Solidification of Cascaded PCM Storages Embedded Within a Channel Under Various Forced Air Flow Strategies

Abstract

In recent years, latent heat storage systems have been received considerable attention as they can provide high thermal storage capacity and optimize energy consumption. Cascaded phase change materials (PCMs) are a significant strategy to manage the gap between energy supply and demand, especially in renewable thermal energy applications. This work is devoted to investigate the unsteady freezing process of cascaded latent heat thermal energy storage systems inside a channel under different forced airflow strategies for winter conditions. Cold air flows through cascaded PCMs in five various ways and starts changing their initial liquid status to the final solid phase. Results discuss the heat transfer and phase transition features of each strategy in four various Reynolds numbers. Two-dimensional finite volume method is utilized to solve the governing equations of incompressible fluid flow in which conduction and convection mechanisms within PCM chambers are taken into account. According to numerical results, U-type and counter flow schemes lead to quick solidification in all Reynolds numbers, while in one-side channel strategy, the system takes a longer time to be completely solidified in all Reynolds numbers except Re = 300 in which parallel flow and middle inlets methods cause later freezing. The aspect ratio of PCM cavities and outlet temperature of the flowing air are also studied for various cases. Results demonstrated that the lower aspect ratio of the counter flow strategy could solidify the PCM faster and could remove the higher value of heat from cavities (higher outlet temperature).