Comparative study of thermally stratified tank using different heat transfer materials for concentrated solar power plant

Abstract

This paper presents a comparative analysis of thermal and mechanical behaviors of the thermally stratified heat storage system using three different heat transfer materials, which are the binary nitrate salt, ternary nitrate salt and liquid lead–bismuth eutectic (LBE) alloy. The discharging behaviors of the tank using three different heat transfer materials are investigated by using both the algebraic and numerical models. For all the three materials, the algebraic results are consistent with the simulation ones. During the discharging process, in comparison, the thermal stratification thickness of the tank using the binary nitrate salt is relatively smaller, which can lead to a better discharging performance. The comparison results of expanding behaviors of the standby tank reveal that the thermal stratification thicknesses of tanks using the three different heat transfer materials all increase with the standby time increased. Compared with the other two materials, the thermal stratification thickness of the tank using the binary nitrate salt is the smallest at the same standby time. The comparison results of mechanical behaviors of the tank demonstrate that the maximum mechanical stress of the tank using the liquid LBE is the greatest, while the tank using the molten salts can have better mechanical properties.

Keywords

• Thermally stratified tank
• Molten salt
• Heavy liquid metal
• Energy storage behavior
• Mechanical analysis