Einstein refrigerator

Einstein refrigerator

Overview

The Einstein-Szilard or Einstein refrigerator is an absorption refrigerator
Absorption refrigerator
An absorption refrigerator is a refrigerator that uses a heat source to provide the energy needed to drive the cooling system...

 which has no moving parts
Moving parts
The moving parts of a machine are those parts of it that move. Machines comprise both moving and fixed parts. The moving parts have controlled and constrained motions....

, operates at constant pressure, and requires only a heat source to operate. It was jointly invented in 1926 by Albert Einstein
Albert Einstein
Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...

 and his former student Leó Szilárd
Leó Szilárd
Leó Szilárd was an Austro-Hungarian physicist and inventor who conceived the nuclear chain reaction in 1933, patented the idea of a nuclear reactor with Enrico Fermi, and in late 1939 wrote the letter for Albert Einstein's signature that resulted in the Manhattan Project that built the atomic bomb...

 and patented in the US on November 11, 1930 .
This is an alternative design from the original invention of 1922 by the Swedish inventors Baltzar von Platen and Carl Munters
Carl Munters
Carl Georg Munters was a Swedish inventor, most known for inventing together with Baltzar von Platen the gas absorption refrigerator now sold by Electrolux...

.

From 1926 until 1933 Einstein and Szilárd collaborated on ways to improve home refrigeration technology.
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Encyclopedia

The Einstein-Szilard or Einstein refrigerator is an absorption refrigerator
Absorption refrigerator
An absorption refrigerator is a refrigerator that uses a heat source to provide the energy needed to drive the cooling system...

 which has no moving parts
Moving parts
The moving parts of a machine are those parts of it that move. Machines comprise both moving and fixed parts. The moving parts have controlled and constrained motions....

, operates at constant pressure, and requires only a heat source to operate. It was jointly invented in 1926 by Albert Einstein
Albert Einstein
Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...

 and his former student Leó Szilárd
Leó Szilárd
Leó Szilárd was an Austro-Hungarian physicist and inventor who conceived the nuclear chain reaction in 1933, patented the idea of a nuclear reactor with Enrico Fermi, and in late 1939 wrote the letter for Albert Einstein's signature that resulted in the Manhattan Project that built the atomic bomb...

 and patented in the US on November 11, 1930 .
This is an alternative design from the original invention of 1922 by the Swedish inventors Baltzar von Platen and Carl Munters
Carl Munters
Carl Georg Munters was a Swedish inventor, most known for inventing together with Baltzar von Platen the gas absorption refrigerator now sold by Electrolux...

.

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 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 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 Szilárd, with Einstein merely acting as a consultant and helping with the patent-related paperwork.

The refrigerator was not immediately put into commercial production, the most promising of their patents being quickly bought up by the Swedish company Electrolux
Electrolux
The Electrolux Group is a Swedish appliance maker.As of 2010 the 2nd largest home appliance manufacturer in the world after Whirlpool, its products sell under a variety of brand names including its own and are primarily major appliances and vacuum cleaners...

. A few demonstration units were constructed from other patents.

Operation


The machine is a single-pressure absorption refrigerator, similar in design to a gas absorption refrigerator. The refrigeration cycle uses ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

 pressure-equalizing fluid, butane
Butane
Butane is a gas with the formula C4H10 that is an alkane with four carbon atoms. The term may refer to any of two structural isomers, or to a mixture of them: in the IUPAC nomenclature, however, butane refers only to the unbranched n-butane isomer; the other one being called "methylpropane" or...

 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 or electric heating element.
In an Einstein refrigerator with the standard working fluids, a water-flow loop serves as an ammonia pump, and the ammonia-flow loop serves as a butane pump. Ammonia and water are suitable choices because ammonia is highly soluble in water and its solubility declines steeply with increasing temperature. Butane is a suitable choice for the refrigerant because it has a suitably low boiling point and is virtually insoluble in water.

On the cold side of a conventional refrigerator, a refrigerant evaporates at a temperature-dependent pressure, Prfr(Tlow). Evaporation absorbs heat from whatever is being cooled, and the vapor flows to a compressor. In an equivalent Einstein refrigerator, the refrigerant liquid evaporates at what is now a partial pressure
Partial pressure
In a mixture of ideal gases, each gas has a partial pressure which is the pressure which the gas would have if it alone occupied the volume. The total pressure of a gas mixture is the sum of the partial pressures of each individual gas in the mixture....

 Prfr(Tlow), mixing with a flow of ammonia vapor to form a gas with a total pressure near the system pressure: Prfr + Pamm = Psys. The mixture flows, not to a pump, but to an ammonia absorber.

On the hot side of a conventional refrigerator, a compressor raises the pressure of the refrigerant vapor, enabling it to condense at a relatively high temperature to deliver heat to an external heat sink. On the hot side of an Einstein refrigerator, an ammonia absorber raises the partial pressure of the refrigerant vapor to accomplish the same result.

The absorber works by removing ammonia vapor by dissolving it in water. As this happens, the gas mixture flows to maintain the nearly constant pressure Psys, and as a consequence, the partial pressure of the refrigerant, Prfr, can approach Psys. At this higher partial pressure, it can condense and deliver heat to an external heat sink, as in a conventional refrigerator.

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

This is the operating principle of the system. Practical implementations include other elements, such as heat exchanger
Heat exchanger
A heat exchanger is a piece of equipment built for efficient heat transfer from one medium to another. The media may be separated by a solid wall, so that they never mix, or they may be in direct contact...

s, means for contacting liquids and vapors, and so forth.
The Einstein refrigerator has been described as "noiseless, inexpensive to produce and durable".

Present day


In September 2008 it was reported that Malcolm McCulloch of Oxford University was heading a three-year project to develop more robust appliances that could be used in locales lacking electricity, and that his team had completed a prototype. He was quoted as saying that improving the design and changing the types of gases used might allow the design's efficiency to be quadrupled.

See also

  • Refrigeration
    Refrigeration
    Refrigeration is a process in which work is done to move heat from one location to another. This work is traditionally done by mechanical work, but can also be done by magnetism, laser or other means...

  • Refrigeration cycle
  • Absorption refrigerator
    Absorption refrigerator
    An absorption refrigerator is a refrigerator that uses a heat source to provide the energy needed to drive the cooling system...

  • Rudolf Goldschmidt
    Rudolf Goldschmidt
    Rudolf Goldschmidt was a German engineer and inventor.Goldschmidt was born in Neubukow and earned an engineering degree in 1878. He spent the following decade working in England with major firms such as Westinghouse. Subsequently he returned to Germany and eventually became a professor at...

     (for the Einstein-Goldschmidt hearing aid)
  • Icy Ball
    Icy Ball
    IcyBall was a name given to two early refrigerators, one made by Australian Sir Edward Hallstrom in 1923, and the other design patented by David Forbes Keith of Toronto, Ontario, Canada , and manufactured by American Powel Crosley Jr., who bought the rights to the device...

  • Timeline of low-temperature technology
    Timeline of low-temperature technology
    The following is a timeline of low-temperature technology and cryogenic technology .-16th century BCE – 17th century CE :...


External links

  • Einstein`s No Electricity/No Freon Fridge Revived at Oxford
  • Goettling, Gary "Einstein's Refrigerator". Completed project that works.
  • Flanigan, Allen, "History and Philosophy of Science (German site) Wolfgang Engels from the University Oldenburg
    Oldenburg
    Oldenburg is an independent city in Lower Saxony, Germany. It is situated in the western part of the state between the cities of Bremen and Groningen, Netherlands, at the Hunte river. It has a population of 160,279 which makes it the fourth biggest city in Lower Saxony after Hanover, Braunschweig...

     rebuilt the original concept— the housing is manufactured out of concrete
    Concrete
    Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...

    , i.e. the total mass of the completed apparatus is around 400 kg with 20 kg of alcohol
    Alcohol
    In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....

    in the refrigeration cycle. The project was completed in 2005.
  • Patent document US1781541 (European Patent Office)
  • Patent document GB282428 (European Patent Office)
  • How kerosene refrigerators work. Archived version of page.