Thermal and mechanical degradation assessment in refractory concrete as thermal energy storage container material in concentrated solar plants

Abstract

This study evaluates the proposal of a concrete storage tank as molten salt container, for concentrating solar power applications. A characterization of the thermal and mechanical properties including compression resistance, density, thermal conductivity and chemical degradation were evaluated in a pilot plant storage tank in contact with solar salt (60%NaNO3 + 40%KNO3) during 120 hours at 565°C. XRD and SEM analysis were carried out after the molten salt test, observing a penetration of salts in the concrete about 14.5 cm. The chemical and mechanical results in the concrete showed a good behaviour and resistance after the exposure test. Nevertheless, the presence of molten salt in the concrete changed its thermal properties, increasing the density and the thermal conductivity in the concrete zones closer to the molten salt reservoir.