Mobile Air Conditioning: Hydrocarbons vs. HFC1234yf
22 December 2009
Automotive Recyclers Association: safety of HFO remains a concern
09 February 2010
Costs too high with unknown prospects
As the SAE confirms, long-standing objections have focused on the anticipated initial cost which the US Environmental Protection Agency (EPA) estimates to be $45-50 lb for Original Equipment (OE) supplies. This is at least 15 times the refrigerant price for currently used refrigerant in car air-conditioners, R134.
The manufacturing of the refrigerant will require new plants, rather than conversion of existing facilities. Until these are put in place, the industry faces the problem of gaining acceptance for the refrigerant until production efficiencies and competition lower the cost closer to that of R134a. But can refrigerant producers invest in new facilities if the refrigerant is not accepted? - a chicken-egg question. Chemical companies starting full-scale R1234yf production would be gambling, while there is the possibility that chemical companies withhold full-scale production to maintain high refrigerant prices.
As a matter of fact, no chemical company has built a new plant yet. Companies seemingly believe the market will be small, as plant construction reportedly takes about two years. The limited supply requirements apparently will be met from small "pilot plants," further exacerbating the cost issue.
Unsolved HFO Patent Issue
According to SAE, at least one leading refrigerant supplier, Arkema, is unwilling to committing to HFC-1234yf until all patent issues are resolved, and at least three patents covering the refrigerant are known.
A servicing structure without structure, OR: How to undermine an EU Directive
Studies discussed at the SAE meeting indicate that the 1234yf systems could also be run with R134a at similar performance levels, while work is being undertaken on using the same PAG oil with both refrigerants. With R134a being much cheaper that 1234yf, this raises the issue of using R134a when servicing 1234yf systems, a practice that would be legal in the US, as it is legal to service systems with any refrigerant on the EPA's SNAP (significant new alternatives policy) list, including R134a. In Europe, retrofitting with R134a, although illegal under the MAC Directive, could still be a possibility in the servicing industry.
And what does that mean for car dealers? Car dealers both in the US and the EU will be required to buy specific equipment for the new refrigerant. After the warranty period, fierce competition from independent shops will arise as they will start servicing 1234yf systems with cheap R134a, hence defeating the purpose of the EU MAC Directive banning the damaging refrigerant as from 2011 on. Special fittings to avoid a re-fill with R134a will not be a solution as adapters “quickly find their way into the service shops”.
A secondary loop system the way forward?
Even ICCC Chairman Ward Atkinson of Sun Test Engineering is starting to have doubts regarding HFO. To the degree that a once clear-cut future of 1234yf is under threat a well-hidden idea comes to the surface again: the use of a secondary-loop system. In that, the refrigerant circuit is confined to under-hood, so a low-global-warming flammable refrigerant such as propane can be used in a protected environment.
Introducing a secondary loop for the front-end heat exchanger would be indeed necessary to mitigate the safety risks associated with HFC-1234yf, such as the development of highly toxic hydrogen fluoride (HF) in the case where the flammable refrigerant burns.
A condenser side secondary system will use a more complex condenser ; a refrigerant-coolant heat exchanger, an additional coolant-air side heat exchanger is required together with a pump for the coolant, a fluid transfer system and an expansion vessel. Efficiencies compared to direct R134a expansion system will be significantly reduced hence fuel consumption will be up.
Hydrocarbons a superior choice in primary or secondary systems
The application of a condenser side secondary loop system would overcome any outstanding safety concerns (flammability) concerning hydrocarbon refrigerants in car air-conditioners in case of a frontal crash. A hydrocarbon secondary loop system would still represent a net savings of at least 80% of equivalent greenhouse gas emissions associated with current R134a systems. Moreover, propane, the best hydrocarbon choice for secondary loop systems, is widely available.
Following the debate some might now conclude that hydrocarbons are more environmentally-friendly, more efficient, much cheaper, immediately available and already widely used in MACs in Australia and the US in primary MAC systems. If the car industry opts for a flammable refrigerant, hydrocarbons that do not entail toxicity risks and price uncertainty are a superior choice to R1234yf.