Study on the thermal performance of thermal energy storage and heating module based on a novel embedded heat pipe

Abstract

A novel embedded heat pipe (HP) for electric thermal energy storage (TES) utilization was designed, which is conveniently embedded in the TES tank, and the evaporation surface and condensation surface are embedded in it. Besides, it can be used with multistage heat pipes. An electric TES heating module for building heating based on the HP was established. The start-up, the temperature uniformity, and heat transfer performance of the HP and the heat storage/release characteristic of the TES module were both studied experimentally. It is found that the novel embedded HP has good heat transfer performance and temperature uniformity. Under the condition of measured heating power, the minimum thermal resistance is as low as 0.077 °C/W, and the equivalent thermal conductivity is up to 91,273 W/(m·°C). In the heat storage process of the TES module, the paraffin completely melts from the top to the bottom, and the axial temperature of the TES module is uniform. But the radial temperature difference is relatively large. In the heat release process, the overall temperature uniformity of the TES module is good. The maximum temperature difference in the radial direction and the axial direction are less than 5 °C and 12 °C, respectively. Besides, the PCM temperature changes rapidly by adjusting the wind speed, and the thermal response of the TES module is quick. In the application of building heating, this TES module can adapt to the need of simultaneous heat storage and heating.