEUTRONIC REACTOR  

DOE Patents (OSTI)

A novel thermal reactor was designed in which a first reflector formed from a high atomic weight, nonmoderating material is disposed immediately adjacent to the reactor core. A second reflector composed of a moderating material is disposed outwardly of the first reflector. The advantage of this novel reflector arrangement is that the first reflector provides a high slow neutron flux in the second reflector, where irradiation experiments may be conducted with a small effect on reactor reactivity.

Spinrad, B.I.

1960-01-12T23:59:59.000Z

406

Thermally actuated thermionic switch  

DOE Patents (OSTI)

A thermally actuated thermionic switch which responds to an increase of temperature by changing from a high impedance to a low impedance at a predictable temperature set point. The switch has a bistable operation mode switching only on temperature increases. The thermionic material may be a metal which is liquid at the desired operation temperature and held in matrix in a graphite block reservoir, and which changes state (ionizes, for example) so as to be electrically conductive at a desired temperature.

Barrus, D.M.; Shires, C.D.

1982-09-30T23:59:59.000Z

407

Thermal via placement in 3D ICs  

E-Print Network (OSTI)

As thermal problems become more evident, new physical design paradigms and tools are needed to alleviate them. Incorporating thermal vias into integrated circuits (ICs) is a promising way of mitigating thermal issues by lowering the thermal resistance of the chip itself. However, thermal vias take up valuable routing space, and therefore, algorithms are needed to minimize their usage while placing them in areas where they would make the greatest impact. With the developing technology of three-dimensional integrated circuits (3D ICs), thermal problems are expected to be more prominent, and thermal vias can have a larger impact on them than in traditional 2D ICs. In this paper, thermal vias are assigned to specific areas of a 3D IC and used to adjust their effective thermal conductivities. The thermal via placement method makes iterative adjustments to these thermal conductivities in order to achieve a desired maximum temperature objective. Finite element analysis (FEA) is used in formulating the method and in calculating temperatures quickly during each iteration. As a result, the method efficiently achieves its thermal objective while minimizing the thermal via utilization.

Brent Goplen

2005-01-01T23:59:59.000Z

408

Experimental and theoretical investigation of high gradient acceleration. Progress report, June 1, 1991--February 1, 1992  

SciTech Connect

This report contains a technical progress summary of the research conducted under the auspices of DOE Grant No. DE-FG0291ER-40648. ``Experimental and Theoretical Investigations of High Gradient Acceleration.`` This grant supports three research tasks: Task A consists of the design and fabrication of a 17GHz of photocathode gun, Task B supports the testing of high gradient acceleration using a 33GHz structure, and Task C comprises theoretical investigations, both in support of the experimental tasks and on critical physics issues for the development of high energy linear colliders. This report is organized as follows. The development of an rf gun design and research progress on the picosecond laser system is summarized in Sec. 2, the status of the studies of the LBL/Haimson high gradient structure, using a 50 MW free-electron laser is summarized in Sec. 3, and theoretical research progress is described in Sec. 4. Supporting material is contained in Appendices A-G.

Bekefi, G.; Chen, C.; Chen, S.; Danly, B.; Temkin, R.J.; Wurtele, J.S.

1992-02-01T23:59:59.000Z

409

Invited paper for the 30th International Thermal Conductivity ...  

Science Conference Proceedings (OSTI)

... of the FRM influences the radiative heat transfer between a ... dry cycling, humidity, impact resistance, industrial atmosphere, salt spray, temperature ...

2010-10-28T23:59:59.000Z

410

Thermal conductivity, microstructure and gas release from a 44 GWd ...  

Science Conference Proceedings (OSTI)

Abstract Scope, Plutonium recycling in mixed oxide fuel (MOX) occurs in more ... burn-up and irradiation temperature profiles and Pu-content on properties and ...

411

Thermal and Electrical Conductivity Study of CNT-Carbon ...  

Science Conference Proceedings (OSTI)

Abstract Scope, A method is developed to incorporate carbon nanotubes in porous carbon microspheres. This is accomplished by dispersing Carbon Nanotubes ...

412

Experimental Technique to Conduct Thermal Shock Test on ...  

Science Conference Proceedings (OSTI)

Failure Analysis Case Studies from Refinery and Petrochemical Pilot Plants ... Failure of Electrical Submersible Pump of Oil Reservoir · Fan Blade Fracture in a  ...

413

Experimental Investigation on Anisotropic Effective Thermal Conductivity of Pebble Bed  

Science Conference Proceedings (OSTI)

Computational Tools, Modeling & Validation / Proceedings of the Nineteenth Topical Meeting on the Technology of Fusion Energy (TOFE) (Part 2)

Takehiko Yokomine

414

Thermal and Electrical Conductivities of Electroplated Gold (A25695)  

E-Print Network (OSTI)

Proc. Of The 17th Target Fabrication Specialists Meeting, San Diego, California, 2006; To Be Published In Fusion Science And Technology17th Target Fabrication Specialists Meeting San Diego California, US, 2006999613445

Bernat, T.P.

2006-12-08T23:59:59.000Z

415

Thermal conductivity and viscosity of self-assembled alcohol ...  

Science Conference Proceedings (OSTI)

... Aldrich) that have hydrophilic heads facing inward and hydropho- bic tails facing outward into the base fluid PAO (Chevron Phillips Chemical ...

2011-06-02T23:59:59.000Z

416

Thermal conductivity of nanoparticle suspensions Shawn A. Putnam,a  

E-Print Network (OSTI)

is the diffusion coefficient of water in ethanol, 2a 50 m is the line-heater separation, and 1/ f is the time required for water to diffuse half the distance between the metal heaters. This corresponds to low for thermodiffusion in our analysis of for water/ ethanol mixtures using dn/dT, cdn/dc, Dc, and thermodiffu- sion

Braun, Paul

417

Determining Thermal Conductivity of Simulated Feed for High Level ...  

Science Conference Proceedings (OSTI)

... of Fluidized Bed Steam Reforming (FBSR) with Hanford Low Activity Wastes ... Level Waste at the Defense Waste Processing Facility through Sludge Batch 7b.

418

Investigation on the Thermal Conductivity of Resin Composite ...  

Science Conference Proceedings (OSTI)

A gas pycnometer was used for measuring volume. The specific heat of the ... Differential Characterization of Ikperejere Iron shale and Iron Sandstone Deposit.

419

Thermally Conductive Graphite Foam - Oak Ridge National Laboratory  

Product Name Manufacturer Relevance CFOAM Touchstone Research Lab Aerospace tooling ... Hypersonic vehicles Aerobraking structures for planetary exploration

420

012- Measurement of Thermal Conductivity of Basic Refractories ...  

Science Conference Proceedings (OSTI)

085- Highly Efficient Comprehensive Utilization of Kaolin Tailings from ... 086- Improvement in Gas Tightness of YSZ Coatings Produced by Atmospheric Plasma Spraying ... 145- The Synergy of XRD and XRF in a Shale and Slate Analysis.

Note: This page contains sample records for the topic "gradients thermal conductivity" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Improved Gas Storage Carbon with Enhanced Thermal Conductivity  

... (DOE target storage value) of methane at standard temperature and pressure is used in adsorbed natural gas applications, including vehicles. ...

422

High Field Electrical Conduction and Its Relation to Thermal ...  

Science Conference Proceedings (OSTI)

Symposium, Advanced Materials for Power Electronics, Power Conditioning, and Power Conversion ... Potential Ceramic Dielectrics for Air Force Applications.

423

Density and Thermal Conductivity of Boron Nitride-alumina Mixed ...  

Science Conference Proceedings (OSTI)

Synthesis and Characterization of Plasma Polymerized Thin Films Deposited from Benzene and Hexamethyldisiloxane Using (PECVD) Method · Synthesis and ...

424

Quantum effects in thermal conduction: Nonequilibrium quantum discord and entanglement  

E-Print Network (OSTI)

We study the process of heat transfer through an entangled pair of two-level system, demonstrating the role of quantum correlations in this nonequilibrium process. While quantum correlations generally degrade with increasing the temperature bias, introducing spatial asymmetry leads to an intricate behavior: Connecting the qubits unequally to the reservoirs one finds that quantum correlations persist and increase with the temperature bias when the system is more weakly linked to the hot reservoir. In the reversed case, linking the system more strongly to the hot bath, the opposite, more natural behavior is observed, with quantum correlations being strongly suppressed upon increasing the temperature bias.

Wu, Lian-Ao

2011-01-01T23:59:59.000Z

425

Thermally Conductive Graphite Foam - Oak Ridge National Laboratory  

• Thermoelectric devices • Radiators • EMI shielding Patent ... Materials Science UT-Battelle, LLC Oak Ridge National Laboratory Office Phone: 865.576.9682

426

Quantum effects in thermal conduction: Nonequilibrium quantum discord and entanglement  

E-Print Network (OSTI)

We study the process of heat transfer through an entangled pair of two-level system, demonstrating the role of quantum correlations in this nonequilibrium process. While quantum correlations generally degrade with increasing the temperature bias, introducing spatial asymmetry leads to an intricate behavior: Connecting the qubits unequally to the reservoirs one finds that quantum correlations persist and increase with the temperature bias when the system is more weakly linked to the hot reservoir. In the reversed case, linking the system more strongly to the hot bath, the opposite, more natural behavior is observed, with quantum correlations being strongly suppressed upon increasing the temperature bias.

Lian-Ao Wu; Dvira Segal

2011-05-06T23:59:59.000Z

427

Composition-Dependent Thermal Conductivity of Several Binary ...  

Science Conference Proceedings (OSTI)

Abstract Scope, Time-domain thermoreflectance (TDTR) measurements using a pump-and-probe femtosecond laser system are employed to rapidly evaluate ...

428

Investigation on the Thermal Conductivity of Inorganic-Filler/Resin ...  

Science Conference Proceedings (OSTI)

Synthesis and Characterization of Pb Free Piezoelectric Ceramics - Barium ... Thermographic Characterization of Tensile Behavior in Railway Bogie Materials.

429

An Analytical Study Of A 2-Layer Transient Thermal Conduction...  

Open Energy Info (EERE)

more complicated two-layer problem that can be computed using inexpensive personal computers and spreadsheet software. The most demanding mathematical requirement is the ability...

430

Conducting fiber compression tester  

DOE Patents (OSTI)

The invention measures the resistance across a conductive fiber attached to a substrate place under a compressive load to determine the amount of compression needed to cause the fiber to fail. 3 figs.

DeTeresa, S.J.

1989-12-07T23:59:59.000Z

431

NSLS Conduct of Operations  

NLE Websites -- All DOE Office Websites (Extended Search)

Securing the X-Ray Tunnel (LS-OPS-0003) Qualified Search Personnel for NSLS Accelerators (LS-ESH-0009) General Procedures Caution Tags (LS-OPS-0004) Conduct of...

432

Hydrodynamic gradient expansion in gauge theory plasmas  

E-Print Network (OSTI)

We utilize the fluid-gravity duality to investigate the large order behavior of hydrodynamic gradient expansion of the dynamics of a gauge theory plasma system. This corresponds to the inclusion of dissipative terms and transport coefficients of very high order. Using the dual gravity description, we calculate numerically the form of the stress tensor for a boost-invariant flow in a hydrodynamic expansion up to terms with 240 derivatives. We observe a factorial growth of gradient contributions at large orders, which indicates a zero radius of convergence of the hydrodynamic series. Furthermore, we identify the leading singularity in the Borel transform of the hydrodynamic energy density with the lowest nonhydrodynamic excitation corresponding to a `nonhydrodynamic' quasinormal mode on the gravity side.

Michal P. Heller; Romuald A. Janik; Przemyslaw Witaszczyk

2013-02-04T23:59:59.000Z

433

Automated apparatus for producing gradient gels  

DOE Patents (OSTI)

Apparatus for producing a gradient gel which serves as a standard medium for a two-dimensional analysis of proteins, the gel having a density gradient along its height formed by a variation in gel composition, with the apparatus including first and second pumping means each including a plurality of pumps on a common shaft and driven by a stepping motor capable of providing small incremental changes in pump outputs for the gel ingredients, the motors being controlled, by digital signals from a digital computer, a hollow form or cassette for receiving the gel composition, means for transferring the gel composition including a filler tube extending near the bottom of the cassette, adjustable horizontal and vertical arms for automatically removing and relocating the filler tube in the next cassette, and a digital computer programmed to automatically control the stepping motors, arm movements, and associated sensing operations involving the filling operation.

Anderson, Norman L. (Clarendon Hills, IL)

1986-01-01T23:59:59.000Z

434

Program predicts reservoir temperature and geothermal gradient  

Science Conference Proceedings (OSTI)

This paper reports that a Fortran computer program has been developed to determine static formation temperatures (SFT) and geothermal gradient (GG). A minimum of input data (only two shut-in temperature logs) is required to obtain the values of SFT and GG. Modeling of primary oil production and designing enhanced oil recovery (EOR) projects requires knowing the undisturbed (static) reservoir temperature. Furthermore, the bottom hole circulating temperature (BHCT) is an important factor affecting a cement's thickening time, rheological properties, compressive strength, development, and set time. To estimate the values of BHCT, the geothermal gradient should be determined with accuracy. Recently we obtained an approximate analytical solution which describes the shut-in temperature behavior.

Kutasov, I.M.

1992-06-01T23:59:59.000Z

435

Thermal to electricity conversion using thermal magnetic properties  

DOE Patents (OSTI)

A system for the generation of Electricity from Thermal Energy using the thermal magnetic properties of a Ferromagnetic, Electrically Conductive Material (FECM) in one or more Magnetic Fields. A FECM is exposed to one or more Magnetic Fields. Thermal Energy is applied to a portion of the FECM heating the FECM above its Curie Point. The FECM, now partially paramagnetic, moves under the force of the one or more Magnetic Fields. The movement of the FECM induces an electrical current through the FECM, generating Electricity.

West, Phillip B [Idaho Falls, ID; Svoboda, John [Idaho Falls, ID

2010-04-27T23:59:59.000Z

436

Geothermal Resource-Reservoir Investigations Based On Heat Flow And Thermal  

Open Energy Info (EERE)

Resource-Reservoir Investigations Based On Heat Flow And Thermal Resource-Reservoir Investigations Based On Heat Flow And Thermal Gradient Data For The United States Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Report: Geothermal Resource-Reservoir Investigations Based On Heat Flow And Thermal Gradient Data For The United States Details Activities (2) Areas (2) Regions (0) Abstract: Several activities related to geothermal resources in the western United States are described in this report. A database of geothermal site-specific thermal gradient and heat flow results from individual exploration wells in the western US has been assembled. Extensive temperature gradient and heat flow exploration data from the active exploration of the 1970's and 1980's were collected, compiled, and synthesized, emphasizing previously unavailable company data. Examples of

437

Ocean thermal energy conversion plants : experimental and analytical study of mixing and recirculation  

E-Print Network (OSTI)

Ocean thermal energy conversion (OTEC) is a method of generating power using the vertical temperature gradient of the tropical ocean as an energy source. Experimental and analytical studies have been carried out to determine ...

Jirka, Gerhard H.

438

QUASI-STEADY CONFIGURATIONS OF CONDUCTIVE INTRACLUSTER MEDIA  

SciTech Connect

The radial distributions of temperature, density, and gas entropy among cool-core clusters tend to be quite similar, suggesting that they have entered a quasi-steady state. If that state is regulated by a combination of thermal conduction and feedback from a central active galactic nucleus (AGN), then the characteristics of those radial profiles ought to contain information about the spatial distribution of AGN heat input and the relative importance of thermal conduction. This paper addresses those topics by deriving steady-state solutions for clusters in which radiative cooling, electron thermal conduction, and thermal feedback fueled by accretion are all present, with the aim of interpreting the configurations of cool-core clusters in terms of steady-state models. It finds that the core configurations of many cool-core clusters have entropy levels just below those of conductively balanced solutions in which magnetic fields have suppressed electron thermal conduction to {approx}1/3 of the full Spitzer value, suggesting that AGN feedback is triggered when conduction can no longer compensate for radiative cooling. And even when feedback is necessary to heat the central {approx}30 kpc, conduction may still be the most important heating mechanism within a cluster's central {approx}100 kpc.

Voit, G. M., E-mail: voit@pa.msu.edu [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)

2011-10-10T23:59:59.000Z

439

Micro-machined thermo-conductivity detector  

DOE Patents (OSTI)

A micro-machined thermal conductivity detector for a portable gas chromatograph. The detector is highly sensitive and has fast response time to enable detection of the small size gas samples in a portable gas chromatograph which are in the order of nanoliters. The high sensitivity and fast response time are achieved through micro-machined devices composed of a nickel wire, for example, on a silicon nitride window formed in a silicon member and about a millimeter square in size. In addition to operating as a thermal conductivity detector, the silicon nitride window with a micro-machined wire therein of the device can be utilized for a fast response heater for PCR applications.

Yu, Conrad (Antioch, CA)

2003-01-01T23:59:59.000Z

440

Energy Gradient Theory of Hydrodynamic Instability  

E-Print Network (OSTI)

A new universal theory for flow instability and turbulent transition is proposed in this study. Flow instability and turbulence transition have been challenging subjects for fluid dynamics for a century. The critical condition of turbulent transition from theory and experiments differs largely from each other for Poiseuille flows. In this paper, a new mechanism of flow instability and turbulence transition is presented for parallel shear flows and the energy gradient theory of hydrodynamic instability is proposed. It is stated that the total energy gradient in the transverse direction and that in the streamwise direction of the main flow dominate the disturbance amplification or decay. A new dimensionless parameter K for characterizing flow instability is proposed for wall bounded shear flows, which is expressed as the ratio of the energy gradients in the two directions. It is thought that flow instability should first occur at the position of Kmax which may be the most dangerous position. This speculation is confirmed by Nishioka et al's experimental data. Comparison with experimental data for plane Poiseuille flow and pipe Poiseuille flow indicates that the proposed idea is really valid. It is found that the turbulence transition takes place at a critical value of Kmax of about 385 for both plane Poiseuille flow and pipe Poiseuille flow, below which no turbulence will occur regardless the disturbance. More studies show that the theory is also valid for plane Couette flows and Taylor-Couette flows between concentric rotating cylinders.

Hua-Shu Dou

2005-01-28T23:59:59.000Z

Note: This page contains sample records for the topic "gradients thermal conductivity" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Beryllium Impregnation of Uranium Fuel: Thermal Modeling of Cylindrical Objects for Efficiency Evaluation  

E-Print Network (OSTI)

With active research projects related to nuclear waste immobilization and high conductivity nuclear fuels, a thermal model has been developed to simulate the temperature profile within a heat generating cylinder in order to imitate the behavior of each design. This work is being done so that it may be used in future research projects to represent how heat is being stored or dissipated in a material that has a uniformly distributed heat source from fission or radiation deposition. The model has been built to have a 2-D visual representation of the temperature distribution. A nodal system is employed for this model so that the user chooses the size of the mesh that will develop an accurate reading for their purposes. The model uses fundamental heat transfer equations and heat conduction properties for different metals. The heat transfer equations that will be used are fundamental and used at each point in the mesh developed by the user to ensure accuracy of the calculation. Below is such an example of an equation that will be used to model the temperature distribution in the cylindrical samples. By choosing the thermal properties associated with the material that is being researched, certain parameters are imposed in the equations automatically. This provides an easy method to see changes in the temperature distribution due to the improvements that have been made. Such parameters are the thermal conductivity and the thermal diffusivity along with others such as the material specific heat. The model will incorporate color variations in the display in order to allow larger meshes to be used while not diminishing the appearance of the results. The color variation will be due to a gradient from red to blue to represent hot to cold.

Lynn, Nicholas

2011-08-04T23:59:59.000Z

442

Irradiance gradients in the presence of participating media and occlusions  

Science Conference Proceedings (OSTI)

In this paper we present a technique for computing translational gradients of indirect surface reflectance in scenes containing participating media and significant occlusions. These gradients describe how the incident radiance field changes with respect ...

Wojciech Jarosz; Matthias Zwicker; Henrik Wann Jensen

2008-06-01T23:59:59.000Z

443

Weak Pressure Gradient Approximation and Its Analytical Solutions  

Science Conference Proceedings (OSTI)

A weak pressure gradient (WPG) approximation is introduced for parameterizing supradomain-scale (SDS) dynamics, and this method is compared to the relaxed form of the weak temperature gradient (WTG) approximation in the context of 3D, linearized, ...

David M. Romps

2012-09-01T23:59:59.000Z

444

Numerical Tests of the Weak Pressure Gradient Approximation  

Science Conference Proceedings (OSTI)

Cloud-resolving simulations of convection over a surface temperature hot spot are used to evaluate the weak pressure gradient (WPG) and weak temperature gradient (WTG) approximations. The premise of the relaxed form of WTG—that vertical velocity ...

David M. Romps

2012-09-01T23:59:59.000Z

445

The Response of a Uniform Horizontal Temperature Gradient to Heating  

Science Conference Proceedings (OSTI)

The response of a uniform horizontal temperature gradient to prescribed fixed heating is calculated in the context of an extended version of surface quasigeostrophic dynamics. It is found that for zero mean surface flow and weak cross-gradient ...

Maarten H. P. Ambaum; Panos J. Athanasiadis

2007-10-01T23:59:59.000Z

446

Mixed Layer Restratification Due to a Horizontal Density Gradient  

Science Conference Proceedings (OSTI)

The restratification in the surface mixed layer driven by a horizontal density gradient following a storm is examined. For a constant layer depth H and constant buoyancy gradient |bx| = M2, geostrophic adjustment leads to new stratification with ...

Amit Tandon; Chris Garrett

1994-06-01T23:59:59.000Z

447

Alternatives to the gradient in optimal transfer line buffer allocation  

E-Print Network (OSTI)

This thesis describes several directions to replace the gradient in James Schor's gradient algorithm to solve the dual problem. The alternative directions are: the variance and standard deviation of buffer levels, the ...

Tanizar, Ketty, 1978-

2004-01-01T23:59:59.000Z

448

Surface Temperature Gradients as Diagnostic Indicators of Midlatitude Circulation Dynamics  

Science Conference Proceedings (OSTI)

Zonal and meridional surface temperature gradients are considered to be determinants of large-scale atmospheric circulation patterns. However, there has been limited investigation of these gradients as diagnostic aids. Here, the twentieth-century ...

Christina Karamperidou; Francesco Cioffi; Upmanu Lall

2012-06-01T23:59:59.000Z

449

Application of high temperature superconductors to high-gradient magnetic separation  

Science Conference Proceedings (OSTI)

High Gradient Magnetic Separation (HGMS) is a powerful technique which can be used to separate widely dispersed contaminants from a host material, This technology can separate magnetic solids from other solids, liquids or gases. As the name implies HGMS uses large magnetic field gradients to separate ferromagnetic and paramagnetic particles. HGMS separators usually consist of a high-field solenoid magnet, the bore of which contains a fine-structured, ferromagnetic matrix material. The matrix material locally distorts the magnetic field and creates large field gradients in the vicinity of the matrix elements. These elements then become trapping sites for magnetic particles and are the basis for the magnetic separation. In this paper we discuss the design and construction of a prototype HGMS unit using a magnet made with high temperature superconductors (HTS). The prototype consists of an outer vacuum vessel which contains the HTS solenoid magnet The magnet is surrounded by a thermal radiation shield and multilayer insulation (MLI) blankets. The magnet, thermal shield and current leads all operate in a vacuum and are cooled by a cryocooler. High temperature superconducting current leads are used to reduce the heat leak from the ambient environment to the HTS magnet.

Daugherty, M.A.; Prenger, F.C.; Hill, D.D.; Daney, D.E.; Worl, L.W.; Schake, A.R.; Padilla, D.D.

1994-06-01T23:59:59.000Z

450

CONDUCTING A RECORDS INVENTORY  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

PROCEDURE FOR CONDUCTING A RECORDS INVENTORY PROCEDURE FOR CONDUCTING A RECORDS INVENTORY Revision 1 10/31/07 Approved by: DOE Records Management Division, IM-23 PROCEDURE FOR CONDUCTING A RECORDS INVENTORY 1. GENERAL. A records inventory is compiling a descriptive list of each record series or system, including the location of the records and any other pertinent data. A records inventory is not a list of each document or each folder. 2. DEFINE THE RECORDS INVENTORY GOAL(S). The goals of a records inventory should be to: a. Gather information for scheduling purposes; b. Prepare for conversion to other media or to identify the volume of classified and/or permanent records in your organization's custody; and c. Identify any existing shortcomings, deficiencies, or problems with

451

FARADAYIC ElectroPhoretic Deposition of YSZ for Use in Thermal Barrier Coatings - Faraday Technology  

NLE Websites -- All DOE Office Websites (Extended Search)

FARADAYIC ElectroPhoretic Deposition FARADAYIC ElectroPhoretic Deposition of YSZ for Use in Thermal Barrier Coatings-Faraday Technology Background Thermal barrier coatings (TBCs) are employed to protect gas turbine engine components. These coating systems provide thermal, oxidation, and mechanical protection; reduce thermal gradients; and lower the metal substrate surface temperature, extending the life of the engine components. Faraday Technology, Inc. (Faraday) is developing a new manufacturing process, the

452

Finite Heat conduction in 2D Lattices  

E-Print Network (OSTI)

This paper gives a 2D hamonic lattices model with missing bond defects, when the capacity ratio of defects is enough large, the temperature gradient can be formed and the finite heat conduction is found in the model. The defects in the 2D harmonic lattices impede the energy carriers free propagation, by another words, the mean free paths of the energy carrier are relatively short. The microscopic dynamics leads to the finite conduction in the model. PACS numbers: 44.10. +I, 05.45.Jn, 05.60.-k, 05.70.Ln The study of heat conduction in models of insulating solids is a rather old and debated problem, and the more general problem is one of understanding the nonequilibrium energy current carrying state of a many body system. The most of the work on heat conduction investigated the process of heat transport in 1D lattices. The different models have been studied for obtaining Fourier’s law, several kinds of factors have been taken into account in the models, such as the nonlinearity, on-site potentials, mass disorder and etc. Then the typical 1D lattices Hamiltonian is

Lei Yang; Yang Kongqing

2001-01-01T23:59:59.000Z

453

Lithium ion conducting electrolytes  

DOE Patents (OSTI)

A liquid, predominantly lithium-conducting, ionic electrolyte having exceptionally high conductivity at temperatures of 100.degree. C. or lower, including room temperature, and comprising the lithium salts selected from the group consisting of the thiocyanate, iodide, bromide, chloride, perchlorate, acetate, tetrafluoroborate, perfluoromethane sulfonate, perfluoromethane sulfonamide, tetrahaloaluminate, and heptahaloaluminate salts of lithium, with or without a magnesium-salt selected from the group consisting of the perchlorate and acetate salts of magnesium. Certain of the latter embodiments may also contain molecular additives from the group of acetonitrile (CH.sub.3 CN) succinnonitrile (CH.sub.2 CN).sub.2, and tetraglyme (CH.sub.3 --O--CH.sub.2 --CH.sub.2 --O--).sub.2 (or like solvents) solvated to a Mg.sup.+2 cation to lower the freezing point of the electrolyte below room temperature. Other particularly useful embodiments contain up to about 40, but preferably not more than about 25, mol percent of a long chain polyether polymer dissolved in the lithium salts to provide an elastic or rubbery solid electrolyte of high ambient temperature conductivity and exceptional 100.degree. C. conductivity. Another embodiment contains up to about but not more than 10 mol percent of a molecular solvent such as acetone.

Angell, C. Austen (Tempe, AZ); Liu, Changle (Tempe, AZ)

1996-01-01T23:59:59.000Z

454

Lithium ion conducting electrolytes  

DOE Patents (OSTI)

The present invention relates generally to highly conductive alkali-metal ion non-crystalline electrolyte systems, and more particularly to novel and unique molten (liquid), rubbery, and solid electrolyte systems which are especially well suited for use with high current density electrolytic cells such as primary and secondary batteries.

Angell, Charles Austen (Mesa, AZ); Liu, Changle (Midland, MI); Xu, Kang (Montgomery Village, MD); Skotheim, Terje A. (Tucson, AZ)

1999-01-01T23:59:59.000Z

455

STABLE HIGH CONDUCTIVITY BILAYERED ELECTROLYTES FOR LOW TEMPERATURE SOLID OXIDE FUEL CELLS  

DOE Green Energy (OSTI)

Solid oxide fuel cells (SOFCs) are the future of energy production in America. They offer great promise as a clean and efficient process for directly converting chemical energy to electricity while providing significant environmental benefits (they produce negligible hydrocarbons, CO, or NO{sub x} and, as a result of their high efficiency, produce about one-third less CO{sub 2} per kilowatt hour than internal combustion engines). Unfortunately, the current SOFC technology, based on a stabilized zirconia electrolyte, must operate in the region of 1000 C to avoid unacceptably high ohmic losses. These high temperatures demand (a) specialized (expensive) materials for the fuel cell interconnects and insulation, (b) time to heat up to the operating temperature and (c) energy input to arrive at the operating temperature. Therefore, if fuel cells could be designed to give a reasonable power output at low to intermediate1 temperatures tremendous benefits may be accrued. At low temperatures, in particular, it becomes feasible to use ferritic steel for interconnects instead of expensive and brittle ceramic materials such as those based on LaCrO{sub 3}. In addition, sealing the fuel cell becomes easier and more reliable; rapid start-up is facilitated; thermal stresses (e.g., those caused by thermal expansion mismatches) are reduced; radiative losses ({approx}T{sup 4}) become minimal; electrode sintering becomes negligible and (due to a smaller thermodynamic penalty) the SOFC operating cycle (heating from ambient) would be more efficient. Combined, all these improvements further result in reduced initial and operating costs. The problem is, at lower temperatures the conductivity of the conventional stabilized zirconia electrolyte decreases to the point where it cannot supply electrical current efficiently to an external load. The primary objectives of the proposed research are to develop a stable high conductivity (> 0.05 S cm{sup -1} at {le} 550 C) electrolyte for lower temperature SOFCs. This objective is specifically directed toward meeting the lowest (and most difficult) temperature criteria for the 21st Century Fuel Cell Program. Meeting this objective provides a potential for future transportation applications of SOFCs, where their ability to directly use hydrocarbon fuels could permit refueling within the existing transportation infrastructure. In order to meet this objective we are developing a functionally gradient bilayer electrolyte comprised of bismuth oxide on the air side and ceria on the fuel side. Bismuth oxide and doped ceria are among the highest ionic conducting electrolytes and in fact bismuth oxide based electrolytes are the only known solid oxide electrolytes to have an ionic conductivity that meets the program conductivity goal.

Eric D. Wachsman; Keith L. Duncan

2001-09-30T23:59:59.000Z

456

Heat Pipe Embedded AlSiC Plates for High Conductivity - Low CTE Heat Spreaders  

SciTech Connect

Heat pipe embedded aluminum silicon carbide (AlSiC) plates are innovative heat spreaders that provide high thermal conductivity and low coefficient of thermal expansion (CTE). Since heat pipes are two phase devices, they demonstrate effective thermal conductivities ranging between 50,000 and 200,000 W/m-K, depending on the heat pipe length. Installing heat pipes into an AlSiC plate dramatically increases the plate’s effective thermal conductivity. AlSiC plates alone have a thermal conductivity of roughly 200 W/m-K and a CTE ranging from 7-12 ppm/ deg C, similar to that of silicon. An equivalent sized heat pipe embedded AlSiC plate has effective thermal conductivity ranging from 400 to 500 W/m-K and retains the CTE of AlSiC.

Johnson, Matthew (DOE/NNSA Kansas City Plant (United States)); Weyant, J.; Garner, S. (Advanced Cooling Technologies, Inc. (Lancaster, PA (United States)); Occhionero, M. (CPS Technologies Corporation, Norton, MA (United States))

2010-01-07T23:59:59.000Z

457

A high-gradient high-duty-factor RF photo-cathode electron gun  

Science Conference Proceedings (OSTI)

We describe the analysis and preliminary design of a high-gradient, high-duty factor RF photocathode gun. The gun is designed to operate at high repetition rate or CW, with high gradient on the cathode surface to minimize emittance growth due to space charge forces at high bunch charge. The gun may also be operated in a solenoidal magnetic field for emittance compensation. The design is intended for use in short-pulse, high-charge, and high-repetition rate applications such as linac based X-ray sources. We present and compare the results of gun simulations using different codes, as well as RF and thermal analysis of the structure.

Robert Rimmer; N. Hartman; S. Lidia; S.H. Wang

2002-08-01T23:59:59.000Z

458

A STUDY OF ATES THERMAL BEHAVIOR USING A STEADY FLOW MODEL  

E-Print Network (OSTI)

thermal conductivity, Aau heat capacity per unit volume, Ca,thermal conductivity Ac and heat capacity per unit volumeCc• Cw• The heat capacity per unit volume of water is All

Doughty, Christine

2013-01-01T23:59:59.000Z

459

Exploration geothermal gradient drilling, Platanares, Honduras, Central America  

DOE Green Energy (OSTI)

This paper is a review and summary of the core drilling operations component of the Honduras Geothermal Resource Development Project at the Platanares geothermal prospect in Honduras, Central America. Three intermediate depth (428 to 679 m) coreholes are the first continuously cored geothermal exploration boreholes in Honduras. These coring operations are part of the Central America Energy Resource Project (CAERP) effort funded by the Agency for International Development (AID) and implemented by the Los Alamos National Laboratory (Los Alamos) in cooperation with the Empresa Nacional de Energia Electrica (ENEE) and the United States Geological Survey (USGS). This report emphasizes coring operations with reference to the stratigraphy, thermal gradient, and flow test data of the boreholes. The primary objectives of this coring effort were (1) to obtain quantitative information on the temperature distribution as a function of depth, (2) to recover fluids associated with the geothermal reservoir, (3) to recover 75% or better core from the subsurface rock units, and (4) to drill into the subsurface rock as deeply as possible in order to get information on potential reservoir rocks, fracture density, permeabilities, and alteration histories of the rock units beneath the site. The three exploration coreholes drilled to depths of 650, 428 and 679 m, respectively, encountered several hot water entries. Coring operations and associated testing began in mid-October 1986 and were completed at the end of June 1987.

Goff, S.J.; Laughlin, A.W.; Ruefenacht, H.D.; Goff, F.E.; Heiken, G.; Ramos, N.

1988-01-01T23:59:59.000Z

460

Ocean Thermal Energy Conversion: An overview  

DOE Green Energy (OSTI)

Ocean thermal energy conversion, or OTEC is a technology that extracts power from the ocean's natural thermal gradient. This technology is being pursued by researchers from many nations; in the United States, OTEC research is funded by the US Department of Energy's Ocean Energy Technology program. The program's goal is to develop the technology so that industry can make a competent assessment of its potential -- either as an alternative or as a supplement to conventional energy sources. Federally funded research in components and systems will help OTEC to the threshold of commercialization. This publication provides an overview of the OTEC technology. 47 refs., 25 figs.

Not Available

1989-11-01T23:59:59.000Z

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461

Production of radioactivity in local soil at AGS (Alternating Gradient Synchrotron) fast neutrino beam  

Science Conference Proceedings (OSTI)

Brookhaven National Laboratory (BNL) has constructed a new neutrino production target station at the Alternating Gradient Synchrotron (AGS). A study has been conducted in the vicinity of the old target area to determine the radiological consequences of operating this experimental facility. Results from all areas of the study are presented along with estimates of the potential environmental impact of the old and new facilities. 12 refs., 15 figs., 3 tabs.

Gollon, P.J.; Rohrig, N.; Hauptmann, M.G.; McIntyre, K.; Miltenberger, R.; Naidu, J.

1989-10-01T23:59:59.000Z

462

Low Temperature Proton Conductivity  

NLE Websites -- All DOE Office Websites (Extended Search)

and and MEAs at Freezing Temperatures Thomas A. Zawodzinski, Jr. Case Western Reserve University Cleveland, Ohio 2 Freezing Fuel Cells: Impact on MEAS Below 0 o C *Transport processes/motions slow down: questions re: lower conductivity,water mobility etc *Residual water will have various physical effects in different portions of the MEA questions re: durability of components 3 3 'States' of Water in Proton Conductors ? Freezing (bulk), bound freezable, bound non freezable water states claimed based on DSC * Freezing water more mobile, allegedly important for high conductivity Analysis common for porous systems Does the presence of these states matter? Why? 4 'State of Water' in PEMs At T < 0 o C *'Liquid-like' water freezes *'Non-freezing' fraction: water of solvation at pore

463

Oxygen ion conducting materials  

DOE Patents (OSTI)

An oxygen ion conducting ceramic oxide that has applications in industry including fuel cells, oxygen pumps, oxygen sensors, and separation membranes. The material is based on the idea that substituting a dopant into the host perovskite lattice of (La,Sr)MnO.sub.3 that prefers a coordination number lower than 6 will induce oxygen ion vacancies to form in the lattice. Because the oxygen ion conductivity of (La,Sr)MnO.sub.3 is low over a very large temperature range, the material exhibits a high overpotential when used. The inclusion of oxygen vacancies into the lattice by doping the material has been found to maintain the desirable properties of (La,Sr)MnO.sub.3, while significantly decreasing the experimentally observed overpotential.

Vaughey, John (Elmhurst, IL); Krumpelt, Michael (Naperville, IL); Wang, Xiaoping (Downers Grove, IL); Carter, J. David (Bolingbrook, IL)

2003-01-01T23:59:59.000Z

464

Thermal spallation drilling  

DOE Green Energy (OSTI)

Thermal spallation drilling is an underdeveloped process with great potential for reducing the costs of drilling holes and mining shafts and tunnels in most very hard rocks. Industry has used this process to drill blast holes for emplacing explosives and to quarry granite. Some theoretical work has been performed, and many signs point to a great future for this process. The Los Alamos National Laboratory has studied the theory of the spallation process and is conducting experiments to prove out the system and to adapt it for use with a conventional rotary rig. This report describes work that has been accomplished at the Laboratory on the development of thermal spallation drilling and some work that is projected for the future on the system. 3 references, 3 figures.

Williams, R.E.

1985-01-01T23:59:59.000Z

465

Thermal Management of Onboard Cryogenic Hydrogen Storage Systems...  

NLE Websites -- All DOE Office Websites (Extended Search)

Plan: (A) System Weight and Volume (C) Efficiency (E) ChargingDischarging Rates (J) Thermal Management Technical Targets In this project, studies are being conducted to develop...

466

Alloy Development for Copper Diamond Composites for Thermal ...  

Science Conference Proceedings (OSTI)

One approach to meeting the challenges is to add diamond particles to a copper matrix to improve thermal conductivity and lower CTE simultaneously.

467

composites for high performance electronic packaging and thermal ...  

Science Conference Proceedings (OSTI)

The applications include; leading edges and engine components for the National Aerospace Plane, radiators for space power, flexible high conductance thermal ...

468

Unglazed transpired solar collector having a low thermal ...  

An unglazed transpired solar collector using solar radiation to heat incoming air for distribution, comprising an unglazed absorber formed of low thermal-conductance ...

469

Ceramic thermal barrier coating for rapid thermal cycling applications  

DOE Patents (OSTI)

A thermal barrier coating for metal articles subjected to rapid thermal cycling includes a metallic bond coat deposited on the metal article, at least one MCrAlY/ceramic layer deposited on the bond coat, and a ceramic top layer deposited on the MCrAlY/ceramic layer. The M in the MCrAlY material is Fe, Ni, Co, or a mixture of Ni and Co. The ceramic in the MCrAlY/ceramic layer is mullite or Al.sub.2 O.sub.3. The ceramic top layer includes a ceramic with a coefficient of thermal expansion less than about 5.4.times.10.sup.-6 .degree.C.sup.-1 and a thermal conductivity between about 1 J sec.sup.-1 m.sup.-1 .degree.C.sup.-1 and about 1.7 J sec.sup.-1 m.sup.-1 .degree.C.sup.-1.

Scharman, Alan J. (Hebron, CT); Yonushonis, Thomas M. (Columbus, IN)

1994-01-01T23:59:59.000Z

470

AQUIFER THERMAL ENERGY STORAGE  

E-Print Network (OSTI)

aquifers for thermal energy storage. Problems outlined aboveModeling of Thermal Energy Storage in Aquifers," Proceed-ings of Aquifer Thermal Energy Storage Workshop, Lawrence

Tsang, C.-F.

2011-01-01T23:59:59.000Z

471

AQUIFER THERMAL ENERGY STORAGE  

E-Print Network (OSTI)

using aquifers for thermal energy storage. Problems outlinedmatical Modeling of Thermal Energy Storage in Aquifers,"Proceed- ings of Aquifer Thermal Energy Storage Workshop,

Tsang, C.-F.

2011-01-01T23:59:59.000Z

472

Heat pipe thermal control of slender optics probes  

SciTech Connect

The thermal design for a stereographic viewing system is presented. The design incorporates an annular heat pipe and thermal isolation techniques. Test results are compared with design predictions for a prototype configuration. Test data obtained during heat pipe startup showing temperature gradients along the evaporator wall are presented. Correlations relating maximum wall temperature differences to a liquid Reynolds number were obtained at low power levels. These results are compared with Nusselt's Falling Film theory.

Prenger, F.C.

1979-01-01T23:59:59.000Z

473

Functionally gradient material for membrane reactors to convert methane gas into value-added products  

DOE Patents (OSTI)

A functionally gradient material for a membrane reactor for converting methane gas into value-added-products includes an outer tube of perovskite, which contacts air; an inner tube which contacts methane gas, of zirconium oxide, and a bonding layer between the perovskite and zirconium oxide layers. The bonding layer has one or more layers of a mixture of perovskite and zirconium oxide, with the layers transitioning from an excess of perovskite to an excess of zirconium oxide. The transition layers match thermal expansion coefficients and other physical properties between the two different materials. 7 figs.

Balachandran, U.; Dusek, J.T.; Kleefisch, M.S.; Kobylinski, T.P.

1996-11-12T23:59:59.000Z

474

Functionally gradient material for membrane reactors to convert methane gas into value-added products  

DOE Patents (OSTI)

A functionally gradient material for a membrane reactor for converting methane gas into value-added-products includes an outer tube of perovskite, which contacts air; an inner tube which contacts methane gas, of zirconium oxide, and a bonding layer between the perovskite and zirconium oxide layers. The bonding layer has one or more layers of a mixture of perovskite and zirconium oxide, with the layers transitioning from an excess of perovskite to an excess of zirconium oxide. The transition layers match thermal expansion coefficients and other physical properties between the two different materials.

Balachandran, Uthamalingam (Hinsdale, IL); Dusek, Joseph T. (Lombard, IL); Kleefisch, Mark S. (Napersville, IL); Kobylinski, Thadeus P. (Lisle, IL)

1996-01-01T23:59:59.000Z

475

Phonon Heat Conduction In A Semiconductor Nanowire  

E-Print Network (OSTI)

ic phonon dispersion due to spatial confinement, and (ii) change in the nonequilibrium phonon distribution due to partially diffuse boundary scattering. Numerical simulation is performed for a silicon nanowire with boundaries characterized by different interface roughness. Phonon confinement and boundary scattering lead to a significant decrease of the lattice thermal conductivity. The value of this decrease and