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The Properties of HFCs and Other Refrigerants
Hydrofluorocarbons (HFCs) were developed as alternatives to the ozone-depleting refrigerants chlorofluorocarbons (CFCs) and hydro-chlorofluorocarbons (HCFCs), which are being phased out inter-nationally under the Montreal Protocol. HFCs are now used as refrigerants for a wide range of applications, including air conditioning, heat pumps (often referred to as reversible air-conditioning), refrigeration, metered dose inhalers, insulation, technical aerosols, solvents and fire extinguishants. A 1998 independent Arthur D. Little report found that HFCs are emerging as the preferred replacement for CFCs and HCFCs because they are safe, energy efficient, cost effective and can be applied to existing product technologies.
In addition, the Technology and Economic Assessment Panel (TEAP) of the Montreal Protocol on Substances that Deplete the Ozone Layer reported in 1999 that HFCs are important to the safe and cost-effective phase-out of CFCs in developing countries, and are essential substitutes for highly important uses of ozone-depleting substances. HFCs are also technically and economically necessary for the phase-out of HCFCs in developed and developing countries.
Alternatives to HFCs are available and are appropriate for some specific applications. However, there is no evidence to show that they will have a lower lifetime impact on the environment and some carry additional hazardous properties. Hydrocarbons (HCs) such as butane and propane are good refrigerants but are highly flammable and explosive. Nevertheless, the costs and energy required for making the use of HCs safe enough do raise the question of viability.
Ammonia is also a good refrigerant, but is highly toxic even in low concentrations and requires highly trained service personnel. Again, safety measures to reduce the risks to acceptable levels increase the system costs and are not applicable to smaller units. Other possible refrigerants such as CO2 and water are being applied in a limited number of applications and could become commercially available in other applications in the medium to long term, subject to technology advances.