Experimental Investigation for Heat Transfer Performance of Heat Pump Water Tank Containing PCM

This paper experimentally studied the heat transfer characteristic of a thermal storage water tank and analyzed the temperature distribution in water tank and also in PCM (Phase Change Material) installed in the upper part of the tank. The impact of Nusselt number and Stefan number on heat transfer performance during the melting and solidifying process were experimentally investigated. The temperature curves of water and PCM as a function of time were obtained during thermal storage and release process in the thermal storage tank. The results showed that: the temperature gradients in each test points were not constant and the water temperature water has significantly stratification during the thermal storage process; the PCM can effectively reduce the fluctuation and descending rate of water temperature during the exothermal process. The heat transfer enhancement between PCM and water was a key factor to improve thermal storage efficiency. It indicates that increasing Nusselt number was most beneficial for heat transfer of PCM, Nusselt number was affected by Stefan number.