How Does a Gas Powered Refrigerator Work?

Gas Refrigerator Basics

Gas powered refrigerators are usually called absorption refrigerators because they work by alternately absorbing and evaporating ammonia gas. They are less efficient than regular refrigerators, because they require a burner, which produces a lot of waste heat. For this reason, they aren't normally used in buildings or cars. They are commonly used in campers and RVs because they don't need an electrical outlet, and can be run off of a propane burner. They are also almost completely silent.

Generator and Condensor

The generator contains a mixture of water and ammonia. A burner heats the mixture. Ammonia evaporates at a lower temperature than water, so the generator is kept at just the right temperature to bubble the ammonia without making the water boil. The ammonia gas drifts up into the condenser, where it cools down and condenses into liquid ammonia, separated from the water.

Evaporator

The ammonia then flows down into a chamber called the condenser. The condenser is filled with hydrogen gas. The ammonia only generates a small part of the total pressure in the chamber. This low partial pressure causes the ammonia to evaporate. As it evaporates, it cools quickly. It is the evaporator that causes the cooling of the refrigerator. A fan blows on the evaporator, making cold air which then circulates around the refrigerator. This also warms up the ammonia in the evaporator.

Completing the Cycle

The absorber next trickles water through the hydrogen/ammonia mixture. Ammonia mixes very easily with water, but hydrogen and water don't readily mix at room temperature. As a result, the ammonia trickles down with the water while the hydrogen stays in the chamber. The hydrogen and water then trickle back down to the generator to start the whole cycle over again.