Latent Thermal Storage Using Sodium Hydroxide-Based Molten Salts. —Compatibility of molten salts—

Although binary mixtures of sodium hydroxide-sodium nitrate and sodium hydroxide-sodium nitrite are promising materials for latent thermal storage in the 200~300°C temperature range, one of the most critical problems for application is the compatibility of these molten salts with metallic materials. The present paper first gives experimental results for compatibility tests on ten different metals at 350°C for up to 4,000 hours. The compatibility study further focussed on the effect of impurity on carbon steels in tests performed at 350°C for up to 10,000 hours. The experimental results showed that carbon steels has the best compatibility with these particular molten salts, and that the content of sodium chloride in the salts has a significant influence on corrosion behavior.