What is the main refrigerant used in automotive air conditioning systems nowadays?
1 Answers
Automotive air conditioning refrigerants (commonly known as Freon or refrigerant) currently consist of two main types: non-environmentally friendly R12 and R134a (HFC-134a). Below are the selection criteria for refrigerants: 1. Consider the type of compressor. Different refrigeration compressors operate on different principles. Positive displacement compressors increase pressure by reducing the volume of refrigerant vapor, generally requiring refrigerants with high volumetric cooling capacity. 2. Consider the required cooling temperature. Depending on refrigerant temperature and cooling conditions, choose high-temperature (low-pressure), medium-temperature (medium-pressure), or low-temperature (high-pressure) refrigerants. Typically, the standard evaporation temperature of the selected refrigerant should be at least 10°C lower than the cooling temperature. Selection should also account for the cooling conditions and operating environment of the refrigeration system. Operating condensation pressure must not exceed the compressor's safety limits. Since automotive air conditioning systems can only use outside air as the cooling medium, they are subject to frequent changes in ambient temperature, wind speed, solar radiation, and heat radiation. These operating conditions dictate the use of high-temperature (low-pressure) refrigerants. While R12 was used in the past, R134a is now predominantly selected. 3. Consider the refrigerant's properties. Based on thermodynamic, physical, and chemical properties, choose refrigerants that are non-toxic, non-explosive, and non-flammable. Ideal refrigerants should have good heat transfer characteristics, low flow resistance, and compatibility with materials used in the refrigeration system.
