Effect of Buoyancy Force in Phase Change Material-Based Metal Hydride Reactor

Abstract In Phase Change Material (PCM) simulations, buoyancy force is used to capture the melting contour. However, for the sake of simplicity, most of the PCM-based Metal Hydride (MH) simulations have ignored the influence of buoyancy in PCM which is crucial in analyzing the heat flow within PCM. This study incorporates the buoyancy term in mathematical models to capture the contour of a melted PCM and also its heat transfer capacity during the hydrogen absorption process. A PCM model with buoyancy force is validated against the experimental values and applied to the MH-PCM models. Incorporating the buoyancy force improves the heat transfer rate in the PCM during melting which benefits in better heat removal from the MH bed. Two designs of MH-PCM models having PCM placed in ring-type and tube-type configurations are discussed. Further, the design optimization in ring-type models was done by changing the PCM-MH volume and sandwiching ratios.