Refrigeration is the process of removing heat In physics and thermodynamics, heat is the process of energy transfer from one body or system to another due to thermal contact, which in turn is defined as an energy transfer to a body in any other way than due to work performed on the body from an enclosed space, or from a substance, and moving it to a place where it is unobjectionable. The primary purpose of refrigeration is lowering the temperature of the enclosed space or substance and then maintaining that lower temperature. The term cooling Cooling is the transfer of thermal energy via thermal radiation, heat conduction or convection. It may also refer to: 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 In physics, cryogenics is the study of the production of very low temperature and the behavior of materials at those temperatures. A person who studies elements under extremely cold temperature is called a cryogenicist. Rather than the relative temperature scales of Celsius and Fahrenheit, cryogenicists use the absolute temperature scales. These.

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 The second law of thermodynamics is an expression of the universal principle of entropy, stating that the entropy of an isolated system which is not in equilibrium will tend to increase over time, approaching a maximum value at equilibrium; and that the entropy change dS of a system undergoing any infinitesimal reversible process is given by δq /, some form of work must be performed to accomplish this. The work is traditionally done by mechanical work In physics, mechanical work is the amount of energy transferred by a force acting through a distance. Like energy, it is a scalar quantity, with SI units of joules. The term work was first coined in 1826 by the French mathematician Gaspard-Gustave Coriolis but can also be done by magnetism Magnetism, a non-contact force, is a category of behaviour of materials that respond at an atomic or subatomic level to an applied magnetic field. For example, the most well known form of magnetism is ferromagnetism such that some ferromagnetic materials produce their own persistent magnetic field. However, all materials are influenced to greater, laser Light Amplification by Stimulated Emission of Radiation is a mechanism for emitting electromagnetic radiation, often visible light, via the process of stimulated emission. The emitted laser light is (usually) a spatially coherent, narrow low-divergence beam, that can be manipulated with lenses. In laser technology, "coherent light" or other means.

Historical applications

Ice harvesting

The use of ice Ice, technically, may be any one of the 15 known crystalline phases of water. In non-scientific contexts, the term usually means the phase known as ice Ih, which is the most abundant of these solid phases on the earth's surface. It can appear transparent or opaque bluish-white colour, depending on the presence of impurities or air inclusions. The 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 A dugout or dug-out, also known as a pithouse, pit-house, earth lodge, mud hut, is a shelter for humans or domestic animals based on a hole or depression dug into the ground. These structures are one of the most ancient types of human housing known to archeologists. Dugouts can be fully recessed into the earth, with a flat roof covered by ground, lined with straw Straw is an agricultural by-product, the dry stalks of cereal plants, after the grain and chaff have been removed. Straw makes up about half of the yield of cereal crops such as barley, oats, rice, rye and wheat. It has many uses, including fuel, livestock bedding and fodder, thatching and basket-making or other insulating materials. The Persians stored ice in pits called yakhchals A yakh-chāl (Persian:یخچال) is an ancient type of refrigerator. Rationing of the ice allowed the preservation of foods over the warm periods. This practice worked well down through the centuries, with icehouses Ice houses originally invented in Persia were buildings used to store ice throughout the year, prior to the invention of the refrigerator. The most common designs involved underground chambers, usually man-made, which were built close to natural sources of winter ice such as freshwater lakes remaining in use into the twentieth century.

In the 16th century, the discovery of chemical refrigeration was one of the first steps toward artificial means of refrigeration. Sodium nitrate Sodium nitrate is the chemical compound with the formula NaNO3. This salt, also known as "Chile saltpeter" or "Peru saltpeter" , is a white solid which is very soluble in water. The mineral form is also known as nitratine or soda niter or potassium nitrate Potassium nitrate is a chemical compound with the chemical formula K , 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 and cakes.^[3]

During the first half of the 19th century, ice harvesting became big business in America. New Englander In one of the earliest European settlements in North America, Pilgrims from England first settled in New England in 1620, to form Plymouth Colony. Ten years later, the Puritans settled north of Plymouth Colony in Boston, thus forming Massachusetts Bay Colony in 1630. In the late 18th century, the New England colonies would be among the first North Frederic Tudor Frederic Tudor was known as Boston's "Ice King", and was the founder of the Tudor Ice Company. During the early 19th Century, he made a fortune shipping ice to the Caribbean, Europe, and even as far away as India from sources of fresh water ice in New England, who became known as the "Ice King", worked on developing better insulation The term thermal insulation can refer to materials used to reduce the rate of heat transfer, or the methods and processes used to reduce heat transfer. Heat energy can be transferred by conduction, convection, radiation or by actual movement of material from one location to another. For the purposes of this discussion only the first three products for the long distance shipment of ice, especially to the tropics.

First refrigeration systems

The first known method of artificial refrigeration was demonstrated by William Cullen Cullen was born in Hamilton, Lanarkshire. His father William was a lawyer retained by the Duke of Hamilton and his mother was Elizabeth Roberton of Whistlebury. He studied at Hamilton Grammar School, then, in 1726, began a General Studies arts course at the University of Glasgow. He began his medical training as apprentice to John Paisley, a at the University of Glasgow The University of Glasgow is the fourth-oldest university in the English-speaking world and one of Scotland's four ancient universities. Located in Glasgow, the university was founded in 1451 and is presently one of seventeen British higher education institutions ranked amongst the top 100 of the world in Scotland Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the southwest. In addition to the mainland, Scotland in 1756 Year 1756 was a leap year starting on Thursday (link will display the full calendar) of the Gregorian calendar (or a leap year starting on Monday of the 11-day slower Julian calendar). Cullen used a pump to create a partial vacuum In everyday usage, vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure. The word comes from the Latin term for "empty". Even putting aside the complexities of the quantum vacuum, the classical notion of a perfect vacuum with gaseous pressure of exactly over a container of diethyl ether Diethyl ether, also known simply as ether, is the organic compound with the formula 2O. It is a colorless and highly flammable liquid with a low boiling point and a characteristic odor. It is the most common member of a class of chemical compounds known generically as ethers. It is a common solvent and was once used as a general anesthetic. Ether, which then boiled The boiling point of an element or a substance is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid, absorbing heat The enthalpy of vaporization, , also known as the heat of vaporization or heat of evaporation, is the energy required to transform a given quantity of a substance into a gas from the surrounding air.^[4] The experiment even created a small amount of ice, but had no practical application at that time.

In 1758, Benjamin Franklin Benjamin Franklin was one of the Founding Fathers of the United States. A noted polymath, Franklin was a leading author and printer, satirist, political theorist, politician, postmaster, scientist, inventor, civic activist, statesman, and diplomat. As a scientist, he was a major figure in the American Enlightenment and the history of physics for and John Hadley, professor of chemistry at Cambridge University, conducted an experiment to explore the principle of evaporation as a means to rapidly cool an object. Franklin and Hadley confirmed that evaporation of highly volatile liquids such as alcohol and ether, could be used to drive down the temperature of an object past the freezing point of water. They conducted their experiment with the bulb of a mercury thermometer as their object and with a bellows used to "quicken" the evaporation; they lowered the temperature of the thermometer bulb down to 7 °F while the ambient temperature was 65 °F. Franklin noted that soon after they passed the freezing point of water (32 °F) a thin film of ice formed on the surface of the thermometer's bulb and that the ice mass was about a quarter inch thick when they stopped the experiment upon reaching 7 °F. Franklin concluded, "From this experiment, one may see the possibility of freezing a man to death on a warm summer's day".^[5]

In 1805, American inventor Oliver Evans Oliver Evans was an American inventor. Evans was born in Newport, Delaware to a family of Welsh settlers. At the age of 14 he was apprenticed to a wheelwright designed but never built a refrigeration system based on the vapor-compression refrigeration Vapor-compression refrigeration is one of the many refrigeration cycles available for use. It has been and is the most widely used method for air-conditioning of large public buildings, private residences, hotels, hospitals, theaters, restaurants and automobiles. It is also used in domestic and commercial refrigerators, large-scale warehouses for cycle rather than chemical solutions or volatile liquids such as ethyl ether.

In 1820, the British scientist Michael Faraday Michael Faraday, FRS was an English chemist and physicist (or natural philosopher, in the terminology of the time) who contributed to the fields of electromagnetism and electrochemistry liquefied ammonia Ammonia is a compound of nitrogen and hydrogen with the formula NH3. 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 indirectly, is also a building block for the synthesis of and other gases by using high pressures and low temperatures.

An American living in Great Britain, Jacob Perkins Jacob Perkins was an Anglo-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 inventions and eventually had twenty-one American and nineteen English patents.[citation needed], 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.^[6]

In 1842, an American physician, John Gorrie John Gorrie , physician, scientist, inventor, and humanitarian, is considered the father of refrigeration and air conditioning. He was born on the Island of Nevis to Scottish parents on October 3, 1802, and spent his chilhood in South Carolina. He received his medical education at the College of Physicians and Surgeons of the Western District of, 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 A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume. That isentropic In thermodynamics, an isentropic process or isoentropic process (ισον = "equal" ; εντροπία entropy = "disorder"(Greek)) is one in which for purposes of engineering analysis and calculation, one may assume that the process takes place from initiation to completion without an increase or decrease in the entropy of the 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.^[7] Gorrie built a working prototype, but his system was a commercial failure.

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.

Meanwhile in Australia, James Harrison James Harrison was an Australian newspaper printer, journalist, politician, and pioneer in the field of mechanical refrigeration began operation of a mechanical ice-making machine in 1851 on the banks of the Barwon River at Rocky Point in Geelong Geelong is a port city located on Corio Bay and the Barwon River, in the state of Victoria, Australia, 75 kilometres (47 mi) south-west of the state capital; Melbourne. Geelong is the second most populated city in Victoria and the fifth most populated non-capital city in Australia. The estimated urban population is 160,991 people.. The City of, Victoria. 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.

Australian For at least 40,000 years before European settlement in the late 18th century, Australia was inhabited by indigenous Australians, who belonged to one or more of the roughly 250 language groups. After sporadic visits by fishermen from the immediate north and discovery by Dutch explorers in 1606, Australia's eastern half was claimed by Britain in 177, Argentine The Argentine claims in Antarctica along with the Falkland Islands, South Georgia, and the South Sandwich Islands (administered by the United Kingdom) shown in light green, and American ^ b. English is the de facto language of American government and the sole language spoken at home by 80% of Americans age five and older. Spanish is the second most commonly spoken language 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 New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses , and numerous smaller islands, most notably Stewart Island/Rakiura and the Chatham Islands. The indigenous Māori language name for New Zealand is Aotearoa, commonly translated as The Land of the Long White Cloud. The Realm of New Zealand also vessel Dunedin in 1882, leading to a meat and dairy boom in Australasia Australasia is a region of Oceania: Australia, New Zealand, the island of New Guinea, and neighbouring islands in the Pacific Ocean. The term was coined by Charles de Brosses in Histoire des navigations aux terres australes . He derived it from the Latin for "south of Asia" and differentiated the area from Polynesia (to the east) and the and South America South America is the southern continent of America, situated in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. It is bordered on the west by the Pacific Ocean and on the north and east by the Atlantic Ocean; North America and the Caribbean Sea lie to the northwest. J & E Hall of Dartford Dartford is the principal town in the borough of Dartford. It is situated in the northwest corner of Kent, England, 16 miles east south-east of central London, England outfitted the 'SS Selembria' with a vapor compression system bring 30,000 carcasses of mutton Lamb, hogget, and mutton are the meat of domestic sheep. The meat of an animal in its first year is lamb; that of an older sheep is hogget and later mutton from the Falkland Islands The Falkland Islands are an archipelago in the South Atlantic Ocean, located approximately 250 nautical miles (460 km; 290 mi) from the coast of mainland South America, The archipelago, consisting of East Falkland, West Falkland and 776 lesser islands, is a self-governing Overseas Territory of the United Kingdom. The capital, Stanley, is on East in 1886.^[8][9]

The first gas absorption refrigeration system using gaseous ammonia dissolved in water (referred to as "aqua ammonia") was developed by Ferdinand Carré Ferdinand Carré was a French engineer, born at Moislains, in the Somme department in 1824. He died in 1894 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 An Icebox was the common appliance for providing refrigeration in the home before technology made compact mechanical refrigerators feasible with ice brought in from commercial suppliers, many of whom were still harvesting ice and storing it in an icehouse Ice houses originally invented in Persia were buildings used to store ice throughout the year, prior to the invention of the refrigerator. The most common designs involved underground chambers, usually man-made, which were built close to natural sources of winter ice such as freshwater lakes.

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.

Domestic mechanical refrigerators became available in the United States around 1911.^[10]

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.

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.

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 refrigerants 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 1920s. 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 danger: these CFC refrigerants answered that need. However, in the 1970s the compounds were found to be reacting with atmospheric ozone, an important protection against solar ultraviolet radiation, and their use as a refrigerant worldwide was curtailed in the Montreal Protocol of 1987.

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