Hydrocarbons and their mixtures as alternatives to environmental unfriendly halogenated refrigerants: An updated overview

Vapor compression refrigeration systems consume high-grade energy and contribute to global warming and ozone layer depletion due to the environmentally unfriendly refrigerants. The use of hydrocarbons offer good drop-in replacements for the existing halogenated refrigerants in terms of environmental impacts and energy consumption. In this study, a review of the previous studies carried out with hydrocarbons as alternative refrigerants in refrigeration, air conditioning and heat pump, and automobile air conditioning systems is presented. An attempt has been made to cover the current status, possibilities, and problems related to the use of hydrocarbons as alternative refrigerants. Hydrocarbon characteristics, allowable refrigerant charge, flammable properties, and safety considerations are also presented. In addition, the study contains also a useful amount of information about the refrigerant properties, environmental impacts, and replacement strategy of conventional refrigerants. Results showed that in spite of highly flammable characteristics, hydrocarbons can offer proper alternatives to the halogenated refrigerants from the standpoint of environment impact, energy efficiency, COP, refrigerant mass, and compressor discharge temperatures. Roadmap on the future work needs in this field is presented. Finally, a summary of previous studies and strategies on pure HC, HC mixtures, and HC/HFC blends used for different applications has been presented and discussed in detail.