Exergetic analysis of a domestic refrigerator with an innovative mini-channel flat tube condenser

Abstract

In this study, the energetic and exergetic performance of a household refrigerator with a unique compact heat exchanger composed of a mini-channel flat tube condenser and offset strip fins (OSF) is investigated experimentally by considering varying amounts of R600a (48–64 g) and capillary tube lengths (2800, 3300, and 3800 mm). The experiments have been performed for two refrigerators involving two different innovative condensers composed of mini-channel flat tube and offset strip fins which have varying orientations instead of conventional wire-on-tube condensers. The experiments were conducted in a climatic chamber at a temperature of 25 ± 0.5°C. According to the standard of IEC 62552:2015, the target temperatures of the fresh food and freezer compartments are set at 4°C and −18°C, respectively. Specific and relative exergy destructions of each component, total exergy destruction, the coefficient of performance, and second-law efficiency of the overall system with two different mini-channel condensers are reported for varying amounts of refrigerant and capillary tube lengths. The major concern of the investigation is to reveal the key components contributing to the degradation of the overall performance of the unique design. It is observed that the evaporator, which has a ratio of 52–69% in total exergy destruction within all investigated cases, is the most exergy destructive component and the exergy destruction of the evaporator decreases when the amount of R600a increases. The mini-channel condensers are the second exergy destructive components with a ratio of 19–22%. As an important outcome of this unique design’s investigation, exergy destruction of the condenser and compressor does not show a monotonic change with respect to the refrigerant amount and capillary length. Besides, the highest coefficient of performance and second-law efficiency are obtained when the amount of R600a is 48–50 g in all three capillary tube lengths.