The use of hydrocarbon mixtures as refrigerants in domestic refrigerators

This paper reports on an experimental study carried our for evaluating the performance parameters of a domestic refrigerator when four ratios of propane, butane and isobutane are used as possible alternative replacements to the traditional R-12 refrigerant. The proposed alternative refrigerants have the advantage of being locally available, cheap and of an environmentally friendly nature. An unmodified R-12 domestic refrigerator was charged and tested with each of the four hydrocarbon mixtures that consist of 100% propane. 75% propane-19.1% butane-5.9% isobutane, 50% propane-38.3% butane-11.7% isobutane and 25% propane-57.5% butane-17.5% isobutane. The parameters investigated are the evaporator capacity, the compressor power, the coefficient of performance (COP) and the cooling rate characteristics. The present work shows that the hydrocarbon mixture with 50% propane-38.3% butane-11.-7% isobutane is the most suitable alternative refrigerant with the best performance among all other hydrocarbon mixtures investigated. When this hydrocarbon mixture was used the evaporator temperature reached -16 degrees C with COP of 3.7 at condenser temperature of 27 degrees C as compared to COP = 3.6 for the traditional R-12 refrigerant at the same temperatures. The refrigerator worked satisfactorily with the proposed alternative refrigerant without the need for any modification or adjustment. (C) 1999 Elsevier Science Ltd. All rights reserved.