Bob Miller of Train Them Now LLC is an all-around good guy, and a respected colleague (and good friend) of those of us here at CCAR. With all the recent ‘chatter’ surrounding the evolution of automotive air-conditioning systems, we asked Bob to chime in with his 2-cents worth on this matter (thanks Bob!).
The End of R-134a Refrigerant – One Step Closer?
The Environmental Protection Agency has proposed that the use of HFC-134a (R-134a) as a refrigerant in passenger cars and light trucks should come to an end in the year 2021. Additionally, the use of the refrigerant as a propellant in fix-a-flat, automotive aerosol lubricants, and brake cleaners is proposed to stop in 2016. That year, the same proposal would ban its use as the propellant in foam-blowing operations, too.
This ruling was proposed on August 16, 2014 and was prompted by President Obama’s Climate Action Plan, which originated in June 2103, that aims at reducing greenhouse gas emissions. By the way, in November of 2014, President Obama and President Xi of China agreed to begin the phasing out of HFC-based refrigerants, as China is a major producer of the R-134a refrigerant that is used in the U.S.
In addition, the EPA’s Significant New Alternatives Program (SNAP) has received an update. SNAP has been around for several decades and focuses on providing alternative substances to replace ozone-depleting substances (ODS) and greenhouse gas producing (GHG) substances (these are “heat trapping” substances that negatively impact global warming).
R-134a came to us through SNAP as a substitute for R-12 back in the 1990s. Time has moved forward, and now R-134a is seen as unacceptable, because of its potential as a greenhouse gas agent. R-134a is not an ozone-depleting substance, but it does have a high Global Warming Potential (GWP) number (1430). This number is a measure of the global warming potential of a substance, and mostly is used for comparisons. In other words, it is a measure of the degree to which the substance produces “greenhouse effect” in our atmosphere, which contributes to global warming. The measure hinges on the GWP of carbon dioxide (CO2), which has a GWP of 1, as it has no measurable effect on global warming. By the way, R-12’s GWP is a whopping 10.900!
We now see three (3) alternative refrigerants have been added to the SNAP list:
The first is R-1234yf, which currently seems to be most favored by vehicle manufacturers. About a dozen new vehicles currently sold in the U.S. use R-1234yf. According to an Automotive News article (December 30, 2013), about 500,000 vehicles using R-1234yf will have passed through new car showrooms in the U.S. by the end of this year. Peter Coll, from Neutronics, Inc. (the refrigerant identifier people) predicts that 80% of the vehicles sold in the U.S. by the end of 2016 will use this new refrigerant. With a GWP number of 4, it is a lot less damaging to the atmosphere. However, cost is likely to become a factor. Peter Coll tells me that Chrysler dealerships are charging $155 for a pound of R-1234yf, and that a ten gallon cylinder is projected to go for around $1000.
Mercedes is the champion of the second new refrigerant, carbon dioxide (CO2). It is true that R-1234yf is flammable, and therefore Mercedes has opted for R-744 (CO2) for the future, even though the Society of Automotive Engineers (SAE) conducted extensive tests on the flammability of R-1234yf and stated that:
“a person was 20,000 times more likely to die in a plane crash than be exposed to a vehicle fire caused by a leak and ignition of R-1234yf . . .” Unquestionably, CO2‘s global warming potential is virtually non-existent. However, system operating pressures will be substantially higher than what we are accustomed to, and will be a consideration. Time will tell how this will be addressed, as the horsepower loss to turn the compressor becomes a concern (think fuel economy), and we just might see an electric-motor driven compressor as a result, just as we see now in many Hybrid vehicles. Also, CO2 is an asphyxiant (it impairs normal breathing by reducing the oxygen available in the air = may kill you), so it will be interesting how that aspect will be addressed. By the way, Jacques Gordon, from the Mobile Air Conditioning Society (MACS) tells us that Volkswagen also has committed to R-744 for the future, and it is rumored by the Green Car Congress that BMW will follow suit.
The third alternative added to the SNAP list is R-152a (with a GWP number of 124). To my knowledge, no vehicle manufacturer has given serious consideration to it, as it is definitely flammable. Two system variations are being considered:
The first is a somewhat conventional direct expansion system, similar to what we are accustomed to, but equipped with a trio of solenoid-controlled valves. Two are normally-closed, and (with no power) will isolate the evaporator in the passenger compartment from the rest of the system. They will perhaps be controlled by the crash sensors that trigger the air bags. In a collision, the power to these two solenoid controlled valves will be shut off, which closes the valves, thus preventing further flammable refrigerant from reaching the passenger compartment. The third proposed solenoid-controlled valve would then vent the refrigerant remaining in the system. Where to, you ask? Perhaps to the atmosphere?
The second system design is a secondary loop system. Here, the R-152a refrigerant passes through a heat exchanger located in the engine compartment (called a chiller), where it pulls the heat off the secondary loop, which is filled with a safe medium, perhaps good old antifreeze. So the R-152a stays in the engine compartment, and the “safe medium” circulates in the passenger compartment.
By the way, both of these system variations may also be the answer to the asphyxiant characteristic of CO2.
An incentive to switch to one of the new refrigerants is offered to vehicle manufacturers by the EPA. Corporate Average Fuel Economy (CAFE) “credits” are offered to vehicle manufacturers that switch to, say, R-1234yf, and build a system that is tested to be leak-proof. These credits will help the vehicle manufacturer meet new, very stringent greenhouse gas and fuel economy standards that are “down the road” . . . By 2025, it is expected that Corporate Average Fuel Economy will have risen to a required fleet average of 54.5 miles per gallon. So, you see, a vehicle manufacturer that offers a vehicle line (of muscle cars and SUVs) with large displacement, hemi engines would see this as an advantage. Currently, six of the eleven vehicles sold in the U.S. with R-1234yf refrigerant, are from Chrysler Corporation.
You know, I remember someone once telling me that the brake systems on cars and light trucks had become stagnant (you see, I’m a ‘vintage’ guy with roots in fixing the cars of the 60s and 70s for a living). Then, downsizing hit when the price of gasoline skyrocketed overnight to a whopping seventy cents a gallon, and brake systems were no longer stagnant. Well, I think mobile air conditioning systems soon will “no longer be stagnant”, either . . . They are definitely on the move!
Train Them Now, LLC