In the early years of the twentieth century, the 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).
During the early 20th century, the vapor absorption system utilizing a water-ammonia mixture gained widespread acceptance; however, it lost significance following the emergence of the vapor compression cycle, which boasted a significantly higher coefficient of performance than the former.