Modeling the thermal energy storage capability of a phase change material confined in a rectangular cavity

Abstract

Phase change materials (PCM) may be used as a thermal energy barrier for applications requiring insulation. This project explores the behavior of pure PCM within a two-dimensional rectangular cavity as a thermal barrier using a new thermal barrier efficiency metric. The dimensionless parameters are determined that dictate the efficiency for one-dimensional transport with cyclical heat flux loading on one side and a convective boundary condition on the opposite side. Two limiting conditions for the PCM behavior (No Phase Change and Full Phase Change) are studied analytically, and numerical models show that the predicted thermal barrier efficiency exceeds these limits, suggesting that the limiting conditions provide useful conservative estimates of PCM performance in designing PCM thermal barriers. Results show that both the No Phase Change limit and Full Phase Change efficiencies decrease with increasing Fourier and decreasing Biot numbers. An expression is derived for the CFD-predicted thermal barrier efficiency as a function of No Phase Change and Full Phase Change efficiencies and the Fourier number when Bi = 0.2.