Numerical Studies on Phase Change Material–Operated Condenser and Preheater for Energy-Efficient Refrigeration Cycle

Abstract

The study investigates using solid–liquid phase change materials (PCMs) as heat exchangers in energy-efficient refrigeration systems. A modified refrigeration cycle flow model was proposed and progressively refined for better performance. Initial simulations used simplified U-tube flow models to reduce complexity, analyzing PCM charging and discharging separately before integrating them into the modified refrigeration system. Various parameters were examined, including the mass flow rate of refrigerant R134a, inlet temperatures of hot and cold refrigerants, and the heat transfer area. The refrigerant, termed HotR, flows through the condenser, while the cooler refrigerant, ColdR, flows through the preheater. PCM acts as the condenser during charging and as the preheater during discharging. Simulation techniques such as the enthalpy-porosity model for the PCM mushy region, the Lee model for evaporation–condensation, and the volume-of-fluid (VOF) multiphase model were utilized to model the PCM-operated condenser accurately. The study offers valuable insights for optimizing PCM utilization in refrigeration cycles. It emphasizes the importance of refining charging and discharging processes to enhance system efficiency and condensation performance. Simulations showed the need for flow rate adjustments to achieve optimal condensation. Using HotR (343 K) and ColdR (263 K) inlet temperatures and a flow rate of 0.000824 kg/s, the system achieved up to 47% condensation and 25.08 K preheating with the integrated setup.