Solar Salt at 620 °C: Impact of Experimental Design on Thermodynamic Stability

Abstract

Sensible thermal storage based on molten nitrate salts gained considerable attention since its first integration in Concentrating Solar Power (CSP) plants. Pushing operating temperatures of the used molten Solar Salt (60 wt% NaNO3, 40 wt% KNO3) beyond 565 °C, would allow even higher thermal-to-electric power conversion efficiencies. Yet, this goal is impaired by the lack of available thermodynamic data given the salt’s complex high temperature decomposition and corrosion chemistry. For the first time, this work presents equilibrium data for Solar Salt at 620 °C by suppressing chemical interactions in the experimental setup. Our data suggests the possibility of Solar Salt being utilized up to 620 °C using simple, yet effective gas management techniques.