Thermalfluid flow within innovative heat storage concrete systems for solar power plants

Purpose The purpose of this paper is to describe an experience of R&D in the field of new technologies for solar energy exploitation within the Italian context. Concentrated solar power systems operating in the field of medium temperatures are the main research objectives, directed towards the development of a new and lowcost technology to concentrate the direct radiation and efficiently convert solar energy into hightemperature heat. Designmethodologyapproach A multitank sensibleheat storage system is proposed for storing thermal energy, with a twotanks molten salt system. In the present paper, the typology of a belowgrade cone shape storage is taken up, in combination with nitrate molten salts at 565C maximum temperature, using an innovative highperformance concrete for structures absolving functions of containment and foundation. Findings Concrete durability in terms of prolonged thermal loads is assessed. The interaction between the hot tank and the surrounding environment ground is considered. The developed FE model simulates the whole domain, and a fixed heat source of 100C is assigned to the internal concrete surface. The development of the thermal and hygral fronts within the tank thickness are analysed and results discussed for longterm scenarios. Originalityvalue Within the medium temperature field, an innovative approach is here presented for the conceptual design of liquid salts concrete storage systems. The adopted numerical model accounts for the strong coupling among moisture and heat transfer and the mechanical field. The basic mathematical model is a single fluid phase nonlinear diffusion one based on the theory by Baant appropriate thermodynamic and constitutive relationships are supplemented to enhance the approach and catch the effects of different fluid phases liquid plus gas.