Investigation of Environmentally-Friendly Alternative Refrigerants for Automotive Air Conditioning Systems

Abstract

The popularity of automotive transport and the length of time people now spend in their cars mean that most vehicles come equipped with an automobile air conditioning (AAC) system. Most of these use refrigerant fluids, which affect the environment and increase global warming. Therefore, many territories have laws that mandate the use of environmentally-friendly refrigerants with zero ozone depletion potential (ODP) and low global warming potential (GWP). The ACCs in most existing motor vehicles use R134a as a refrigerant, which has a high GWP. The aim of this study is to investigate alternatives to R134a that are characterized by environmentally-friendly qualities such as low GWP, are available and can be charged directly into an existing system without modification. Therefore, thermodynamic analysis of an AAC system containing R134a was conducted and the results compared with blends formed by mixing hydrocarbons (HCs) (R290/R600a), which are flammable, environmentally-friendly and ultra-low GWP refrigerants, with R134a (R600a/R290/134a). The mixing of HCs and R134a led to reduced flammability and used R134a in a ratio within low GWP criteria, to decrease the cost and the amount of its banked. Refprop software was used for the thermodynamic analysis. Theoretical results revealed that the blend of (R600a/R290/134a) with a mass ratio (43/35/22) has low GWP, provides the same level of refrigerant performance and can be used directly without any modification to the system.