Experimental Comparison of R600a Domestic Refrigerator with Fin and Metal Foam Evaporator Under Tropical Conditions

Conventional fin-and-tube evaporators in domestic refrigeration systems exhibit reduced performance under elevated ambient conditions, particularly in tropical climates. This study experimentally evaluates a 190 L domestic refrigerator modified with an externally wrapped copper metal foam coated evaporator operating with isobutane refrigerant, which has a low global warming potential. A dual-evaporator configuration enabled side-by-side comparison with a fin-tube evaporator under identical ambient temperatures of 30 °C–40 °C and cabinet temperatures of 0 °C–15 °C. Key performance indicators included the coefficient of performance, evaporator cooling capacity, compressor power input, and volumetric refrigeration capacity. Integration of open-cell copper foam with 90% and 30 pores per inch improved phase-change heat transfer and refrigerant distribution, resulting in a 25%–31% increase in coefficient of performance, a 14%–18% rise in cooling capacity, a 10%–19% enhancement in volumetric refrigeration capacity, and up to 12% reduction in compressor power compared with the conventional system. These improvements are attributed to intensified nucleate boiling, enhanced thermal conductivity, and uniform superheat development. The enhancement strategy allows drop-in retrofitting without changes to system layout, refrigerant charge, or control logic, offering a scalable approach for improving efficiency in tropical climates.