Computational studies on a latent thermal energy storage system with integral heat pipes for concentrating solar power

Latent thermal energy storage system (LTES) is an effective technique for storing solar energy and load management with advantages including isothermal operation and high-energy storage density. However, the low thermal conductivity of the phase change material (PCM) in a LTES reduces the melting and solidification rates of the PCM, which is sought to be increased for a viable operation of the energy storage system. This paper investigates an approach to reducing the thermal resistance of PCM through embedded heat pipes which are passive heat transfer devices that efficiently transfer large amount of thermal energy between the phase change material and a heat transfer fluid (HTF). A transient three-dimensional computational analysis of a shell-and-tube LTES embedded with heat pipes is performed for melting (charging) and solidification (discharging) to determine the position of melt front, energy stored and effectiveness of the heat pipe embedded configurations as a function of time. The influence of the number and orientation of heat pipes and the configuration of the system are analyzed to identify designs that lead to improved effectiveness.