Coupled Experimental Study and Thermodynamic Modeling of Melting Point and Thermal Stability of Li2CO3-Na2CO3-K2CO3 Based Salts

Abstract

Nitrate based salts have application as a heat transfer fluid and thermal energy storage media in solar field installations and are normally used from 200 °C up to maximum temperatures of ∼550 °C. Molten K2CO3-Na2CO3-Li2CO3 could potentially be used as heat transfer fluid and thermal energy storage media to replace nitrate salts due to its wider temperature operating window (400–900 °C), which improves the heat transfer efficiency. There will be improved operability and the process will be more economical viable if the lower temperature at which carbonate salts can operate could be decreased. This paper explores the melting point and high temperature stability of K2CO3-Na2CO3-Li2CO3 based salt mixtures, the effect of atmosphere and the effect of additives to the melt using experimental investigation and thermodynamic modeling.