Well I have decided to further my overclocking endevours so I am building a direct die phase change system. I will be using an store bought A/c because this is my first unit I stick to "KISS." I will be using Propane gas as a refigerant. So my A/c is 5,050 btu, overpowered but it works. I am making a crap homemade block out of store bought fittings. So I am speculating to see temps of -30c or so idle and with proper tweaking head down to -40C. So yesterday I ordered my manifold gauge, vacuum pump, .031 capillary line, some schrader valves, and a filter/dryer. I will be getting some 1/4" tube and tee's today for use on the low side of the unit going to the evaporator or block. So I am taking a very bold and frowned upon move in the HVAC world and sweating(soldering) instead of brazing for a few reasons: Its quicker, easyer, and cheaper. I am using Propane so it is not harmful to have a leak so if something fails, no big deal really. So today I made my evap(Based off of a guy over at XS) all it is is a 1" endcap soldered to a 1" to 1/2" reducer soldered to a small piece of 1/2" pipe soldered to a 1/2" to 1/4" reducer. Then filled with copper wool. Here is a pic:


This is the unit I will be working with:

As you see the large radiator lookin thing is the condenser where high pressure gas is cooled and turned to liquid, the smaller one is the evaporator where the liqid boils off in a low pressure(vaccum) environment. So the evaporator will be cut off and replaced with the evap shown above. Schrader valves will be added to the low and high ends of the unit for charging and evacuating, a filter/dryer will also be pressent to eliminate and trace amounts of water my .75 micron vacuum pump can not pull out. I am still trying to figure out how I am going to mount my block(I will eventually buy a mass produced phase block that is more user friendly) but I am thinking using a metal plate that screws over it on to the mounting brackets. Then insulate the hell out of it.

So tomorrow I will take it to get it evacuated, cut off the stock evap, find a metal plate for my evap, start bending and fitting hose, and figuring out some basic design questions and where to put my valves at. If all goes well I will get some soldering done. The farthest I can go is running my 1/4" from my new evap to the compressor and from compressor to the condenser plus add the tee's. Then I wait for my other parts to arrive so I can complete the system and begin to vacuum and charge it. So as you see it is a VERY basic setup with a lot of basic things but I am hopin' it will work out as a starter project ad open the doors of refrigerated computing to me!

Well today I fianlly got some work done!. I have gotten my filter dryer ijnstalled to the low end of the condensor and a line from compressor to the condesnor complete with schrader valve. Tomorrow I am going to pick up more 1/4" since I am nearly out(need another 10 feet) and am praying my guages and vacuum pump get here. Tomorrow if all goes well I will finish connecting my suction and cap tube to my evap and I can leak/pressure test. If all goes well then it't time to fill her up with Propane and make something cold! So tomorrow I should get some pics posted because now my camera is dead. So for all/any of you watching my completely primitive phase project you can watch for some pics tomorrow afternoon of what I have so far and maybe a complete setup! 

Maybe it's just 'cause I'm new, but at -30, won't condensation be an issue?

And people think us wacko simpit builders are crazy!

In your spare time maybe you can convert it into a still and make some whiskey  .

Careful with that propane gas.  It is not much.... but it is very flamable.  The gaseous state is heavier than air and it will pool if it leaks.  Find a spark ignition source and you'll get a nice little mess to deal with.  ( I work with propane a lot doing kiln combustion engineering work. )

Good luck.

best,

......................john

Besides that, won't pumping propane through the compressor heat it up enough for it to combust? I'm reminded of a trick I've seen, where someone replaced the air in a friends trailer tire with propane, and when he hit the highway, the heat from the friction of the tires on the road was enough to light it and BOOM! Just seems like an awful lot of effort for a few extra Mhz.

Well I don't know either John but I am not a Pioneer in using R-290, it has worked for many others before me, so im gonna give it a shot.

It is a lot of effort but it is fun and cool, learn a lot from it as well. Sometimes you might get a few extra Mhz sometimes you might get a few extra Ghz, it just depends on the CPU and the temp. People use phase and run the Core 2 Duos at 5 Ghz 24/7 easily.

The compressors are know to reach 100c, very hot it's probably not enough to make it spontaneously combust, even under pressure. The tire thing was probably ignited by enough heat, pressure, and some other source such as static electricity.

Well since it was a joke, im sure evacuation procedures were not taken heh, im still pondering if Propane is volatile enough to just ignite with pressure and some heat alone.

GunnerMan wrote on Jul 2^nd, 2007 at 3:50pm:


Propane is compressed to the liquid state for storage and transport.  So pressure alone is not an issue.  However, as the temperature of the liquid goes up, the vaporization rate increases, and hence the pressure if it is in a fixed volume containment.  

So what pressures are your soldered seals suitable for?  And what pressures are the walls of common soft drawn or hard drawn Cu pipe made to withstand?  And if you have sanded away some pipe wall to make the interface for the computer chip flat, how much has the heat of the grinding work weakened the pipe, and how much has the thinning weakened it?

All questions that enquiring minds want to know.  

If there is no O present, there can be no combustion.  Combustion (a slow explosion) is supported only when there is O availabe to support the exothermic conversion to CO and HO.  But even a tiny amount of O could support SOME combustion if it was ignited, and that would result in a sudden and significant increase in gas temperature and the gas volume in the containment, hence the pressure, possibly rupturing it and allowing more O to enter the picture.  

So that brings me to the question, what level of vacume will that pump pull?  100% ?

As a demonstration to deal with the "familiarity breeds contempt" part of things with my college kiln design classes, I often take a SMALL amount of propane gas (using a plumber's hand torch) and "pour" it into a bucket.  It stays there 'cause it is heavier than air.  Then from a safe distance I toss a lit cigarette butt into the bucket.  It is not well aerated cause there is no real good mixing going on with the air, but it still makes a nice big "pop" and gets the point across about how little propane it takes to make a nice mini-explosion.

One cubic foot of propane gas at STP (Standard Temperature and Pressure) contains the potential energy of about 2500 BTUs........ give or take.  A single match completely burned contains about one BTU of potential energy.  So one cubic foot of propane suddenly combusting is like burning 2500 matches all at once.  Your 2 Oz. of liquid propane probably has about 2000 BTUs of potential energy.  So you have about 2000 matches that could get "set off".

Please be careful.  I thought you already were VERY familiar with working with HVAC and propane and such before you undertook this one.  Isn't there a different refridgerant you can utilize?

best,

..................john