Editing Ammonia solution (section)

=== Absorption refrigeration ===
In the early years of the twentieth century, the [[Heat pump and refrigeration cycle#Vapor absorption cycle|vapor absorption cycle]] using water-ammonia systems was popular and widely used, but after the development of the vapor compression cycle it lost much of its importance because of its low [[coefficient of performance]] (about one fifth of that of the vapor compression cycle). Both the Electrolux refrigerator<ref>[http://engineersedge.weebly.com/uploads/4/6/8/0/4680709/domestic_electrolux_refrigerator.pdf ''Vapour Absorption Cycle - Domestic Electrolux Refrigerator'']</ref> and the [[Einstein refrigerator]] are well known examples of this application of the ammonia solution.