Thermodynamic Performance Analysis and Optimization of Domestic Refrigerator with Varying Refrigerant Charge and Capillary Tube Lengths

In this paper, thermodynamic performance analysis and optimization of a domestic refrigerator were experimentally carried out by simultaneously varying the refrigerant charge (wr) and the capillary tube length (L). Continuous running and cycling tests were performed on a domestic refrigerator under tropical conditions using three refrigerants (R12, LPG and R600A) with different capillary tube lengths and various charges. The results show that the design temperature and pull-down time set by ISO for small refrigerator are achieved earlier using refrigerant charge 60g of LPG with 1.5m capillary tube length. The highest COP (4.8) was obtained using 60g charge of LPG with L = 1.5m. The average COP obtained using LPG was 1.14% and 15.09 % higher than that of R600a and R12 respectively. Based on the results of this study, R600a offered lowest power consumption. The compressor consumed 20 % less power compared to LPG and 32% less power than R12 in the system. In conclusion, the system performed best with LPG in terms of COP and cooling capacity. In term of power consumption R600a performed best.This shows that both LPG and R600A can be used as replacement for R12 in domestic refrigerator