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Einstein refrigerator

Einsteins and Szilrds patent application.

The EinsteinSzilard or Einstein refrigerator is anabsorption refrigeratorwhich has nomoving parts, oper-ates at constant pressure, and requires only a heat sourceto operate. It was jointly invented in 1926 byAlbert Ein-

steinand his former studentLe Szilrdand patented inthe US on November 11, 1930 (U.S. Patent 1,781,541).This is an alternative design from the original inventionof 1922 by the Swedish inventorsBaltzar von PlatenandCarl Munters.

1 History

From 1926 until 1933 Einstein and Szilrd collaboratedon ways to improve home refrigeration technology. Thetwo were motivated by contemporary newspaper reports

of a Berlin family who had been killed when a seal intheir refrigerator broke and leaked toxic fumes into theirhome. Einstein and Szilrd proposed that a device with-

Annotated patent drawing.

out moving parts would eliminate the potential for sealfailure, and explored practical applications for differentrefrigeration cycles. Einstein used the experience he hadgained during his years at the Swiss Patent Office to applyfor valid patents for their inventions in several countries,the two eventually being granted 45 patents in their namesfor three different models.

It has been suggested that most of the actual invent-ing was performed by Szilrd, with Einstein merely act-ing as a consultant and helping with the patent-relatedpaperwork.[1]

The refrigerator was not immediately put into commer-cial production, the most promising of their patents beingquickly bought up by the Swedish companyElectrolux.A few demonstration units were constructed from otherpatents.

2 Operation

The machine is a single-pressure absorption refrigerator,similar in design to a gas absorption refrigerator. The re-

frigeration cycle usesammoniapressure-equalizing fluid,butane refrigerant, and water absorbing fluid, has no mov-ing parts, and does not require electricity to operate,

1

https://en.wikipedia.org/wiki/Butanehttps://en.wikipedia.org/wiki/Ammoniahttps://en.wikipedia.org/wiki/Electroluxhttps://en.wikipedia.org/wiki/Carl_Muntershttps://en.wikipedia.org/wiki/Baltzar_von_Platen_(inventor)https://www.google.com/patents/US1781541http://localhost/var/www/apps/conversion/tmp/scratch_7/%EE%BF%80https://en.wikipedia.org/wiki/Albert_Einsteinhttps://en.wikipedia.org/wiki/Albert_Einsteinhttps://en.wikipedia.org/wiki/Moving_partshttps://en.wikipedia.org/wiki/Absorption_refrigerator

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2 7 EXTERNAL LINKS

needing only a heat source, e.g. a small gas burner or elec-tric heating element or even solar energy. In an Einsteinrefrigerator with the standard working fluids, a water-flowloop serves as an ammonia pump, and the ammonia-flowloop serves as a butane pump. Ammonia and water aresuitable choices because ammonia is highly soluble in wa-

ter and its solubility declines steeply with increasing tem-perature. Butane is a suitable choice for the refrigerantbecause it has a suitably low boiling point and is virtuallyinsoluble in water.

On the cold side of a conventional refrigerator, a re-frigerant evaporates at a temperature-dependent pressure,Pr (T). Evaporation absorbs heat from whatever isbeing cooled, and the vapor flows to a compressor. Inan equivalent Einstein refrigerator, the refrigerant liquidevaporates at what is now a partial pressure Pr(T),mixing with a flow of ammonia vapor to form a gas witha total pressure near the system pressure: Pr +Pa =

P. The mixture flows, not to a pump, but to an ammo-nia absorber.

On the hot side of a conventional refrigerator, a compres-sor raises the pressure of the refrigerant vapor, enablingit to condense at a relatively high temperature to deliverheat to an external heat exchanger. On the hot side ofan Einstein refrigerator, an ammonia absorber raises the

partialpressure of the refrigerant vapor to accomplish thesame result.

The absorber works by removing ammonia vapor by dis-solving it in water. As this happens, the gas mixture flows

to maintain the nearly constant pressure P, and asa con-sequence, the partial pressure of the refrigerant, Pr , canapproachP. At this higher partial pressure, it can con-dense and deliver heat to an externalheat convector, as ina conventional refrigerator.

The condensed refrigerant liquid cannot dissolve in waterand, in the case of butane, it will float, making it easyto separate and return to the evaporator. Meanwhile, theammonia/water solution flows to an ammonia generator,where the heat source that powers the refrigerator raisesthe temperature of the solution, driving out the ammoniaand providing the ammonia vapor that is the other input

to the evaporator.This is the operating principle of the system. Practicalimplementations include other elements, such as meansfor contacting liquids and vapors, and so forth. The Ein-stein refrigerator has been described as noiseless, inex-pensive to produce and durable.

3 Present day

In September 2008 it was reported that Malcolm Mc-Culloch ofOxford Universitywas heading a three-year

project to develop more robust appliances that could beused in locales lacking electricity, and that his team hadcompleted a prototype. He was quoted as saying that im-

proving the design and changing the types of gases usedmight allow the designs efficiency to be quadrupled.[2]

4 See also

Refrigeration

Refrigeration cycle

Absorption refrigerator

Rudolf Goldschmidt(for the EinsteinGoldschmidthearing aid)

Icy Ball

Timeline of low-temperature technology

5 Notes

[1] Dannen, Geene (1997), The EinsteinSzilard Re-frigerators, Scientific American 276 (1): 9095,doi:10.1038/scientificamerican0197-90

[2] Alok, Jha (21 September 2008). Einstein fridge designcan help global cooling.The Guardian.

6 References

Einstein, A., L. Szilrd, Refrigeration (Appl: 16December 1927; Priority: Germany, 16 December1926)U.S. Patent 1,781,541, 11 November 1930.

Einstein, A., L. Szilrd, Accompanying notes andremarks for Pat. No. 1,781,541. Mandeville Spe-cial Collections Library USC. Box 35, Folder 3,1927; 52 pages.

Einstein, A., L. Szilrd, Improvements Relatingto Refrigerating Apparatus. (Appl: 16 Decem-ber. 1927; Priority: Germany, 16 December 1926).

Patent Number 282,428 (United Kingdom). Com-plete accept.: 5 November 1928.

7 External links

Einstein`s No Electricity/No Freon Fridge Revivedat Oxford

Goettling, Gary extquotedblEinsteins Refrigeratorextquotedbl. Completed project that works.

Flanigan, Allen, extquotedblHistory and Philosophy

of Science(German site) Wolfgang Engels from theUniversityOldenburgrebuilt the original conceptthe housing is manufactured out ofconcrete, i.e. the

https://en.wikipedia.org/wiki/Concretehttps://en.wikipedia.org/wiki/Oldenburghttp://www.uni-oldenburg.de/presse/f-aktuell/05-363.htmlhttp://www.uni-oldenburg.de/presse/f-aktuell/05-363.htmlhttp://gtalumni.org/Publications/magazine/sum98/einsrefr.htmlhttp://www.greenoptimistic.com/2008/09/21/einstein-fridge/http://www.greenoptimistic.com/2008/09/21/einstein-fridge/https://www.google.com/patents/US1781541https://en.wikipedia.org/wiki/The_Guardianhttp://www.guardian.co.uk/science/2008/sep/21/scienceofclimatechange.climatechangehttp://www.guardian.co.uk/science/2008/sep/21/scienceofclimatechange.climatechangehttp://dx.doi.org/10.1038%2Fscientificamerican0197-90https://en.wikipedia.org/wiki/Digital_object_identifierhttps://en.wikipedia.org/wiki/Scientific_Americanhttp://www.sciamdigital.com/gsp_qpdf.cfm?ISSUEID_CHAR=6E731865-2EE0-4A4F-9DE4-6702DA7E2AE&ARTICLEID_CHAR=2E0F4600-5E37-4953-A4D4-24BBC99F092http://www.sciamdigital.com/gsp_qpdf.cfm?ISSUEID_CHAR=6E731865-2EE0-4A4F-9DE4-6702DA7E2AE&ARTICLEID_CHAR=2E0F4600-5E37-4953-A4D4-24BBC99F092https://en.wikipedia.org/wiki/Timeline_of_low-temperature_technologyhttps://en.wikipedia.org/wiki/Icy_Ballhttps://en.wikipedia.org/wiki/Rudolf_Goldschmidthttps://en.wikipedia.org/wiki/Absorption_refrigeratorhttps://en.wikipedia.org/wiki/Refrigeration_cyclehttps://en.wikipedia.org/wiki/Refrigerationhttps://en.wikipedia.org/wiki/Oxford_Universityhttps://en.wikipedia.org/wiki/Radiatorhttps://en.wikipedia.org/wiki/Heat_exchangerhttps://en.wikipedia.org/wiki/Partial_pressure

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3

total mass of the completed apparatus is around 400kg with 20 kg ofalcoholin the refrigeration cycle.The project was completed in 2005.

Patent document US1781541 (European Patent Of-fice)

Patent document GB282428 (European Patent Of-fice)

How kerosene refrigerators work. Archived versionof page.

http://web.archive.org/web/20061206174734/http://www.cam.net.uk/home/StKilda/electrolux.htmlhttp://v3.espacenet.com/origdoc?DB=EPODOC&IDX=GB282428http://v3.espacenet.com/origdoc?DB=EPODOC&IDX=GB282428http://v3.espacenet.com/origdoc?DB=EPODOC&IDX=US1781541http://v3.espacenet.com/origdoc?DB=EPODOC&IDX=US1781541https://en.wikipedia.org/wiki/Alcohol

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4 8 TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES

8 Text and image sources, contributors, and licenses

8.1 Text

Einstein refrigeratorSource:http://en.wikipedia.org/wiki/Einstein_refrigerator?oldid=620486961Contributors:XJaM, SimonP, Heron,Cosmicforce, Michael Hardy, Reddi, Robertb-dc, Itai, Ed g2s, AlainV, Chris 73, Jredmond, Blainster, Tobias Bergemann, Giftlite, Tomharrison, Marcika, DO'Neil, Gzornenplatz, Edcolins, Mineminemine, Karol Langner, Jcm, Rich Farmbrough, Egregius, Roodog2k, Roy-Boy, Bobo192, Duk, Cmdrjameson, Jjk, Slicky, Jeltz, Gene Nygaard, Kupojsin, Wackyvorlon, Uncle G, Kelisi, PhilHoward, Waldir,Rjwilmsi, Avochelm, BradBeattie, DVdm, Hillman, DMahalko, Gaius Cornelius, Dialectric, Howcheng, Salmanazar, SmackBot, FrannyWentzel, Jerome Charles Potts, Audriusa, Xiner, Mion, ML5, P199, Tawkerbot2, Dricherby, Magioladitis, Jackson Peebles, MartinBot,Goingstuckey, Potatoswatter, Almazi, TXiKiBoT, P1h3r1e3d13, Malcolmxl5, Janopus, Napishtim, ClueBot, Arakunem, Lampak, BO-Tarate, Addbot, Glane23, Flatfish89, Lightbot, AnomieBOT, FrescoBot, OgreBot, Full-date unlinking bot, RjwilmsiBot, Salvio giuliano,Acather96, ZroBot, Susfele, Xanchester, ClueBot NG, Marsha Watson, 069952497a, Acetotyce, Jinkinson and Anonymous: 89

8.2 Images

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File:Einstein_Refrigerator_pat1781541_clarified.jpg Source: http://upload.wikimedia.org/wikipedia/commons/5/55/Einstein_Refrigerator_pat1781541_clarified.jpgLicense:Public domainContributors:

http://www.google.com/patents?id=t0BRAAAAEBAJ&pg=PA1&source=gbs_selected_pages&cad=2#v=onepage&q&f=false Originalartist:Einstein/Szilard with annotations by P. Brandon Malloy

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8.3 Content license

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