Improving the AC system's efficiency

[teoman]

It already cycles on and off.

[redpoint5]

I've heard it said before that R12 was a more efficient refrigerant than R134a, but was eliminated due to the ozone depleting CFCs. As far as I was able to research, efficiency is measured as COP (coefficient of performance), and R134a has a higher COP (better).

Anyone know which is more efficient? If R134a is more efficient, why was R12 ever used in the first place?

[Piotrsko]

Because it was cheaper to use and install, used a "normal" lube oil not a synthetic and worked well enough. 134 and its variants were designed after the ozone hole.

[samwichse]

Originally Posted by redpoint5

I've heard it said before that R12 was a more efficient refrigerant than R134a, but was eliminated due to the ozone depleting CFCs. As far as I was able to research, efficiency is measured as COP (coefficient of performance), and R134a has a higher COP (better).

Anyone know which is more efficient? If R134a is more efficient, why was R12 ever used in the first place?

R12 works with simple mineral oil. IIRC R134a requires synthetic POE oil (which can replace mineral oil in R12 systems, too)... so I'd guess it was a problem of first practically usable discovery.

[oil pan 4]

The hole in the ozone is still there and bigger than ever.
It's more than likely always been there.

[teoman]

I have ordered some cheapo misting nozzles. I will install them on the front bumper spraying on the condenser and maybe the compressor head to give the AC system a boost in efficiency.

I have also been logging the intake temperature of my TDI. Usually the intake temperature is a few degrees C higher than ambient temperature. When the AC is switched on, the temp goes up 10-15 degs C above ambient.

Hot air is not good for the diesel either, I am hoping this misting will be able to cool things down without consuming a tonne of water.

Something that resembles this:

https://www.youtube.com/watch?v=NmzLaaFQjiQ

[teoman]

Come to think of it, if it was a gasoline car, making a hot air intake over it would be a good idea.

[teoman]

Video of the results:

https://youtu.be/O0MY0diHo4U

[teoman]

https://newatlas.com/mistbox-air-con...ecooler/38139/

That is a commercial system that increases the efficiency of A/C systems by using evaporative cooling by means of water misting the intake air.


Here is an educated discussion on the matter:
https://hvac-talk.com/vbb/showthread...condenser-unit


The main concearn is rusting the coils and getting mineral deposits.

The key point seems to be having the spray as far away from the condenser as possible.

Shouldn’t automotive systems be more resilient ot road grime and debris gathering on the condenser.

[EcoCivic]

Originally Posted by teoman

https://newatlas.com/mistbox-air-con...ecooler/38139/

That is a commercial system that increases the efficiency of A/C systems by using evaporative cooling by means of water misting the intake air.


Here is an educated discussion on the matter:
https://hvac-talk.com/vbb/showthread...condenser-unit


The main concearn is rusting the coils and getting mineral deposits.

The key point seems to be having the spray as far away from the condenser as possible.

Shouldn’t automotive systems be more resilient ot road grime and debris gathering on the condenser.

I tried a homemade version of that on my car's AC using a pump up sprayer and some hose. I didn't check the pressures or temperatures (I will retest that soon and report back), but the AC did seem to perform a little better when idling in traffic. That is until I ran out of water.

I didn't use it for long enough to damage the condenser, but it might have if I used it for longer. A car's AC condenser is (to the best of my knowledge) no less susceptible to mineral buildup than a house AC unit's condenser. This problem could be eliminated by using distilled water, but that would get expensive if you have to buy the water.

However, you could use the condensate from your home AC system as a source of free distilled water. I installed a mini split in my living room but I have been too lazy to run a drain line, so it's draining into a trash can. I use that water for radiator water, in my water cooled computer, and to wash the car.