Experimental and numerical investigation of temperature distribution and heat loss of molten salt tank foundation at different scales

The two-tank thermal energy storage system with a mixture of sodium nitrate and potassium nitrate is one of the most common ways in concentrated solar power plants. However, the unreasonable thermal performance of tank foundations such as excessive heat loss and overheating of concrete slab could result in local molten salt solidification and foundation settlement. This work proposes a novel foundation configuration with road base, light expanded clay aggregate, thermal clay blocks and fire bricks as insulation materials. The temperature distribution and heat loss of the tank foundations are studied at different scales through experimental and numerical methods. A laboratory foundation is set up to prove the feasibility of foundation materials, which is used in the thermal energy storage system of the 1 MWth pilot plant. According to the results, the pilot foundation has a reasonable temperature distribution. Moreover, the foundation configuration and materials are applied to an industrial molten salt tank foundation. The maximum temperature of external surface of the foundation drops from 162.6 °C to 37.3 °C, the maximum temperature of concrete slab decreases from 96.1 °C to 43.2 °C, and the heat loss of foundation reduces by 39.8%. The results indicate that the foundation with the proposed configuration and materials could enhance the thermal performance of the tank foundation and decrease the heat loss through the tank foundation. The proposed foundation is of great significance for guiding the construction of the thermal storage system of commercial concentrated solar power plants.