Einstein refrigerator

The Einstein refrigerator is an absorption refrigerator which has no moving parts and requires only a heat source to operate. It was jointly invented in 1926 by Albert Einstein and his former student Leó Szilárd and patented in the US on November 11 1930 (US patent|1,781,541).This is an alternative design from the original invention of 1922 by the Swedish inventors Baltzar von Platen and Carl Munters.


From 1926 until 1933 Einstein and Szilárd collaborated on ways to improve home refrigeration technology. The two were motivated by contemporary newspaper reports of a Berlin family who had been killed when a seal in their refrigerator broke and leaked toxic fumes into their home. Einstein and Szilárd proposed that a device without moving parts would eliminate the potential for seal failure, and explored practical applications for different refrigeration cycles. Einstein used the experience he had gained during his years at the Swiss Patent Office to apply for valid patents for their inventions in several countries, the two eventually being granted 45 patents in their names for three different models.

It has been suggested that most of the actual inventing was performed by Szilárd, with Einstein merely acting as a consultant and helping with the patent-related paperwork. Additionally, Einstein's name lent the research prestige and credibility.Citation | last = Dannen | first = Gene | author-link = | last2 = | first2 = | author2-link = | title = The Einstein-Szilárd Refrigerator | newspaper = Scientific American | pages = | year = | date = January 1997 | url = ]

The refrigerator was not immediately put into commercial production, the most promising of their patents being quickly bought up by the Swedish company AB Electrolux to protect its refrigeration technology from competition. A few demonstration units were constructed from other patents.

The invention of Freon in 1930 rendered the vapour compression process the standard for refrigeration.


The machine is a single-pressure absorption refrigerator, similar in design to a gas absorption refrigerator. The refrigeration cycle uses ammonia (pressure-equalizing fluid), butane (refrigerant), and water (absorbing fluid), has no moving parts, and does not require electricity to operate, needing only a heat source, e.g. a small gas burner.

The ammonia is introduced into the evaporator, causing the refrigerant to evaporate due to the fact that the partial pressure of the refrigerant is reduced, and the mix of gases then passed through to a condenser where it comes into contact with the absorption liquid. Since ammonia is soluble in water and butane is insoluble, the ammonia gas is absorbed by the water, freeing the butane. Heat is thus first given from the butane to the ammonia as the gases mix, and then from the ammonia to the water, as the ammonia leaves the butane, taking heat with it, and dissolves into the water. The butane then assumes the pressure inside the condenser, which is enough to make it liquefy. Since butane's specific gravity is less than that of ammonia in solution in water, the liquid butane floats on top of the ammonia solution. The liquid butane then passes back to the evaporator to repeat the cycle. The ammonia solution flows to a heat exchanger where a heat source drives it from the water as a gas again and it returns to the evaporator.

The Einstein refrigerator has been described as "noiseless, inexpensive to produce and durable".

See also

* Refrigeration
* Refrigeration cycle
* Absorption refrigerator
* Rudolf Goldschmidt (for the Einstein-Goldschmidt hearing aid)
* Icy Ball
* Timeline of low-temperature technology



* Einstein, A., L. Szilárd, "Refrigeration" (Appl: 16 December 1927; Priority: Germany, 16 December 1926) US patent|1781541, 11 November 1930.
* Einstein, A., L. Szilárd, "Accompanying notes and remarks for Pat. No. 1,781,541". Mandeville Special Collections Library USC. Box 35, Folder 3, 1927; 52 pages.
* Einstein, A., L. Szilárd, "Improvements Relating to Refrigerating Apparatus." (Appl: 16 December. 1927; Priority: Germany, 16 December 1926). Patent Number 282,428 (United Kingdom). Complete accept.: 5 November 1928.

External links

* [http://www.greenoptimistic.com/2008/09/21/einstein-fridge/ Einstein`s No Electricity/No Freon Fridge Revived at Oxford]
* Delano, Andrew, " [http://www.me.gatech.edu/energy/andy_phd/index.html Design Analysis of the Einstein Refrigeration Cycle] ". Georgia Institute of Technology. June 1998.
* Goettling, Gary " [http://gtalumni.org/Publications/magazine/sum98/einsrefr.html Einstein's Refrigerator] ". Completed project that works.
* Flanigan, Allen, " [http://www.uni-oldenburg.de/presse/f-aktuell/05-363.html History and Philosophy of Science] " (German site) Wolfgang Engels from the University Oldenburg rebuilt the original concept— the housing is manufactured out of concrete, i.e. the total mass of the completed apparatus is around 400 kg with 20 kg of alcohol in the refrigeration cycle. The project was completed in 2005.
* [http://v3.espacenet.com/origdoc?DB=EPODOC&IDX=US1781541 Patent document US1781541 (European Patent Office)]
* [http://v3.espacenet.com/origdoc?DB=EPODOC&IDX=GB282428 Patent document GB282428 (European Patent Office)]
* [http://web.archive.org/web/20061206174734/http://www.cam.net.uk/home/StKilda/electrolux.html How kerosene refrigerators work] . Archived version of page.

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