Well, today while pouring over old issues of Life Magazine I came across this ad for the Servel Electrolux gas refrigerator and it spurred me to investigate how burning propane can make ice cubes.
The answer (from How Stuff Works) is as follows:
First heat from burning propane or kerosene is applied to an ammonia and water solution that is contained in the refrigerator's in the generator.
As the mixture reaches the boiling point of ammonia, it flows into the separator where the ammonia and water are, well, separated. The ammonia gas flows upward into the condenser, dissipates heat and converts back to a liquid.
Liquid ammonia then travels to the refrigerator's evaporator where it mixes with hydrogen gas and evaporates, chilling the refrigerator's cold box.
The ammonia and hydrogen gases flow to the absorber where the water from the separator is re-mixed with the ammonia and hydrogen gases. As the ammonia forms a solution with the water it releases the hydrogen gas, which flows back to the evaporator for re-use while the ammonia/water solution flows toward the generator to repeat the cycle.
There you have it, the basic workings of a propane-powered refrigerator!
