Air compressor heat exchanger

Augiedoggie

Well-Known Member
#1
I have an ancient Campbell Hausfield 3.5 horsepower electric compressor that was damaged when a friend accidently dropped it down basement stairs. After it's crash landing the electric motor failed and was repowered with a 5 horse Honda motor pirated from a pressure washer with bad pump. Fabricated an adjustable motor base and bored motor belt pulley and replaced air pilot valve and she ran great. But...
Compressor always had way too much moisture in discharge air. Constant frustration when using blast cabinet. Compressor has filter regulator water trap and blast cabinet has filter and water trap and the bastard continues to frustrate me when abrasive blasting for long periods. Figured heat exchanger was the trick, but didn't have a free one available until recently. While working on my old truck I got a bit rough when replacing transmission cooler hoses and bent the aftermarket aluminum transmission cooler. Give the bastard a bit of a tweak and was afraid it could break on the road, so it was replaced. No reason it couldn't be repurposed for aftercooler for my homebrewed gas air compressor and if it breaks there it won't leave me stranded. Fabricated some tubing fittings and fastened trans cooler on belt guard to allow air flow from compressor flywheel. Adapted the entire project from stuff I have hoarded and purchased at yard sales and flea markets and such. Run testing has found the trans cooler is doing exactly as I hoped. Seems air is much more dry and the repuropsed trans cooler is warm on input side and cooler on tank side. We'll see how she goes when I get serious blast cabinet use in humid weather. 20250321_142712.jpg
 

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#2
I am curious as to how this will remove any moisture. If humid air goes through the pump, then into your cooler, doesn't it then go into the tank?
Did it have moisture problems with the electric motor?
 

Augiedoggie

Well-Known Member
#3
There is inherent moisture is in atmosphere. Compressor draws air in and when compressed it creates heat. When heated air contacts cool air tank it quickly shrinks and water droplets form on cool tank surface. Cloud of moisture in air tank gets caught up in air leaving tank. Some residual water remains in tank and cycle repeats constantly. Trans cooler installation works like heat exchanger to cool compressed air a bit before entering tank. Cooler air should create less temperature differential between pumped air and tank surface. Hopefully it works as planned
 
#5
I'm diggin it... if a guy's doesn't hv one layin around perhaps a trip to the u pull it yard, aka "Man Mall" one could be had for cheap I'm thinking anyway.

Plz keep us posted how it turns/ works out
 

Augiedoggie

Well-Known Member
#11
Wowzer! I purchased trans cooler at the AutoZone store nearby and it was $80.00... ouch!!! Either way I had to get it finished. Can't leave truck apart waiting for delivery truck
 
#12
I built a similar setup and found that without a water trap after the cooling radiators the water still went into the main tank but the temp of the air in the tank was much cooler, and it held less moisture. I added an old air trap (to collect the water from the radiators) and never have even the slightest moisture in the air when I paint or when using air tools for extended times.
 

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Augiedoggie

Well-Known Member
#13
Testing results are in today for my transmission cooler/heat exchanger. Today was first time I ran compressor for several hours while abrasive blasting some parts in blast cabinet. Seems my crude heat exchanger worked well. I have two filters with moisture traps inline and after running blast cabinet for several hours without any moisture problems as it normally had. After shutdown I manually opened water drains on cabinet and compressor and had only a shot of water vapor escape. Previous usage without heat exchanger would usually have a healthy 10 or 15 second stream of water drain out. Overall it seems like it was a worthwhile effort
 
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