How Does a Refrigerator in a Camper Work?

What is a Camper Refrigerator?

A camper refrigerator is markedly different than a home refrigerator. They do not use electricity, as this would prove to be too big a drain on the battery of most campers. Instead they rely on a series of basic chemical reactions and the application of heat within a closed system of tubes and pipes both beneath the refrigerator's cooling box and within the casing itself. For this to work, a heat source must be available at all times. The most economically feasible and common heat source is propane. One might also refer to this kind of refrigerator as an absorption refrigerator, named after the chemical reactions that take place in the sealed casing.

Structure

The basic structure of the camper refrigerator is not all that different from any fridge you might find in your home, though smaller to save space. The metal veins or coils looping through the fridge's casing are the same as a normal electrical refrigerator. What they differ in is where an electrical fridge would have a motor at the bottom, five different structures take its place. They are linked by more piping and carefully placed to take advantage of the pull of gravity as well as the lifting properties of vapor. These components are the generator, separator, condenser, evaporator and absorber.

How Does a Refrigerator in a Camper Work?

The propane tank is connected to a burner that sits beneath the generator. The generator is essentially a reservoir, containing a liquid mixture of ammonia and water. The solution boils and passes up through a pipe into a separator. Ammonia has a lower boiling point than water, turning to gas while the water stays in liquid form. The ammonia rises upward into the condenser while the water travels down into the absorber. The ammonia's heat dissipates within the condenser, causing it to revert back to liquid form. From there it flows down into the evaporator, where it mixes with hydrogen gas in an endothermic reaction. The mixture is an incredibly cold gas that is sucked by a difference in air pressure through the cooling coils of the fridge, chilling the fridge's contents. Once it's completed a circuit of the coils, it's dumped down into the absorber, where the water is. Ammonia combines more easily with water than it does hydrogen. For that reason the ammonia becomes a liquid and recombines with the water, while the hydrogen gas rises back up into the evaporator. The water-ammonia mix flows down into the generator to repeat the process.