Phase Change Material, PCM-to-refrigerant Heat Exchanger, Air-conditioning System, PCM Melting, Heat Transfer Coefficient
Recently, the application of phase change material (PCM) for thermal energy storage shows great potential because of PCM’s capability to absorb heat within a narrow range of temperatures. However, most previous studies used single phase liquid as the heat transfer fluid. The use of two-phase fluid is very limited, which can be applied in many fields, such as waste heat recovery and personal cooling systems. To fill this research gap, a shell-and-tube configured PCMto-refrigerant heat exchanger (PCMRHX) coupled in a refrigeration system was investigated experimentally and numerically in this study. The enthalpy method was applied to the phase change process analysis, and the finite-volume method was employed to address the two-dimensional PCMRHX numerical solution. Simulation results were validated against the experiment data, including refrigerant and PCM temperature profiles, PCMRHX capacity, mass flow rate, COP, and other system-level performance. This study also analyzed the evolutions of the uneven PCM melting in the refrigerant flow direction and its effects on the condensing temperature. Moreover, the parametric study was conducted for the compressor speed. Results show that the transient PCMRHX and system model can predict the experimental data within a deviation of 7%. The PCM near the condenser outlet melts slower than other sections because of the low refrigerant heat transfer coefficient in the subcooled liquid region. This paper introduces a validated model for PCMRHX. The model and observations could be valuable for related PCM heat exchanger design.