Evaluation of heat storage and release in a double shell and tube heat exchanger with a PCM layer

In this study, a thermal storage type heat exchanger that combines heat storage and heat exchange functions has proposed and the heat transfer characteristics of the new type of heat exchanger were analyzed through experiments. The proposed thermal storage type heat exchanger has a shell and tube structure and allows mutual heat transfer between three or more mediums, including a phase change material (PCM). This thermal storage type heat exchanger contains 52.2 kg of a PCM with a phase change temperature of 68.8 °C to provide heat storage function. The heat transfer experiment of the heat exchanger confirmed the effect of the temperature change of the heating medium under the same flow conditions. Furthermore, due to the structural characteristics of the thermal storage type double shell and tube heat exchanger (TSDHE), the phenomenon of three-medium heat exchange (hot water-cold water, hot water-PCM, additional water-PCM) was verified during the experimental process. In particular, due to the PCM filled inside the heat exchanger, the cold water received a heat transfer of 3 kW or higher from the PCM for at least 5 min (maximum 33 min), even when the hot water supply (heat source) was stopped. The results of this study will be used as basic data for applying a thermal storage type evaporator to a high temperature heat pump that generates steam using industrial waste heat.