Ineos Fluor's announcement that it intends to market AC-4, a blend refrigerant, drew criticism from some attendees at the Climate Control sessions at this year's SAE World Congress in Detroit. The critics' overarching refrain was that the marketing had come too late and that AC-4 would now join the ranks of R-1234yf and R-744 in a slow bid to industry-wide adoption. The latter two are the only low-global-warming auto A/C refrigerants that industry is actively considering to replace R-134a, in response to the European Union-mandated phase-out that begins on "new-type" vehicles starting in January 2011.
AC-4 is a three-part blend, with the primary ingredient a hydrofluoro-olefin (HFO), in this case HFO-1243zf. The leading industry choice, R-1234yf, also is an HFO, but it's a single compound, which the automotive industry normally prefers because it provides consistent temperatures at the evaporator inlet and outlet, simplifying system control. Blends often fractionate. That is, they separate into the individual ingredients during A/C operation, making temperature control more difficult and affecting the blend composition as normal leakage occurs over time in automotive A/C systems. However, a particular blend may minimize these issues, and if other characteristics are more favorable than the competition, it could gain acceptance.
With AC-4, Ineos Fluor said that it has "performance equal to or better than R-134a," and the company is still working to better quantify the improvement. R-1234yf is approximately 5% lower in efficiency than R-134a but, with modest system redesign to adjust for its characteristics, has been shown to be equal to R-134a in efficiency and cooling capacity.
AC-4 has a global warming number of "under 150," Ineos Fluor said, which means it meets the 150 limit set by the European regulators. R-744 (carbon dioxide used as a refrigerant) has a number one; R-1234yf is 4. Like R-1234yf, AC-4 is minimally flammable, and Ineos Fluor said the two are close in this regard. However, Ineos Fluor said that AC-4 may have superior materials compatibility than R-1234yf, as well as lubrication miscibility temperatures closer to R-134a, using a commonly specified PAG oil (poly alkylene glycol).
All early toxicity results, particularly the subchronic, have been good, Ineos Fluor announced, and it promised to continue releasing results as longer-term tests are completed. Further, the company said that it would have commercial quantities by 2011 and that the cost could be lower than R-1234yf because fewer reaction steps are needed in the production process. However, an OE engineer who spoke not for attribution said his information indicated the cost might not be significantly lower. And a refrigerant scientist said he foresees many issues that will have to be resolved. One reason that R-1234yf has been accepted is that an industry-wide effort was made to test the refrigerant, and a similar effort for another refrigerant that seems to promise only modest upgrades would be difficult to mount.
AC-4's best opportunity was seen as a refrigerant that could easily be interchanged with R-1234yf at a later date, if its promises for better performance and lower cost pan out. If Ineos Fluor could demonstrate that the refrigerant meets those expectations, it might find market opportunities.