Solar storage systems using salt hydrate latent heat and direct contact heat exchange—II Characteristics of pilot system operating with sodium sulphate solution

Abstract

The operating characteristics of Glauber's salt as a heat storage medium were studied in a pilot heat storage system using direct phase contact heat exchange. The effect of several variables was studied over many complete cycles of the unit, including variable HTF flow rate and inlet temperature, wall insulation, internals to redisperse the HTF and prolonged shutdown of the system. Thermal efficiencies generally exceeded 85 per cent and were often greater than 90 per cent. These values are higher than those reported for smaller heat storage vessels. Volumetric heat transfer coefficients were also determined and correlated with the HTF superficial velocity.