RESUMO

A mathematical model, based on the enthalpy method, has been developed to study the thermal behavior and performance of a shell-and-tube heat storage unit employing two phase change materials (PCMs) with different melting temperatures. The shell space is filled with PCMs, and a heat-transfer fluid (HTF) flows by forced convection through the inner tube. This latent heat storage unit (LHSU) can be used for solar heating water applications. Heat is stored by day and it is recovered at night, which reduces the consumption of electricity for heating the water. The proposed model was initially validated with experimental results. Numerical investigations were conducted to examine the effects of the mass flow rate on the thermal performance of the LHSU during both charge (melting) and discharge (solidification). The effects of the HTF inlet temperature and the initial temperature of the PCMs were also investigated for charge and discharge, respectively.