STUDY ON THE THERMAL PERFORMANCE OF A PACKED BED MOLTEN SALT THERMOCLINE THERMAL STORAGE SYSTEM

Base on the continuous solid model of porous medium, which accounts for the heat losses though the wall and the pump energy, the thermal performance of a packed bed molten salt thermocline sensible thermal storage system was investigated. A parameter study of the packed bed height, porous, particle diameter, and fluid flow rate was carried out to evaluate the charging/discharging efficiency, overall thermal efficiency and especially exergy efficiency. The results showed that both the particle diameter and the packed bed height have significant influence on the thermal performance of the packed bed. The overall efficiency is improved from 0.891 to 0.931 and the exergy efficiency is improved from 0.879 to 0.923 when increasing the packed bed height from 2 m to 6 m; as for the particle diameter, increasing it from 5 mm to 40 mm results in a decrease in the overall efficiency from 0.956 to 0.875 and the exergy efficiency from 0.951 to 0.861.