Performance Enhancement of a Household Refrigerator Using Phase Changing Materials (PCMs) and Nanoparticles

A refrigerator is the most common and efficient method for preserving food and medicine, although its continuous operation consumes a considerable amount of energy. Thus, this study investigated and evaluated the overall performance of a household refrigerator with phase change materials (PCMs) and nanoparticles. The PCMs are applied to the evaporator (evaporator cold storage, ECS) and condenser (condenser heat storage, CHS) individually and simultaneously. Also, a refrigerator with dual energy storage (DES) and combined energy storage (CES) is proposed. The former included CHS and ECS and the latter involved CHS, ECS, and PCM panels in the fridge cabinet. PCMs were organic paraffins, inorganic salt hydrates, and distilled water. The energy consumption of refrigerators is assessed using ISO standards. Isobutane (R600a) was a refrigerant in the system. The experiments included the application of multiple PCMs to the condenser and evaporators. PCM with copper oxide (CuO) nanoparticles is tested on the condenser alone. As a result, through extensive analysis and testing, the overall performance of the refrigerator was optimized. The CHS effectively improved the coefficient of performance (COP) and kept the temperature of the cabinets, while the ECS efficiently saved energy and reduced temperature fluctuation within the cabinets. The most significant optimizations were by DES and CES due to the combination of cons and pros of using PCMs on the condenser, evaporator, and fridge cabinet individually. The energy savings for CHS cases, ECS cases, DES, and CES were 10.87-21.24%, 15.21-23.47%, 24.29%, and 26.42%, respectively. The COP improvements for CHS tests, ECS tests, DES, and CES were 1.58-7.56%, 4.35-5.50%, 8.81%, and 9.10%, respectively. Although their temperatures increased, the fluctuation temperature in the fridge and freezer cabinets dropped by 15.53-56.53% and 0.61-26.46%, respectively.