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Crepeau, John

Publications and source records attributed to Crepeau, John.

7 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

SCALE ANALYSIS AND EXPERIMENTAL RESULTS OF A SOLID/LIQUID PHASE-CHANGE THERMAL ENERGY STORAGE SYSTEM

A detailed experimental study has been carried out to evaluate the heat transfer performance of a solid/liquid phasechange thermal energy storage system. The phase-change material (PCM) and metal foam are contained in a vertically oriented test cylinder that is cooled or heated at its outside boundary, resulting in radially inward melting, respectively. Detailed quantitative time-dependent volumetric temperature distributions and melt-front motion and shape data were obtained. As the PCM melts, the interface moves away from the surface of the heat source/sink, and a thermal resistance layer is built up, resulting in a reduced heat transfer rate and/or increased temperature difference between the system to be cooled (or heated) and the PCM. The phase-change medium was 99% pure eicosane, with a melting temperature of 36.5oC. Results have been generalized to apply to any low-Stefan number PCM. A heat transfer scale analysis was used in order to help in interpretation of the data and development of heat transfer correlations. In the scale analysis, conduction heat transfer in the solid and natural convection heat transfer in liquid were considered. Comparison of experimental data with scale-analysis predictions of the solid-liquid interface position and temperature distribution was performed.

25 ENERGY STORAGE↗
DOE OSTI2014

Numerical and experimental investigation of melting with internal heat generation within cylindrical enclosures

There have been significant efforts by the heat transfer community to investigate the melting phenomenon of materials. These efforts have included the analytical development of equations to represent melting, numerical development of computer codes to assist in modeling the phenomena, and collection of experimental data. The understanding of the melting phenomenon has application in several areas of interest, for example, the melting of a Phase Change Material (PCM) used as a thermal storage medium as well as the melting of the fuel bundle in a nuclear power plant during an accident scenario. The objective of this research is two-fold. First a numerical investigation, using computational fluid dynamics (CFD), of melting with internal heat generation for a vertical cylindrical geometry is presented. Second, to the best of authors knowledge, there are very limited number of engineering experimental results available for the case of melting with Internal Heat Generation (IHG). An experiment was performed to produce such data using resistive, or Joule, heating as the IHG mechanism. The numerical results are compared against the experimental results and showed favorable correlation. Uncertainties in the numerical and experimental analysis are discussed. Based on the numerical and experimental analysis, recommendations are made for future work.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2013

Scale/Analytical Analyses of Freezing and Convective Melting with Internal Heat Generation

Using a scale/analytical analysis approach, we model phase change (melting) for pure materials which generate constant internal heat generation for small Stefan numbers (approximately one). The analysis considers conduction in the solid phase and natural convection, driven by internal heat generation, in the liquid regime. The model is applied for a constant surface temperature boundary condition where the melting temperature is greater than the surface temperature in a cylindrical geometry. The analysis also consider constant heat flux (in a cylindrical geometry).We show the time scales in which conduction and convection heat transfer dominate.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2012

Solid–Liquid Phase Change Driven by Internal Heat Generation

This article presents results of solid-liquid phase change, the Stefan Problem, where melting is driven internal heat generation, in a cylindrical geometry. The comparison between a quasi-static analytical solution for Stefan numbers less than one and numerical solutions shows good agreement. The computational results of phase change with internal heat generation show how convection cells form in the liquid region. A scale analysis of the same problem shows four distinct regions of the melting process.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2012

Update on Ultrasonic Thermometry Development at Idaho National Laboratory

The Idaho National Laboratory (INL) has initiated an effort to evaluate the viability of using ultrasonic thermometry technology as an improved sensor for detecting temperature during irradiation testing of advanced fuels proposed within the Fuel Cycle Research and Development (FCR&D) program sponsored by the U.S. Department of Energy (US DOE). Ultrasonic thermometers (UTs) work on the principle that the speed at which sound travels through a material (acoustic velocity) is dependent on the temperature of the material. UTs have several advantages over other types of temperature sensors . UTs can be made very small, as the sensor consists only of a small diameter rod which may or may not require a sheath. Measurements may be made up to very high temperature (near the melting point of the sensor material) and, as no electrical insulation is required, shunting effects observed in traditional high temperature thermocouple applications are avoided. Most attractive, however, is the ability to introduce multiple acoustic discontinuities into the sensor, as this enables temperature profiling with a single sensor. The current paper presents initial results from FCR&D UT development efforts. These developments include improved methods for fabricating magnetostrictive transducers and joining them to waveguides, characterization of candidate sensor materials appropriate for use in FCR&D fuels irradiations (both ceramic fuels in inert gas and sodium bonded metallic fuels), enhanced signal processing techniques, and tests to determine potential accuracy and resolution.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1996

Determination of Stability and Translation in a Boundary Layer

Reducing the infinite degrees of freedom inherent in fluid motion into a manageable number of modes to analyze fluid motion is presented. The concepts behind the center manifold technique are used. Study of the Blasius boundary layer and a precise description of stability within the flow field are discussed.

Crepeau, John↗