Absorption refrigerator

In 1748 in Glasgow, William Cullen invented the basis for modern refrigeration, although he is not credited with a usable application.

In 1922, two students at the Royal Institute of Technology in Stockholm, Sweden, Baltzar von Platen and Carl Munters, enhanced the principle with a three-fluid configuration.

Commercial production began in 1923 by the newly-formed company AB Arctic, which was bought by Electrolux in 1925.

AB Electrolux established a subsidiary in the United States, named Dometic Sales Corporation.

[3] At the 2007 TED Conference, Adam Grosser presented his research of a new, very small, "intermittent absorption" vaccine refrigeration unit for use in third world countries.

The main difference between the two systems is the way the refrigerant is changed from a gas back into a liquid so that the cycle can repeat.

An absorption refrigerator changes the gas back into a liquid using a method that needs only heat, and has no moving parts other than the fluids.

The absorption cooling cycle can be described in three phases: The system thus silently provides for the mechanical circulation of the liquid without a usual pump.

A third fluid, gaseous, is usually added to avoid pressure concerns when condensation occurs (see below).

Energy from an electric motor or internal combustion engine is required to operate the compressor pump.

The intake of warm, moist air is passed through a sprayed solution of salt water.

The cooling cycle starts with liquid ammonia at room temperature entering the evaporator.

The condensed (liquid) ammonia flows down to be mixed with the hydrogen gas released from the absorption step, repeating the cycle.

Absorption cooling process
1: boiler 2: separation chamber 3: ammonia-poor water back-pipe 4: ammonia condense 5: pressure balance pipe 6: liquid ammonia pipe 7: evaporator (inside cabinet) 8: ammonia gas pipe 9: absorber (water absorbs ammonia)
Water spray absorption system
Domestic absorption refrigerator.
1. Hydrogen enters the pipe with liquid ammonia
2. Ammonia and hydrogen enter the inner compartment. Volume increase causes a decrease in the partial pressure of the liquid ammonia. The ammonia evaporates, taking heat from the liquid ammonia (ΔH Vap ) lowering its temperature. Heat flows from the hotter interior of the refrigerator to the colder liquid, promoting further evaporation.
3. Ammonia and hydrogen return from the inner compartment, ammonia returns to absorber and dissolves in water. Hydrogen is free to rise.
4. Ammonia gas condensation (passive cooling).
5. Hot ammonia gas.
6. Heat insulation and distillation of ammonia gas from water.
7. Electric heat source.
8. Absorber vessel (water and ammonia solution).
Thermal image of a Domestic absorption refrigerator of a comparable type to the one in the labelled image above. Colour indicates relative temperature: blue=cold, red is hottest. The heat source (7) is contained entirely within the insulation section (6).