Thermodynamic Analysis and Effects of Replacing HFC by Fourth-Generation Refrigerants in VCR Systems

The third-generation refrigerants belonging to hydrofluorocarbons (HFCs) do not contribute to ozone depletion. However, HFCs are listed as greenhouse gases by Kyoto Protocol because of their relatively high global-warming potential (GWP). At present the research is now mainly focused on refrigerants with zero ozone depletion potential (ODP) and less GWP, which are termed as Fourth generation refrigerants. This paper analyzes the advancement in refrigerants, and presented the different options in choosing a refrigerant with respect to international agreements to curb the stratospheric ozone depletion and global warming. The hydrofluoroolefins (HFOs) i.e., fourth generation refrigerants are available in limited quantities and also their performance is not completely tested in different applications. Hence this paper aims at assessing the performance of fourth generation refrigerants in terms of their mass flow rate requirement and COP for a specified cooling load and compared with the existing third generation refrigerants in usage. It is found that fourth generation refrigerants COP is low and mass flow rate and power requirements are high. However, HFO1234ze(E) can replace R134a as its performance is almost similar to R134a with an added advantage of low GWP