Effects of PCM thermophysical properties on thermal storage performance of a shell-and-tube latent heat storage unit

An orthogonal experiment with five factors and four levels was designed and numerical studies were performed to reveal the effects of molten salt PCM thermophysical properties on heat and exergy storage performance of a shell-and-tube latent heat storage (LHS) unit. The range analysis, regression analysis and optimization were conducted. The PCM selection criteria were established. The results show that for short time LHS system, the order of PCM properties effects on heat storage performance is melting temperature, thermal conductivity, specific heat, density and melting enthalpy successively. PCM with lower melting temperature, higher thermal conductivity and specific heat is beneficial to improve the heat storage rate and heat storage quality. For long time heat storage system, the order of PCM properties effects on heat storage performance is density, melting enthalpy, specific heat, melting temperature and thermal conductivity successively. PCM with higher density, melting enthalpy and specific heat can both improve the heat storage rate and heat storage quality. The orthogonal experiment method is reliable to investigate the effects of PCM properties on LHS performance; and the optimization based on regression analysis is more efficient than that based on range analysis.