A thermal model which simulates combined conductio and phase change characteristics of thermal energy storage (TES) material is presented. Both the model and results are provided herein for the purpose of benchmarking the conduction and phase change capabilities of recently developed and unvalidated microgravity TES computer programs.
The model was originally developed to support the design and analysis of the NASA lewis Research Center TES experiment. This report also serves as the preliminary documentation of the thermal models constructed for this experimental effort. The phase change approach developed for the model can be applied to most commercial thermal analyzers and also can be used for other phase change applications. It is again emphasized that the principle intent of this report is to present a model and results for evaluating (benchmarking) computer codes that have been recently developed to predict the behavior of phase change materials in a microgravity environment.
Specifically, operation of the TES-1 experiment is simulated. The heart of the TES-1 experiment is the TES specimen. The specimen is mounted in an approved shuttle payload container known as a Get-Away-Special (GAS), which is also included in the model. The TES specimen consists of the torus shaped TES canister which contains the phase change material (PCM), the conductor rod, and the radiator flare. A heater radiates heat to the outer radius of the TES canister during melting of the PCM. After the lithium fluoride PCM is completely melted, the heater is turned off and latent heat is transferred from the PCM to the conductor rod at the TES canister inner radius. The removed heat is radiated to the environment from the TES radiator flare during solidification. A series of five melting/freezing cycles are simulated.
Skarda, J.R., Thermal Modeling With Solid/Liquid Phase Change of the Thermal Energy Storage Experiment, NASA Technical Memorandum, NASA Lewis Research Center, Cleveland, OH, TM 103770, pp. 1-45, November, 1991.