Development of salt formulations with low melting temperatures

Kurzfassung

Multicomponent salt mixtures are attractive candidates as sensible heat storage material and heat transfer fluid (HTF) for concentrating solar power (CSP) applications. For parabolic through CSP plants, these mixtures could be attractive HTFs in the solar receivers. Multicomponent salt mixtures can have much lower melting temperatures compared to currently utilized mixtures such as Solar Salt. Hence, novel salt mixtures with a low melting temperature could minimize the freezing problem that could occur in parabolic through CSP plants. The paper presents novel alkali nitrate/nitrite mixtures with melting temperatures well below 100 °C. It is known that the identification of new multicomponent salt mixtures is complex and time consuming as the number of degrees of freedom in phase diagrams grows rapidly with the number of salts. So far, research focused on high-throughput experimental methods and multi-component phase diagram predictions. This paper presents an alternative experimental method which significantly reduces the number of experiments to identify the compositions of minimum melting mixtures. Measurements on known and unknown multicomponent salt mixtures demonstrate this alternative method. The minimum melting composition of the unknown system Ca,K,Li,Na//NO2,NO3 with a liquidus temperature of about 70 °C was identified.