Charge air cooling with freon

8

88fiero

Member
I brought this topic up in another thread but to avoid getting the other thread more off topic, I'm starting a new thread.

Air-to-air and air-to-liquid intercooloers have been used for many years on superchargers and turbos. These make a lot of sense when running lots of boost. However in either case the charge air temp cannot ever be below ambient unless you use an ice chest like some drag racers do. With less than 10 psi of boost and 90 'F ambient where I live the reduction in charge air temp makes an intercooler hard to justify. However there are a few companies that are now selling kits where the coolant for a air-to-liquid intercooler is chilled by using freon from the car's A/C system. Here are a couple


killerchiller.com

Kincaid Performance Inc.

Run ice cold intercooler temps with our Killer Chiller heat exchanger designed to piggyback the vehicle's AC system.
killerchiller.com killerchiller.com

But the heat exchanger for the intake air on a air-to-liquid system is not that expensive:

Water to Air Intercoolers

We have a wide selection of water to air intercoolers.
www.frozenboost.com

And a plate exchanger to cool the liquid coolant with freon is not that expensive:

www.ebay.com

20-Plate 4-1/4" x 12" Brazed Plate Heat Exchanger, 1" MPT Ports, 316L St. Steel | eBay

Inlet/Outlet sizes: 1" Male NPT (MPT) threaded, U.S. standard threads. Plate & Outlets Material: AISI 316L Stainless Steel. Plumbing Systems. Brazing Material: 99.9% pure copper. Radiant Floor Heating.
www.ebay.com

And a pump to circulate the coolant is not that expensive

www.ebay.com

OSIAS Electric Intercooler Water Pump 317GPH 12V Air 0392022002 for Range Rover | eBay

22718756, 15076931, 125-9020, 0392022002, 0 392 022 002. 2012-2013 for Range Rover Autobiography Auxiliary Water Pump (Electric). 2013 for Range Rover Base Auxiliary Water Pump (Electric). 2010-2013 for Range Rover HSE Auxiliary Water Pump (Electric).
www.ebay.com

Then just need an expansion valve, a small expansion tank (say 2 gallons and a solenoid valve, hoses and fittings
 
OK, thanks for starting a new thread, we hijacked Alec's! LOL Yep, I am in Houston, so pretty much the same situation. It sounded to me like the Killerchiller was a direct freon to air intercooler but looking at it again the site calls it an add on for turbos already running water/air intercoolers. Not real sure why you couldn't make a direct freon to air intercooler as there are billions of air/freon heat exchangers in service, but I haven't seen any freon/air intercoolers. Maybe the Dakar or one of the other applications that was mentioned was direct freon to air. I will do some more research.
 
My target car is a 2.8L V-6 that doesn't have great volumetric efficiency at high rpm. With 10 psi of boost and 60 'F intake temperature it will flow a maximum 1400 lbs/hr of air. If the supercharger outlet is 200 'F then the delta T for the intercooler is 140 'F. The heat capacity of air is about 0.25 btus/lb-'F. So the intercooler duty is:

1400 * 140 * 0.25 = 49,000 btu/hr

There are 12,000 btu/hr per ton of refrigeration capacity so 49,000/12,000 = 4.1 tons. That's a lot. I don't know what the typical car system is but I'm thinking more like 1 ton. Plus you don't want the A/C compressor to run at WOT. That why it makes sense to pre-chill a quantity of water and then only use it during WOT runs - sorta like a battery.

49,000 btu/hr = 204 btu's in 15 seconds

Water has a heat capacity of 1 btu/lb-'F. Water weighs 8.34 lbs/gal

So if we started with 2 gallons of water at 30 'F then the temperature rise in 15 seconds is:

204 / 1 / 8.34 /2 = 12 degrees. Then if the A/C system is 1 ton of capacity the time to recover is 204 btu's / 12,000 btu/hr = 0.017 hours or 1 minute. Of course that assumes that the freon to coolant heat exchanger has enough surface area.
 
I see why they are using cold water as a freon buffer for intercoolers. I ran through the quick calcs for freon only and the main problem that I ran up against is accommodation space for the freon vapor.

On a quick look, I can buy close to a 2 ton electric variable speed AC compressor that weighs about 14 pounds, but it requires 24V. To go to any bigger electric AC compressor requires equipment to step up the voltage even more. Due to the power required, running two compressors would be a big amperage pull. So, assuming one compressor, to get to the ~ 200 BTU needed for 15 seconds at 10 PSI boost, requires only 2.4 pounds of R-134a liquid, but results in almost 17 gallons of R-134a vapor. Assuming I can compress 1/2 of that it still leaves over 8 gallons of vapor. Assuming the intercooler temp goes up 15 degrees F and thus pressure goes up about 10 psi, that knocks the vapor volume down about another 25%, but still leaves me with ~ 6.3 gallons of vapor storage needed above the vapor already in the suction system. I didn't account for any space in the vapor AC lines or the thermal mass of the intercooler, which will help some, but not a lot. I assumed 35 degree starting intercooler temp just to avoid any water vapor freezing.

So, it looks like it would take a quite large, high-pressure tank on the vapor (suction) side to operate using freon only - not very practical! Makes a lot more sense to have a small, chilled water tank to store cooling capacity for the short-term power boosts. One possibly practical alternative is if someone can come up with a higher voltage battery supply and charging system that can keep up with a 4 ton electric AC compressor and has reasonable size/cost. You already knew this, but I wanted to work through it myself. Thanks again for sharing your insight!
 
Bumping for interest!
I'm an HVAC/Refrigeration Owner and have seen lots of different Refrigeration setups.
With any System design, there is the Total Capacity (BTU's per hour), but then there is also the design choice of Delta T vs. Airflow in CFM when taking the Total capacity into account.

Here are the different useful formulas for looking into this: (We can probably ignore Humidity and Latent Heat removal for simplicity)
maxresdefault.jpg
 
What is going to power the compressor? The power it takes to reduce the charge temps, is always going to be more than what you will gain from lower charge air temps.
I'm not saying it won't work. It would be better suited to cool an engine down after a pull. Or an aftercooler or pre cooler for a liquid to air intercooler
 
there's a kit to do this on factory supercharged cars.. it adds some valves to the ac system and cools the intercooler. they say it works very well, but it's probably better suited to a air to water setup where you cool the water in the tank with the ac system when not in boost and then it turns off at wot.


killerchiller.com

Kincaid Performance Inc.

Run ice cold intercooler temps with our Killer Chiller heat exchanger designed to piggyback the vehicle's AC system.
killerchiller.com killerchiller.com
 
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