Investigation of performance improvement of a household freezer by using natural circulation loop

Abstract

Growing number of household refrigerators and freezers also increase the overall energy consumption and number of household refrigerators have grown nearly 3% per year. On the other hand, investigations showed that household refrigerators have a significant technical energy saving potential of up to 30–40%. In this study, a single-phase natural circulation loop is considered as a suction line heat exchanger between the high and low pressure sides of conventional refrigeration cycle of a household chest freezer. The potential heat transfer by the single-phase natural circulation loop is studied by a CFD analysis, considering the possible temperature range for refrigeration cycle and geometrical parameters that affect the loop performance. The performance map of this refrigeration cycle is presented for different compressor suction and discharge pressures (LP/HP), discharge temperatures (T2) and different compressor speeds. The results indicate that the highest amount of heat transfer is obtained for the single-phase natural circulation loop with aspect ratio of 0.8 and pipe diameter of 6.53 mm. Moreover, the single-phase natural circulation loop provides 11.5% efficiency improvement for the household freezer for maximum compressor speed at lowest T2 and LP/HP. Considering reduction in required compressor work, SPNCmL assisted refrigeration system has a wider operating range.