Entransy dissipation-based thermal resistance optimization of slab LHTES system with multiple PCMs arranged in a 2D array

Abstract

A two-dimensional (2D) model for slab latent heat thermal energy storage (LHTES) system was developed to predict the melting of multiple phase change materials (PCMs). The performance of the slab LHTES system with multiple PCMs arranged in a 2D array was optimized based on the entransy theory, in which the transient heat conduction in the PCM slab was considered. The formula of the entransy dissipation-based thermal resistance of the slab LHTES system was deduced. A novel optimization criterion was proposed based on the minimum entransy dissipation-based thermal resistance principle, with which the melting temperatures of multiple PCMs arranged in a 2D array were optimized. According to the optimization analysis, the appropriate PCMs from literature were selected and the melting processes of the optimized multiple PCMs were investigated. Furthermore, the effect of the PCM thermal conductivity on multiple PCMs arrangement was studied. The results show that the thermal performance of the slab LHTES system is significantly improved using the optimized multiple PCMs arranged in a 2D array compared to that using single PCM. And the multiple PCMs arranged in a 2D array is preferred when PCM slab conduction thermal resistance and hot fluid convection thermal resistance are at the same level.