Critical evaluation of R134a, R1234yf and R744 in passenger car cooling systems

The Montreal Protocol on Substances that Deplete the Ozone Layer and the Kyoto Protocol to the United Nations Framework Convention on Climate Change have an effect on the refrigerants industry. Both documents have implemented prohibitions within applications of substances which are responsible for ozone depletion and global warming. These protocols have strong influence on refrigeration industry. As a result, the whole world industry has accepted the chlorofluorocarbons (CFCs - Freon) phase out and new ecological refrigerant like hydrofluorocarbon (HFCs) and CO₂. The automotive industry must keep up with these changes. Constructions of cooling systems in cars has to face the requirements set by new refrigerants. Furthermore, changing the production profile of large car companies towards electric and hybrid cars increases this need. This development has a significant impact on solutions installed in passenger vehicles. The paper presents the critical evaluation of R134a, R1234yf and R744 in cooling systems of passenger cars. The possibility of using them in common air - conditioning systems with the motor drive and in heat pump of the electric vehicle is presented. The influence of the new refrigerants application in car production process was analyzed and commented. The thermodynamics and ecological aspects were analyzed.