Gas and Propane Refrigerators

If you own an RV, chances are you have a gas- or propane-powered refrigerator. These refrigerators are interesting because they have no moving parts and use gas or propane as their primary energy source. Also, they use heat to produce the cold inside the refrigerator.

A gas refrigerator uses ammonia as the coolant, and water, ammonia and hydrogen gas to create a continuous cycle for the ammonia. The refrigerator has five main parts:

Generator - creates ammonia gas
Separator - separates the ammonia gas from water
Condenser - where hot ammonia gas is cooled and condensed to create liquid ammonia
Evaporator - where liquid ammonia converts to a gas to create cold temperatures inside the refrigerator
Absorber - absorbs the ammonia gas in water

It works like this:

Heat is applied to the ammonia and water solution in the generator. (The heat comes from burning gas, propane or kerosene.)
As the mixture reaches the boiling point of ammonia, it flows into the separator.
Ammonia gas flows upward into the condenser, dissipates heat and converts back to a liquid.
The liquid ammonia makes its way to the evaporator where it mixes with hydrogen gas and evaporates, producing cold temperatures inside the refrigerator's cold box.
The ammonia and hydrogen gases flow to the absorber where the water collected in the separator in step No. 2 mixes with the ammonia and hydrogen gases.
The ammonia forms a solution with the water and releases the hydrogen gas, which flows back to the evaporator.
The ammonia-and-water solution flows toward the generator to repeat the cycle.