Thermo-physical properties of NaCI - Na2CO3- NaOH as a high-temperature sensible heat storage medium

A novel ternary salt mixture composed of sodium chloride, sodium carbonate and sodium hydroxide (Na-Cl-CO3-OH) was developed for high-temperature sensible thermal energy storage (HTSTES) application. The melting point and the heat capacity of the Na-Cl-CO3-OH mixture was measured using a differential scanning calorimeter. The final melting temperature of the blend was estimated as 347.3°C. The average heat capacity of the blend was calculated as 1.50 J g-1 K-1 by following the ASTM standard E1269. The mass loss of the molten salt mixture was studied up to 1000°C using a thermogravimetric analyser in three different atmospheres, and the salt was found to be stable over 700°C. In terms of cost, Na-Cl-CO3-OH mixture costs approximately 4.5 USD/kWh, around 60% less than the commercial "solar salt" nitrate salt mixture