Supporters of R744 in Mobile A/C Systems Express Problems with 1234yf Refrigerant
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Supporters of R744 in Mobile A/C Systems Express Problems with 1234yf Refrigerant

The growing reluctance over 1234yf has now led its own proponents and Original Equipment Manufacturers (OEMs) to dreadfully search for a system solution that would enable the use of the refrigerant, no matter what the system cost and efficiency implications

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Stronghold for 1234yf is crumbling – part I

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An editorial from R744.com  

Concerns over the safety risks pertaining to the use of the latest HFC generation refrigerant has led OEMs and 1234yf proponents to discuss a secondary-loop MAC system — a solution entailing high system costs and low efficiency levels. It now turns out that the additional cost for 1234yf was never realistically evaluated.

In a February press release, the German Environment Agency (UBA) presented test findings by the German Federal Institute for Materials Research and Testing (BAM) confirming the high safety risks incurred by the use of the latest HFC generation refrigerant HFC-1234yf (or HFO-1234yf).

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This was shortly after the US-based Automotive Recyclers Association (ARA) expressed their concern over the safety risks that 1234yf would pose to automotive recycling staff and the general public.

The growing reluctance over 1234yf has now led its own proponents and Original Equipment Manufacturers (OEMs) to dreadfully search for a system solution that would enable the use of the refrigerant, no matter what the system cost and efficiency implications.

Chairman Interior Climate Control Committee (ICCC) of SAE International Ward Atkinson raised the possibility of a secondary-loop system again at the ICCC meeting held during the SAE 2010 World Congress on 13-15 April 2010. In such a system type, the refrigerant circuit is confined to under-hood, so a low-global-warming flammable refrigerant can be used in a protected environment.

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A secondary loop system would mitigate only part of the risk…
Indeed, introducing a secondary loop for the front-end heat exchanger would mitigate to some extent 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 after a front crash accident. Some risk would persist, however, in case of a severe crash accident destroying the refrigerant line near the compressor and exhaust pipe.

… And at what cost?
A condenser side secondary system considered by OEMs will use a more complex condenser, a refrigerant-coolant heat exchanger, an additional coolant-air side heat exchanger required together with a pump for the coolant, a fluid transfer system and an expansion vessel.

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The additional system costs for the secondary condenser-side loop would amount to €100-150, much higher than the additional costs for an R744 MAC of about €20-30 assuming annual production of 1 million units. And that is on top of the cost of the 1234yf refrigerant itself, the price of which is expected to be 10 times the price for R134a.

Costs would even be higher if an OEM decides to limit the risks in the cabin of the vehicle by introducing also an evaporative-side secondary system. Different system configurations undertaken by different OEMs would lead to market division and consumer confusion with regards to safety levels.

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The costs are even higher when one considers system efficiency. Efficiencies of the condenser side secondary system compared to direct R134a expansion system will be significantly reduced hence fuel consumption will be up.

Reduced efficiency of the 1234yf secondary loop MAC system would mean that indirect CO2 emissions would exceed the direct CO2 emissions saved through the use of a low-global warming potential (GWP) refrigerant.

1234yf cost was never realistically evaluated
R744 MAC technology has been sidelined for reasons of cost and efficiency. Now it turns out that, as the additional cost for 1234yf was never realistically evaluated, the opposite is true.

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To read the second installment of this editorial, Stronghold for 1234yf is Crumbling — Part II, click here.

For more on the issue of using R744 in mobile air conditioning systems, visit http://www.r744.com/

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