Absorption is as old a technique as compression. In 1860 Ferdinand Carré built the first absorption machine. Since then, absorption has been successfully employed with varying degrees of use, depending on the trends of each country.
Absorption equipment can be considered as the most environmentally friendly alternative to air conditioning and other utilities where refrigeration is needed since they do not use CFC or HCFC and in addition can use natural gas as their primary power source.
The critical thermodynamic balances that absorption needs for its operation, as well as the low yields obtained, made its practical use problematic. However, the technology, both in design and in materials and control elements, has revolutionized so much that nowadays there is a wide range of high reliability and energy efficiency equipment superior to its predecessors.
A few years ago, manufacturers introduced direct-flame double-stage equipment (also known as a double-effect) capable of delivering chilled water to standard air conditioning temperature (7-12ºC). This opens a wide field of application for all those applications where the production of chilled water for air conditioning is required. Direct flame equipment may have a heating cycle to provide hot water in winter.
Feeding flexibility (hot water, steam or direct flame) makes it suitable for different types of use, or it can enhance other forms of energy efficiency, such as cogeneration.
In many countries, absorption has been used mainly in industrial processes where there is residual heat at the same time as cooling is required. Another field of application is domestic kerosene or LPG refrigerators for places without electricity.
