Intense competition for the next-generation MAC refrigerant

Less than 3 years before the January 1, 2011 deadline for using fluorinated gases (F-gases) with a GWP higher than 150 in the new models of cars according to the European Directive 2006/40 on emissions from mobile air-conditioning (MAC) systems, there is intense competition regarding the alternative refrigerant which will replace R-134a (GWP: 1300). - R-152a (HFC) has a relatively low GWP (140) but is flammable and thus must be equipped with an isolating secondary loop so that passengers are never endangered, meaning added expense and weight. - CO2 (R-744) has a GWP of 1, which is negligible but poses engineering challenges due in particular to the high pressures required to operate it; however, several automotive suppliers are developing CO2-based MAC systems and are currently running fleet tests. These suppliers include Nippon Denso in Japan, Ixetic GmbH and Behr in Germany, Valeo in France, and Delphi and Visteon in the US. CO2 has been chosen as the next-generation refrigerant in MAC systems by the German Association of the Automotive Industry (VDA) in Summer 2007 (see Newsletter No. 32) and Ixetic announced in December 2007 that it is "producing the world's first CO2 compressor for air conditioners in serial form" following a "series order received from a renowned car manufacturer". - In parallel, chemical companies such as Honeywell, DuPont and Ineos-Fluor have rushed to develop new alternative refrigerants; 3 blends, named Fluid H, DP-1 and AC-1 achieved varying degrees of success when Fluid H was dropped over flammability and Ozone Depletion Potential (ODP) while the 2 other failed to meet toxicity criteria. Honeywell and DuPont recently teamed up to develop a new candidate, HFO-1234yf, and initial test results were presented during VDA's Winter Meeting in February 2008. According to these companies, HFO-1234yf (CF3CF=CH2) has a very low GWP of 4, 0 ODP, low toxicity and system performance very similar to that of R-134a, and mild flammability (significantly better than R-152a, with potential to use it in a direct-expansion system); the goal is "to match R-134a as closely as possible to minimize the transition costs for the equipment manufacturers". The next steps for this new blend will be to complete property testing (in particular on toxicity and flammability) and to obtain EPA SNAP approval.