How Does an Air Conditioner Work Using Ammonia?

Function

• The way an air conditioner works is very similar to the way a refrigerator works. Just like the refrigerator, an air conditioner has a low-boiling-point fluid called a refrigerant that travels through a pipe or line at high pressure. At some point along the pipe, the fluid squeezes through a narrow expansion valve, causing its pressure to drop dramatically as it expands on the other side. The drop in pressure causes the refrigerant to evaporate.

Evaporator

• When the ammonia refrigerant evaporates, it absorbs heat. The section of pipe where this process occurs is called the evaporator, and it's positioned in such a way that it's exposed to inside air. A fan sucks air across the evaporator, cooling the air and blowing it back into the room to keep it nice and cool. As the air cools, the water vapor it contains condenses, so the air conditioner also dries the internal air as well.

Compression

• The compressor sucks the ammonia vapor from the evaporator and compresses it, turning it back into a high-pressure liquid. Condensation releases heat, and so the refrigerant releases a considerable amount of heat as it flows through another section of pipe called the condenser. The condenser is positioned in such a way that it's exposed to the outside air, and a fan blows outside air across it to get rid of the excess heat. From here, the ammonia refrigerant travels back through the expansion valve and into the evaporator again.

Considerations

• Ammonia is a great refrigerant because it has a low boiling point, a relatively high specific heat capacity and no impact on the ozone layer -- unlike various chlorinated hydrocarbon refrigerants called CFCs. Unfortunately, ammonia is potentially toxic, so an undetected leak could pose a health hazard. That's why most modern air conditioners use other refrigerants, although ammonia was one of the first chemicals employed in this capacity.