Modifying Air Cooled Condensers

[mytekcontrols]

Hi Guys,

I have an upcoming AutoC project that will require a very small air cooled condenser. So I have several condensers that were originally evaporators in window AC units, and I was thinking maybe I could just cut one of these down to size (see below).

https://lh4.googleusercontent.com/-MYFkP5aj8P8/UtBZ9hStegI/AAAAAAAAAys/NmAb90-o5d0/s800/modify_condenser.jpg

The RED outline shows approximately the area I wish to use. So my main question, is how best to cut the aluminum fin material without it looking like total ghetto when I'm done?

Anybody try to do this before :shrug:

[n00b 0f l337]

A couple have. Two ways to do it.
1) Cut well past where you want, then pull back fins until your where you want
2) VERY SLOWLY with a hand saw.

Or... Get one of the right size.

And what size do you need Mytek? And do you need it at that fin density?

[Moc]

Yeah I tried it back in 2009: http://www.extremecooling.de/forum/threads/1982-Verfl%C3%BCssigerverkleinerung Here you can see how it looked before: http://www.extremecooling.de/forum/attachment.php?attachmentid=7363&stc=1&d=1266344849 .I think I used a band saw or a grinder... not sure. But I just cutted the thing once, parallel to the fins....
It is a lot of work and the results will look :banana::banana::banana::banana:. Better try harder to find a proper condensor. You could ask Ron, maybe he has an old Mach/Vapochill condenser flying around. They are pretty small.

[mytekcontrols]

Yeah I tried it back in 2009: http://www.extremecooling.de/forum/threads/1982-Verfl%C3%BCssigerverkleinerung Here you can see how it looked before: http://www.extremecooling.de/forum/attachment.php?attachmentid=7363&stc=1&d=1266344849 .I think I used a band saw or a grinder... not sure. But I just cutted the thing once, parallel to the fins....
It is a lot of work and the results will look :banana::banana::banana::banana:. Better try harder to find a proper condensor. You could ask Ron, maybe he has an old Mach/Vapochill condenser flying around. They are pretty small.

Actually that doesn't look bad. But perhaps you are right, it probably would be easier to find the correct condenser to begin with.

Adam to answer your question; I am looking for something that is 5" square having 1/4" tubing in two rows being about 1" thick. It needs to deal with about 150-175 watts of heat.

[n00b 0f l337]

Let me see what I have.
I might have something exactly what your looking for, but a little light on fin density....

[mytekcontrols]

Let me see what I have.
I might have something exactly what your looking for, but a little light on fin density....

Fin density probably shouldn't be a problem, actually easier to keep clean if it has some space (somewhat self cleaning). If you do have something, I would very much appreciate it, and perhaps we could trade something in the process.

[n00b 0f l337]

Not a problem mate, just send me your address and I'll let you know when it's on the way.

[mytekcontrols]

Not a problem mate, just send me your address and I'll let you know when it's on the way.
PM sent -- Thanks :)

[mytekcontrols]

Well I decided to go ahead and try my luck at customizing the window AC evaporator, thus making it into a small air condenser. So the first thing I needed to do was chop it up.

http://i.imgur.com/SpGtXpE.jpg

And then pull off the extra fin material on the cut end to expose the tubes for brazing.

http://i.imgur.com/isoxahF.jpg

Cleaned up and ready to braze in copper loops.

http://i.imgur.com/wVqELsO.jpg

Brazing completed.

http://i.imgur.com/n9NkYxk.jpg

Size comparison to fan.

http://i.imgur.com/IQygmv7.jpg

And now it's ready to use in my project :)

[Patrickclouds]

beautiful condenser

well done ;)

[Buckeye]

WOW that came out very nice ! :)

[Moc]

Wow! Great work indeed!

[mytekcontrols]

Thank you guys :)

Actually the hardest part was making the return loops. Tried several methods before I found one that would let me make such tight bends in 1/4" od copper tubing (bend radius was too small for any bender I had access to). The best results were obtained using the 'fill it with salt' method.

For the form, I found that one of my swaging tools had a radius of the perfect size. Still got a slight kink on the inside of the bend, but nothing that was big enough to worry about.

Luckily two of the original return bends were usable, so I only had to make 3 new ones.

The Zip Cutter as I call it, did a great job of cutting through the aluminum fin material and the copper tubing. I picked it up from a place called Harbor Freight for about $15 new.

[n00b 0f l337]

Very nicely done, I would recommend next time cutting and drilling some 16ga steel sheet to fit over the exposed new ends.
Still need that condenser though? I've been swamped and hadn't shipped it yet.

[NKrader]

came out way better than i was expecting! good job

[mytekcontrols]

Very nicely done, I would recommend next time cutting and drilling some 16ga steel sheet to fit over the exposed new ends.
Thanks for the tip, and it's good advice, but it'll not be required on this one since I am just running tests to determine size requirements for my application.


Still need that condenser though? I've been swamped and hadn't shipped it yet.
If you don't need it, and you don't mind shipping it, yes it might come in handy for what I am trying to do.

[mytekcontrols]

I thought you guys might like to see the HX Stack that the small condenser is being used with (there are 3 nested coils).

http://i.imgur.com/lHX9th0.jpg

The compressor will be shipped to me the end of this month, and is a 1.9 cc/rev Aspen 24 VDC Rotary.

I would imagine that this will probably be the smallest -140 C AutoC ever built.

[n00b 0f l337]

I love it. It's so cute.

[Buckeye]

Very nice work. You do a great job on those coils :)

[n00b 0f l337]

Will it be possible to get adequate insulation with so little layer space? Also, one phase sep post outer coil?

[mytekcontrols]

Will it be possible to get adequate insulation with so little layer space? Also, one phase sep post outer coil?
The foam I use is good for 125 degrees C delta T with only 3/4" thickness. My coils are spaced about 1/2" apart, with the warmest on the outside and the coldest on the inside, seeing only a delta T of perhaps 75 or less per stage. So all things cnsidered it should be ok.

Not exactly sure what your last question meant, but if you reference the last CryoBUG pipimg diagrams, this is nearly identical in design with only one phase sep.

BTW; that is the final cap tube strainer at the top (using miniature strainer), and the evap retun line next to it. Currently there is no final cap tube attached.

[n00b 0f l337]

Very cool. Just got confused there for a moment.
Coil is shipped to you, just had to have my brother visit the workshop and dig one up.

[mytekcontrols]

Very cool. Just got confused there for a moment.
Coil is shipped to you, just had to have my brother visit the workshop and dig one up.
Thank you, I hope that didn't cause you too much trouble :)

Edit: the condenser arrived today, and it looks like a good alternative to what I custom made. Thanks a bunch Adam :up: