Refrigeration is the process of removing heat from an enclosed space, or from a substance, and rejecting it elsewhere for the primary purpose of lowering the temperature of the enclosed space or substance and then maintaining that lower temperature. The term cooling refers generally to any natural or artificial process by which heat is dissipated. The process of artificially producing extreme cold temperatures is referred to as cryogenics. For other uses, see Heat (disambiguation) In physics, heat, symbolized by Q, is energy transferred from one body or system to another due to a difference in temperature. ... Heat flow along perfectly insulated wire Conduction is the transfer of heat or electric current from one substance to another by direct contact. ... In physics or engineering, cryogenics is the study of the production of very low temperatures (below –150 °C, –238 °F or 123 K) and the behavior of materials at those temperatures. ...

Cold is the absence of heat, hence in order to decrease a temperature, one "removes heat", rather than "adding cold." In order to satisfy the Second Law of Thermodynamics, some form of work must be performed to accomplish this. This work is traditionally done by mechanical work but can also be done by magnetism, laser or other means. However, all refrigeration uses the three basic methods of heat transfer: convection, conduction, or radiation. The second law of thermodynamics is an expression of the universal law of increasing entropy. ... In physics, mechanical work is the amount of energy transferred by a force. ... In thermal physics, heat transfer is the passage of thermal energy from a hot to a colder body. ... Convection in the most general terms refers to the movement of currents within fluids (i. ... Heat conduction or thermal conduction is the spontaneous transfer of thermal energy through matter, from a region of higher temperature to a region of lower temperature, and acts to equalize temperature differences. ... Radiant heat redirects here. ...

Historical applications

Ice harvesting

The use of ice to refrigerate and thus preserve food goes back to prehistoric times.^[1][2] Through the ages, the seasonal harvesting of snow and ice was a regular practice of most of the ancient cultures: Chinese, Hebrews, Greeks, Romans, Persians. Ice and snow were stored in caves or dugouts lined with straw or other insulating materials. The Persians stored ice in pits called yahairas. Rationing of the ice allowed the preservation of foods over the cold periods. This practice worked well down through the centuries, with icehouses remaining in use into the twentieth century. This article is about water ice. ... A dugout or dug-out is a shelter dug out of the ground. ... Bales of straw bundles of rice straw Pile of straw bales, sheltered under a tarpaulin Straw is an agricultural byproduct, the dry stalk of a cereal plant, after the nutrient grain or seed has been removed. ... An ancient ice house, called a yakhchal, built in Kerman, Iran during the middle ages, for storing ice during summers. ...

In the 16th century, the discovery of chemical refrigeration was one of the first steps toward artificial means of refrigeration. Sodium nitrate or potassium nitrate, when added to water, lowered the water temperature and created a sort of refrigeration bath for cooling substances. In Italy, such a solution was used to chill wine.^[3] Made of Porn and sex things Inhalation respiratory irritation Skin May cause irritation. ... R-phrases   S-phrases   Supplementary data page Structure and properties n, εr, etc. ...

During the first half of the 19th century, ice harvesting became big business in America. New Englander Frederic Tudor, who became known as the "Ice King", worked on developing better insulation products for the long distance shipment of ice, especially to the tropics. This article is about the region in the United States of America. ... Frederic Tudor (September 4, 1783 - February 6, 1864) was Bostons Ice King, the founder of the Tudor Ice Company, and a merchant who made a fortune shipping ice to the Caribbean, Europe, and even as far away as India from sources of fresh water in New England. ... Wikimedia Commons has media related to: Thermal insulation Thermal insulation on the Huygens probe Rockwool Insulation, 1600 dpi scan against the grain Rockwool Insulation, 1600 dpi scan with the grain The term thermal insulation can refer to materials used to reduce the rate of heat transfer, or the methods and...

First refrigeration systems

The first known method of artificial refrigeration was demonstrated by William Cullen at the University of Glasgow in Scotland in 1748. Cullen used a pump to create a partial vacuum over a container of diethyl ether, which then boiled , absorbing heat from the surrounding air. The experiment even created a small amount of ice, but had no practical application at that time. William Cullen (April 15, 1710 – February 5, 1790) was a Scottish physician and chemist. ... Look up Vacuum in Wiktionary, the free dictionary. ... This article is about the chemical compound. ... Italic text This article is about the boiling point of liquids. ... The heat of vaporization is a physical property of substances. ...

In 1805, American inventor Oliver Evans designed but never built a refrigeration system based on the vapor-compression refrigeration cycle rather than chemical solutions or volatile liquids such as ethyl ether. Oliver Evans Oliver Evans (13 September 1755 – 15 April 1819) was a United States inventor. ... Vapor-compression refrigeration[1][2] is one of the many refrigeration methods available for use. ...

In 1820, the British scientist Michael Faraday liquefied ammonia and other gases by using high pressures and low temperatures. Michael Faraday, FRS (September 22, 1791 – August 25, 1867) was an English chemist and physicist (or natural philosopher, in the terminology of that time) who contributed to the fields of electromagnetism and electrochemistry. ... For other uses, see Ammonia (disambiguation). ...

An American living in Great Britain, Jacob Perkins, obtained the first patent for a vapor-compression refrigeration system in 1834. Perkins built a prototype system and it actually worked, although it did not succeed commercially.^[4] Jacob Perkins (9th July 1766 - 30th July 1849) was an American inventor and physicist born in Newburyport, Massachusetts, and was apprenticed to a goldsmith. ...

In 1842, an American physician, John Gorrie, designed the first system for refrigerating water to produce ice. He also conceived the idea of using his refrigeration system to cool the air for comfort in homes and hospitals (i.e., air-conditioning). His system compressed air, then partially cooled the hot compressed air with water before allowing it to expand while doing part of the work required to drive the air compressor. That isentropic expansion cooled the air to a temperature low enough to freeze water and produce ice, or to flow "through a pipe for effecting refrigeration otherwise" as stated in his patent granted by the U.S. Patent Office in 1851.^[5] Gorrie built a working prototype, but his system was a commercial failure. NSHC statue of John Gorrie John Gorrie, (October 3, 1802 – June 29, 1855) physician, scientist, inventor, and humanitarian, is considered the father of refrigeration and air conditioning. ... A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume. ... An isentropic process (a combination of the Greek word iso -same- and entropy) is one during which the entropy of working fluid remains constant. ... The United States Patent and Trademark Office (PTO or USPTO) is an agency in the United States Department of Commerce that provides patent and trademark protection to inventors and businesses for their inventions and corporate and product identification. ...

Alexander Twining began experimenting with vapor-compression refrigeration in 1848 and obtained patents in 1850 and 1853. He is credited with having initiated commercial refrigeration in the United States by 1856.

Dunedin, the first commercially successful refrigerated ship.

Meanwhile, James Harrison who was born in Scotland and subsequently emigrated to Australia, begun operation of a mechanical ice-making machine in 1851 on the banks of the Barwon River at Rocky Point in Geelong. His first commercial ice-making machine followed in 1854 and his patent for an ether liquid-vapour compression refrigeration system was granted in 1855. Harrison introduced commercial vapor-compression refrigeration to breweries and meat packing houses and by 1861, a dozen of his systems were in operation. Image File history File links Size of this preview: 800 × 528 pixelsFull resolution (1650 × 1089 pixel, file size: 306 KB, MIME type: image/jpeg) 1875 painting of SS Dunedin,47cm by 77cm oil on canvas by Frederick Tudgay (1841-1921), originally owned by the Ships captain, John Whitson. ... Image File history File links Size of this preview: 800 × 528 pixelsFull resolution (1650 × 1089 pixel, file size: 306 KB, MIME type: image/jpeg) 1875 painting of SS Dunedin,47cm by 77cm oil on canvas by Frederick Tudgay (1841-1921), originally owned by the Ships captain, John Whitson. ... The Dunedin in 1876, wearing the colours of Shaw Savill and Albion line of London (retained in 1882). ... James Harrison (1816 - September 3, 1893) was a Scottish-Australian pioneer in the field of mechanical refrigeration. ...

Australian, Argentinean and American concerns experimented with refrigerated shipping in the mid 1870s, the first commercial success coming when William Soltau Davidson fitted a compression refrigeration unit to the New Zealand vessel Dunedin in 1882, leading to a meat and dairy boom in Australasia and South America. Australia, officially the Commonwealth of Australia, is the sixth-largest country in the world, the only country to occupy an entire continent, and the largest in the region of Australasia/Oceania. ... Argentina is a Spanish-speaking country in southern South America, situated between the Atlantic Ocean in the east. ... ‘’’William Soltau Davidson’’’ 15 June 1846-July 17 1924, New Zealand pioneer of refrigerated shipping. ... The Dunedin in 1876, wearing the colours of Shaw Savill and Albion line of London (retained in 1882). ... Australasia Australasia is a term variably used to describe a region of Oceania: Australia, New Zealand, and neighbouring islands in the Pacific Ocean. ... South America South America is a continent crossed by the equator, with most of its area in the Southern Hemisphere. ...

The first gas absorption refrigeration system using gaseous ammonia dissolved in water (referred to as "aqua ammonia") was developed by Ferdinand Carré of France in 1859 and patented in 1860. Due to the toxicity of ammonia, such systems were not developed for use in homes, but were used to manufacture ice for sale. In the United States, the consumer public at that time still used the ice box with ice brought in from commercial suppliers, many of whom were still harvesting ice and storing it in an icehouse. It has been suggested that this article or section be merged with Absorptive refrigeration The absorption refrigerator is a refrigerator that utilizes a heat source to provide the energy needed to drive the cooling system rather than being dependent on electricity to run a compressor. ... The Ice Box is a 5,010-seat multi-purpose arena in Lincoln, Nebraska. ... An ancient ice house, called a yakhchal, built in Kerman, Iran during the middle ages, for storing ice during summers. ...

Thaddeus Lowe, an American balloonist from the Civil War, had experimented over the years with the properties of gases. One of his mainstay enterprises was the high-volume production of hydrogen gas. He also held several patents on ice making machines. His "Compression Ice Machine" would revolutionize the cold storage industry. In 1869 he and other investors purchased an old steamship onto which they loaded one of Lowe’s refrigeration units and began shipping fresh fruit from New York to the Gulf Coast area, and fresh meat from Galveston, Texas back to New York. Because of Lowe’s lack of knowledge about shipping, the business was a costly failure, and it was difficult for the public to get used to the idea of being able to consume meat that had been so long out of the packing house. Lowe in the Intrepid observing at Battle of Fair Oaks Thaddeus Sobieski Constantine Lowe (born Jefferson, New Hampshire, August 20, 1832–died Pasadena, California, January 18, 1913) was an American aeronaut, scientist and inventor. ... This article is about the chemistry of hydrogen. ...

Domestic mechanical refrigerators became available in the United States around 1911.^[6] Fridge redirects here. ...

Widespread commercial use

By the 1870s breweries had become the largest users of commercial refrigeration units, though some still relied on harvested ice. Though the ice-harvesting industry had grown immensely by the turn of the 20th century, pollution and sewage had begun to creep into natural ice making it a problem in the metropolitan suburbs. Eventually breweries began to complain of tainted ice. This raised demand for more modern and consumer-ready refrigeration and ice-making machines. In 1895 German engineer Carl von Linde set up a large-scale process for the production of liquid air and eventually liquid oxygen for use in safe household refrigerators. Carl Paul Gottfried von Linde (born 11 June 1842 in Berndorf (Oberfranken); died 16 November 1934 in Munich) was a German engineer who developed the basics of modern refrigeration technology. ...

Refrigerated railroad cars were introduced in the US in the 1840s for the short-run transportation of dairy products. In 1867 J.B. Sutherland of Detroit, Michigan patented the refrigerator car designed with ice tanks at either end of the car and ventilator flaps near the floor which would create a gravity draft of cold air through the car.

By 1900 the meat packing houses of Chicago had adopted ammonia-cycle commercial refrigeration. By 1914 almost every location used artificial refrigeration. The big meat packers, Armour, Swift, and Wilson, had purchased the most expensive units which they installed on train cars and in branch houses and storage facilities in the more remote distribution areas. Armour and Company was an American slaughterhouse and meatpacking company founded in Chicago, Illinois in 1867 by the Armour brothers led by Philip Danforth Armour (1832–1901). ...

It was not until the middle of the 20th century that refrigeration units were designed for installation on tractor-trailer rigs (trucks or lorries). Refrigerated vehicles are used to transport perishable goods, such as frozen foods, fruit and vegetables, and temperature-sensitive chemicals. Most modern refrigerators keep the temperature between -40 and +20 °C and have a maximum payload of around 24 000 kg. gross weight (in Europe).

Home and consumer use

With the invention of synthetic refrigerations based mostly on a chlorofluorocarbon (CFC) chemical, safer refrigerators were possible for home and consumer use. Freon is a trademark of the Dupont Corporation and refers to these CFC, and later hydrochlorofluorocarbon (HCFC) and hydrofluorocarbon (HFC), refrigerants.

Developed in the late 1920's, these refrigerants were considered at the time to be less harmful than the commonly used refrigerants of the time, including methyl formate, ammonia, methyl chloride, and sulfur dioxide. The intent was to provide refrigeration equipment for home use without endangering the lives of the occupants. These CFC refrigerants answered that need.

The Montreal Protocol

As of 1989, CFC-based refrigerant was banned via the Montreal Protocol due to the negative effects it has on the ozone layer. The Montreal Protocol was ratified by most CFC producing and consuming nations in Montreal, Quebec, Canada in September 1987. Greenpeace objected to the ratification because the Montreal Protocol instead ratified the use of HFC refrigeration, which are not ozone depleting but are still powerful global warming gases. Searching for an alternative for home use refrigeration, dkk Scharfenstein (Germany) developed a propane-based CFC as well as an HFC-free refrigerator in 1992 with assistance from Greenpeace.^{[citation needed]} The largest Antarctic ozone hole recorded as of September 2006 For other similarly-named agreements, see Montreal Convention (disambiguation). ... The ozone layer is a layer in Earths atmosphere which contains relatively high concentrations of ozone (O3). ... Greenpeace protest against Esso / Exxon Mobil. ... Greenpeace protest against Esso / Exxon Mobil. ...

The tenets of the Montreal Protocol were put into effect in the United States via the Clean Air Act legislation in August 1988. The Clean Air Act was further amended in 1990. This was a direct result of a scientific report released in June 1974 by Rowland-Molina^[7], detailing how chlorine in CFC and HCFC refrigerants adversely affected the ozone layer. This report prompted the FDA and EPA to ban CFCs as a propellant in 1978 (50% of CFC use at that time was for aerosol can propellant). It has been suggested that this article or section be merged into Clean Air Act. ... General Name, symbol, number chlorine, Cl, 17 Chemical series nonmetals Group, period, block 17, 3, p Appearance yellowish green Standard atomic weight 35. ... Hydrochlorofluorocarbons (HCFCs) is one of a class of fluorocarbon compounds that are used primarily as chlorofluorocarbon (CFC) substitutes. ... The United States Food and Drug Administration is the government agency responsible for regulating food, dietary supplements, drugs, cosmetics, medical devices, biologics and blood products in the United States. ... EPA redirects here. ...

• In January 1992, the EPA required that refrigerant be recovered from all automotive air conditioning systems during system service.

• In July 1992, the EPA made illegal the venting of CFC and HCFC refrigerants.

• In June 1993, the EPA required that major leaks in refrigeration systems be fixed within 30 days. A major leak was defined as a leak rate that would equal 35% of the total refrigerant charge of the system (for industrial and commercial refrigerant systems), or 15% of the total refrigerant charge of the system (for all other large refrigerant systems), if that leak were to proceed for an entire year.

• In July 1993, the EPA instituted the Safe Disposal Requirements, requiring that all refrigerant systems be evacuated prior to retirement or disposal (no matter the size of the system), and putting the onus on the last person in the disposal chain to ensure that the refrigerant was properly captured.

• In August 1993, the EPA implemented reclamation requirements for refrigerant. If a refrigerant is to change ownership, it must be processed and tested to comply with the American Refrigeration Institute (ARI) standard 700-1993 (now ARI standard 700-1995) requirements for refrigerant purity.

• In November 1993, the EPA required that all refrigerant recovery equipment meet the standards of ARI 740-1993.

• In November 1995, the EPA also restricted the venting of HFC refrigerants. These contain no chlorine that can damage the ozone layer (and thus have an ODP (Ozone Depletion Potential) of zero), but still have a high global warming potential.

• In December 1995, CFC refrigerant importation and production in the US was banned.

It is currently planned to ban all HCFC refrigerant importation and production in the year 2030, although that will likely be accelerated.

Current applications of refrigeration

Probably the most widely-used current applications of refrigeration are for the air-conditioning of private homes and public buildings, and the refrigeration of foodstuffs in homes, restaurants and large storage warehouses. The use of refrigerators in our kitchens for the storage of fruits and vegetables has allowed us to add fresh salads to our diets year round, and to store fish and meats safely for long periods.

In commerce and manufacturing, there are many uses for refrigeration. Refrigeration is used to liquify gases like oxygen, nitrogen, propane and methane for example. In compressed air purification, it is used to condense water vapor from compressed air to reduce its moisture content. In oil refineries, chemical plants, and petrochemical plants, refrigeration is used to maintain certain processes at their required low temperatures (for example, in the alkylation of butenes and butane to produce a high octane gasoline component). Metal workers use refrigeration to temper steel and cutlery. In transporting temperature-sensitive foodstuffs and other materials by trucks, trains, airplanes and sea-going vessels, refrigeration is a necessity. This article is about the chemical element and its most stable form, or dioxygen. ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... Propane is a three-carbon alkane, normally a gas, but compressible to a liquid that is transportable. ... Methane is a chemical compound with the molecular formula . ... For other uses, see Condensation (disambiguation). ... View of the Shell/Valero Martinez oil refinery An oil refinery is an industrial process plant where crude oil is processed and refined into useful petroleum products. ... A Chemical plant is an industrial process plant that manufactures chemicals, usually on a large scale. ... Petrochemicals are chemical products made from raw materials of petroleum (hydrocarbon) origin. ... Alkylation is the transfer of an alkyl group from one molecule to another. ... Butylene, also known as butene, is the name of the three isomeric hydrocarbon gases with chemical formula C4H8. ... Butane, also called n-butane, is the unbranched alkane with four carbon atoms, CH3CH2CH2CH3. ... A gas station pump offering five different octane ratings. ...

Dairy products are constantly in need of refrigeration, and it was only discovered in the past few decades that eggs needed to be refrigerated during shipment rather than waiting to be refrigerated after arrival at the grocery store. Meats, poultry and fish all must be kept in climate-controlled environments before being sold. Refrigeration also helps keep fruits and vegetables edible longer.

One of the most influential uses of refrigeration was in the development of the sushi/sashimi industry in Japan. Prior to the discovery of refrigeration, many sushi connoisseurs suffered great morbidity and mortality from diseases such as hepatitis A^{[citation needed]}. However the dangers of unrefrigerated sashimi was not brought to light for decades due to the lack of research and healthcare distribution across rural Japan. Around mid-century, the Zojirushi corporation based in Kyoto made breakthroughs in refrigerator designs making refrigerators cheaper and more accessible for restaurant proprietors and the general public. Species Hepatitis A virus Hepatitis A (formerly known as infectious hepatitis) is an acute infectious disease of the liver caused by the hepatovirus hepatitis A virus. ... The Zojirushi Corporation (Japanese: Zōjirushi Mahōbin Kabushiki Gaisha) is a Japanese multinational manufacturer and marketer of vacuum flasks and consumer electronics including electric water boilers and rice cookers. ...

Methods of refrigeration

Methods of refrigeration can be classified as non-cyclic, cyclic and thermoelectric.

Non-cyclic refrigeration

In these methods, refrigeration can be accomplished by melting ice or by subliming dry ice. These methods are used for small-scale refrigeration such as in laboratories and workshops, or in portable coolers. This article is about water ice. ... Sublimation of an element or substance is a conversion between the solid and the gas phases with no intermediate liquid stage. ... Dry ice pellet sublimating in water Dry ice block sublimating in air. ... For other uses of the word, see cooler (disambiguation) A cooler most commonly is an insulated box, used to keep food or drink cool. ...

Ice owes its effectiveness as a cooling agent to its constant melting point of 0 °C (32 °F). In order to melt, ice must absorb 333.55 kJ/kg (approx. 144 Btu/lb) of heat. Foodstuffs maintained at this temperature or slightly above have an increased storage life. Solid carbon dioxide, known as dry ice, is used also as a refrigerant. Having no liquid phase at normal atmospheric pressure, it sublimes directly from the solid to vapor phase at a temperature of -78.5 °C (-109.3 °F). Dry ice is effective for maintaining products at low temperatures during the period of sublimation. The melting point of a solid is the temperature range at which it changes state from solid to liquid. ... Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ...

Cyclic refrigeration

Main article: Heat pump and refrigeration cycle

This consists of a refrigeration cycle, where heat is removed from a low-temperature space or source and rejected to a high-temperature sink with the help of external work, and its inverse, the thermodynamic power cycle. In the power cycle, heat is supplied from a high-temperature source to the engine, part of the heat being used to produce work and the rest being rejected to a low-temperature sink. This satisfies the second law of thermodynamics. Thermodynamic heat pump and refrigeration cycles are the models for heat pumps and refrigerators. ... A thermodynamic cycle is a series of thermodynamic processes which returns a system to its initial state. ... The second law of thermodynamics is an expression of the universal law of increasing entropy. ...

A refrigeration cycle describes the changes that take place in the refrigerant as it alternately absorbs and rejects heat as it circulates through a refrigerator. It is also applied to HVACR work, when describing the "process" of refrigerant flow through an HVACR unit, whether it is a packaged or split system. Fridge redirects here. ...

Heat naturally flows from hot to cold. Work is applied to cool a living space or storage volume by pumping heat from a lower temperature heat source into a higher temperature heat sink. Insulation is used to reduce the work and energy required to achieve and maintain a lower temperature in the cooled space. The operating principle of the refrigeration cycle was described mathematically by Sadi Carnot in 1824 as a heat engine. In physics, mechanical work is the amount of energy transferred by a force. ... Wikimedia Commons has media related to: Thermal insulation Thermal insulation on the Huygens probe Rockwool Insulation, 1600 dpi scan against the grain Rockwool Insulation, 1600 dpi scan with the grain The term thermal insulation can refer to materials used to reduce the rate of heat transfer, or the methods and... Sadi Carnot in the dress uniform of a student of the École polytechnique Nicolas Léonard Sadi Carnot (June 1, 1796 - August 24, 1832) was a French physicist and military engineer who gave the first successful theoretical account of heat engines, now known as the Carnot cycle, thereby laying the... A Carnot heat engine is a hypothetical engine that operates on the reversible Carnot cycle. ...

The most common types of refrigeration systems use the reverse-Rankine vapor-compression refrigeration cycle although absorption heat pumps are used in a minority of applications. Vapor-compression refrigeration[1][2] is one of the many refrigeration methods available for use. ... It has been suggested that this article or section be merged with Absorptive refrigeration The absorption refrigerator is a refrigerator that utilizes a heat source to provide the energy needed to drive the cooling system rather than being dependent on electricity to run a compressor. ...

Cyclic refrigeration can be classified as:

1. Vapor cycle, and
2. Gas cycle

Vapor cycle refrigeration can further be classified as:

1. Vapor compression refrigeration
2. Vapor absorption refrigeration

Vapor-compression cycle

(See Heat pump and refrigeration cycle and Vapor-compression refrigeration for more details)

The vapor-compression cycle is used in most household refrigerators as well as in many large commercial and industrial refrigeration systems. Figure 1 provides a schematic diagram of the components of a typical vapor-compression refrigeration system. Thermodynamic heat pump and refrigeration cycles are the models for heat pumps and refrigerators. ... Vapor-compression refrigeration[1][2] is one of the many refrigeration methods available for use. ...

Figure 1: Vapor compression refrigeration

The thermodynamics of the cycle can be analyzed on a diagram^[8][9] as shown in Figure 2. In this cycle, a circulating refrigerant such as Freon enters the compressor as a vapor. From point 1 to point 2, the vapor is compressed at constant entropy and exits the compressor superheated. From point 2 to point 3 and on to point 4, the superheated vapor travels through the condenser which first cools and removes the superheat and then condenses the vapor into a liquid by removing additional heat at constant pressure and temperature. Between points 4 and 5, the liquid refrigerant goes through the expansion valve (also called a throttle valve) where its pressure abruptly decreases, causing flash evaporation and auto-refrigeration of, typically, less than half of the liquid. Image File history File links Refrigeration. ... Thermodynamics (from the Greek θερμη, therme, meaning heat and δυναμις, dynamis, meaning power) is a branch of physics that studies the effects of changes in temperature, pressure, and volume on physical systems at the macroscopic scale by analyzing the collective motion of their particles using statistics. ... A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume. ... For other uses, see: information entropy (in information theory) and entropy (disambiguation). ... In physics, superheating (sometimes referred to as boiling retardation, boiling delay, or defervescence) is the phenomenon in which a liquid is heated to a temperature higher than its standard boiling point, without actually boiling. ... In systems involving heat transfer, a condenser is a heat exchanger which condenses a substance from its gaseous to its liquid state. ... There are very few or no other articles that link to this one. ... The flash (or partial) evaporation is one of the simplest unit operations. ...

Figure 2: Temperature–Entropy diagram

That results in a mixture of liquid and vapor at a lower temperature and pressure as shown at point 5. The cold liquid-vapor mixture then travels through the evaporator coil or tubes and is completely vaporized by cooling the warm air (from the space being refrigerated) being blown by a fan across the evaporator coil or tubes. The resulting refrigerant vapor returns to the compressor inlet at point 1 to complete the thermodynamic cycle. Image File history File links RefrigerationTS.png‎ Image:RefrigerationTS.jpg with JPEG artifacts removed by a four-line Python program. ...

The above discussion is based on the ideal vapor-compression refrigeration cycle, and does not take into account real-world effects like frictional pressure drop in the system, slight thermodynamic irreversibility during the compression of the refrigerant vapor, or non-ideal gas behavior (if any). A reversible process (or reversible cycle if the process is cyclic) , in thermodynamics, is a process that can be reversed by means of infinitesimal changes in some property of the system (Sears and Salinger, 1986). ... An ideal gas or perfect gas is a hypothetical gas consisting of identical particles of zero volume, with no intermolecular forces, where the constituent atoms or molecules undergo perfectly elastic collisions with the walls of the container and each other and are in constant random motion. ...

More information about the design and performance of vapor-compression refrigeration systems is available in the classic "Perry's Chemical Engineers' Handbook".^[10] Perrys Chemical Engineers Handbook was first published in 1934 and the seventh edition was published in 1997. ...

Vapor absorption cycle

(See Gas absorption refrigerator for more details)

In the early years of the twentieth century, the vapor absorption cycle using water-ammonia systems was popular and widely used but, after the development of the vapor compression cycle, it lost much of its importance because of its low coefficient of performance (about one fifth of that of the vapor compression cycle). Nowadays, the vapor absorption cycle is used only where waste heat is available, where heat is derived from solar collectors, or electricity is unavailable. The absorption refrigerator is a refrigerator that utilizes a heat source to provide the energy needed to drive the cooling system rather than being dependent on electricity to run a compressor. ... The coefficient of performance, or COP (sometimes CP), of a heat pump is the ratio of the output heat to the supplied work or where Q is the useful heat supplied by the condenser and W is the work consumed by the compressor. ... A laundromat in California with solar collectors on the roof. ...

The absorption cycle is similar to the compression cycle, except for the method of raising the pressure of the refrigerant vapor. In the absorption system, the compressor is replaced by an absorber which dissolves the refrigerant in a suitable liquid, a liquid pump which raises the pressure and a generator which, on heat addition, drives off the refrigerant vapor from the high-pressure liquid. Some work is required by the liquid pump but, for a given quantity of refrigerant, it is much smaller than needed by the compressor in the vapor compression cycle. In an absorption refrigerator, a suitable combination of refrigerant and absorbent is used. The most common combinations are ammonia (refrigerant) and water (absorbent), and water (refrigerant) and lithium bromide (absorbent). Lithium bromide, or LiBr, is chemical compound of lithium and bromide that is extremely hygroscopic and often used as a dessicant. ...

Gas cycle

When the working fluid is a gas that is compressed and expanded but doesn't change phase, the refrigeration cycle is called a gas cycle. Air is most often this working fluid. As there is no condensation and evaporation intended in a gas cycle, components corresponding to the condenser and evaporator in a vapor compression cycle are the hot and cold gas-to-gas heat exchangers in gas cycles. Look up air in Wiktionary, the free dictionary. ... A heat exchanger is a device for transferring heat from one fluid to another, where the fluids are separated by a solid wall so that they never mix. ...

The gas cycle is less efficient than the vapor compression cycle because the gas cycle works on the reverse Brayton cycle instead of the reverse Rankine cycle. As such the working fluid does not receive and reject heat at constant temperature. In the gas cycle, the refrigeration effect is equal to the product of the specific heat of the gas and the rise in temperature of the gas in the low temperature side. Therefore, for the same cooling load, a gas refrigeration cycle will require a large mass flow rate and would be bulky. The Brayton cycle is a constant-pressure cycle named after George Brayton (1830–1892), the American engineer who developed it. ... The Rankine cycle is a thermodynamic cycle. ...

Because of their lower efficiency and larger bulk, air cycle coolers are not often used nowadays in terrestrial cooling devices. The air cycle machine is very common, however, on gas turbine-powered jet aircraft because compressed air is readily available from the engines' compressor sections. These jet aircraft's cooling and ventilation units also serve the purpose of pressurizing the aircraft. An Air Cycle Machine (ACM) is the refrigeration unit of the environmental control system used in pressurized turbine-powered aircraft. ... This machine has a single-stage centrifugal compressor and turbine, a recuperator, and foil bearings. ... Flying machine redirects here. ...

Thermoelectric refrigeration

Thermoelectric cooling uses the Peltier effect to create a heat flux between the junction of two different types of materials. This effect is commonly used in camping and portable coolers and for cooling electronic components and small instruments. Thermoelectric cooling uses the Peltier effect to create a heat flux between the junction of two different types of materials. ... The Peltier-Seebeck effect, or thermoelectric effect, is the direct conversion of heat differentials to electric voltage and vice versa. ... flux in science and mathematics. ...

Magnetic refrigeration

Main article: Magnetic refrigeration

Magnetic refrigeration, or adiabatic demagnetization, is a cooling technology based on the magnetocaloric effect, an intrinsic property of magnetic solids. The refrigerant is often a paramagnetic salt, such as cerium magnesium nitrate. The active magnetic dipoles in this case are those of the electron shells of the paramagnetic atoms. Magnetic refrigeration is a cooling technology based on the magnetocaloric effect. ... Adiabatic demagnetization is a technique for attaining temperatures well below 1 kelvin. ... Intrinsic is used to describe a characteristic or property of some thing or action which is specific to that thing or action, and which is wholly independent of any other object, action or consequence. ... Simple Illustration of a paramagnetic probe made up from miniature magnets. ... This article is about common table salt. ... General Name, Symbol, Number cerium, Ce, 58 Chemical series lanthanides Group, Period, Block n/a, 6, f Appearance silvery white Standard atomic weight 140. ... General Name, symbol, number magnesium, Mg, 12 Chemical series alkaline earth metals Group, period, block 2, 3, s Appearance silvery white solid at room temp Standard atomic weight 24. ... Trinitrate redirects here. ... For the indie-pop band, see The Magnetic Fields. ... The Earths magnetic field, which is approximately a dipole. ... Example of a sodium electron shell model An electron shell, also known as a main energy level, is a group of atomic orbitals with the same value of the principal quantum number n. ...

A strong magnetic field is applied to the refrigerant, forcing its various magnetic dipoles to align and putting these degrees of freedom of the refrigerant into a state of lowered entropy. A heat sink then absorbs the heat released by the refrigerant due to its loss of entropy. Thermal contact with the heat sink is then broken so that the system is insulated, and the magnetic field is switched off. This increases the heat capacity of the refrigerant, thus decreasing its temperature below the temperature of the heat sink. For other uses, see: information entropy (in information theory) and entropy (disambiguation). ...

Because few materials exhibit the required properties at room temperature, applications have so far been limited to cryogenics and research. In physics or engineering, cryogenics is the study of the production of very low temperatures (below –150 °C, –238 °F or 123 K) and the behavior of materials at those temperatures. ...

Other methods

Other methods of refrigeration include the air cycle machine used in aircraft; the vortex tube used for spot cooling, when compressed air is available; and thermoacoustic refrigeration using sound waves in a pressurised gas to drive heat transfer and heat exchange. An Air Cycle Machine (ACM) is the refrigeration unit of the environmental control system used in pressurized turbine-powered aircraft. ... The vortex tube, also known as the Ranque-Hilsch vortex tube, is a mechanical device that separates gas into hot and cold streams. ... Sonic or thermoacoustic refrigeration is a technology that uses high-amplitude sound waves in a pressurised gas to pump heat from one place to another. ...

Unit of refrigeration

Domestic and commercial refrigerators may be rated in kJ/s, or Btu/h of cooling. Commercial refrigerators in the US are mostly rated in tons of refrigeration, but elsewhere in kW. One ton of refrigeration capacity can freeze one short ton of water at 0 °C (32 °F) in 24 hours. Based on that: A kilojoule (abbreviation: kJ) is a unit of energy equal to 1000 joules. ... The British thermal unit (BTU or Btu) is a unit of energy used in the Power, Steam Generation and Heating and Air Conditioning industry globally. ... Look up ton in Wiktionary, the free dictionary. ... The short ton is a unit of mass equal to 907. ...

Latent heat of ice (i.e., heat of fusion) = 333.55 kJ/kg ≈ 144 Btu/lb

One short ton = 2000 lb

Heat extracted = (2000)(144)/24 hr = 288000 Btu/24 hr = 12000 Btu/hr = 200 Btu/min

1 ton refrigeration = 200 Btu/min = 3.517 kJ/s = 3.517 kW^[11]

A much less common definition is: 1 tonne of refrigeration is the rate of heat removal required to freeze a metric ton (i.e., 1000 kg) of water at 0 °C in 24 hours. Based on the heat of fusion being 333.55 kJ/kg, 1 tonne of refrigeration = 13,898 kJ/h = 3.861 kW. As can be seen, 1 tonne of refrigeration is 10% larger than 1 ton of refrigeration. Heat of fusion is the amount of heat energy which must be absorbed or lost for 1 gram of a substance to change states from a solid to a liquid or vice versa. ... Look up pound in Wiktionary, the free dictionary. ... The kilowatt (symbol: kW) is a unit for measuring power, equal to one thousand watts. ... This article is about the metric tonne. ... This article is about the metric tonne. ... For other uses, see Celsius (disambiguation). ... Heat of fusion is the amount of heat energy which must be absorbed or lost for 1 gram of a substance to change states from a solid to a liquid or vice versa. ...

Most residential air conditioning units range in capacity from about 1 to 5 tons of refrigeration.

See also

Einstein and Szilárds patent application. ... A freezer is a home appliance, usually found above the refrigerator that keeps foods frozen. ... A heat pump is a machine or device that moves heat from one location (the source) to another location (the sink), using work. ... HVAC may also stand for High-voltage alternating current HVAC systems use ventilation air ducts installed throughout a building that supply conditioned air to a room through rectangular or round outlet vents, called diffusers; and ducts that remove air from return-air grilles Fire-resistance rated mechanical shaft with HVAC... The inside of a fridge A refrigerator (sometimes shortened to fridge) is an electrical appliance that uses refrigeration to help preserve food. ... Vintage Ice Cream Truck in Harper Woods, Michigan, USA. An ice cream van (British) or ice cream truck (American) is a commercial vehicle which serves as a travelling retail outlet for ice cream, usually during the summer. ... Icyball was a small refrigeration system marketed to homes and businesses without electricity. ... Laser cooling is a technique that uses light to cool atoms to a very low temperature. ... The pot-in-pot refrigerator, also known as a Zeer pot is a way of keeping food cool without electricity. ... A refrigerant is a compound used in a heat cycle that undergoes a phase change from a gas to a liquid and back. ... A refrigeration cycle describes the changes that take place to a refrigerant in absorbing heat and subsequently radiating it as it is circulated around a refrigerator. ... Fridge redirects here. ... A string of refrigerator cars owned by Pacific Fruit Express is mechanically-supplied with fresh ice at an Oxnard, California produce packing plant in the Spring of 1964. ... The reefer is a type of ship typically used to transport perishable commodities which require temperature-controlled transportation, mostly fruits, meat, fish, vegetables, dairy products and other foodstuffs. ... Containers loaded on a container ship with the refrigeration units visible A reefer is a refrigerated container used in intermodal freight transport for transportation of temperature sensitive cargo. ... Seasonal Energy Efficiency Ratio (SEER) is a measurement of efficiency for cooling devices such as heat pumps and air conditioners. ... Timeline of low-temperature technology c. ... Vapor-compression refrigeration[1][2] is one of the many refrigeration methods available for use. ... There are very few or no other articles that link to this one. ...

References

“PDF” redirects here. ... A kibibyte (a contraction of kilo binary byte) is a unit of information or computer storage, commonly abbreviated KiB (never kiB). 1 kibibyte = 210 bytes = 1,024 bytes The kibibyte is closely related to the kilobyte, which can be used either as a synonym for kibibyte or to refer to... “PDF” redirects here. ... A kibibyte (a contraction of kilo binary byte) is a unit of information or computer storage, commonly abbreviated KiB (never kiB). 1 kibibyte = 210 bytes = 1,024 bytes The kibibyte is closely related to the kilobyte, which can be used either as a synonym for kibibyte or to refer to... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 140th day of the year (141st in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 140th day of the year (141st in leap years) in the Gregorian calendar. ... The University of California, Irvine is a public coeducational research university situated in Irvine, California. ... Perrys Chemical Engineers Handbook was first published in 1934 and the seventh edition was published in 1997. ...

Additional reading

• Refrigeration volume, ASHRAE Handbook, ASHRAE, Inc., Atlanta, GA
• Stoecker and Jones, Refrigeration and Air Conditioning, Tata-McGraw Hill Publishers
• Mathur, M.L., Mehta, F.S., Thermal Engineering Vol II
• MSN Encarta Encyclopedia
• Andrew D. Althouse, Carl H. Turnquist, Alfred F. Bracciano (2003). Modern Refrigeration and Air Conditioning, 18th Edition, Goodheart-Wilcox Publishing. ISBN 1590702808. 
• Anderson, Oscar Edward (1972). Refrigeration in America: A history of a new technology and its impact. Kennikat Press, 344. ISBN 0804616213. 
• Shachtman, Tom (2000-12-12). Absolute Zero: And the Conquest of Cold. Mariner Books, 272. ISBN 0618082395. 
• Woolrich, Willis Raymond (1967). The men who created cold: A history of refrigeration,, [1st ed.], Exposition Press, 212. 

External links

• "The Refrigeration Cycle", from HowStuffWorks
• American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE)
• British Institute of Refrigeration
• Refrigerant Recovery Environment Services
• "Notes on vapor-compression refrigeration", Queens University (Canada)
• "The ideal vapor compression refrigeration cycle", University of Nevada (US)
• Refrigeration History
• Scroll down to "Continuous-Cycle Absorption System"
• US Department of Energy: Technology Basics of Absorption Cycles
• Calendar of Inventive Contributors to the Development of Refrigeration, 1748-1885, a short history of the evolution of the refrigerator.
• Refrigeration (from The Handbook of Texas Online)