Three-dimensional oscillating heat pipes with novel structure for latent heat thermal energy storage application

Abstract

Abstract Latent heat thermal energy storage (LHTES) has been considered as a good approach to alleviate energy source shortage and reduce environment pollution. As a high effective heat transfer device, heat pipes have been utilized in the LHTES unit to assist the melting and solidification of phase change material (PCM). To improve the thermal performance of the LHTES unit, three-dimensional oscillating heat pipes (3D-OHPs) with novel structures have been designed and manufactured in the current work. Thermal performance of 3D-OHPs with different turns and filling ratios under different cooling air velocities and inclination angles was experimentally tested. Then, a LHTES unit based on the 3D-OHP was built and tested, the charge and discharge performance was compared with that of another LHTES unit assisted by a conventional heat pipe (CHP). Composite PCMs with different thermal conductivity were utilized in the LHTES units. The results showed that the 3D-OHP could operate well to assist thermal energy storage process of the LHTES unit, especially when the thermal conductivity of PCM was low. Compared with the CHP LHTES unit, the 3D-OHP LHTES unit showed about 32% increase in charging efficiency. During the discharge process, the 3D-OHP LHTES unit had a better temperature uniformity because of the novel structure of 3D-OHP, which was helpful for avoiding potential heat accumulation.