Cyclic and standby behavior evaluations of liquid lead-bismuth eutectic thermal energy storage tank for concentrated solar power

Abstract

This paper presents a simulation study on the sensible thermal energy storage (STES) tank using liquid lead-bismuth eutectic and packed medium. The cyclic, charging, discharging and mechanical performances of the STES tank are investigated. The results reveal that the stable operation process of the STES tank can be achieved after five cycles are completed. When the STES tank operates stably, the discharging efficiency is 91.9%, the discharging duration is 5.3 h, and the peak maximum mechanical stress of the steel wall is 138 MPa. With the standby time increased from 0 h to 9 h, the thermocline expands and thus the thermocline thickness increases from 2.7 m to 5.8 m. But after about 9 h, the thermocline thickness variation is relatively small. As the standby time increases from 0 h to 24 h, the heat loss power of the tank decreases from 313.1 kW to 263.1 kW, and the total heat loss of the tank increases linearly. When the standby time is 24 h, the total heat loss is 2.38 × 1010 J. It can be concluded that the STES tank using lead-bismuth eutectic can operate stably, and thus has relatively good potential for the application in concentrated solar power plants.