Numerical investigation on thermal rate capability and Ragone plots of thermal energy storage device

Heat pump systems integrated with latent heat thermal energy storage (LHTES) have been proven to exhibit superior performance in building cooling and heating source systems, particularly in energy efficiency and operational stability. However, the systematic evaluation of the practical performance metrics (i.e., energy and power density) remains limited attention. This study aims to establish a comprehensive framework for optimizing PCM properties (thermal conductivity and density) and evaluating the operational performance (charging rate) of an LHTES tank. Initially, a numerical model of an energy storage tank incorporating phase change material (PCM) is created and validated. Further, thermal rate capability and Ragone plot are introduced to characterize the specific energy and power of the LHTES tank. Subsequently, a series of investigations on the key parameters is conducted to elucidate the effects of PCM properties and operating conditions. Ultimately, the parameter sensitivity analysis approach is implemented to optimize the variable selection process. The results indicate that the superior performance is achieved with a charging rate of 1.5 h −1 , PCM thermal conductivity of 2.0 W m −1 K −1 , and PCM density of 700 kg m −3 . This framework guides the superior design of an LHTES tank. • A three-dimensional latent heat thermal energy storage tank model is proposed. • The thermal rate capability and Ragone plots are employed to evaluate the specific power and energy of thermal energy storage device. • The effects of thermal conductivity, density, and charging rate on power density and phase transition behavior are investigated. • The parameter sensitivity analysis approach is implemented for optimization. • The thermal conductivity of 2.0 W m −1 K −1 and density of 700 kg m −3 at a charging rate of 1.5 h −1 perform superior performance.