Search Menu
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information
Search Scholarly Publications

4 Search Results

Sorted by Relevance
Save Results
...

  1. Validation of hydrogen gas stratification and mixing models

    Wu, Hsingtzu ; Zhao, Haihua - Annals of Nuclear Energy (Oxford)
    Two validation benchmarks confirm that the BMIX++ code is capable of simulating unintended hydrogen release scenarios efficiently. The BMIX++ (UC Berkeley mechanistic MIXing code in C++) code has been developed to accurately and efficiently predict the fluid mixture distribution and heat transfer in large stratified enclosures for accident analyses and design optimizations. The BMIX++ code uses a scaling based one-dimensional method to achieve large reduction in computational effort compared to a 3-D computational fluid dynamics (CFD) simulation. Two BMIX++ benchmark models have been developed. One is for a single buoyant jet in an open space and another is for amore » large sealed enclosure with both a jet source and a vent near the floor. Both of them have been validated by comparisons with experimental data. Excellent agreements are observed. The entrainment coefficients of 0.09 and 0.08 are found to fit the experimental data for hydrogen leaks with the Froude number of 99 and 268 best, respectively. In addition, the BIX++ simulation results of the average helium concentration for an enclosure with a vent and a single jet agree with the experimental data within a margin of about 10% for jet flow rates ranging from 1.21 × 10⁻⁴ to 3.29 × 10⁻⁴ m³/s. In conclusion, computing time for each BMIX++ model with a normal desktop computer is less than 5 min.« less

  2. Optimizing luminescent solar concentrator design

    Hernandez-Noyola, Hermilo ; Potterveld, David H. ; Holt, Roy J. ; ... - Energy & Environmental Science
    Luminescent Solar Concentrators (LSCs) use fluorescent materials and light guides to convert direct and diffuse sunlight into concentrated wavelength-shifted light that produces electrical power in small photovoltaic (PV) cells with the goal of significantly reducing the cost of solar energy utilization. In this paper we present an optimization analysis based on the implementation of a genetic algorithm (GA) subroutine to a numerical ray-tracing Monte Carlo model of an LSC, SIMSOLAR-P. The initial use of the GA implementation in SIMSOLAR-P is to find the optimal parameters of a hypothetical ‘‘perfect luminescent material’’ that obeys the Kennard Stepanov (K-S) thermodynamic relationship betweenmore » emission and absorption. The optimization balances the efficiency losses in the wavelength shift and PV conversion with the efficiency losses due to re-scattering of light out of the collector. The theoretical limits of efficiency are provided for one, two and three layer configurations; the results show that a single layer configuration is far from optimal and adding a second layer in the LSC with wavelength shifted material in the near infrared region significantly increases the power output, while the gain in power by adding a third layer is relatively small. Here, the results of this study provide a theoretical upper limit to the performance of an LSC and give guidance for the properties required for luminescent materials, such as quantum nanocrystals, to operate efficiently in planar LSC configurations« less

  3. Longitudinal bunch monitoring at the Fermilab Tevatron and Main Injector synchrotrons

    Thurman-Keup, R. ; Bhat, C. ; Blokland, W. ; ... - Journal of Instrumentation
    The measurement of the longitudinal behavior of the accelerated particle beams at Fermilab is crucial to the optimization and control of the beam and the maximizing of the integrated luminosity for the particle physics experiments. Longitudinal measurements in the Tevatron and Main Injector synchrotrons are based on the analysis of signals from resistive wall current monitors. This study describes the signal processing performed by a 2 GHz-bandwidth oscilloscope together with a computer running a LabVIEW program which calculates the longitudinal beam parameters.

  4. Devices for maintaining optical access in high-temperature coal combustion environments

    Cook, Robert L. ; Hester, Leslie R. - Review of Scientific Instruments
    Advanced optical diagnostic techniques and instruments are being developed to operate successfully in the high-temperature coal combustion environments of large scale facilities. The success of these instruments depends heavily on maintaining a clear optical path into and out of the gas stream for long periods of time. The buildup of slag at the access port and contaminate fouling of the optical window require special systems to maintain the optical path. The rationale for, and design of, two such systems are presented in this article. The first system, a remotely operated window changer, provides for exchanging fouled windows for clean windows.more » The second system, a remotely operated slagbuster, provides for removing slag buildup in the access port. The design and operation of both systems are discussed. Parts lists, drawings, and schematics are presented also.« less
...
Search for:
All Records
Subject
OPTIMIZATION
Refine by:
Article Type
Availability
Journal
Creator / Author
more less
Publication Date
Research Organization