Investigation on the thermal performance of a high-temperature latent heat storage system

Owing to the virtues of high energy density and constant charging/discharging temperature, the high-temperature latent heat storage (LHS) technology has been preferred for heat storage in concentrated solar power (CSP) system. An experimental system for high-temperature LHS is designed and established. The thermal performance such as total charging/discharging time, average charging/discharging power and overall heat storage efficiency of a high-temperature LHS unit is investigated in detail. And, the performance enhancement of LHS unit by using annular fins is also experimentally examined. It is indicated that with adding annular fins to enhance the heat transfer between phase change material (PCM) and heat transfer fluid, the distribution of PCM temperature becomes more uniform and the maximum temperature difference in the PCM is greatly decreased, which benefits for reducing the thermal stress in the system. Also, it is shown that the average charging and discharging powers are, respectively, increased by 6.8% and 9.1%, and the overall heat storage efficiency of the LHS unit is increased from 34.4% to 44.1% with adding annular fins. Besides, a mathematical model is presented for simulating the thermal performance of the high-temperature LHS unit, and good agreements are achieved between the numerical results and experimental data.