On November 11, 1930, Albert Einstein and Leo Szilard received a United States patent for their invention of a refrigerator that, uniquely for motor-driven cooling devices, had no moving parts. Described by the two as an “absorption refrigerator,” but what understandably came to be known as the “Einstein refrigerator,” the invention was more than a thought experiment: Its patent was actually licensed by the Swedish appliance maker Electrolux. But it ended up being superseded by the invention of freon, a gas that became the standard refrigerator coolant until its environmental impact became understood in the 1970s.
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Leo Szilard (1898-1964) is best known for conceiving, in 1933, of the idea of a nuclear chain reaction, and of the vast amounts of energy that such a reaction could release. It was the letter he wrote to President Franklin D. Roosevelt, in 1939, on the military potential of nuclear fission that led to the Manhattan Project and the atomic bomb.. Later, he became an advocate of disarmament. In the 1920s, however, in Berlin, he and Albert Einstein worked together on a number of straightforward engineering problems.
It was in 1926 that Einstein shared with the younger scientist his distress at reading a newspaper account of a family in Berlin whose parents and children had died in their sleep after a seal in the refrigerator had failed, and they had been poisoned by the toxic fumes that were emitted.
A snag in design
The electrically powered refrigerator was still relatively new – at the time, most people still cooled their food in iceboxes – and the coolants, such as methyl chloride, they employed were poisonous. If a leak developed, the results could be fatal, as demonstrated in Berlin.
The two men believed that if they could design a refrigerator with no moving parts, it would be unlikely to sustain leaks.
They did achieve that, resulting in a refrigerator that relied on the laws of chemistry and thermodynamics (the field in which Szilard had written his doctorate) rather than a motor to generate the cooling effect.
Because of Einstein’s time working in a Swiss patent office, in the early 20th century, he was familiar with the process of applying for a patent. That enabled him and Szilard to license several inventions without the need of a patent lawyer.
The two had a Hungarian engineer named Albert Korodi build a prototype of the refrigerator, and submitted their application for a patent on December 16, 1927. U.S. patent 1781541, assigned to the Electrolux Corporation, was issued in New York on this date in 1930.
However, one snag with their invention is that it was not considered particularly efficient.
In recent years, several different teams have tried to revive the Einstein Refrigerator, partly because freon is ecologically toxic and partly because around 1.3 billion worldwide people live without a power supply. In 2008, for example, a flurry of newspaper reports described the efforts of an electrical engineer at the University of Oxford to develop a variety of energy-efficient appliances that could be used in areas that lacked an electricity supply. Oxford's Malcolm McCulloch, an associate professor of energy technologies, claimed that his team had built a prototype that, by using a different combination gases, could potentially be four times more efficient than the Einstein-Szilard version.
Like Einstein and Szilard's original, McCulloch's device does not use the noxious freon. Moreover, to keep the machine, whatever gases it winds up using, from being an environmental blight like today's refrigerator technology– McCulloch had the idea of developing a way to power the alt-neu Einstein fridge using solar energy, rather than a cord to the socket in the wall. And in another nod to the environment, since Einstein-type fridges do not have moving parts, they tend to last and last and last.
Even so, for all the roughly four dozen patents Einstein and Szilard would receive over the years for refrigeration technology alone, not one has ever reached a customer's home. So far.