01 February 1996

International Status Report on Compression Systems with Natural Working Fluids


Natural working fluids such as ammonia, hydrocarbons, carbon dioxide, water and air, receive growing attention as sound, long-term replacements for the CFCs and HCFCs that are commonly used in today’s air conditioners, heat pumps and refrigeration equipment. As natural substances they not only pose no risk to the ozone layer, they also present little or no other threat to the environment. In practice, the application of natural working fluids can be difficult. Some are toxic or flammable and additional costs can be incurred. Furthermore, it is always important to ensure that the efficiency of equipment is not downgraded by using new working fluids, as this could result in other negative environmental consequences. The challenge in using natural working fluids is to build safe and reliable systems, that are equal to or better than alternative systems in terms of both costs and energy efficiency. Annex 22 of the IEA Heat Pump Programme, “Compression Systems with Natural Working Fluids”, is the International Energy Agency’s response to this challenge. The eight member countries (Canada, Denmark, Japan, The Netherlands, Norway, Switzerland, UK and USA) of this Annex aim to stimulate technology development, accelerate application, and expand knowledge on the “naturals”. This report presents an international overview of a study conducted on the status of the use of natural working fluids in compression systems in the eight participating countries of Annex 22 – and in Germany, Sweden and Austria.Furthermore it contains the results of a survey on the state-of-the-art technology in this field.


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