Consumers purchase propane-fueled refrigerators for use in recreational vehicles and when they choose to live off the power grid. In solar-powered homes, operating an electric refrigerator alone requires up to 18 solar modules, making refrigeration expensive. Propane refrigerators use a small flame in the cooling cycle.
Gas refrigerators use ammonia to provide cooling. The flame heats a solution of ammonia and water to produce pure ammonia. As the ammonia reaches its boiling point, it moves into the separator while still a liquid and flows toward the evaporator. In the evaporator, the liquid ammonia and hydrogen gas mix as the liquid evaporates, cooling the inside of the refrigerator. The gases continue to flow into an absorber where they mix with the previously separated water to form a solution and release the hydrogen gas. After the solution returns to the generator, the cooling cycle begins again.
Gas refrigerators differ from electric models in several ways. They have no moving parts, so they often last much longer than their electric counterpart. While both models use thermostats to control the temperature, in the gas refrigerator, the flame continues to burn continually, with the thermostat regulating the amount of heat it produces. It provides constant cooling without the noise or vibration of a compressor motor.