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Phase Change Cooler

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Frosty_47

New Member
Hello,

The hot summer days are here and I want to build a compressor cooled portable cooler for camping so that me and my buddies can have cold beer for 2+ days. I have a hefty battery pack with build in-inverter that can be used to power the compressor. My only problem is finding a very tiny and lightweight compressor. The rest is simple...

Oh I tried using thermal-electric couples but the efficiency of them is very low, plus you need a giant heat spreader to cool them. So compressor sounds like a better choice.

If anyone know where I can get a small compressor, please provide a link...
 
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tcmtech

Banned
Most Helpful Member
Try surpluscenter.com Or strip one out of an old window AC unit or a freezer or refrigerator or a dehumidifier. All of them have small efficient compressor units that are easy to rework into something else! Hit a few garage sales and see what you can find!
 

Frosty_47

New Member
Try surpluscenter.com Or strip one out of an old window AC unit or a freezer or refrigerator or a dehumidifier. All of them have small efficient compressor units that are easy to rework into something else! Hit a few garage sales and see what you can find!
Nah i need something much smaller than that. I already thought of all those things. All of those units have very large compressors. Though a simpler solution might be to just find a small bar fridge and take that along. They are very efficient and it saves me the trouble of having to connect an evaporator, condenser, and other crap...

Oh, and I just love how people are no longer surprised of craziness here. I mean surely you see a lot of people going camping with a cooler that has built in phase change system.
 
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kchriste

New Member
Forum Supporter
Look into an absorption type fridge which runs on propane. They do make portable ones but a new one would be expensive:
http://www.electro-tech-online.com/custompdfs/2009/06/rc4000-specs.pdf
You could scavenge one from an old RV, but be careful about mixing beer and homemade propane devices.
Or you could find a cold mountain stream just like you see in the beer commercials! Remember to pick up your empties after picking up the babes. ;)
 

Frosty_47

New Member
Look into an absorption type fridge which runs on propane. They do make portable ones but a new one would be expensive:
http://www.electro-tech-online.com/custompdfs/2009/06/rc4000-specs-1.pdf
You could scavenge one from an old RV, but be careful about mixing beer and homemade propane devices.
Or you could find a cold mountain stream just like you see in the beer commercials! Remember to pick up your empties after picking up the babes. ;)
LoL! I always pick up my empties.

Well most domestic fridges use propane for the refrigerant these days. So I honestly don't see how that's any better than a small bar fridge. Maybe I can cascade some of those USB fridges: :rolleyes:

 

tcmtech

Banned
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Oh, and I just love how people are no longer surprised of craziness here. I mean surely you see a lot of people going camping with a cooler that has built in phase change system.
I dont post 3/4's of the day to day stuff I work and play with! The 1/4 I do let this forum onto gets enough questionable attention as is! :eek:
Theres a reason you dont see me jump all over people with interesting and unique ideas.

How small of compressor do you want?
I scrapped several small dehumidifiers last year that had compressors less than 4 inches in diameter and 6 inches long! They only used about 90 watts I think.
Cute but to small for me to find any useful purpose for them. The compressors worked fine too! The cheap aluminum condenser coils rotted out on them and leaked out the freon.
 
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Frosty_47

New Member
I dont post 3/4's of the day to day stuff I work and play with! The 1/4 I do let this forum onto gets enough questionable attention as is! :eek:
Theres a reason you dont see me jump all over people with interesting and unique ideas.

How small of compressor do you want?
I scrapped several small dehumidifiers last year that had compressors less than 4 inches in diameter and 6 inches long! They only used about 90 watts I think.
Cute but to small for me to find any useful purpose for them. The compressors worked fine too! The cheap aluminum condenser coils rotted out on them and leaked out the freon.
Was it a gradual leak ?

I found an old windows AC unit and decided to salvage the condenser + evaporator. So when I cut the coil, Lord and Behold! Oil and freon were blasted out for 5 minutes! There was a cloud of oil covering 2 houses down the street. I got lucky that neighbors were not home at a time, otherwise they would have made me clean up all that oil mess on their driveway :eek:

Oh, 6" by 4" sounds just right. I will look for some old dehumidifiers than...
 

Frosty_47

New Member
The fridge I posted the link to burns the propane to make things cold. It uses absolutely NO electricity to cool. Here is a wiki link that explains the concept:
Absorption refrigerator - Wikipedia, the free encyclopedia
WOW! That is Amazing!

Sorry it was not clear to me the first time, but now that I read some of wiki article on it, I am absolutely blown away that such systems exist. This means I can probably modify the damn thing and make it run of heat generated by a typical camping fire.

Thanks for sharing this with me!
 

tcmtech

Banned
Most Helpful Member
When you open an AC system you need to let it bleed off slowly from the highest point in the system if possible. The freon gets dissolved in the compressor oil and acts just like a dropped soda can when you open it quickly! :eek::D

I believe they were slow leaks and being on the lower pressure evaporator side there was not a lot of pressure but there was a bit of oil that pointed out the corroded spots that leaked easily enough.

For $10 at a garage sale what do you got to loose?
 

BrownOut

Banned
WOW! That is Amazing!

Sorry it was not clear to me the first time, but now that I read some of wiki article on it, I am absolutely blown away that such systems exist. This means I can probably modify the damn thing and make it run of heat generated by a typical camping fire.

Thanks for sharing this with me!
Most RV's have this system. I wish a I could remember the name for it...

ETIT: I just remembered, it's called Absortion Refrigeration
 
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BrownOut

Banned
I found an old windows AC unit and decided to salvage the condenser + evaporator. So when I cut the coil, Lord and Behold! Oil and freon were blasted out for 5 minutes! There was a cloud of oil covering 2 houses down the street. I got lucky that neighbors were not home at a time, otherwise they would have made me clean up all that oil mess on their driveway
HAHAHAHAHA! Best laugh of the day so far!
 

Hero999

Banned
I have a few questions, not that I'll ever do this, I'm just interested.

How do you re-fill the refrigeration system when you've modified and reassembled it into your own system?

Where can you buy refrigerant from?

How do you bend the copper pipe without crushing it?

I take it that you can just solder the pipe together.
 

tcmtech

Banned
Most Helpful Member
Air conditioner work is fairly easy. But like anything else you will need some specialty tools.
You will need a filler port which is basically like the tire stem on a vehicle but a different size. Many of the factory made units have them built onto the compressor on on the low pressure side of the system.
Ideally you will need to use a vacuum pump to draw down the system and remove all of the air that gets into it. A second AC compressor will make a good vacuum pump. Its what I made mine out of.

If your lucky you will find a R-134A built system so all you need to do is get a 12 oz can at the auto store of local super store and the filling system that goes with it. Or if you know a buddy that does A/C systems just get him to do the whole thing!

If its a older unit it will most likely have R-22 freon and believe it or not propane is the near identical equivalent to R-22 freon! And fully compatible with the existing oil and system. Technically when the scenting agent (ethyl mercaptane) is removed propane is then classified as an actual refrigerant under the name R-290. And is commonly used world wide. Its dirt cheap, has a far more Eco friendly rating than any of the common US refrigerants, and is more efficient than the common US refrigerants typically used. And it works with almost any type of bi phase cooling system.

The A/C code purists will say dont use it because its flammable but as you already know the systems are full of very flammable oil that shoots out as a mist when broke open any way.
 

killivolt

Well-Known Member
I have a few questions, not that I'll ever do this, I'm just interested.

How do you re-fill the refrigeration system when you've modified and reassembled it into your own system?

Where can you buy refrigerant from?

How do you bend the copper pipe without crushing it?

I take it that you can just solder the pipe together.
I got out of the refrigeration business a long time ago. But they have a tube bender looks like a coil spring if it's copper. Heating a copper tube will anneal and soften it. If you bend it to much it will work harden again.

Connection are made by a swedg kind of looks like a punch but it is the same size as the inside diameter of the tube and gradually gets larger to the point that previous tube that was the same size will now fit into the other cleaning and fluxing the joint and apply heat sweat the joint with solder let cool.

Once you have good clean tight connections they have a valve you solder onto the tube near the compressor it's called a saddle valve. Once on you pierce the tube with the sharpen valve stem part of the assembly it sort of looks like a bike tire stem but sharp. They make a quick valve system that just fits over the tube clamps down and then you pierces it in the same manner.

Do it on both sides of the compressor professionals will evacuate the unit using both stems and charging valves and hoses one hose to each side and one to the evacuation unit. It should be pulled into a semi vacum about 27"
typically and you don't alway need to use 2 valves it's just faster you could just use one on the intake side of the compressor.

Afterward you close the valves and let it set if you do not rise in pressure it's likely there is no leak. However, it could be boiling up water vapor and you didn't let it stay on the evacuation unit long enough.

If it is then you charge it on the low-side first. After you have disconnected and sealed the valve on the discharge side of the compressor. Reading the systems charge label aids in knowing what the pressure and temp is for the low side of the system to be when fully charged.

They also use a system of weight and a professional spends lees time because he can charge a system with liquid rather than with vapor.

kv
 

smanches

New Member
Do most of these small compressors (window AC, dehumidifiers, etc) have a built in motor, or would it be easy to change it to a DC motor?
 

killivolt

Well-Known Member
Do most of these small compressors (window AC, dehumidifiers, etc) have a built in motor, or would it be easy to change it to a DC motor?
Which do you refer to ? The Compressor or the Fans ?

Compressors are hermetically sealed cans and yes have motors attached to the pump. I'm sure they built them DC somewhere on the planet ? They make a grinding machine that can open them but usually it set's the oil on fire and ruins the compressor. But, if you going to modify it anyways then weld it back together, I guess then. Ya.

I never mentioned that the small RV style refrigerators are normally Ammonia systems and only need a heat source as said before. But, they are pressure tested at about 500 psi the systems use steel tubing instead of copper.

I got out of the business back when they started the laws over the CFC's anyone caught could face a fine of $25,000 I don't know if anyone has ever been fined before though.


kv
 
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tcmtech

Banned
Most Helpful Member
If you want a real eye opening read go to the EPA's own website and read the full rules and regulations on air conditioning.
I bet you start thinking every big A/C service dealer is a crooked lying cheating rip off/con artist!
I buy freon and do my own A/C work and I do it for others as well with no license or certification and without any concern for legal hassle. I am 100% legal by the rules and regulations in doing it too!
If you read the EPA stuff you will see how and why any one can as well.

The EPA rules and regulations in general are after distorted, misquoted or often made up by many of the A/C business people just to justify outrageous mark ups and extortionist pricing on common goods that are in fact cheap public purchase and install domain items!
 
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