cooling systems

[deus_sum]

Ok I was thinking of getting a water cooling system then I thought why use water when I can use a refrigerator. Now my only problem is attaching my cpu to the cooling system I thought of using a water block but I didn?t think it could take the pressure any suggestions?

<P ID="edit"><FONT SIZE=-1><EM>Edited by deus_sum on 12/27/02 06:51 PM.</EM></FONT></P>

 

[LCARS]

Well, gee. How much pressure are you talking about? I assume around 30psi inside the evaporator in question.

I think SwifTech's MCW462-U waterblock http://www.swiftnets.com/ might be sturdy enough to take the pressure/temp. But the inlet and outlet holes will have to be drilled and tapped to take new fittings.

But won't the compressor be really loud?

 

[svol]

And how about condensation?

You have to isolate all tubes and the entire waterblock + socket + back of your mobo.

My PC eats so much money that I'm in 'desperate' need of it to buy PC3500 RAM, help Svol with his OC project!
--- PM me for information.

 

[scalar]

Are you talking about splicing a CPU cooler into the refrigeration lines? If you don't know anything about refrigeration systems, then this is likely going to be an impossible job, or it won't work very well at all.

I assume you know there is a special gas inside the lines. If you cut the refrigerator pipeline to install your cooler, the gas will blow out and the refrigerator will no longer work.

Consumer fridges are not meant to be serviced. Most are factory sealed, and do not have fill valves but instead have the fill lines soldered shut. If it breaks, you are normally supposed to just throw it away and buy another.

In order to splice in a cooler block, you'd have to replace the evaporator section with your cpu block. If you have no idea what the evaporator even is, stop now.

Next you'd have to scavenge moisture out of the lines. In the process of modifying the evaporator section, moisture will no doubt migrate into the lines as you are installing your CPU block. Moisture in the lines is Very Bad, and can cause total compressor failure if it freezes into crystals inside the suction portion of the compressor.

Purging moisture usually involves an inert "dry" gas like bottled nitrogen, blowing it through the lines and compressor to evaporate any moisture, then venting it out the high-side of the line.

Once purged, you draw the system down with a high vacuum to remove as much nitrogen as possible, and then "charge" the system with fresh refrigerant. You not only need to use the right kind of refrigerant, but also the right amount of a compatible lubricant.

If you fill the system without any oil, the compressor will fail fairly quickly. If you fill it with the wrong oil, it may not get along with the oil that was already in the system and form slime that can damage the compressor or plug up the lines.

All of this is probably way out of the range for a person without a degree in a Heating/Ventilation/Air-Conditioning (HVAC) program, and indeed most of the guages and refrigerants can't be sold to you unless you're licensed to do HVAC work.

Merely cutting open refrigerant lines also happens to be illegal at this point due to the ozone-depletion concerns of Refrigerant-12 (R-12). If you are to do this project legally, you are required to use a refrigerant scavenging rig to recover the refrigerant for recycling. Only then can you move on to modifying the refrigerator to be used with your project.

Scavengers cost a minimum of $3000, and you can probably score a HVAC license by first getting a 2yr Associate degree from a nearby tech college... so as you can see this is adding up to be a really expensive and time consuming little project..

 

[scalar]

There is an easier way to still do what you want, but not have to deal with refrigerant gases and scavenging and all that.

Get a CPU waterblock... and another CPU waterblock. Mount the second waterblock inside the fridge and press it tightly against the freezer coils. This way heat from the CPU is directly picked up and carried away by the freezer coils.

If you're cooling a video chip and/or motherboard chip as well, then either get a bigger plate to mount in the freezer, or use two CPU blocks in series in the freezer.

You should use properly mixed automotive antifreeze in the lines, to keep the water in the waterblock lines from freezing. You may also need a slightly larger water pump to deal with the thicker antifreeze liquid.

(Don't drill holes in the freezer coils/plates when installing the waterblock on them, or the refrigerant will blow out. A lightweight compression-spring mount would probably be just fine.)

 

[LCARS]

Well, Ester oil should do just fine, or Pag oil. Both can be found at Pep-Boys.

I'd use R-134a. It's easy on the ozone, non toxic, and cheap. Plus it, again, can be found at any autoparts store in 12oz cans.

But R-134a boils at around 4*C (40*F), and since you have 'connections' I'd go with something that boils well below freezing.

If you can get it, try R-502 (Just as safe as R-134a), it boils at -45*C!

 

[scalar]

Maybe you'll find it at Pep Boys, maybe you won't. Some states ban the sale of small cans of any refrigerant to consumers:

<A HREF="http://datcp.state.wi.us/trade/regulation/trade/refrigerants/" target="_new">http://datcp.state.wi.us/trade/regulation/trade/refrigerants/</A>

<b>Refrigerant sales in Wisconsin are restricted to licensed businesses. This applies to all refrigerants including R-134a, the common replacement refrigerant used in motor vehicle air conditioning viewed as non-ozone depleting.

The sale of small containers of refrigerant (containers holding less than 15 pounds) is also prohibited in Wisconsin. These are container sizes generally marketed to the do-it-yourselfer who are generally not trained nor equipped to properly service vehicle air conditioning and trailer refrigeration systems.</b>



Having a charging kit alone isn't enough. You still need the fill ports which don't exist on consumer fridges in order to attach the can, and the kits only include standard screw-on adapters for the valves on automotive systems.

After cutting the lines and resoldering you need to draw down the system with a vacuum pump, as well as check for leaks with a leak detector, and the kits don't cover any of that either. The kits assume you are working on a car which is only just low on refrigerant and is still properly sealed, etc. That is not the case with this project.


And even though R134a does not destroy the ozone, federal regulations still require you to recover it anyway. The instructions included with the automotive charging kits will tell you this. Here's one of those kits right here:

<A HREF="http://www.refrigerantsales.com/cooltop.html" target="_new">http://www.refrigerantsales.com/cooltop.html</A>

<b>Q. Does this refrigerant need to be recovered (captured)?

A. Yes. Under US EPA rules and regulations, all CFC, HCFC, HFC refrigerants and just about anything else needs to be recovered and not be vented into the atmosphere. Refrigerants which require recovery are R-12, R-22, R-134a, Cooltop, Autofrost, and all the other current "legal" R-12 replacements at the current time. The only refrigerants which may be vented are air (nitrogen), water, CO2, ammonia, and pure hydrocarbons according to US EPA rules. You are not likely to encounter any of these, as they will not work and will damage the system. Cooltop consists of 100% hydrofluorocarbons, so it must be captured and returned to a reclaimer.</b>



Good luck getting R-502. It's one of the banned refrigerants like R-12, and requires a special license to purchase. And at $800 for a 30lb bottle, it's a little expensive.

<A HREF="http://www.refrigerantsales.com/st_r502.html" target="_new">http://www.refrigerantsales.com/st_r502.html</A>



<P ID="edit"><FONT SIZE=-1><EM>Edited by scalar on 12/29/02 05:02 AM.</EM></FONT></P>

 

[svol]

Start reading Wusy... he want to connect his waterblock to a phase-change system and he's not going to put his mobo inside a fridge.

My PC eats so much money that I'm in 'desperate' need of it to buy PC3500 RAM, help Svol with his OC project!
--- PM me for information.

 

[LCARS]

Hey, Maybe he could use a Mini Freezer as a tower!

 

[svol]

Well you will need to isolate the freezer and stall all your CDROMs, FDs and HDs outside otherwise they wont work.

My PC eats so much money that I'm in 'desperate' need of it to buy PC3500 RAM, help Svol with his OC project!
--- PM me for information.

 

[scalar]

Putting the floppy drive, CDROM, etc outside the fridge requires cutting some holes, and here's another little fridge detail.

If there aren't big looping coils of pipe hanging off the back side of the fridge, then the coils are probably mounted on the inside walls of the fridge.

I have a 2cu-ft dorm fridge like this. When it is cooling, the metal exterior of the fridge becomes very warm, because the coils are in the walls and the whole outside of the fridge is used as the heatsink.

Trying to cut a cable-access hole through the wall of a fridge like this may very well cut one of those refrigerant lines. (Fssssssssssssssssssss!!!!!!!!! Oops, you just killed the fridge.)

With a fridge like this, you'd be better off cutting a notch in the rubber door seal and running the cables through the gap rather than trying to cut a hole through the side or top of the fridge.

-Scalar

 

[scalar]

As long as you keep it closed and you seal around the cables coming into the fridge, it should stay fairly low humidity inside.

But it'll probably slowly build up ice on the freezer coils if you run the fridge all the time, so you should make it so that you can remove the computer guts if you need to defrost those coils..

If you turn off the fridge when you turn off the computer, there better be a big water catch-pan under the coils, because any water that froze onto the coils will then melt when the fridge is off, and the water may possibly drip onto your motherboard, power supply, etc.

...actually you should have a big water catch-pan under the coils no matter what, because even if you run the fridge all the time, if you have a power outage the ice will start to melt and drip..

 

[LCARS]

Hmmm... Couldn't you just cut 2 or 3 rectangles in the door and make brackets to hold the CD and floppy drive?

Although I guess there's still the matter of how this super cool computer will be powered.

 

[scalar]

I don't think that'd work too well. The drive would hang into the fridge and so will be chilled internally.

With the front of the drive sticking through the fridge door, the faceplates of the drives would be constantly wet with moisture, since the internals would be cooled but the face is exposed to the outside humid air.

Also, any CD or floppy ejected from the drives would be cold, and so it'd get covered with moisture when pulled out of the drive. This may not be good for floppies.

In any case, you'd have to wait for the disk to warm up and dry off before you could reinsert the disk and use it again. A fogged CD doesn't read too well, and the floppy may not spin properly if it is wet with moisture.

...but give it a try and let us know how it worked out.

It'd probably work okay if you have dry winter air. Hot humid summer air would be more of a condensation problem.<P ID="edit"><FONT SIZE=-1><EM>Edited by scalar on 12/31/02 05:58 PM.</EM></FONT></P>

 

[LCARS]

Ew... I know, I'll be like those crazy swedes and cool my computer with liquid Nitrogen!

It's the perfect plan.

 

[svol]

Also HDs wont function with temps around 0C.

My PC eats so much money that I'm in 'desperate' need of it to buy PC3500 RAM, help Svol with his OC project!
--- PM me for information.

 

[scalar]

Well, most dorm fridges don't get that cold, so it'd probably be okay for a hard drive.

But, after doing some <A HREF="http://www-2.cs.cmu.edu/~cap/raid/chillers/dormfridge/" target="_new">reading on the 'net</A> it sounds like a little dorm fridge can only remove about 100 BTU's an hour.

<A HREF="http://www.energy.iastate.edu/WindManual/Text-Conversion.html" target="_new">Another site</A> says that "Btu/hour = Watts x 3.413"

So, if your computer consumes 50 watts total, and you mounted all the heat-generating components inside the fridge (power supply, motherboard, hard drive), it would produce 50 watts x 3.413, or 170.65 BTUs/hr.

Right there you can see a problem.. most desk computers use a lot more energy than that, and at 50 watts of power usage you've already exceeded the cooling capacity of a small fridge.

A more realistic value is around 100 watts of power, which comes out to 341.3 BTUs/hr.. three times the heat-extraction capacity of a typical dorm fridge.

So basically, the little fridge would not be able to remove heat fast enough. As you'd run the computer, the temperature inside would slowly rise until your computer overheated.

 

[scalar]

'course, you could increase the heat-removal capacity of a dorm fridge by making some changes.

Most dorm fridges use convection cooling so they can be built as cheaply as possible, and that reduces cooling efficiency.

The hot condenser coils on the back are typically open-air without fans, so the fridge depends on slow air convection currents to remove the heat from the condenser.

You could boost the BTU/hr efficiency by enclosing these coils on the back of the fridge in a narrow sheetmetal duct, and using large low-speed fans to blow air up through the duct across the condenser.

The inside of a dorm fridge is much the same. There's a cold plate in there, and the fridge just makes that cold. The cooled air around it slowly sinks and cools the food below, then the warmed air slowly rises back up and touches the cold plate, continuing the cycle.

You could boost the internal cooling efficiency that by essentially mounting CPU heatsinks and fans on the cold evaporator, to blow air around and cool the inside of the fridge more quickly.

..though if your goal is silence, well I've just thrown that plan out the window, with a row of four or five low-speed fans blowing air up across the backside of the fridge, and four or five inside the fridge blowing on the evaporator..

-Scalar

 

[knowan]

And with all the heat the CPU is putting out your fridge compressor will be running all the time, adding to the noise level.

Does anyone know how the de-humidifier works inside a freezer? I haven't been able to find a small stand alone freezer that offers this option, only the fridge/freezer units seem to have it.

And also, if you want to reduce the number of cables going into and out of the freezer then consider wireless. A wireless keyboard and mouse will get rid of 2 wires. You could set up a wireless network and mount the hard drive and cd-rom inside a second computer. Then you have only the power cable snaking out of the freezer.

Of course, that's assuming that all these wireless devices will work through the walls of the freezer, which is somewhat doubtfull as the freezer walls contain alot of metal.

I remember seeing a picture of someone who did this (I think they were in New Zealand). As well I saw someone who had a water block attached to a water cooler (you know, those things in offices that everyone gets their water from). They both worked, but the freezer guy had all his cables snaking out of the freezer as this was before the time of wireless.

I also have seem pictures of people who built their computers inside of briefcases, toolboxes, and in one case a castle built out of lego pieces.

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