Einstein refrigerator

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Einstein and Szilárd's patent application.
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 (U.S. Patent 1,781,541 ).

Contents

[edit] 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.[1]

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; however, concerns about the effects of Freon as an ozone depleting agent may cause a reevaluation of Einstein and Szilard's design.

[edit] 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 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".[1]

[edit] See also

[edit] Notes

  1. ^ a b Dannen, Gene (January 1997), “The Einstein-Szilard Refrigerator”, Scientific American 

[edit] References

[edit] External links