Experimentally-validated numerical studies of thermal performance enhancement of latent thermal energy storage systems with periodically reciprocating flow

Abstract

The effects of periodic reversal of flow direction of a heat transfer fluid (HTF) on the heat transfer rate in a latent thermal energy storage system (LTESS) are numerically investigated for consecutive melting and freezing cycles of phase change material (PCM). Numerical results are validated with experimental measurements. Parametric studies are performed, where different parameters that affect the thermal performance of LTESS are varied independently. The effects of these variations on the thermal performance of LTESS with periodically reciprocating and unidirectional HTF flow are studied. Periodically reciprocating HTF flow results in increased uniformity of temperature and temperature gradients throughout the PCM for both melting and freezing cycles, compared to unidirectional flow. Increasing the flow rate of HTF, increases the relative heat transfer rate enhancement with reciprocating flow for both melting and freezing cycles. An optimal reciprocation period of LTESS which is dependent on other parameters, is noticed to produce the maximum relative thermal performance enhancement with the periodically reciprocating flow. Increasing the latent heat of fusion or thermal conductivity of PCM increases the relative effects of reciprocation nonlinearly.