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["Warren F. Smith" <WarrenSmith AT PalmettoBuilders.net>]

>>>This is really going the other direction, but I have an old Servel
>>>refrigerator, which uses ammonia/water as it's coolant, and
>>what amounts
>>>to a propane pilot flame to "excite" the refrigerant. No
>>moving parts, no
>>>noise, no power, just relatively expensive propane.
>>
>>You're breaking my heart. I once left an old Servel behind in
>>a basement
>>because it was so large and heavy. I'd love to have it now.
>>
>>>It seems to me that a fridge like this could be located near
>>a hot water
>>>source with a circulation pump (wood, solar, electric, gas, flubber
>>>powered, or whatever) or a loop added off a radiant heat
>>system. Coiled
>>>copper tubing inserted into the fridges firebox would
>>provide enough heat.
>>
>>I must be missing something. Okay, we have hot water. Now
>>what? How do I
>>use that to make cold air in a cold box?

The Servel has a rectangular "firebox" with a cylinder passing through it
lengthwise. The propane pilot is directed through this tube. It's a little
larger flame than a pilot, but smaller, and much less heat than say a butane
plumbers torch. The other end of the firebox connects to a "flue" which
exhausts up the back of the fridge. The flue is made from that
tar-impregnated cardboard stuff like the old sewer pipe we call "Orangeburg
Pipe" around here, to give you some idea of how little heat you're dealing
with. The firebox contains the ammonia refrigerant, and it has a very low
boiling point. the flame boils it, it pressurizes, travels into the
refrigerator where it passes through an expansion valve into the cooling
coils, absorbs heat from the fridge contents, condenses and flows back into
the firebox. Copper tubing coiled like a spring and inserted into the 1-1/2"
or so tube through the firebox, then supplied with hot water could/should
have the same effect. I know electric elements are sold as back-ups for the
LP gas refrigerators.

>>
>>>  RV's use LP refrigerators still, so the technology is
>>still available.
>>
>>Yes, I have and need to have repaired a 3-way small fridge
>>intended for RV
>>use. It is headed for the summer kitchen and will be powered
>>by propane.
>>
>>>  I've seen some plans on the internet for homemade ammonia
>>refrigerant
>>> systems
>>
>>I can put copper together but not stainless tubing. How does
>>one get around
>>the need for non-copper lines, which ammonia corrodes?

I'll look for the links to the homemade absorption systems. I don't remember
the pressures involved but maybe they were using compression fittings. Also,
there are bound to be hydraulic system components that could perform this,
with non-corrosive and high pressure components.

The ammonia refrigerant is a sealed system, so you aren't dealing corrosives
in the hot water aspect. I'd bet your three way fridge will work off hot
water. I'd be interested in your trying it.

Warren

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