Theoretical formulation and numerical simulation of thermal performance enhancements for cascade thermal energy storage systems

Abstract

Cascaded Thermal Energy Storage (CTES), a term that refers to a thermal energy storage system with multiple phase chance materials (PCMs), has been suggested as a solution for heat transfer reduction through the process of heat exchange by reducing temperature differences. The PCMs used are thus paraffin waxes with different melting temperatures. A numerical simulation was made to determine the optimum length of a CTES system compared with use of a single PCM. The enthalpy-porosity theory was utilised to simulate the phase transition of the PCM, and the simulations then used to mimic the charging and discharging of thermal energy storage of optimum length at different heat transfer fluid flow rates. The results indicated that heat transfer can be greatly enhanced, and melting and solidification time significantly reduced, by using multiple PCMs as compared with using a single PCM.