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Vapour-compression refrigeration or vapor-compression refrigeration system (VCRS), in which the refrigerant undergoes
phase change In chemistry, thermodynamics, and other related fields, a phase transition (or phase change) is the physical process of transition between one state of a medium and another. Commonly the term is used to refer to changes among the basic State of ...
s, is one of the many
refrigeration cycle Thermodynamic heat pump cycles or refrigeration cycles are the conceptual and mathematical models for heat pump, air conditioning and refrigeration systems. A heat pump is a mechanical system that allows for the transmission of heat from one locat ...
s and is the most widely used method for
air conditioning Air conditioning, often abbreviated as A/C or AC, is the process of removing heat from an enclosed space to achieve a more comfortable interior environment (sometimes referred to as 'comfort cooling') and in some cases also strictly controlling ...
of buildings and automobiles. It is also used in domestic and commercial refrigerators, large-scale warehouses for chilled or frozen storage of foods and meats, refrigerated trucks and railroad cars, and a host of other commercial and industrial services. Oil refineries, petrochemical and
chemical A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., w ...
processing plants, and natural gas processing plants are among the many types of industrial plants that often utilize large vapor-compression refrigeration systems. Cascade refrigeration systems may also be implemented using two compressors. Refrigeration may be defined as lowering the temperature of an enclosed space by removing heat from that space and transferring it elsewhere. A device that performs this function may also be called an air conditioner, refrigerator,
air source heat pump An air source heat pump (ASHP) is a type of heat pump that can absorb heat from outside a structure and release it inside using the same vapor-compression refrigeration process and much the same equipment as air conditioners but used in the oppo ...
, geothermal heat pump, or chiller (
heat pump A heat pump is a device that can heat a building (or part of a building) by transferring thermal energy from the outside using a refrigeration cycle. Many heat pumps can also operate in the opposite direction, cooling the building by removing ...
).


Description of the vapor-compression refrigeration system

Vapor-compression uses a circulating liquid refrigerant as the medium which absorbs and removes heat from the space to be cooled and subsequently rejects that heat elsewhere. Figure 1 depicts a typical, single-stage vapor-compression system. All such systems have four components: a compressor, a condenser, a metering device or
thermal expansion valve A thermal expansion valve or thermostatic expansion valve (often abbreviated as TEV, TXV, or TX valve) is a component in vapor-compression refrigeration and air conditioning systems that controls the amount of refrigerant released into the evapo ...
(also called a
throttle A throttle is the mechanism by which fluid flow is managed by constriction or obstruction. An engine's power can be increased or decreased by the restriction of inlet gases (by the use of a throttle), but usually decreased. The term ''throttle'' ...
valve), and an evaporator. Circulating refrigerant enters the compressor in the thermodynamic state known as a
saturated vapor Vapor pressure (or vapour pressure in English-speaking countries other than the US; see spelling differences) or equilibrium vapor pressure is defined as the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phase ...
and is compressed to a higher pressure, resulting in a higher temperature as well. The hot, compressed vapor is then in the thermodynamic state known as a superheated vapor and it is at a temperature and pressure at which it can be condensed with either cooling water or cooling air flowing across the coil or tubes. The superheated vapor then passes through the condenser. This is where heat is transferred from the circulating refrigerant to an external medium, allowing the gaseous refrigerant to cool and
condense Condensation is the change of the state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle. It can also be defined as the change in the state of water vapor to ...
into a liquid. The rejected heat is carried away by either the water or the air, depending on the type of condenser. The condensed liquid refrigerant, in the thermodynamic state known as a saturated liquid, is next routed through an expansion valve where it undergoes an abrupt reduction in pressure. That pressure reduction results in the adiabatic
flash evaporation Flash evaporation (or partial evaporation) is the partial vapor that occurs when a saturated liquid stream undergoes a reduction in pressure by passing through a throttling valve or other throttling device. This process is one of the simplest un ...
of a part of the liquid refrigerant. The auto-refrigeration effect of the adiabatic flash evaporation lowers the temperature of the liquid and vapor refrigerant mixture to where it is colder than the temperature of the enclosed space to be refrigerated. The cold refrigerant liquid and vapor mixture is then routed through the coil or tubes in the evaporator. Air in the enclosed space circulates across the coil or tubes due to either thermal
convection Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the conve ...
or a fan. Since the air is warmer than the cold liquid refrigerant, heat is transferred which cools the air and causes evaporation of the liquid, returning it to a gaseous state whilst absorbing heat. While liquid remains in the refrigerant flow, its temperature will not rise above the boiling point of the refrigerant, which depends on the pressure in the evaporator. Most systems are designed to evaporate all of the refrigerant to ensure that no liquid is returned to the compressor. To complete the
refrigeration cycle Thermodynamic heat pump cycles or refrigeration cycles are the conceptual and mathematical models for heat pump, air conditioning and refrigeration systems. A heat pump is a mechanical system that allows for the transmission of heat from one locat ...
, the refrigerant vapor from the evaporator is again a saturated vapor and is routed back into the compressor. Over time, the evaporator may collect ice or water from ambient humidity. The ice is melted through defrosting. The water from the melted ice or the evaporator then drips into a drip pan, and the water is carried away by gravity or a condensate pump.


Refrigerants

The
selection Selection may refer to: Science * Selection (biology), also called natural selection, selection in evolution ** Sex selection, in genetics ** Mate selection, in mating ** Sexual selection in humans, in human sexuality ** Human mating strateg ...
of working fluid has a significant impact on the performance of the refrigeration cycles and as such it plays a key role when it comes to designing or simply choosing an ideal machine for a certain task. One of the most widespread refrigerants is "
Freon Freon ( ) is a registered trademark of the Chemours Company and generic descriptor for a number of halocarbon products. They are stable, nonflammable, low toxicity gases or liquids which have generally been used as refrigerants and as aerosol prope ...
". Freon is a trade name for a family of haloalkane refrigerants manufactured by DuPont and other companies. These refrigerants were commonly used due to their superior stability and safety properties: they were not flammable at room temperature and atmospheric pressure, nor obviously toxic as were the fluids they replaced, such as sulfur dioxide. Haloalkanes are also an order(s) of magnitude more expensive than petroleum-derived flammable alkanes of similar or better cooling performance. Unfortunately, chlorine- and fluorine-bearing refrigerants reach the upper atmosphere when they escape. In the stratosphere, substances like CFCs and
HCFC Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are fully or partly halogenated hydrocarbons that contain carbon (C), hydrogen (H), chlorine (Cl), and fluorine (F), produced as volatile derivatives of methane, ethane, and propa ...
s break up due to UV radiation, releasing their chlorine free-radicals. These chlorine free-radicals act as
catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...
s in the breakdown of ozone through chain reactions. One CFC molecule can cause thousands of ozone molecules to break down. This causes severe damage to the ozone layer that shields the Earth's surface from the Sun's strong UV radiation and has been shown to lead to increased rates of skin cancer. The chlorine will remain active as a catalyst until and unless it binds with another particle, forming a stable molecule. CFC refrigerants in common but receding usage include R-11 and R-12. Newer refrigerants with reduced ozone depletion effect such as
HCFC Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are fully or partly halogenated hydrocarbons that contain carbon (C), hydrogen (H), chlorine (Cl), and fluorine (F), produced as volatile derivatives of methane, ethane, and propa ...
s ( R-22, used in most homes today) and HFCs ( R-134a, used in most cars) have replaced most CFC use. HCFCs in turn are being phased out under the
Montreal Protocol The Montreal Protocol is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion. It was agreed on 16 September 1987, and entered into force o ...
and replaced by hydrofluorocarbons (HFCs), that do not contain
chlorine Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine i ...
atoms. Small example of common HFCs in current use:
R-410A R-410A, sold under the trademarked names AZ-20, EcoFluor R410, Forane 410A, Genetron R410A, Puron, and Suva 410A, is a zeotropic but near- azeotropic mixture of difluoromethane (CH2F2, called R-32) and pentafluoroethane (CHF2CF3, called R-125) tha ...
(which is itself a blend of other HFCs: R-32 and R-125) ; designed to be a drop-in replacement for R-22 in existing installations and
R-404A A refrigerant is a working fluid used in the refrigeration cycle of air conditioning systems and heat pumps where in most cases they undergo a repeated phase transition from a liquid to a gas and back again. Refrigerants are heavily regulated du ...
(blend of HFCs: R-125, R-134a, and
R-143a 1,1,1-Trifluoroethane, or R-143a or simply trifluoroethane, is a hydrofluorocarbon (HFC) compound that is a colorless gas. It should not be confused with the much more commonly used HFC gas R-134a, nor confused with the isomeric compound 1,1,2-tr ...
, and was developed as a substitute refrigerant for R-502 and R-22). However, CFCs, HCFCs, and HFCs all have very large
global warming potential Global warming potential (GWP) is the heat absorbed by any greenhouse gas in the atmosphere, as a multiple of the heat that would be absorbed by the same mass of carbon dioxide (). GWP is 1 for . For other gases it depends on the gas and the time ...
(GWP). More benign refrigerants are currently the subject of research, such as supercritical
carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
, known as
R-744 Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon diox ...
. These have similar efficiencies compared to existing CFC- and HFC-based compounds, and have many orders of magnitude lower global warming potential. General industry and governing body push are toward more GWP-friendly refrigerants. In industrial settings
ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...
, as well gasses like ethylene, propane, iso-butane and other
hydrocarbons In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or e ...
are commonly used (and have own R-x customary numbers), depending on required temperatures and pressures. Many of these gases are unfortunately flammable, explosive, or toxic; making their use restricted (i.e. well-controlled environment by qualified personnel, or a very small amount of refrigerant used). HFOs which can be considered to be HFC with some carbon-carbon bonds being double bounds, do show promise of lowering GWP very low to be of no further concern. In the meantime, various blends of existing refrigerants are used to achieve the required properties and efficiency, at a reasonable cost and lower GWP.


Thermodynamic analysis of the system

The
thermodynamics Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of th ...
of the vapor compression cycle can be analyzed on a temperature versus
entropy Entropy is a scientific concept, as well as a measurable physical property, that is most commonly associated with a state of disorder, randomness, or uncertainty. The term and the concept are used in diverse fields, from classical thermodynam ...
diagram as depicted in Figure 2. At point 1 in the diagram, the circulating refrigerant enters the compressor as a saturated vapor. From point 1 to point 2, the vapor is isentropically compressed (compressed at constant entropy) and exits the compressor as a superheated vapor. Superheat is the amount of heat added above the boiling point. From point 2 to point 3, the vapor travels through part of the condenser which removes the superheat by cooling the vapor. Between point 3 and point 4, the vapor travels through the remainder of the condenser and is condensed into a saturated liquid. The condensation process occurs at essentially constant pressure. Between points 4 and 5, the saturated liquid refrigerant passes through the expansion valve and undergoes an abrupt decrease of pressure. That process results in the adiabatic flash evaporation and auto-refrigeration of a portion of the liquid (typically, less than half of the liquid flashes). The adiabatic flash evaporation process is isenthalpic (occurs at constant enthalpy). Between points 5 and 1, the cold and partially vaporized refrigerant travels through the coil or tubes in the evaporator where it is totally vaporized by the warm air (from the space being refrigerated) that a fan circulates across the coil or tubes in the evaporator. The evaporator operates at essentially constant pressure and boils off all available liquid there after adding 4–8
kelvin The kelvin, symbol K, is the primary unit of temperature in the International System of Units (SI), used alongside its prefixed forms and the degree Celsius. It is named after the Belfast-born and University of Glasgow-based engineer and phy ...
s of superheat to the refrigerant in order to make sure the liquid has evaporated completely. This is a safeguard for the compressor, as it cannot pump liquid. The resulting refrigerant vapor returns to the compressor inlet at point 1 to complete the thermodynamic cycle. The above discussion is based on the ideal vapor-compression refrigeration cycle which does not take into account real world items like frictional pressure drop in the system, slight internal irreversibility during the compression of the refrigerant vapor, or non-ideal gas behavior (if any).


Types of gas compressors

The most common compressors used in refrigeration are reciprocating and scroll compressors, but large chillers or industrial cycles may use rotary screw or centrifugal compressors. Each application prefers one or another due to size, noise, efficiency, and pressure issues. Compressors are often described as being either open,
hermetic Hermetic or related forms may refer to: * of or related to the ancient Greek Olympian god Hermes * of or related to Hermes Trismegistus, a legendary Hellenistic figure based on the Greek god Hermes and the Egyptian god Thoth ** , the ancient and m ...
, or semi-hermetic, to describe how the compressor and/or motor is situated in relation to the refrigerant being compressed. Variations of motor/compressor types can lead to the following configurations: *Hermetic motor, hermetic compressor *Hermetic motor, semi-hermetic compressor *Open motor (belt driven or close coupled), hermetic compressor *Open motor (belt driven or close coupled), semi-hermetic compressor Typically in hermetic, and most semi-hermetic compressors (sometimes known as accessible hermetic compressors), the compressor and motor driving the compressor are integrated, and operate within the refrigerant system. The motor is hermetic and is designed to operate, and be cooled by, the refrigerant being compressed. The obvious disadvantage of hermetic motor compressors is that the motor drive cannot be maintained in situ, and the entire compressor must be removed if a motor fails. A further disadvantage is that burnt out windings can contaminate whole refrigeration systems requiring the system to be entirely pumped down, and the refrigerant replaced. An open compressor has a motor drive which is outside of the refrigeration system, and provides drive to the compressor by means of an input shaft with suitable gland seals. Open compressor motors are typically air-cooled and can be fairly easily exchanged or repaired without degassing of the refrigeration system. The disadvantage of this type of compressor is a failure of the shaft seals, leading to loss of refrigerant. Open motor compressors are generally easier to cool (using ambient air) and therefore tend to be simpler in design and more reliable, especially in high pressure applications where compressed gas temperatures can be very high. However the use of liquid injection for additional cooling can generally overcome this issue in most hermetic motor compressors.


Reciprocating compressors

Reciprocating compressors are piston-style, positive displacement compressors.


Rotary screw compressors

Rotary screw compressors are also positive displacement compressors. Two meshing screw-rotors rotate in opposite directions, trapping refrigerant vapor, and reducing the volume of the refrigerant along the rotors to the discharge point. Small units are not practical due to back-leakage but large units have very high efficiency and flow capacity.


Centrifugal compressors

Centrifugal compressors are dynamic compressors. These compressors raise the pressure of the refrigerant by imparting velocity or dynamic energy, using a rotating impeller, and converting it to pressure energy.


Centrifugal Compressor Surge

Chillers with centrifugal compressors have a 'Centrifugal Compressor Map' that shows the "surge line" and the "choke line." For the same capacity ratings, across a wider span of operating conditions, chillers with the larger diameter lower-speed compressor have a wider 'Centrifugal Compressor Map' and experience surge conditions less than those with the smaller diameter, less expensive, higher-speed compressors. The smaller diameter, higher-speed compressors have a flatter curve., As the refrigerant flow rate decreases, some compressors change the gap between the impeller and the volute to maintain the correct velocity to avoid surge conditions.


Scroll compressors

Scroll compressors are also positive displacement compressors. The refrigerant is compressed when one spiral orbits around a second stationary spiral, creating smaller and smaller pockets and higher pressures. By the time the refrigerant is discharged, it is fully pressurized.


Others

File:Diaphram pump.svg, Diaphragm pump File:TF30 Side Cut Compressor HP.jpeg, Axial-flow compressor of a jet engine File:Liquid ring.png, Liquid ring File:Roots blower - 2 lobes.svg, Roots blower


Compressor lubrication

In order to lubricate the moving parts of the compressor, oil is added to the refrigerant during installation or commissioning. The type of oil may be mineral or synthetic to suit the compressor type, and also chosen so as not to react with the refrigerant type and other components in the system. In small refrigeration systems the oil is allowed to circulate throughout the whole circuit, but care must be taken to design the pipework and components such that oil can drain back under gravity to the compressor. In larger more distributed systems, especially in retail refrigeration, the oil is normally captured at an oil separator immediately after the compressor, and is in turn re-delivered, by an oil level management system, back to the compressor(s). Oil separators are not 100% efficient so system pipework must still be designed so that oil can drain back by gravity to the oil separator or compressor. Some newer compressor technologies use
magnetic bearing A magnetic bearing is a type of bearing that supports a load using magnetic levitation. Magnetic bearings support moving parts without physical contact. For instance, they are able to levitate a rotating shaft and permit relative motion with v ...
s or air bearings and require no lubrication, for example the
Danfoss Danfoss is a Danish multinational company, based in Denmark, with more than 40,043 employees globally. Danfoss was founded in 1933 by engineer Mads Clausen. History Beginning (1933–1966) In 1933 Mads Clausen (1905–1966) founded ''Dansk ...
Turbocor range of centrifugal compressors. Avoiding the need for oil lubrication and the design requirements and ancillaries associated with it, simplifies the design of the refrigerant system, increases the heat transfer coefficient in evaporators and condensers, eliminates the risk of refrigerant being contaminated with oil, and reduces maintenance requirements.


Control

In simple commercial refrigeration systems the compressor is normally controlled by a simple pressure switch, with the expansion performed by a capillary tube or
thermal expansion valve A thermal expansion valve or thermostatic expansion valve (often abbreviated as TEV, TXV, or TX valve) is a component in vapor-compression refrigeration and air conditioning systems that controls the amount of refrigerant released into the evapo ...
. In more complex systems, including multiple compressor installations, the use of electronic controls is typical, with adjustable set points to control the pressure at which compressors cut in and cut out, and temperature control by the use of electronic expansion valves. In addition to the operational controls, separate high-pressure and low-pressure switches are normally utilised to provide secondary protection to the compressors and other components of the system from operating outside of safe parameters. In more advanced electronic control systems the use of floating head pressure, and proactive suction pressure, control routines allow the compressor operation to be adjusted to accurately meet differing cooling demands while reducing energy consumption.


Other features and facts of interest

The schematic diagram of a single-stage refrigeration system shown in Figure 1 does not include other equipment items that would be provided in a large commercial or industrial vapor compression refrigeration system, such as: *A horizontal or vertical pressure vessel, equipped internally with a demister, between the evaporator and the compressor inlet to capture and remove any residual, entrained liquid in the refrigerant vapor because liquid may damage the compressor. Such vapor-liquid separators are most often referred to as "suction line accumulators". (In other industrial processes, they are called "compressor suction drums" or "knockout pots".) *Large commercial or industrial refrigeration systems may have multiple expansion valves and multiple evaporators in order to refrigerate multiple enclosed spaces or rooms. In such systems, the condensed liquid refrigerant may be routed into a pressure vessel, called a receiver, from which liquid refrigerant is withdrawn and routed through multiple pipelines to the multiple expansion valves and evaporators. *Filter Dryers, installed before the compressors to catch any moisture or contaminants in the system and thus protect the compressors from internal damage *Some refrigeration units may have multiple stages which requires the use of multiple compressors in various arrangements. In most of the world, the
cooling capacity Cooling capacity is the measure of a cooling system's ability to remove heat. It is equivalent to the heat supplied to the evaporator/boiler part of the refrigeration cycle and may be called the "rate of refrigeration" or "refrigeration capacity". ...
of refrigeration systems is measured in
watt The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after James ...
s. Common residential air conditioning units range in capacity from 3.5 to 18 kilowatt. In a few countries it is measured in " tons of refrigeration", with common residential air conditioning units from about 1 to 5 tons of refrigeration.


Applications


Economic analysis


Advantages

*Very mature technology. *Relatively inexpensive. *Can be driven directly using mechanical energy (water, car or truck motor) or with electrical energy. *Efficient up to 60% of Carnot's theoretical limit (as evaluated in
ASHRAE The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE ) is an American professional association seeking to advance heating, ventilation, air conditioning and refrigeration The term refrigeration refers to the ...
testing conditions: evaporation temperature of −23.3 °C, condensing temperature of 54.4 °C, and ambient temperature of 32 °C) based on some of the best commercially available compressors, as produced by manufacturers
Danfoss Danfoss is a Danish multinational company, based in Denmark, with more than 40,043 employees globally. Danfoss was founded in 1933 by engineer Mads Clausen. History Beginning (1933–1966) In 1933 Mads Clausen (1905–1966) founded ''Dansk ...
, Matsushita
Copeland
Embraco
Bristol
and Tecumseh. However, many refrigeration systems use compressors that have lower efficiencies of between 40 and 55%, since the 60% efficient ones cost almost twice as much as the lower efficiency ones.


Disadvantages

Many systems still use
HCFC Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are fully or partly halogenated hydrocarbons that contain carbon (C), hydrogen (H), chlorine (Cl), and fluorine (F), produced as volatile derivatives of methane, ethane, and propa ...
refrigerants, which contribute to depletion of the Earth's ozone layer. In countries adhering to the
Montreal Protocol The Montreal Protocol is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion. It was agreed on 16 September 1987, and entered into force o ...
, HCFCs are due to be phased out and are largely being replaced by ozone-friendly HFCs. However, systems using HFC refrigerants tend to be slightly less efficient than systems using HCFCs. HFCs also have an extremely large
global warming potential Global warming potential (GWP) is the heat absorbed by any greenhouse gas in the atmosphere, as a multiple of the heat that would be absorbed by the same mass of carbon dioxide (). GWP is 1 for . For other gases it depends on the gas and the time ...
, because they remain in the atmosphere for many years and trap heat more effectively than
carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
. With the ultimate phasing out of HCFCs already a certainty, alternative non- haloalkane refrigerants are gaining popularity. In particular, once-abandoned refrigerants such as
hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ...
s ( butane for example) and CO2 are coming back into more extensive use. For example,
Coca-Cola Coca-Cola, or Coke, is a carbonated soft drink manufactured by the Coca-Cola Company. Originally marketed as a temperance drink and intended as a patent medicine, it was invented in the late 19th century by John Stith Pemberton in Atlant ...
's vending machines at the
2006 FIFA World Cup The 2006 FIFA World Cup, also branded as Germany 2006, was the 18th FIFA World Cup, the quadrennial international football world championship tournament. It was held from 9 June to 9 July 2006 in Germany, which had won the right to host th ...
in Germany used refrigeration utilizing CO2.
Ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...
(NH3) is one of the oldest refrigerants, with excellent performance and essentially no pollution problems. However, ammonia has two disadvantages: it is toxic and it is incompatible with copper tubing.


History

In 1805, the American inventor
Oliver Evans Oliver Evans (September 13, 1755 – April 15, 1819) was an American inventor, engineer and businessman born in rural Delaware and later rooted commercially in Philadelphia. He was one of the first Americans building steam engines and an advoca ...
described a closed vapor-compression refrigeration cycle for the production of ice by ether under vacuum. Heat would be removed from the environment by recycling vaporized refrigerant, where it would move through a compressor and condenser, and would eventually revert to a liquid form in order to repeat the refrigeration process over again. However, no such refrigeration unit was built by Evans. In 1834, an American expatriate to Great Britain,
Jacob Perkins Jacob Perkins (9 July 1766 – 30 July 1849) was an American inventor, mechanical engineer and physicist. Born in Newburyport, Massachusetts, Perkins was apprenticed to a goldsmith. He soon made himself known with a variety of useful mechanical i ...
, built the first working vapor-compression refrigeration system in the world. It was a closed-cycle that could operate continuously, as he described in his patent: :I am enabled to use volatile fluids for the purpose of producing the cooling or freezing of fluids, and yet at the same time constantly condensing such volatile fluids, and bringing them again into operation without waste. His prototype system worked although it did not succeed commercially. A similar attempt was made in 1842, by American physician,
John Gorrie John B. Gorrie (October 3, 1803 – June 29, 1855) was a Nevisian-born American physician and scientist, credited as the inventor of mechanical refrigeration. Early life Born on the Island of Nevis in the Leeward Islands of the West Indies t ...
, who built a working prototype, but it was a commercial failure. American engineer Alexander Twining took out a British patent in 1850 for a vapor compression system that used ether. The first practical vapor compression refrigeration system was built by James Harrison, a British journalist who had emigrated to Australia. His 1856 patent was for a vapor compression system using ether, alcohol or ammonia. He built a mechanical ice-making machine in 1851 on the banks of the Barwon River at Rocky Point in Geelong,
Victoria Victoria most commonly refers to: * Victoria (Australia), a state of the Commonwealth of Australia * Victoria, British Columbia, provincial capital of British Columbia, Canada * Victoria (mythology), Roman goddess of Victory * Victoria, Seychelle ...
, and his first commercial ice-making machine followed in 1854. Harrison also introduced commercial vapor-compression refrigeration to breweries and meat packing houses and, by 1861, a dozen of his systems were in operation in Australia and England. The first gas absorption refrigeration system using gaseous ammonia dissolved in water (referred to as "aqua ammonia") was developed by
Ferdinand Carré Ferdinand Philippe Edouard Carré (11 March 1824 – 11 January 1900) was a French engineer, born at Moislains (Somme) on 11 March 1824. Carré is best known as the inventor of refrigeration equipment used to produce ice. He died on 11 January 19 ...
of France in 1859 and patented in 1860.
Carl von Linde Carl Paul Gottfried von Linde (11 June 1842 – 16 November 1934) was a German scientist, engineer, and businessman. He discovered a refrigeration cycle and invented the first industrial-scale air separation and gas liquefaction processes, whi ...
, an engineering professor at the Technological University Munich in Germany, patented an improved method of liquefying gases in 1876. His new process made possible using gases such as
ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...
, sulfur dioxide , and methyl chloride (CH3Cl) as refrigerants and they were widely used for that purpose until the late 1920s.


See also

*
Absorption refrigerator An absorption refrigerator is a refrigerator that uses a heat source (e.g., solar energy, a fossil-fueled flame, waste heat from factories, or district heating systems) to provide the energy needed to drive the cooling process. The system uses tw ...
**
Einstein refrigerator 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 form ...
*
Air conditioning Air conditioning, often abbreviated as A/C or AC, is the process of removing heat from an enclosed space to achieve a more comfortable interior environment (sometimes referred to as 'comfort cooling') and in some cases also strictly controlling ...
*
Flash evaporation Flash evaporation (or partial evaporation) is the partial vapor that occurs when a saturated liquid stream undergoes a reduction in pressure by passing through a throttling valve or other throttling device. This process is one of the simplest un ...
*
Heat pump A heat pump is a device that can heat a building (or part of a building) by transferring thermal energy from the outside using a refrigeration cycle. Many heat pumps can also operate in the opposite direction, cooling the building by removing ...
* Heating, ventilation, and air conditioning (HVAC) * Magnetic refrigeration * Refrigerant *
Refrigeration The term refrigeration refers to the process of removing heat from an enclosed space or substance for the purpose of lowering the temperature.International Dictionary of Refrigeration, http://dictionary.iifiir.org/search.phpASHRAE Terminology, ht ...
*
Refrigeration cycle Thermodynamic heat pump cycles or refrigeration cycles are the conceptual and mathematical models for heat pump, air conditioning and refrigeration systems. A heat pump is a mechanical system that allows for the transmission of heat from one locat ...
* Working fluid


References


Further reading

*


External links


"The ideal vapor compression refrigeration cycle", University of Nevada (US)
* ttps://home.howstuffworks.com/refrigerator4.htm "The Refrigeration Cycle", from HowStuffWorksbr>Scientific papers about CO2 heat pumps and refrigeration
{{Authority control American inventions Chemical processes Cooling technology Gas technologies Heating, ventilation, and air conditioning Industrial gases Industrial processes Thermodynamic cycles