Experimental investigation of the thermal performance of a sand -basalt heat storage system for beam -down solar concentrators />

The performance of a novel combined receiver storage system (RSS) for beam down solar concentrators was studied experimentally and compared with a previous numerical model. The proposed RSS consists of a ground-mounted tank placed at the focal point of the secondary reflectors of the beam down system. The tank contains a mixture of sand and basalt as a storage media. The top of the tank is covered by a black, metal absorber plate to receive the concentrated solar radiation and pass it as heat into the storage media. Conductive rods are then employed to facilitate the distribution of heat within this media. The function of these rods is to overcome the low thermal diffusivity of sand and conduct the absorbed heat deep into the storage media, hence invoking more volume in the storage process. In this paper, the effect of various configurations of conductive rods as well as the mixture ratios on the performance of the proposed RSS are studied experimentally. A comparison between the numerical and the experimental results in terms of temperature distribution is also presented. The results showed that up to 73% of the energy received by the RSS could be stored as useful energy inside the storage media depending on the mixture ratio and the configuration of the conducting rods.