Corrosion and Mechanical Assessment in LiNO3 Molten Salt as Thermal Energy Storage Material in CSP Plants
Abstract
The development of solar thermal energy in Chile, leads to the realization of applied research in such a way that new technologies and applications suitable to the conditions of the Atacama Desert can be proposed. In view of the search for new fluids feasible to be applied in CSP technology as thermal energy storage using molten salts, this research proposes the use of the mixture composed by 30wt.% LiNO3 – 13wt.% NaNO3 – 57wt.% KNO3. Corrosion has been evaluated on different carbon and stainless steels (T22, T91, VM12, 304, OC-4) and a Ni base alloy (HR-224). In order to monitorize corrosion, Electrochemical Impedance Spectroscopy and Linear polarization technique have been applied in order to obtain the corrosion rate and the corrosion mechanism as well. Corrosion rates obtained for 304, HR224 and OC-4 alloys was 1.82, 1.63 and 1.93 (mm / year), respectively. Finally, the effect of molten salts on the mechanical properties of materials used in CSP plants is also studied, determining the most suitable method for this evaluation.