Help with Phase change cooling

[Shep]

I just got a 6000 BTU AC unit and want to try building a phase chang system but I have no idea where to start. The compressor uses 134a so freon is no problem to get. It is a 220V compressor but I have found a couple 5000w step up transformers, the electrical I can handle, besides it was free. I need to know how the block needs to be built and which lines from the compressor are high and low pressure.

[Intraveinous]

I won't even try to mislead you as I know nothing about Phase change, but Bump so maybe someone who does know something will see it...
Peace
John

[cowanrg]

yeah, there IS a guy in the forum that built his own phase change cooling thing. he should be able to help you.

free stuff is great :)

[ptcg]

220V.... 6000BTU! Think that's a bit too large for PC cooling.. you should try to dig up something MUCH smaller... Try to get a 115V or even a DC unit..

When you decide to go at it.. check my website.. You should find just about everything you need there..

(Try to get a unit that has a small radiator-like condensor.. The large ones like on the back of a fridge are too large & awkward to use on a PC... At least I feel they are)

If you have any questions, feel free to email me or shoot me an ICQ.

The way the lines go is as follows:

There should be a large line coming out of the compressor going to the condensor(radiator).. from there it should turn into a much smaller line (capillary tube).. this runs to the evaporator(the piece that actually gets cold)... from there it goes back to a larger tube which returns to the compressor.

The side before between the evap & radiator is the high side.. the return line or at the compressor is the low side.

If you're going to attach it directly to the CPU, you need to make an evap for it.. this can be done several ways... Like a water-block, with passages for the refrigerant... Or even just a large hollowed out cavity... I made mine with passages to try to make it as small as possible & easy to insulate.
I've seen a some that were just empty copper plumbing end caps, soldered to a cold plate.... harder to insulate, but probably run colder.. You'll have to do some research to decide which way you want to go with it.

[ptcg]

Oh, almost forgot.. I was speaking with some HVAC tech guys & they said that BTUs=WATTSx3.5 (about) so...

An unOCd Athlon 1200Mhz=70watts (approx)
70x3.5=245BTUs

Mine is running about 100Watts
100x3.5=350BTUs

6000 is WAY overkill!

[Shep]

Originally posted by ptcg
Oh, almost forgot.. I was speaking with some HVAC tech guys & they said that BTUs=WATTSx3.5 (about) so...

An unOCd Athlon 1200Mhz=70watts (approx)
70x3.5=245BTUs

Mine is running about 100Watts
100x3.5=350BTUs

6000 is WAY overkill!

I realize 6000 is overkill, but like I said it was free. Thanks for the info am going to check out your site right now.

[ptcg]

Wasn't meaning to put you down.. Just posting some tech info.. Mine is supposed to be a 3000btu unit, so mines extreme overkill too!

The guys I spoke with told me to get a smaller compressor too.. Mine was only $50 & a new one is over $300, so I'll have to make do with the overkill!

[Shep]

I checked out your site. Your compressor did not have any way to fill it? I have two valves in the copper tubing, I am guessing that is were mine is filled at.
I am trying to decide on a block also, was thinking of a flat peice of copper the same size as the base of a mc462 and soldering a copper plumbers cap to it. I can get Aluminum easier than copper, but don't know if it will work as well since the tubes will be copper and will need to be soldered in place. If I go with the copper should I put pins or something under the cap or will just an open space work best?

[ptcg]

Mine was filled and the tubes were crimped and soldered (not a serviceable unit I guess).. I had to make my own access valve.

I don't know how much luck you'll have soldering aluminum to copper.. Don't think it will work very well.

If you use a large, thick piece of copper, it should be able to absorb & disperse the heat enough that you would only need a hollow cap for it. Here's (http://server39.hypermart.net/xoverclocker/supercool11.html) someone who did just that.

I made mine the way I did to keep it small enough to insulate easily. Mine won't keep the CPU under 0C (it hangs around 9C), but it's not frosting up at all so I have no worry of condensation..
It would seem that the size and design of the evap plays a large role in how cold it maintains. If you're just going for 'freeze the hell out of it', Using a large, thick cold plate with a copper cap is the way to go (just harder to insulate).

As far as putting pins in the base, I think any help dispersing the heat into the refrigerant would keep it running colder (more surface area always helps). Again, remember that the colder it runs, the harder it will be to insulate.

If you saw on my site, I did try using a hollowed out evap the same size as the solid one.. It didn't work well at all.. I made the one solid with the passages in it to give the refrigerant more surface to pull heat off of... I would actually like to remake it a little larger (maybe 1 1/4" dia.) with more, smaller passages in it.. I think that would lower my temps A LOT. (on my hollow one, the walls were too thin to absorb the heat from the CPU efficiently. A large cold plate under it would have fixed this too.)

[Ghost68]

I found some huge wall mount air conditioner in my parents garage a few weeks ago, just looked at the specs yesterday... 20,000 BTU!!! The compressor stands a foot tall!!! so i think ill talk to my uncle (he used to work in refrigeration) and see about making a custom setup maybe as a water chiller or just straight up supercoolin...:burn:

[tft]

would it be better/cheaper to go for a peltier & watercooled system, or for a refrigeration sys. How noisy is the compressor?
Would this be a practical project for someone who doesn't have much experience in this area?
Thanks

[Wonko The Sane]

I saw an article at octools.com (http://www.octools.com/index.cgi?caller=articles/phasechange/phasechange.html) where someone was using phase change. they said that the temp of the cpu would vary when the compressor cycled on and off,so they phase change cooled water, and used the chilled water to cool the cpu. I'd think if your compressor is on all the time though, it wouldn't fluctuate temps, but i'm not sure.