Einstein's and Szilárd's patent application.

Annotated patent drawing.

The Einstein–Szilard or Einstein refrigerator is an absorption refrigerator which has no moving parts, operates at constant pressure, and requires only a heat source to operate. It was jointly invented in 1926 by Albert Einstein and his former student Leó Szilárd, who patented it in the U.S. on November 11, 1930 (U.S. Patent 1,781,541 ). The three working fluids in this design are water, ammonia and butane.[1] The Einstein refrigerator is a development of the original three-fluid patent by the Swedish inventors Baltzar von Platen and Carl Munters.

History [ edit ]

From 1926 until 1934 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 failed 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 were eventually 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,[2] but others assert Einstein labored over the project.[3]

The refrigerator was not immediately put into commercial production; the most promising of their patents being quickly bought up by the Swedish company Electrolux. Einstein and Szilard earned $750 (the equivalent of $10,000 in 2017).[3] A few demonstration units were constructed from other patents.

In 2007, a prototype of a commercial refrigeration device intended for use as a vaccine cooler was shown by Adam Grosser at a TED Talk;[4] the prototype operates at constant pressure, requiring exposure to a cooking fire to activate it. Once heated, the prototype would serve as a refrigerator for 24 hours. As of 2019, Grosser's prototype has not yet been put into commercial production[citation needed].

In 2008, electrical engineers at Oxford University's Energy and Power Group, part of the university's Department of Engineering Science,[5] revived the Einstein refrigerator as an attempt to produce a no-electricity refrigerator suitable for use in rural areas.[1] The group, led by Malcolm McCulloch noted that the design was still "far from being commercialized",[1] but might allow the efficiency of the original Einstein-Szilárd design to be quadrupled.[6]

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