Heat storage is important for addressing the intermittency of solar energy and allowing continuous operation of solar thermal applications. Although packed bed sensible heat storage systems using rocks have been widely studied for high-temperature applications, limited experimental research has focused on medium-temperature (100–300 °C) air-rock systems integrated with parabolic dish concentrators and embedded heat exchangers for steam generation. This study experimentally investigates an integrated system consisting of a cylindrical stainless steel thermal storage container (0.035 m 3 ) filled with dolerite rocks, heated from the bottom using a parabolic solar dish concentrator with a copper absorber located at the focal point, and equipped with an embedded helical copper coil for heat extraction and steam generation. The results demonstrated significant temperature stratification, with maximum temperatures of 263 °C at the bottom absorber region and 114 °C at the top of the storage unit under an average beam solar radiation of 738 W/m 2 , indicating good temperature stratification formation. The helical coil heat exchanger successfully extracted thermal energy to generate steam at temperatures above 96 °C with a water flow rate of 5 L/h. The integrated system achieved maximum charging and discharging efficiencies of 67% and 61%, respectively. These findings demonstrate the technical feasibility of integrating bottom-heated dish concentrators with rock-bed storage and helical coil heat exchangers for decentralized medium-temperature steam generation applications.
Abrha et al. (Thu,) studied this question.