How Does a Propane Freezer Work?

Heating Ammonia

Propane refrigeration works effectively in a cycle of heat, evaporation and condensation. A mixture of ammonia, water and hydrogen is stored inside a cooling unit. This unit is heated--using liquid propane gas so that no moving components are necessary--until bubbles containing small amounts of ammonia rise to the surface of the unit. This solution is passed through a tube called the siphon pump while the gas form of ammonia is sent to the water separator. Water vapor is condensed and directed back toward the cooling unit's boiling system while the actual dry vapor moves on to the condenser.

Ammonia Vapor

When ammonia vapor comes into contact with the air flowing above the condenser, it is condensed into liquid ammonia. This liquid ammonia is sent on to the evaporator, where hydrogen is passed over its surface. This lessens the vapor's pressure, causing it to evaporate. The temperature inside the refrigerator or freezer is lowered when the ammonia, as the result of this process, extracts heat from the food storage area. Afterward, the remaining mixture of ammonia and hydrogen vapor passes on to the absorber.

Ammonia Solution

A continuous trickle of the ammonia solution is leaked into the upper part of the propane refrigerator or freezer where the absorber is located. It then takes up the ammonia (from the mixture of ammonia and hydrogen vapor). Remaining hydrogen, once separated, is left to rise through the absorber coil and back to the evaporator--in order to unmechanically repeat the process.

New Ammonia Solution

Important Notes

Free air circulation must be continued above the condenser and absorber tanks so that the heat may be correctly dissipated into the surrounding air. Heat must be maintained at the correct temperature--enough to boil ammonia--and with proper application so that the unit may function properly (beginning with heating the cooling unit).