Cold Traps, Ice, Salt, Dry Ice, Etc...

[MtnDawg]

As I was sitting around waiting for parts to arrive, after having vapor distilled a bunch of really dirty cans of Power 5X butane, I got to thinking. I live in a rural area, which makes the task of getting large amounts of ice or dry ice a time consuming task. It was also apparent that a salt/ice bath required constant maintenance, not to mention the mess, and dry ice and alcohol have a limited shelf life. I needed a reusable cold bath that didn't require a trip to the store.

I had an old window style air conditioner that I had stopped using a couple of years ago, and a collection of plastic coolers sitting around. It occurred to me that I might be able to repurpose the air conditioner and a cooler to create a cold bath that I could fire up at will.

I used a mix of about 75% ethylene glycol and 25% distilled water in the cooler, and dropped the evaporator side of the AC unit into the solution. Using a paint mixer attachment on my drill I periodically agitated the solution to draw it through the fins of the evaporator. Using this method Allowed me to chill the antifreeze solution down to about -10F in about 45 minutes. That's considerably colder than an ice bath, and way less hassle than alcohol and dry ice. A 30# recovery tank drops into the cooler perfectly.

The only change I plan to make is to swap ethylene glycol out with propylene glycol. Ethylene glycol is toxic, propylene glycol is much safer. I have a herd of dogs that I have to watch out for.

It looks like a dang ol' redneck refrigerator, but it works great so far.

 

[Muckman420]

I'd do it

 

[Graywolf]

Hee, hee, hee, good job repurposing! Thanks for sharing!

I believe in the engineering 101 principle, that anything that works, isn't stupid.

What kind of cooler and what size window shaker?"

Pictures?

 

[MtnDawg]

Ah yes, details.

The window AC unit was a "Hampton Bay" 10,000 BTU model. It's made by LG. It was fairly easy to disassemble. I had to remove the thermostat from its location on the evaporator and fake it out to get the compressor to come on, and I disco'd the AC fan motor from the controller head. That's about it.

The cooler is a "Rubbermaid" model. The only specific feature of this cooler is that it has a split top, so the side with the evaporator stays covered and protected. Anything of similar size would work.

Here are some pictures of "Frankenfridge:"

 

[MtnDawg]

I'm also using an indoor/outdoor thermometer with the outdoor sensor immersed in the coolant. You can see the temp of the coolant is around 16F in the photo. It had been sitting for about 14 hours after having been down to -10F the night before.

I also had to cut a notch in the wall of the cooler as a pass through for the evaporator tubing. The condenser is cooled with a house fan. I'm thinking of putting the compressor and condenser in an enclosure with a fan, and palletizing the whole thing so I can move it with a pallet jack.

 

[MtnDawg]

I let it run for a few hours. I was curious if the coolant would freeze before the evaporator reached an equilibrium. I think this is as cold as it's gonna go.

That's -28.8F, without a tank dunked in it. Putting the recovery tank into the cooler displaces enough coolant to cover the entire evaporator which could drop the temp even further. We'll see.

 

[aSilvrHaze]

How'd this turn out for you?