Effect of Na2CO3 content on thermophysical properties, corrosion behaviors of KNO3-NaNO2 molten salt

Molten salt is popularly used as high temperature heat transfer and thermal energy storage medium. In order to decrease the melting point and increase decomposition temperature of molten salt, phase diagrams for KNO3- 3- NaNO2 2 binary nitrates were calculated. And the binary salt with the lowest eutectic point was prepared. Furthermore, the effect of Na2CO3 2 CO 3 addition on optimal selected KNO3-NaNO2 3-NaNO 2 binary molten salt thermophysical properties and corrosion behavior are experimentally investigated. The results show that the addition of 7 wt% Na2CO3 2 CO 3 to KNO3-NaNO2 3-NaNO 2 binary molten salt can lower the melting point by 5.8 %. The addition of 9 wt% Na2CO3 2 CO 3 to KNO3-NaNO2 3-NaNO 2 binary molten salt can increase the decomposition temperature by 20.6 %, enhance the specific heat capacity by 4.8 % and increase the thermal conductivity by 7.5 %, but at the same time viscosity increased about 70 % at 300 degrees C. Meanwhile, the density increases with the increase of Na2CO3 2 CO 3 content addition. The average corrosion rate of 316 stainless steel increases with the increasing of Na2CO3 2 CO 3 content, which is consistent with the cross-section SEM results.