Optimizing LHS system using PCM in a tube-in-tank design for emergency cooling

Abstract

Thermal Energy Storage (TES) systems are normally utilized to assist water chillers to cut down operational cost. With the development of heat-transfer-enhancement technique, there is potential for TES systems using the latent heat of Phase Change Materials (PCMs) for emergency cooling applications. The Latent Heat Storage (LHS) systems might be able to provide thermal energy around PCM melting temperature. This study numerically calculated the basic unit of the system in a tube-in-tank design and analyzed the results by the characteristic figure, which shows the relationship between the capacity effectiveness and the heat transfer effectiveness. The parameter of the equivalent thermal conductivity of the PCM is investigated to improve the characteristic capacity effectiveness of the LHS, and the parameter of inlet temperature is evaluated by testing the operational stability of the LHS when the thermal load is unsteady. According to the numerical results, most of the stored thermal energy in the LHS can be discharged effectively around the PCM melting temperature. The characteristic capacity effectiveness can reach approximate 3 at 80% heat transfer effectiveness, indicating a three times quantity of the thermal energy provided by an equivalent water tank.