|MLA Citation:||Bloomfield, Louis A. "Question 920"|
How Everything Works 23 Jul 2018. 23 Jul 2018 <http://howeverythingworks.org/print1.php?QNum=920>.
But there is a second type of ammonia refrigerator that makes use of an absorption cycle—ammonia dissolves extremely well in cool water but not so well in hot water. In an absorption cycle refrigerator, a concentrated solution of ammonia in water is heated in a boiler until most of the ammonia is driven out of the water as a high-pressure gas. This hot, dense ammonia gas then enters a condenser, where it gives up heat to its surroundings and becomes a cooler liquid. The liquid ammonia then enters a low-pressure evaporator, where it evaporates into a cold gas. This evaporation process draws heat out the evaporator and refrigerates everything nearby. Finally, the ammonia gas must be returned to the boiler to begin the process again. That return step makes use of the absorption process, in which the ammonia gas is allowed to dissolve in relatively pure, cool water. The gas dissolves easily in this water and thus maintains the low pressure needed for evaporation to continue in the evaporator. The now concentrated ammonia solution flows to the boiler where the ammonia is driven back out of the water and everything repeats.