Experimental Study on Performance of Shell-in-tube Latent Heat Thermal Energy Storage System

The latent heat of phase change material (PCM) can be used to enhance the heat storage capacity of latent heat thermal energy storage (LHTES) system. However, the low thermal conductivity of PCM limits the application of LHTES systems. In this paper, the thermal conductivity of PCM was enhanced by adding expanded graphite into PCM, and the thermal storage characteristics of the shell-in-tube LHTES system were experimentally studied under different water flow rates. The pure pentadecane and composite pentadecane with a mass fraction of 30% expanded graphite were adopted. The experimental results show that, for the pentadecane with a mass fraction of 30% expanded graphite as thermal storage medium, there exists a significant peak for the effective thermal storage coefficient and relative thermal storage ratio at Re = 4298 during cooling discharging, and the heat exchange efficiency and heat storage capacity achieve relative balance. Moreover, at Re = 4298, the effective energy storage coefficient increases up to 336.84% by using pentadecane with a mass fraction of 30% expanded graphite compared with the pure pentadecane. © 2021, Science Press. All right reserved.