HFCs join the fray as CO2 takes a bow at MAC summit
REFRIGERANT producers and car air conditioning suppliers are locked in a contest to come up with a replacement for R134a in car air conditioning systems.

Under the forthcoming European F-Gas regulations R134a is to be banned in all new vehicles by 2011, and in all new cars by 2017. Until now, much of the work on alternatives, which must have GWPs lower than 150, has centred on CO2, but critics say that this would probably require radical changes and the costly redesign of conventional automotive ac systems.

However, at a special Mobile Air Conditioner Summit in Austria in February, leading car ac component suppliers Behr, Obrist, Valeo and Visteon all showed cars using CO2 as the refrigerant.

It is estimated that some 100,000 cars using CO2 air conditioning could be sold in Europe by 2008, rising to two million by 2011.
Attendees at the conference backed CO2 over the flammable HFC R152a that had also been put forward as an alternative.

Pre-empting the conference, both DuPont and Honeywell announced the development of low GWP, HFC refrigerants as possible alternatives.

DuPont is said to be carrying out final tests on a new batch of HFC refrigerants for vehicle air conditioning systems which may eventually find wider use in air conditioning and refrigeration applications. At the same time, rival Honeywell chose the EC-hosted Mobile Air Conditioning Summit to announce the development of a new patented refrigerant.  

Compatible

Both manufacturers say their new refrigerants have a low GWP and are expected to be compatible with conventional R134a automotive ac systems with only minor modifications.

DuPont says that its refrigerants will be available within three to five years, in time to meet the F-gas deadline. They are currently undergoing performance, toxicity and safety testing, and are expected to be non-flammable. According to the chemical companies these newly developed refrigerants are expected to offer similar performance to R134a and would not require a complete system redesign.


Mark Baunchalk, DuPont Refrigerants's global business manager announced himself confident in the progress achieved to date.
'DuPont's new refrigerant compounds may have the potential to be leveraged into more sustainable cooling solutions for other air conditioning and refrigeration applications, and we will be investigating that in the near future,' he revealed.

Encouraging

Richard Preziotti, vice president and general manager for Honeywell's Fluorine Products business, described the results of tests on its new refrigerant as 'encouraging'.

'The testing has shown that our new technology can be used as a direct replacement for HFC-134a with minimal re-engineering of automotive systems. We believe it is a more practical and cost-effective solution than CO2.'

Initial feedback from customers was said to have been positive.
While neither company is disclosing the constituents of the refrigerants as yet, they could be based on a blend of R152a, a refrigerant which, with a GWP of 140, comes in just under the 150 limit of the F-gas regulations. Being flammable, the other constituent(s) are likely to include a suppressant.

An added difficulty with the use of R152a in vehicle air conditioning systems is said to be the comparatively high compressor discharge temperature which lies between the levels of R134a and R22.
Another possibility, which Honeywell has patents on is an azeotropic-like blend of R32 and a fire suppressant called CF31.