Experimental evaluation of a domestic refrigerator working with LPG

Liquefied petroleum gas (LPG) of 60% propane and 40% commercial butane has been tested as a drop-in substitute for R134a in a single evaporator domestic refrigerator with a total volume of 10 ft(3) (0.283 m(3)). Continuous running and cycling tests were performed on that refrigerator under tropical conditions using different capillary tube lengths and various charges of R134a and LPG. Continuous running and cycling results showed that R134a with a capillary tube length of 4 m and charge of 100 g or LPG with capillary tube lengths from 4.0 to 6.0 and charge of 50 g or more satisfy the required freezer air temperature of -12 degrees C. The lowest electric energy consumption was achieved using LPG with combination of capillary tube length of 5 m and charge of 60 g. This combination achieved higher volumetric cooling capacity and lower freezer air temperature compared to R134a. Experimental results of the refrigerator using LPG of 60 g and capillary tube length of 5 m were compared with those using R134a of 100 g and capillary tube length of 4 m. Pull-down time, pressure ratio and power consumption of LPG refrigerator were lower than those of R134a refrigerator by about 7.6%, 5.5% and 4.3%, respectively. Also, actual COP of LPG refrigerator was higher than that of R134a by about 7.6%. Lower on-time ratio and energy consumption of LPG refrigerator by nearly 14.3% and 10.8%, respectively, compared to those of R134a refrigerator were achieved. In conclusion, the proposed LPG seems to be an appropriate long-term candidate to replace R134a in the existing refrigerator, except capillary tube length and initial charge. (c) 2005 Elsevier Ltd. All rights reserved.