Einstein refrigerator 599941 214971644 2008-05-26T03:35:49Z Franny Wentzel 440439 /* External links */ fixed broken link {{expert-portal|Technology}} [[Image:Einstein Refrigerator.png|thumb|200px|Einstein and Szilárd's patent application.]] The '''Einstein refrigerator''' is an absorption-type [[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}}). ==History== 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 Szilard 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 Szilard, with Einstein merely acting as a consultant and helping with the patent-related paperwork. Additionally, Einstein's name lent the research prestige and credibility.<ref name=delano1>{{Citation | last = Dannen | first = Gene | author-link = | last2 = | first2 = | author2-link = | title = The Einstein-Szilard Refrigerator | newspaper = [[Scientific American]] | pages = | year = | date = January 1997 | url = }}</ref> The refrigerator was not immediately put into commercial production, the most promising of their patents being quickly bought up by the Swedish company [[Electrolux|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 [[Vapor-compression refrigeration|vapour compression]] process the standard for refrigeration; however, concerns about the effects of Freon as an ozone depleting agent may cause a reevaluation of Einstein and Szilard's design. ==Operation== 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 (heat transfer)|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".<ref name=delano1/> == See also == * [[Refrigeration]] * [[Refrigeration cycle]] * [[Rudolf Goldschmidt]] (for the Einstein-Goldschmidt hearing aid) * [[Icy Ball]] ==Notes== {{reflist}} == References == * Einstein, A., L. Szilard, "Refrigeration" (Appl: [[16 December]] [[1927]]; Priority: Germany, [[16 December]] [[1926]]) {{US patent|1781541}}, [[11 November]] [[1930]]. * Einstein, A., L. Szilard, "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. Szilard, "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 == * 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&mdash; 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. [[Category:Cooling technology]] [[Category:Albert Einstein|Refrigerator]] [[he:המקרר של איינשטיין]] [[sl:Einsteinov hladilni stroj]]