Review on modeling approaches for packed-bed thermal storage systems

Several authors have established single-tank packed-bed storage as a promising alternative that can be coupled with renewable thermal energy sources. The use of such systems can ensure a cost reduction of approximately 33%, compared to two-tank systems, which represents the dominating solution for high-temperature storage. Herein, an overview of the modeling approaches for assessing the yield and efficiency of packed-bed energy storage systems is presented. Additionally, the validation approaches used as well as the conventional materials and structures employed in such systems are described. One of the critical issues that affect the simulation models’ performance in packed-bed energy storage systems is the treatment of the radiation exchange among particles. The impacts of the radiation phenomena on the overall performance and internal temperature distribution of the tank, which facilitate the identification of the operating conditions within the influence of radiation and are significant for analytical purposes are discussed herein. Through parametric analysis, it is demonstrated that the radiation heat transfer coefficient could be as high as 32% of the magnitude of the convection coefficient; thus, it should not be underestimated when analyzing operation temperatures above 750 °C.