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View Full Version : Why are there always 2 refrigerants for air conditioning? Would 1 not work?







coolguy4
25-06-2017, 12:32 AM
This question has been on my mind for years. WHY are certain gases (R12, R134A and recently R1234YF) always used for car AC and another(R22 and R410A) always used for home AC? To me it would seem that the refrigerant that works well in a car AC would work well in a window or central AC unit also, or vise versa. They have the same basic goals: Keep your car or house at about 65-75 degrees while using as little energy as possible and being as environmentally friendly as possible, while still preferably being non flammable, running at reasonable pressures and being non toxic. Is that logic not accurate? I think that the reason the refrigerant for a car AC and home AC is different is so you have to buy and stock more types than really necessary, making the big chemical companies very wealthy. I think that almost all AC systems have WAY more in common than not. Any input is very much appreciated! Thanks!

cadwaladr
25-06-2017, 01:59 AM
Ok I will add input,r22,r12 are now banned substances well over here and soon to be worldwide,so the alternatives for these are for r22 it depends which route the manufacturers do some went down the r410 route some went r407,on car ac r12 they switched to r134a car ac compressors and pipework seals etc cannot use the alternatives for r22,now from 1st January 2017 r1234 had to be used again this gas cannot be used in a 134a system hope that throws some light on the subject.

coolguy4
25-06-2017, 02:28 AM
Ok I will add input,r22,r12 are now banned substances well over here and soon to be worldwide,so the alternatives for these are for r22 it depends which route the manufacturers do some went down the r410 route some went r407,on car ac r12 they switched to r134a car ac compressors and pipework seals etc cannot use the alternatives for r22,now from 1st January 2017 r1234 had to be used again this gas cannot be used in a 134a system hope that throws some light on the subject.

Thank you for the input. I know that CFC's and HCFC's were banned, but what I was really asking is why gas for a car AC would be used in a car, but not for houses and vice versa. Obviously the designs of the systems are different, but since the system is basically designed around the gas, why are car AC systems designed to use R134A and house AC systems, weather a window unit or a central AC system designed for R410A?

Saturatedpsi
25-06-2017, 04:57 AM
I really don't know a lot about MVAC, but can make a few guesses. The higher boiling point refrigerants, like 12 and 134, keep the condensing pressures lower. I read somewhere typical auto system pressures are 30/200 psi. If the system was 22, the pressures would be 60/325 for the same saturated temps.

I doubt efficiency concerns with MVAC are comparable to those for comfort cooling. The lower boiling point gases do more cooling with less refrigerant, so less mass flow is necessary, allowing smaller tubing. I suppose all that adds up to greater efficiency with 22 or 410.

coolguy4
25-06-2017, 03:47 PM
Hmm, interesting argument. Yes, car AC systems run at much lower pressures compared to home AC systems. What do you mean by "I doubt efficiency concerns with MVAC are comparable to those for comfort cooling."? I think that efficiency of a car AC is very important also. The car companies are very concerned about gas mileage, and the longer the compressor runs and the more force it takes to turn it while it is running, the worse the gas mileage will be. Also, why would lower pressures be more important for a car AC than a home AC?

cadwaladr
25-06-2017, 04:24 PM
Not sure where this questioning is going but,car ac driven by the engine is by design not a constant compressor speed whereas fixed ac is,

FaultCode
25-06-2017, 05:02 PM
Also mobile ac had more joint 'O' ring seals so lower pressures are useful.

coolguy4
25-06-2017, 05:25 PM
Also mobile ac had more joint 'O' ring seals so lower pressures are useful.

Good point about auto AC systems using a lot of o rings, but I do not think that is the whole reason for developing a separate gas just for car AC systems. Thanks for the response.

coolguy4
25-06-2017, 05:31 PM
Not sure where this questioning is going but,car ac driven by the engine is by design not a constant compressor speed whereas fixed ac is,

Another great point, another consideration is that the airflow over the condenser varies significantly between driving down the highway at 80 MPH and sitting in traffic, where the only airflow the condenser gets is from the fan. Thank you for the reply.

FaultCode
25-06-2017, 11:05 PM
I think that the usage of R134a came about because of its similarities to R12 which it replaced.

R12 was the first gas used because that was what was used just about everywhere at the start. It wasn't specially developed for cars it was what they had to hand.

coolguy4
26-06-2017, 01:34 AM
I think that the usage of R134a came about because of its similarities to R12 which it replaced.

R12 was the first gas used because that was what was used just about everywhere at the start. It wasn't specially developed for cars it was what they had to hand.

True. Why was R22 developed to use in AC systems then? Is it more efficient than R12?

cadwaladr
26-06-2017, 02:18 AM
This guy's postings are negative,is it me or is this just a history lesson? it's jumping all over the place I like a debate on stuff but hey get this r22 and other old refrigerants have been banned game over,move on rant over!

Saturatedpsi
26-06-2017, 02:37 AM
What do you mean by "I doubt efficiency concerns with MVAC are comparable to those for comfort cooling."? I think that efficiency of a car AC is very important also. The car companies are very concerned about gas mileage, and the longer the compressor runs and the more force it takes to turn it while it is running, the worse the gas mileage will be. Also, why would lower pressures be more important for a car AC than a home AC?

I've yet to see any automobile advertising give any efficiency rating on the air conditioners...if they were overly concerned with compressor run times, they wouldn't build cars with black interiors.

So far as pressures, I'm just guessing they'd rather design around 200 psi, rather than 350 (R-22) or 550 (R-410A).

coolguy4
26-06-2017, 03:23 AM
I've yet to see any automobile advertising give any efficiency rating on the air conditioners...if they were overly concerned with compressor run times, they wouldn't build cars with black interiors.

So far as pressures, I'm just guessing they'd rather design around 200 psi, rather than 350 (R-22) or 550 (R-410A).

I have not seen any car companies give efficiency ratings on the AC system either, but I think it would be very hard to determine the efficiency of an auto AC system because of a lot of factors not present when rating the efficiency of a home AC. For example, engine, and therefore compressor RPM varies significantly while driving, and airflow over the condenser varies greatly with speed. The efficiency of the system on car x may comparatively be very good at idle sitting still but not good on the highway compared to the system in car y. I actually do think that they are concerned with compressor on time because if I remember correctly, feel free to correct me if I am wrong, the highway fuel economy test cycle is performed at 55 MPH WITH THE AC ON MAX. The more time the compressor is on, the worse the gas mileage rating will be. I have no idea why they build cars with black interiors. I guess that is what people want? But on the fuel economy test cycle, they could probably use any interior color they want for the test vehicle anyway, but I could be wrong.

Saturatedpsi
26-06-2017, 05:48 AM
Getting back to your original question: why 2 refrigerants?

FaultCode gave the best answer. Both R-12 and R-22 were invented about the same time, but 12 was the weapon of choice for smaller systems likely due to the lower operating pressures. When it was scheduled for the phase out, the chemists got together and designed an ozone friendly replacement (134A) with similar properties and similar operating pressures. And the new one to replace 134A (1234yf) has similar operating pressures.

R-22 has a greater net refrigerating effect per pound and was initially used in larger commercial/industrial applications, but was eventually adopted for use in the smaller tonnage equipment. And of course, since 22 is also on the phase-out list, something had to be invented to replace it...R410A

So one could say, there's always been one refrigerant for cars, and eventually just one for houses. Had there not been the environmental issues over CFC's/HCFC's, R-12 would likely still be in automobile air conditioners and R-22 would still be king in the rest of the stuff. And agree or not, the mobile AC industry appears to prefer lower operating pressures while the stationary people opt for something more efficient.

All that came from these two links:

R-12 Facts (https://en.wikipedia.org/wiki/Dichlorodifluoromethane)

R-22 Trivia (http://www.achrnews.com/articles/117171-85-years-of-leadership-old-vs-new-r22-vs-r410a)