PCM Heat Storage Charged with a Double-Reflector Solar System

Abstract

A “Solar Salt” (NaNO3–KNO3 60 : 40 molar mixture) latent heat storage has been charged by direct solar illumination. Solar Salt as a Phase Change Material (PCM) can be an attractive small scale heat storage solution, as the melting temperature of about 220°C can be suitable for cooking purposes. The tests were made with a double-reflector setup. In this setup a secondary reflector positioned above the focal point of the primary reflector directs the rays onto a heat storage positioned below a hole in the primary reflector. The reflectors are tracking the sun, but the storage is stationary. The direct illumination of the absorber top plate during the tracking of the sun melted the salt in the storage through conducting fins. This is a system where portable heat batteries can be charged, during sunshine hours, and then provide heat for cooking during evening times.