Characterization of Gravels for Solar Thermal Applications

Solar thermal energy storage can provide significant solutions for the sustenance of clean and affordable energy supply. Gravel physico-thermal measurements describes the gravels properties which govern the flow of heat through the gravels (density, porosity, thermal conductivity, and thermal capacity). This paper investigated the physico-thermal properties of gravels at transient state conditions. Seven different gravels of volcanic origin were tested for thermal conductivity, thermal effusivity, thermal diffusivity, specific heat capacity using the transient heat source method with the aid of KD2 thermal analyser, while density was determined through the gas jar method. Results indicate that Awulema gravels sourced from sourced from Ohimini local government area of Benue State, Nigeria State, Nigeria had the highest specific heat capacity, thermal conductivity and relatively good thermal effusivity (admittance) suitable for seasonal sensible heat storage application. The physico-thermal properties of the gravels (density, thermal conductivity, thermal effusivity, thermal diffusivity and specific heat capacity) gave results similar to the ones found in literature. The pertinence of laboratory investigation of sensible materials for solar thermal heat storage and transfer is vital for meeting solar thermal energy requirement during solar radiation off peak period. It is recommended that solar thermal heat storage applications such as gravel-water pit, gravels storage for district heating and solar drying be develop and verified using the materials