Experimental Test of Properties of KCl-MgCl2 Eutectic Molten Salt for Heat Transfer and Thermal Storage Fluid in Concentrated Solar Power Systems

The eutectic mixture of MgCl2-KCl molten salt is a high temperature heat transfer and thermal storage fluid able to be used at temperatures up to 800 degrees C in concentrating solar thermal power systems. The molten salt thermophysical properties are reported including vapor pressure, heat capacity, density, viscosity, thermal conductivity, and the corrosion behavior of nickel-based alloys in the molten salt corrosion at high temperatures. Correlations of the measured properties as functions of molten salt temperatures are presented for industrial applications. The test results of tensile strength of two nickel-based alloys exposed in the molten salt at a temperature of 800 degrees C from 1-week length to 16-week length are reported. It was found that the corrosion and strength loss is rather low when the salt is first processed to remove water and oxygen.