project: DIY phasechange unit

[omega]

hey guys,

been notified of these neck of the woods by marci (on www.over-clock.com forums) a couple of months ago in an unrelated thread, but i think it's time i registered, and called upon your knowledge.

i`m in the first stages of a DIY phasechange project, and not having used phasechange cooling before i`m a n00b to stuff.

currently have the following kit:
danfoss SC21F compressor (495w)
Aspena T6215Z compressor (790w)
and a tiddly little danfoss rated at 73w.

to come:
condensor
mach 1 head
driers
tubing and valves/connectors etc

in the process of getting some valves so i can connect our aircon machine (r134a) at work upto it and gas it up FOC. 507 MIGHT be done later on.

i must stress this project is just for fun, and mainly for hands on rather than using it as a cooling method for my main rig. performance isnt essential, but 1/2 the reason i`m doing the project. main reason is for hands on and just for the hell of it - hence mach1 head, and not a baker/chilly evap head

1 main question i`m stuck on, and the other is a recommendation:
1 - capilary tube length. this is the main thing i`m stuck on. how do i know (roughly) what length i need as a starting point. i read the length has something todo with gas quantity,gas type, compressor size, condensor performance etc etc so i dont expect a specific figure.
there must be some way of guesstimating the length needed?

as for the recommendation, what should i be looking for in condensor terms?
cooling 790w is not to be taken lightly, so i`ll need a condensor to cool it. question is, how big do i need? size isnt too much of an issue, but obviously an 8foot condensor is a touch OTT.

would a 790w compressor do more damage than good?
i just though that using a 227w pelt on a GPU and you suffer from unwanted freezing and damages the card? would a 790w compressor be a similar situation, and the danfoss 495w be more realistic?

[bigben2k]

You want http://xtremeresources.com/ , home of Bowman1964, among notorious other phase change experts.

[omega]

ok, thanks

[redleader]

Or http://www.xtremesystems.org

They're based on the same database as resources (at least I think, my account seems to work on both and I registered at only one), but are 10x as active when it comes to phasechange.

[crane]

I put together my ghetto phase change direct die system using a condensor from a bottled water dispenser...it was about 14" wide x 3' long,so I just started folding the thing up. I had to cut the little grid or cross pieces to make it compact down,but it ended up being 14" x 6". Folded rather nicely considering its steel 3/16" tube.
I hooked up a bigger condensor ,one with 3/8 tube and I didn't like it...i beleive the bigger coil had problems with trapping liquid and oil. The small ID condensor allows everything to be pushed through even though it makes 30 turns from inlet to outlet.
As far as cap tube goes....its not that critical for what i did,my project was more of a self-satisfaction thing. I used any where from 6' to 9' and even went as far as cutting and splicing cap tube together to add or remove lengths.Look for a kit that has a dryer and tube together ...its called a "KAP KIT".I found several on ebay.
My unit gets -40 unloaded 2-3 f loaded measured on the backside of the CPU with a probe epoxied behind the die.Its an old 1333 Tbird running @1600 so it runs warm.I'm using BBQ 12-a..lol aka propane.
Another thing I did was to use R134A retrofit fittings for cars on my system so that my gauges would just snap on for monitering and charging..I couldn't seem to find any braze on R12 shrader fittings any where.
Most expensive "must have " item will be a good vacuum pump...but I found mine at a pawnshop for $85.00. If you don't properly evaucuate, tiny ice balls will clog the cap tube and give you fits.

[redleader]

You can get the fittings from rparts.com or local suppliers. They're prety cheap.

Also, you don't need a real vacuum pump. If you're patient, an old compressor will work as well. Though if you do that with propane, its best to vaccum it, charge it, vaccum and so on a few times. Annoying, but a good pump costs about 3x times as much as a simple phase change system, so its not worth it IMO unless you're doing a lot of systems.

[crane]

I guess your definition of "need " is different than mine.To be able to do a proper evacuation, you'll need a true vacuum pump.

[redleader]

The only thing a compressor may not do is get all the water out, and even that depends on how well you do it.

However if you used BBQ propane, you've already charged your system with many times more water then was already in the system. Which makes a true pump unneeded (though handy since its faster) since you'll have water in the system anyway.

[maxSaleen]

Propane is an excellent refrigerant. I'm having an HVAC guy recharge an old prommie that had a broken condensor. As redleader mentioned, by using propane you can circumvent the H20 problem that you'd have with say R22 or R504.

[redleader]

Well I wouldn't say circumvent. The water is still there and you should use a dryer to try and avoid damaging your system.

[redleader]

Just in case anyone still had doubts, you can in fact vacuum with a compressor setup and boil off the water:

http://www.xtremesystems.org/forums/...t=67081&page=2

[crane]

I do,in fact, have doubts. Still.
Keyword is microns.

[redleader]

Originally Posted by crane

I do,in fact, have doubts. Still.
Keyword is microns.

Irrelevent. Boiling off the water is a binary thing. Either you can do it, or you cannot. I've shown that you can, and thus you are wrong.

[crane]

Making 3 ounces of water jump around in a glass jar is a far cry from having a totally dehydrated system with all of the condensables removed. Cap tubes,condensors,evaporators and the inside of compressor look nothing like a glass jar.
It may work fine,I don't care... I have a deep vacuum pump that was built to properly evacuate AC systems because thats what works. Odd thats what HVAC pro's use too,isn't it?
Let it rest.

[redleader]

Making 3 ounces of water jump around in a glass jar is a far cry from having a totally dehydrated system with all of the condensables removed. Cap tubes,condensors,evaporators and the inside of compressor look nothing like a glass jar.

Yeah, 3 oz is way more water then is in a typical system.

It may work fine,I don't care...

Then why are you still posting? And still hitting refresh on this thread long after it died?

I have a deep vacuum pump that was built to properly evacuate AC systems because thats what works. Odd thats what HVAC pro's use too,isn't it?

Wow good for you.

Let it rest.

You revived the thread