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The consideration of flammable chemical refrigerant HFC1234yf as “drop-in” replacement for R134a in Mobile Air Conditioning (MAC) has put on the table an option fiercely objected to so far: energy efficient hydrocarbon “drop-in” refrigerant for MAC applications.

Flammability of refrigerants has traditionally been considered an inherent impediment to their use in Mobile Air Conditioning (MAC) applications. The argument of flammability has been used by chemical refrigerant producers to marginalise hydrocarbons that offer an environmentally friendly, more efficient, much cheaper and immediately available alternative to HFCs.

Many consumers around the world opt for hydrocarbons in MACs

At an industry event last month in Torino, Italy, intensive discussion evolved around the question whether hydrocarbon could replace R134a in MACs. According to Nicholas Cox of Earthcare Products, today over 10 million car air conditioners worldwide have been converted from fluorocarbon to hydrocarbon refrigerant, about half of these in North America. Almost all of them have been drop-in conversions usually costing less than €50. Panama, Indonesia, Australia, Korea, Philippines and China also have many systems with drop-in hydrocarbon MAC charges.

Cox maintained that “the great benefit of HFC1234yf is that it requires relatively little fire suppressant to make it non-flammable. With the benefit of hindsight, the producers should have used fluoroketones or fluoroethers as fire suppressants but instead opted for CF3I, trifluoroiodomethane. This is used by the US Air Force as a fire suppressant and high altitude emissions have been found to be ozone depleting, so its use in MAC refrigerants is not permitted. But instead of returning to the laboratory to test other fire suppressants, the producers decided that it would be easier to amend the safety regulations! Thus any benefit to be derived from the use of HFC1234yf rather than the other flammable options is entirely dependant on the creation of a new refrigerant category – A2L.”

The status of hydrocarbon use in MACs had been discussed earlier this year at Atmosphere 2009, with participants of the conference pledging for revisiting the possible safe use of hydrocarbons in MACs. As example served Australia, where hydrocarbons are commonly used as refrigerant in MACs and an estimated 30 to 35 tons of hydrocarbons are provided annually for this application. At least one Australian small-scale vehicle manufacturer uses HyChill refrigerants in their production, while another manufacturer is seriously considering the possibility thanks to the excellent results being achieved by one of its distributors who converts the systems to hydrocarbons prior to delivery. And he is not the only one to do so in Australia: a number of Original Equipment Manufacturer distributors are removing R134a and replacing it with hydrocarbons prior to delivery of new vehicles.

Hydrocarbon refrigerant: the “drop-in” MAC solution of choice

Proponents of the proposed chemical refrigerant HFC1234yf have been heavily promoting its “drop-in” capabilities as an advantage over other solutions. What they have not been promoting is the fact that this capability leaves open the possibility of “reverse engineering” in the service market: given the choice between an expensive service refrigerant - HFC1234yf - and a cheap one - R12, R134a or R152a - an honest MAC service garage will give the customer the choice and the customer will most likely choose the cheapest option. A dishonest garage, on the other hand, will use the cheapest refrigerant but charge the highest price. Given that the highest proportion of leaks are from vehicles that have previously leaked, any of the claimed environmental benefits from HFC1234yf will be lost after the first top up.

Another possibility would be of course to top up the HFC1234yf system with hydrocarbon refrigerant. This would result in replacing an expensive, and flammable “drop-in” refrigerant that has low-GWP but unknown further environmental attributes and is less efficient than R134a, with a cheap and flammable “drop-in” refrigerant that has low-GWP but well-known further environmental attributes and is more energy efficient compared to HFC134a. So why not use hydrocarbons in the first place?