Development of a mechanical mixing system of sensible heat storage equipment for a beam down solar concentrator

Abstract

One of the merits of a solar thermal utility is that the cost of heat storage is lower than that of an electrical battery. Furthermore, a power generation system using solar thermal energy with heat storage equipment is capable of stabilizing its output. For a parabolic trough solar concentrator, molten salt is adopted as the heat storage material using latent heat. However, molten salt is applicable only up to 600 °C; this temperature is not sufficiently high for adaptation to a solar central receiver system. Therefore, we designed and produced sensible heat storage equipment for a beam down solar concentrator (a central receiver system) to offer higher temperature storage. Heat storage materials in this device are mechanically mixed, and receive the concentrated sunlight on the focal plane of the solar concentrator. First, the radiation flux distribution under CPC (Compound Parabolic Concentrator) was measured using thin film heat flux sensors to obtain the input energy for the storage equipment. Next, an experiment was carried out using the storage equipment and the beam down solar concentrator. The maximum temperature was found to reach 1070 °C at the center of the heat storage tank in this experimental conditions, and the stored energy was approximately 14 % of the incident energy.

Keywords

• solar concentrator
• sensible heat storage
• solar receiver
• renewable energy
• thin film heat flux sensor