ABSTRACT
The discrepancy between energy supply and demand can be overcome by the implementation of a proper energy storage system. Latent thermal energy storage employing PCM is the most effective way of thermal energy storage due to its advantages of high energy storage density and its isothermal operation. In a latent heat storage system, energy is stored during melting while it is recovered during solidification of the PCM.
The present work is a numerical study of a latent heat storage unit (LHSU) consisting of a shell-and-tube configuration. The shell space is filled with three phase change materials (PCMs) with different melting temperatures. A heat transfer fluid (HTF: air) flows through the inner tube and transfers the heat to the PCMs. In this study, a comparison of the thermal performance of the latent heat storage unit using three phase change materials (LHSU3) with that of single PCM (LHSU1) is carried out. Enthalpy based formulation of the energy is used for the phase change process. The governing conjugate equations are solved numerically employing finite volume approach. The results are validated with the experimental data available in literature. Numerical investigations are carried out to examine the impact of the key parameters on the thermal performances of the latent heat storage units during charging process (melting). The key parameters include the HTF inlet temperature, the mass flow rate of the HTF, the melt fractions of PCMs and the shell configurations. Results show an appreciable enhancement in the rate of melting of PCM and nearly uniform exit temperature of heat transfer fluid in LHSU having multiple PCM. This parametric study provides guidelines for system thermal performance and design optimization.
