Melting Processes of Phase Change Material in Sidewall-Heated Cavity

Melting processes of phase change material (PCM) confined in a rectangular cavity with an isothermal vertical wall are investigated to quantify the transition criterion between different melting regimes. A series of numerical simulations are conducted via the phase-change lattice Boltzmann method, and the results show that the temperature field in the liquid PCM region changes from the structure with two thermal boundary layers to the structure with two thermal boundary layers plus a convection region. Moreover, the results also indicate that the heat transfer mechanism undergoes a transition from conduction to convection when the relative thickness between the convention region and the thermal boundary reaches a critical value. This value (transition criterion) can be quantified by the critical melted volume fraction, and its dependence on Rayleigh number, Prandtl number, and aspect ratio of cavity is theoretically derived in this study. Then, based on the transition criterion, a piecewise correlation of melted volume fraction is proposed, which considers the effect of different melting regimes and is proven to predict the literature’s result.