An experimental investigation on melting and solidification behavior of phase change material in cylindrical latent heat storage units with minichannel

Abstract

The latent heat storage using phase change materials (PCM) has relative advantages compared to other thermal energy storage methods, according to numerous studies in the literature. The design of the heat exchanger are very important for performances of latent heat storage systems. Although there are studies using PCM in different design heat exchangers in recent years, they are quite limited. In this study, a design different from the literature has been used to create an alternative to latent energy storage (LHS) systems by passing different diameter minichannel through a cylindrical enclosure. The thermal effect of the PCM on both the charge and discharge process have been studied at different inlet temperatures of the HTF. Moreover, different flow rates of HTF and different minichannel diameters have been studied only for the charge process. According to the experimental results, as the inlet temperature has been raised from 60°C to 65°C, 70°C, 75°C, 80°C, start of the melting time has decreased by 51.22%,62.99%, 64.46%, 73.28%, respectively. As the minichannel diameter has been decreased from 1.9mm to 1.5mm and from 1.5mm to 1.21mm, the liquid fraction has decreased by 10.6 and 50.5%, respectively, for 75°C HTF inlet temperature conditions. Additionally, the results has showed that the effect of HTF flow rate on thermal energy storage (TES) can be negligible. It was concluded that the optimal shell-tube radius ratio could be up to about 25 in the LHTES systems studied. It is a very important result for engineering systems using PCM for energy storage in heat exchangers.