mini fridge cooling

[tft]

I was thinking on making a sub-zero cooling setup out of a mini fridge. But, I heard that if you have all that heat from the system (I'm going to be using the fridge in place of a radiator in my watercooling system) going to the fridge, it has to work harder to keep the temps down, which leads to a shortened life span for the fridge. From what I've read, under this kind of load, they only last for a few months.
Is this true?
Any ideas on how to stop this from happening?
Thanks

 

[occool]

Doesn't it depend on quality fridge you are using?

 

[Tiger]

This is a lot more complicated than it first appears. I wrote an article in January which you will find here . I also suggest reading the thread entitled Project X where a number of the participants are building chillers or have built them and there is a wealth of info in that thread.

 

[CSaddict]

It all has to due with the amount that the compressor has to cycle to keep the T-stat satisfied. If the compressor runs all the time and /or goes on and off all the time it will burn out sooner. It's like overclocking, the harder you push it the less it lasts.

 

[tft]

How much less....
Will it be that it will take a few years off the life span, and it'll only go for two or three years, or will it be more like 2 to 3 months.
Thanks for the info

 

[Tiger]

According to a site dealing with domestic appliances a refrigerator is one of the longest lived appliances in the home with an average lifespan of 14 years. Even if the fridge worked an extra 50% per day that would reduce its lifespan by 25% or an expected lifespan of 11 years. If the compressor is cooled using fans then this factor would be removed because the compressor would work cooler than it would in normal use. The likely cause of compresssor failure in most domestic fridges is that the brushes in the electric motor wear out. Since the actual compressor is designed to run at a certain temp plus a built in over-temp compensation it is unlikely that failure would be due to overheating.

 

[tft]

Thanks.
So then with a fan or two on the compressor, I won't have to worry

 

[Ocelaris]

TFT,
You and I are in the same boat with hot compressors... wish it were women anyways, Tiger believes that compressors will not overheat, and he knows more than I do... And he is probably right, your fridge won't burn out. but I worry anyways, besides, if it's simply a matter of attaching heatsinks, hey, that's easy! For me, I feel that cooling the compressor helps a great deal, I mean, the cooler the compressor, the cooler the refrigerant, and the greater of a drop in pressure right? I know that by directing all the air from my fan blowing over the condenser, over the compressor, and adding a couple of small heatsinks, I was able to achieve ~5*C lower reservoir temps.

Tiger,
In your article you get your fridge down to -16*C, or the reservoir at least? what refrigerant is that using? Is it R12? When I had my refrigerator on fully, without any refrigerant, I could get the reservoir air down to -30*C or about, but with liquid I can only get -5*C. Should I assume I am losing heat from my reservoir? Maybe I'll foam it some more!!! When in doubt, Foam it up! Thanks, Bill

 

[Tiger]

Tiger,
In your article you get your fridge down to -16*C, or the reservoir at least? what refrigerant is that using? Is it R12? When I had my refrigerator on fully, without any refrigerant, I could get the reservoir air down to -30*C or about, but with liquid I can only get -5*C. Should I assume I am losing heat from my reservoir? Maybe I'll foam it some more!!! When in doubt, Foam it up! Thanks, Bill

i agree 100% with cooling the compressor it does make a hang of a difference not only to the performance of the compressor in that the compressor is actually producing higher pressures and this results in better heat loss via the condenser and secondly there is heat loss via primary cooling of the gas. So cooling the compressor is really good. What I was trying to get across is the fact that because a fridge suddenly starts working for 12 hours a day instead of 8 hours a day is not going to cause it to suddenly fail in a few months. As I said above maybe it will knock a few years off but who cares you probably wont be using it 6 months time because you have hacked another fridge apart and are using on-die refrigeration anyway.
I am using R12 based system and it is very impressive as the res holds 20L (about 4gallons) and it takes it down to -25C and under load will hold it at about -17.5C. I have done a lot more insulation since I wrote the article and the fridge is filled with styrofoam blocks, chips and newspaper filling every crevice I can find and that has improved things a few C.
But today is day of great celebration because I picked up a 1.333 AXIA Y for a song on e-bay (the guy didn't know it was an AXIA). Just got 1140 out of the Duron 800 yesterday.