By introducing HFC-134a as the replacement refrigerant for CFC-12 in motorcar air conditioning, the automobile industry will comply with the present national and international legislation for the phase-out of ozone-depleting substances.
A transition to this new fluid will, however, result in emissions of several hundred thousand tonnes of a new and unfamiliar chemical compound to the atmosphere each year, involving both known negative consequences like global warming, and potential risks of serious unknown environmental effects.
A new, efficient and environmentally benign automobile air conditioning system “MAC-2000” has been developed at The Norwegian Institute of Technology, in cooperation with Hydro Aluminium.
The new system is based on a trans-critical vapour compression cycle with carbon dioxide as the refrigerant. Although working pressures and component design are different, the basic principle of the CO2 system is similar to present CFC/HFC units. The new concept offers a complete solution to all environmental problems associated with motorcar air conditioning and eliminates all uncertainty with respect to possible unforeseen environmental effects.
By development and testing of a laboratory prototype, it has been documented that the CO2 system is highly competitive to present CFC-12 and HFC-134a units in terms of performance, cost, weight and dimensions.
Use of CO2 as a refrigerant gives a number of additional economic and practical advantages. Examples are: No need for recycling or recovery, low cost of fluid, excellent availability, well-known properties, and more compact machinery and components.