Thermal performance analysis of concentric-tube latent heat storage systems integrated with varying energy source under various charging strategies

Abstract

This study presents a comprehensive assessment of the performance of a vertical concentric tube thermal storage system. The system is charged using constant and variable solar energy sources similar to real-world conditions. The initial part of the work focuses on identifying the suitable optimal phase change material for maximizing energy storage. It later evaluates the impact of using a variable energy source compared to a constant source for charging the system. A performance assessment of the system is carried out for two approximated constant energy source cases (constant time-averaged and constant peak fluid temperatures) and an actual variable energy source (unsteady fluid temperature). The findings indicate that constant time-averaged and peak charging temperatures can lead to under-prediction by up to 25.65 % and over-prediction by up to 32.72 % in the energy storage compared to the actual case considering variable charging temperature. Two charging strategies are proposed and compared with the established cascade methodology, revealing the potential for improving thermal energy storage. The dynamic charging strategy shows promising results with potential energy storage gains of up to 55.57 %. This study emphasizes the importance of considering the variable charging source and highlights effective strategies for enhancing energy storage in the thermal storage systems.