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Title: Effect of surface properties on nucleate pool boiling

Abstract

A series of experiments on nucleate pool boiling was performed by use of an oxygen-free copper rod and platinum wires of different surface properties under both normal gravity condition and microgravity condition. As a result of the experiments, under normal gravity condition, the bubbling on thick cracked silicone-coated surfaces and that on scale surfaces were more vigorous than that on mirror-finished (copper) surfaces, that on bare (Pt) surfaces, that on thin silicone-coated surfaces and that on thick silicone-coated surfaces. The boiling curves on the mirror-finished surface, the bare surface, the thin silicone-coated surface and the thick cracked silicone-coated surface were equal to those predicted by the Rohsenow's correlation. The superheats on the thick silicone-coated surface and the scale surface were larger than those predicted by the Rohsenow's correlation. The boiling curves on the non-cracked silicone-coated surface and the scale surface corrected by those heat resistance were equal to those predicted by the Rohsenow's correlation. The superheat on the thick silicone-coated surface corrected by its heat resistance was smaller than that predicted by the Rohsenow's correlation. The thick cracked silicone-coated surface enhanced the nucleate boiling heat transfer. On the other hand, under microgravity condition, the bubbles stayed around heated surfaces exceptmore » scale surfaces. The boiling curve on the bare surface under microgravity condition was equal to that under normal gravity condition. The effect of surface properties on the nucleate boiling heat transfer under microgravity condition was equal to that under normal gravity condition.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Tokyo Univ. of Mercantile Marine, Koutou (JP)
OSTI Identifier:
20026822
Resource Type:
Conference
Resource Relation:
Conference: 5th ASME/JSME Thermal Engineering Joint Conference, San Diego, CA (US), 03/14/1999--03/19/1999; Other Information: 1 CD-ROM. Operating system required: Windows i386(tm), i486(tm), Pentium (R) or Pentium Pro, MS Windows 3.1, 95, or NT 3.51, 8 MB RAM, MacIntosh and Power MacIntosh with a 68020 or greater processor, System software version 7.1, 3.5 MB RAM (5 MB for PowerMac) 6 MB available hard-disk space, Unix; PBD: 1999; Related Information: In: Proceedings of the 5th ASME/JSME thermal engineering joint conference, [3600] pages.
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; NUCLEATE BOILING; POOL BOILING; SURFACE PROPERTIES; BUBBLE GROWTH; WEIGHTLESSNESS

Citation Formats

Haze, Ikuya, Tomemori, Hideki, Motoya, Daiju, and Osakabe, Masahiro. Effect of surface properties on nucleate pool boiling. United States: N. p., 1999. Web.
Haze, Ikuya, Tomemori, Hideki, Motoya, Daiju, & Osakabe, Masahiro. Effect of surface properties on nucleate pool boiling. United States.
Haze, Ikuya, Tomemori, Hideki, Motoya, Daiju, and Osakabe, Masahiro. 1999. "Effect of surface properties on nucleate pool boiling". United States. doi:.
@article{osti_20026822,
title = {Effect of surface properties on nucleate pool boiling},
author = {Haze, Ikuya and Tomemori, Hideki and Motoya, Daiju and Osakabe, Masahiro},
abstractNote = {A series of experiments on nucleate pool boiling was performed by use of an oxygen-free copper rod and platinum wires of different surface properties under both normal gravity condition and microgravity condition. As a result of the experiments, under normal gravity condition, the bubbling on thick cracked silicone-coated surfaces and that on scale surfaces were more vigorous than that on mirror-finished (copper) surfaces, that on bare (Pt) surfaces, that on thin silicone-coated surfaces and that on thick silicone-coated surfaces. The boiling curves on the mirror-finished surface, the bare surface, the thin silicone-coated surface and the thick cracked silicone-coated surface were equal to those predicted by the Rohsenow's correlation. The superheats on the thick silicone-coated surface and the scale surface were larger than those predicted by the Rohsenow's correlation. The boiling curves on the non-cracked silicone-coated surface and the scale surface corrected by those heat resistance were equal to those predicted by the Rohsenow's correlation. The superheat on the thick silicone-coated surface corrected by its heat resistance was smaller than that predicted by the Rohsenow's correlation. The thick cracked silicone-coated surface enhanced the nucleate boiling heat transfer. On the other hand, under microgravity condition, the bubbles stayed around heated surfaces except scale surfaces. The boiling curve on the bare surface under microgravity condition was equal to that under normal gravity condition. The effect of surface properties on the nucleate boiling heat transfer under microgravity condition was equal to that under normal gravity condition.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1999,
month = 7
}

Conference:
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  • The external, nucleate pool-boiling heat-transfer coefficient in R-114 with up to 10% oil (by mass) was measured on a smooth copper tube and on a porous-coated copper-nickel tube. The heat flux was varied from 160 to 30,000 Btu/hr . ft/sup 2/ (0.5 to 95 kW/m/sup 2/) at boiling temperatures of 28 F and 44 F (-2.2/sup 0/C and 6.7/sup 0/C). The porous-coated surface was found to improve the heat-transfer coefficient over the smooth surface by a factor of 7 to 10 in oil-free R-114. The presence of up to 3% oil caused about a 35% reduction in the heat-transfer coefficientmore » of the porous-coated surface at all heat fluxes. With 6% or more oil, the boiling performance of this surface declined drastically at heat fluxes in excess of 9500 Btu/hr . ft/sup 2/ (30 kW/m/sup 2/). Some plausible mechanisms to explain the observed behavior are described.« less
  • A numerical study of saturated pool nucleate boiling with an emphasis on the effect of surface topography is presented. The numerical model consisted of solving the three-dimensional transient heat conduction equation within the heater subjected to nucleate boiling over its upper surface. The surface topography model considered the distribution of the cavity and cavity angles based on exponential and normal probability functions. Parametric results showed that the saturated nucleate boiling curve shifted left and became steeper with an increase in the mean cavity radius. The boiling curve was found to be sensitive to the selection of how many cavities weremore » selected for each octagonal cell. A small variation in the statistical parameters, especially cavity radii for smooth surfaces, resulted in noticeable differences in wall superheat for a given heat flux. This result indicated that while the heat transfer coefficient increased with cavity radii, the cavity radii or height alone was not sufficient to characterize the boiling curve. It also suggested that statistical experimental data should consider large samples to characterize the surface topology. The boiling curve shifted to the right when the cavity angle was obtained using a normal distribution. This effect became less important when the number of cavities for each cell was increasing because the probability of the potential cavity with a larger radius in each cell was increased. When the contact angle of the fluid decreased for a given mean cavity radii, the boiling curve shifted to the right. This shift was more pronounced at smaller mean cavity radii and decreased with increasing mean cavity radii.« less
  • A novel array of microscale heaters has been developed to measure the heat transfer coefficient at many points underneath individual bubbles during boiling as a function of space and time. This heater array enables the local heat transfer from a surface during the bubble growth and departure process to be measured with very high temporal and spatial resolution, and should allow better understanding of the boiling heat transfer mechanisms by pinpointing when and where in the bubble departure cycle large amounts of wall heat transfer occur. Such information can provide much needed data regarding the important heat transfer mechanisms duringmore » the bubble departure cycle, and can serve as benchmarks to validate many of the analytical and numerical models used to simulate boiling. The current array has 148 heaters within a 3 mm diameter circle. Feedback loops similar to those used in hot-wire anemometry are used to keep each heater at a constant temperature, and the power required to do this is directly related to the heat transfer coefficient. A description of the heater performance and construction, the feedback loops, the computer control circuit, and the calibration rig are described.« less
  • The spatial and temporal variations of local surface temperature and heat flux for saturated pool nucleate boiling are investigated parametrically using a numerical model. The numerical model consisted of solving the three-dimensional transient heat conduction equation within the heater subjected to nucleate boiling over its upper surface. The surface topography model to distribute the cavities over the boiling surface used a Monte Carlo scheme. All cavities were assumed to be conical in shape. The cavity radii are obtained using an exponential probability density function with a known mean value. Local surface temperatures showed significant spatial and temporal variations, depending uponmore » the surface topography and the heater material and thickness. However, the surface-averaged temperature showed practically no temporal variation. The temporal variations in local temperatures caused the surface-averaged heat flux to vary significantly. The temporal variations in the surface-averaged heat flux were similar for smooth and rough and thick and thin copper and nickel plates. Results indicated that the use of a classical energy balance equation to evaluate the surface heat flux must consider the spatial variation of the temperature. Results also showed that any thermocouple embedded beneath the surface of the heater does not follow the temporal variations at the surface.« less