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Refrigerator compressor IDEAS

Posted: Mon Jul 21, 2008 7:49 pm
by VH_man
I am looking for a refrigerator compressor, and when i do get one i want to do some stuff too it.

Firstly, I remember reading somewhere that the giant black thing can be removed to leave a much smaller "pump" that still functions. Is this true?

if so, i plan on adding a watercooling system for computers (i have one laying around............) to the pump to help keep the temperature down, and then using this to pressurize a large air chamber with a pressure switch on it to act as a "high pressure" shop air supply.....

If you cant take the black thing off, whats the best way to keep the thing cool?

and im always looking for one......... so........

Posted: Mon Jul 21, 2008 8:03 pm
by ralphd
Well, I'm in the business and there is some truth to your reading. You can remove it and it will still pump. It will not pump a large volume of air though. It was designed for a small closed loop system.
The air that it pumps will have a residual of oil with it and eventually it will be gone and seize. If you try to paint with it you will get fisheye because of the oil.
My advice is to use a heatpipe or even a small airconditioner with a flexduct between it and your pc.

Posted: Mon Jul 21, 2008 8:05 pm
by VH_man
i realize it doesnt pump a large volume of air........... lol. im quite aware of that.......... my plan is to make it able to pump for a VERY long time WITHOUT seizing. what do you reccomend?

i can add a valve that will drip oil into the inlet...... if thats something that would be neccicary.

Posted: Mon Jul 21, 2008 8:08 pm
by iisthemuffin
Exactly how long is a fridge compressor good for? i can easily get one but am wondering if its worth the trouble.

Posted: Mon Jul 21, 2008 11:28 pm
by POLAND_SPUD
I don't have much time right now so more details later...

there is a lot of information on them... and yes there are people who run them almost all day... there is a large number of possible solutions: computer fans, imersing the whole compressor in oil etc. just use your imagination

Posted: Tue Jul 22, 2008 12:35 am
by Gippeto
I cut one of these apart, the pictures can be found here;

http://s245.photobucket.com/albums/gg76 ... ompressor/

The compressor "proper" runs in an oil bath. There are no bearings, or piston rings. It is all cast iron.

Without a constant oil "supply" the thing would seize in no time.

If you could add an oil pump and oil cooler (liquid-liquid?), you would be able to "dump" the generated heat, and run the thing for a very long time. (I think?)

Posted: Tue Jul 22, 2008 2:47 am
by POLAND_SPUD
IMO it's not the best idea to remove the casing and there are several reasons why you shouldn't do it.

Casing keeps everything toghether, it protects all moving parts from exposure to dust or any other things that could dammage them.

What is more it protects you from the danger of electrification (becasue it's grounded) and also because you're not exposed to cables).

Moreover, you don't have to worry that you or anyone else may accidentaly touch the pump itself so there is no risk of injuries (chop chop!! AAHhh!! where's my finger dude ?!? :D ) .
Finaly, casing makes it quiet.




Now as far as cooling them down is concerned there is a large number of ways you can do this.

1.
If you could add an oil pump and oil cooler (liquid-liquid?), you would be able to "dump" the generated heat, and run the thing for a very long time. (I think?)
this is possibly the most efficient way to dissipate heat but a bit complicated at the same time

2. You can immerse the whole compressor (with the casing on) in a container filled with oil. Oil does not conduct electricity so you should be fine (please double check that this statement is true for the oil you want to use). The increased mass and surface exposed to heat should help it to keep it cool for a lon time. Additionally you can put a coil made from thin copper pipe and run water through it to remove heat from the container

3. you can add a fan to dissipate heat. Some people suggest that even a 12V fan should do the job (check this forum for more info and use google.com I couldn't find it now but htere are other peole who did that http://forums.lr4x4.com/index.php?s=ef5 ... 9710&st=20)
I've noticed that it takes more time for my compressor to get warm on a windy day so this seems to make sense. Of course if you can increase the surface of a fridge compressor by adding radiators you can dissipate heat more effectively


EDIT yes hyldgaard is right if they are to cold or if you put to thick oil they have problems to start. (it looks like this -> they start and run for a few seconds then the safty relay switch turns them off. Then it takes up to 30 seconds before they turn on again. When they are warm enoguh they begin to run normaly.)[/quote]

Posted: Tue Jul 22, 2008 2:47 am
by hyldgaard
Keep in mind that if you cool it too much, it will have problems starting.

Posted: Tue Jul 22, 2008 6:02 am
by VH_man
hmm. i was thinking copper coils filled with water running through the radiator from the back of an Air conditioner with a 120V AC fan (a desk fan) running over it, and an old drill powering one of those drill pumps to cycle the water through the system. This way, i not only get water cooling, i can power the entire thing off of an outlet supply and not worry about power transformers and things like that.

and the cooling system would be activated by a swtich by me. i plan to put a temperature stick usually used for checking turkeys on the thing to make sure it doesnt get TOO hot, and so that i can control the cooling system. Mabey i could even swtich it on and off depending on the heat.....

anyway, when i do get one, i will do the run to see what pressure it goes up to, and in that find out how hot it gets ect.

but yes, i plan on making this thing run for a VERY long time. (wink wink it might not be for a free-standing air chamber..... think CANNON :D)

Posted: Tue Jul 22, 2008 6:23 am
by POLAND_SPUD
anyway, when i do get one, i will do the run to see what pressure it goes up to, and in that find out how hot it gets ect.
yeah that's the way you should do it. Build it first then you can start to think about other things...

well I'll check today how well air cooling works for mine...

Posted: Tue Jul 22, 2008 2:42 pm
by POLAND_SPUD
apparently air cooling works.. unfortunatelly I wasted a 12V computer fan before I even put it on the compressor, which isn't surprising when you use 5 times the current it can take :? but I think that it should work with this...

To contudt the test I've used an old fan from an car engine hooked up to 3.5V and 800 mA, which gave a small but constant flow of air comparable to a 12V computer fan. I run it constantly for 1.5 hour while shooting at the same time and it was only a little warm....

if you want to test how well a 12V computer fan works you have to do it yourself becasue this one the last one I had