Experimental Study of a Novel Thermal Storage System using Sands with High-Conductive Fluids Occupying the Pores

摘要

Because of the capability of large capacity thermal storage, concentrated solar power (CSP) technology is getting more attentions in the recent years. The energy storage allows power generation using solar energy during the late afternoon and evening time. For a large capacity of thermal energy storage, a dual-media system is typically adopted for reducing the use of the heat transfer fluid (HTF), which is usually expensive. In a dual-media system, the solid material must have large heat capacity and be inexpensive. One type of configuration for a dual-media system is that HTF flowing in pipes which are imbedded into the solid material. The present study considers sands, a major component of concrete, as low-cost solid thermal storage materials. The novel approach is that the sand is saturated with high thermal conductive fluid. Compared to using concrete for thermal storage, this method avoids issues of heat transfer degradation associated with the mismatch of thermal expansion of pipes and concrete. Since only sands are porous materials and the heat transfer performance is low, a high conductive fluid (XCELTHERM® 600 hot oil) was used to saturate sands, which then forms a new thermal storage material that can have better heat transfer. Results of thermal storage process with sands only and with the oil-saturated sands are presented and discussed.