The carmaker has caused consternation by saying HFO 1234yf is not safe in some conditions. Andrew Gaved reports
The development of HFO 1234yf as a replacement for R134a in car air conditioning has been dealt a serious blow by carmaker Daimler questioning flammability claims for the gas.
The car manufacturer has requested that its Mercedes range be allowed to continue using R134a following tests that it says cast doubt on the HFO’s safety near hot exhaust components.
Daimler said it constructed its own test to reproduce the effect of a head-on collision, dynamically dispersing refrigerant to mimic a ruptured refrigerant line in the presence of a hot exhaust system. The results found R1234yf was flammable under such conditions, whereas R134a was not.
As a result the carmaker flatly announced it would not be using the refrigerant.
Honeywell, co-producer of HFO 1234yf, has strenuously defended the refrigerant’s safety and last month dispatched technical specialists to the US in a bid to alleviate the carmakers’ concerns. European chief Paul Sanders said: “We are very, very convinced that the product is safe and that the industry will accept it as the solution.”
But naturally there is now concern that the nervousness will spread to the automotive community. Following the Daimler announcement, automotive engineering organisation SAE International has called carmakers together to discuss the ongoing issues and investigate forming a co-operative research programme to evaluate the new findings. The carmaker is regarded as a global technology leader so any doubts it has are taken seriously by the sector.
At Chillventa, Honeywell expressed surprise and frustration as it had reason to believe all the safety arguments had been won.
Mr Sanders said: “The refrigerant has been passed as safe by [German engineering federation] the VDMA, at a meeting where all the suppliers and second tier suppliers and Daimler were present. It is frankly unacceptable at this late stage.”
DuPont, the other co-producer of 1234yf, has also gone to extraordinary lengths to reassure the automotive industry, and after meeting Daimler itself has concluded the test “is not new information”.
HFO 1234yf is not the only feasible HFO solution and the Daimler incident has also given the opportunity to rival refrigerant manufacturers to step up their negotiations with carmakers.
But refrigerant sources were clear that the Daimler decision would have serious consequences.
“The EC has let the carmakers effectively have an extra year to meet the Directive already,” said one source. “They would surely see any further extension as weakening the authority of their original ruling. But something has to give. You could add R134a to R1234yf to address its flammability, but then that would send the GWP higher than is currently allowed for in the MAC Directive. So if Daimler’s tests hold good, the EC would either have to move on GWP or they would have to endorse another refrigerant.”
Another source agreed, saying: “Unless and until Daimler is reassured, everything is up for grabs.”
This is a crucial time for HFO development, since while the Daimler questions are leading to caution over HFO 1234yf, HFOs for stationary refrigeration are equally waiting on a statement of intent, this time from the EC. Many in the industry believe the ‘accelerator pedal’ will not be pressed on HFOs until the EC reports on its expectations for HFC phase-down in the F-Gas Review. If there is a demand for a rapid phase-down of HFCs, the infrastructure for HFO will be stepped up accordingly,
But at the moment there is clearly caution among those gearing up to work with the new generation refrigerants.
Bitzer chief technology officer Rainer Groβe-Kracht told RAC that while Bitzer was currently testing compressors with HFO, it was important to be measured in development. He said: “The industry can ramp up too fast and inadvertently destroy a refrigerant’s reputation if the end-users reject it.”
He added there was still work to do on how the refrigeration systems behave with the new gas. “It is not so much an issue for compressors as HFO blends are behaving much like R134a, and even increasing refrigeration capacity, but the question is the system, the oils and the additives and we don’t have much experience there yet. And if HFOs have such a short atmospheric life, how are they going to behave over time in the system? We don’t know yet.”
Emerson Climate Technologies European president Jean Janssen confirmed the sense of caution. He said: “We want to reduce GWP, but it has to be done in a way that the end-user can pay for it.”