Homemade refrigerated compressed air dryer

[Don'tTryThisAtHome]

I live in Houston and the relative humidity hovers around 80% most of the time. I needed a solution for removing excess moisture from my compressed air for painting. Looking at my compressor, my thoughts drifted to the deep freezer located right next to it.

Went out to the local Home Depot, picked up 50' of 3/8" OD copper refrigeration coil and tube bending tools. I couldn't find any flared fittings and almost bought copper connectors to solder in, but I reluctantly went to another hardware store to purchase the flared fittings. That's how the copper tubing is connected to the brass adapters.

Almost didn't add a drip leg, it does catch a lot of water and ice. Measured inlet temperature to the coil at around 110 degrees, outlet was at 40 degrees, even after letting compressor run constantly for 20 minutes. Pressure drop through the coil wasn't excess for painting, it's the only time I will be using the coil. Freezing will be a real issue if air isn't constantly moving through the coil, I'll most likely remove it from the freezer and let defrost every now and then.

 

[IndyGarage]

Interesting idea.


Would it be possible to convert a small dorm refrigerator to be dedicated for this use, so you don't have to put it in and out of the freezer? Not sure if they can be made cold enough - but I bet they would freeze if you could tamper with the thermostat a bit.

They only cost about $75 new and I see them at the curb every once in awhile for the garbage man, I bet many of those still work.

 

[bonneyman]

Love the ingenuity!

I wonder if a discarded low-temp reach in freezer would work, or maybe even a motor home's 12 volt reefer unit? With the OP's obvious skills I'm sure there are many possibilities.

 

[Don'tTryThisAtHome]

I think soldering or installing a heat bridge between the inlet and discharge tubes close to the connectors will help to cool inlet air, and warm up/defrost the discharge air.

 

[Arne73]

My Atlas Copco dryer at work runs 34-37f. A dorm fridge might go down that low, don't know if it would keep up on the temp.
Great idea!

 

[Don'tTryThisAtHome]

I believe you're correct about using a small dorm fridge, a lot of heat is being pump into the freezer. I partially melted my ice cream that sat too close to the coils while testing discharge temperatures for an extended period. This shouldn't be a problem when in use for painting.