# converting regular frig.



## Al. Countryboy (Oct 2, 2004)

Last year I saw were someone was trying to sell plans on the internet on how to make a AC frig. work using solar energy. From what I could tell, it looked as though they were possibly heating the coils at the back of the frig. with some copper coils sort of like a solar water heater. Is this possible without elect.? Can not find the site again, but saw somewhere in South America I believe where they were making ice using a very primative device.


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## Guy_Incognito (Jul 4, 2006)

You can adapt a basic 3-way fridge (like you get in caravans) to solar. You need to heat the section that normally gets its heat from the gas burner with solar hot water (probably pressurised), or just focused sunlight on it. You'd have to have a fairly large solar collector to get enough heat there to drive the process along.

I don't think a normal fridge can be adapted that way - the refrigeration cycle is completely different.

You can also make your own using an ammonia-based refrigeration cycle freezer. Here's a link that shows how to make a large one that can make 10 pounds of ice for every solar heating/cooling cycle.


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## ET1 SS (Oct 22, 2005)

There is a thread on this BBS, about ammonia frigs.


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## wy_white_wolf (Oct 14, 2004)

Guy_Incognito said:


> You can adapt a basic 3-way fridge (like you get in caravans) to solar. You need to heat the section that normally gets its heat from the gas burner with solar hot water (probably pressurised), or just focused sunlight on it. You'd have to have a fairly large solar collector to get enough heat there to drive the process along..


I've always wondered about this. I have 3 of the old propane fridges. 2 are in good working order but one the burner is bad and have thought about experimenting with it. How hot do you think solar would have to get the water to make this work?

Any links to people who have already done this?


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## Guy_Incognito (Jul 4, 2006)

Well, seeing as you're driving ammonia gas out of a water solution under pressure, my rough guess is "fairly hot"  - I've never actually seen any temperature specs. But seeing as generally they're run by a few hundred watts from a 12V heater, you could extrapolate from there.

For example, insolation in my area near the equator is generally regarded at 1000W per square meter. From that, and knowing that I need a few hundred watts of heat (at least!) at the boiler of a fridge and you have a good start.

You could (probably) devise a system like this :

- Make a big reflector out of a large rectangular sheet of tin curved into a semicircle.
- Run a black pipe along the long axis of the sheet at the focal point, so you'll have the heat focused all the way along the pipe. Slant the pipe/collector a bit so it slopes up towards the outlet end of your collector.
-Run that pipe UP to and around the boiler of your fridge, insulate suitably, etc etc.
-Run the pipe from the boiler DOWN back to your collector and leave uninsulated.
-Fill and seal with some high-boiling point liquid. High concentrations of ethylene gycol (antifreeze) will increase the boiling point - so will increasing the pressure.

The system should theoretically (!) thermosyphon then. You might want to insulate the outward facing side of your collector pipe to minimise heat loss as the bulk of the heat's coming from the reflector side. 

Point the reflector east/west facing the sun and get the sun angle right for your time of year and away it should go. A few square metres of collector area should give enough heat off at the boiler to drive everything along.


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## jnap31 (Sep 16, 2005)

We just had a thread someplace on HT about this not to long ago I posted several links to some neat things people were doing with directing solar onto amonia to freeze ice. Or maybe I just read about it when I surfed and did not post the links cant remember.


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