Sensitivity analysis of thermophysical properties on PCM selection under steady and fluctuating heat sources: A comparative study

Abstract

Previous studies on phase change material (PCM) selection for latent thermal energy storage (LTES) mainly focused on steady heat source conditions without considering the effects of thermal fluctuation of real heat sources, and how fluctuating heat sources will affect the charging performance of LTES and material selection is still unclear. This study aims to compare the difference in material selection for a shell-and-tube LTES under steady and fluctuating heat sources, which comprehensively considers the effects of PCM thermophysical properties including the melting temperature, density, specific heat capacity, thermal conductivity and latent heat, as well as their interaction effects. By taking heat storage capacity and charging rate as objectives, orthogonal experiment design and stepwise regression analysis have been conducted to specify the significant factors among these parameters under steady and fluctuating heat source conditions. To further investigate the difference in the ranking of candidate PCMs under two conditions, fourteen pre-screened PCMs are ranked under steady and fluctuating heat sources. The results show that the order of prominent factors for heat storage capacity is ρ·Cp, followed by ρ·L under both conditions. However, when considering the charging rate, temperature fluctuation will weaken the effect of melting temperature, and strengthen the effect of specific heat capacity and latent heat. The order of prominent factors for charging rate is λ·Cp and Cp·L under fluctuating heat source. According to the ranking results, LiNO3-NaNO2 within the melting temperature of 100–200 °C has an excellent comprehensive charging performance under both conditions.