Feedback On...The Incredible Wood-Burning Refrigerator

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And I expect to keep you posted on that work. Here, for example, is a refrigerator-similar to Dale's-that was designed many years back by another MOTHER reader, Stephan A. Sieradzki. Note that Steve's freezing mechanism has a built-in cutoff that operates automatically just in case that pot of ammonia and water does get too hot.-MOTHER.

Twenty-three years ago, while living in Europe, I designed a simple refrigeration unit with two tanks joined by a length of pipe. The assembly was mounted on a pivot in such a way that the condenser-evaporator could move in and out of an icebox, while the boiler absorber-tank moved correspondingly to and from a location over a gas flame. The system is gravity operated, fully automatic, and could be adapted for operation with any heat source (including solar).

Anyway, my diagram tells the story better than I can. It shows the unit in cooling position. From there, the cycle goes like this:

When most of the ammonia has been absorbed by the boiler, the added weight overcomes the force of the lower magnet, allowing the assembly to pivot into the position shown by the broken lines. In that mode, the pipe depresses the control rod, opening the gas valve to the burner.

Ammonia is driven from the boiler and condenses inside the evaporator. When enough of the coolant liquid has collected in the second chamber, the weight shifts again overpowering the upper magnet and swinging the setup back into its cooling phase. With the pressure thus removed from it, the control rod shuts off the flow of gas.

During the heating cycle, the opening in the ice chest is kept sealed by the counter weighted inside closure. If the ammonia pipe overheats-indicating a malfunction a link in the safety pad melts, causing an immediate shut off of gas to the burner.

Stephan A. Sieradzki Manteo, N.C.

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