A refrigerator (often called a "fridge" for short) is a cooling appliance comprising a thermally insulated compartment and a heat pump—chemical or mechanical means—to transfer heat from it to the external environment, cooling the contents to a temperature below ambient. Refrigerators are extensively used to store foods which spoil from bacterial growth if not refrigerated. A device described as a "refrigerator" maintains a temperature a few degrees above the freezing point of water; a similar device which maintains a temperature below the freezing point of water is called a "freezer." The refrigerator is a relatively modern invention among kitchen appliances. It replaced the icebox, which had been a common household appliance for almost a century and a half prior. For this reason, a refrigerator is sometimes referred to as an "icebox".History:-
Before the invention of the refrigerator, icehouses were used to provide cool storage for most of the year. Placed near freshwater lakes or packed with snow and ice during the winter, they were once very common. Using natural means to cool foods is still done today. On mountainsides, runoff from melting snow higher up is a convenient way to cool drinks, and during the winter months simply placing milk outside is sufficient to greatly extend its useful life.
In the 11th century, the Persian physicist and chemist, Ibn Sina (Avicenna), invented the refrigerated coil, which condenses aromatic vapours.This was a breakthrough in distillation technology and he made use of it in his steam distillation process, which requires refrigerated tubing, to produce essential oils.
The first known artificial refrigeration was demonstrated by William Cullen at the University of Glasgow in 1748. Between 1805, when Oliver Evans designed the first refrigeration machine that used vapor instead of liquid, and 1902 when Willis Haviland Carrier demonstrated the first air conditioner, scores of inventors contributed many small advances in cooling machinery. In 1850 or 1851, Dr. John Gorrie demonstrated an ice maker. In 1857, Australian James Harrison introduced vapor-compression refrigeration to the brewing and meat packing industries. Ferdinand Carré of France developed a somewhat more complex system in 1859. Unlike earlier compression-compression machines, which used air as a coolant, Carré's equipment contained rapidly expanding ammonia. The absorption refrigerator was invented by Baltzar von Platen and Carl Munters in 1922, while they were still students at the Royal Institute of Technology in Stockholm, Sweden. It became a worldwide success and was commercialized by Electrolux. Other pioneers included Charles Tellier, David Boyle, and Raoul Pictet. Carl von Linde was the first to patent and make a practical , and compact refrigerator.In a few exceptional cases, mechanical refrigeration systems had been adapted by the start of the 20th century for use in the homes of the very wealthy, and might be used for cooling both living and food storage areas. One early system was installed at the mansion of Walter Pierce, an oil company executive.General Electric sought to develop refrigerators of its own, and in 1915 the first Guardian unit was assembled in a back yard wash house as a predecessor to the Frigidaire. In 1916 Kelvinator and Servel introduced two units among a field of competing models. This number increased to 200 by 1920. In 1918, Kelvinator had a model with automatic controls.These home units usually required the installation of the mechanical parts, motor and compressor, in the basement or an adjacent room while the cold box was located in the kitchen. There was a 1922 model that consisted of a wooden cold box, water-cooled compressor, an ice cube tray and a 9 cubic foot compartment for $714. (A 1922 Model-T Ford cost about
$450.) In 1923 Frigidaire introduced the first self-contained unit. About this same time porcelain covered metal cabinets began to appear. Ice cube trays were introduced more and more during the 1920s; up to this time freezing was not an auxiliary function of the modern refrigerator.The introduction of Freon expanded the refrigerator market during the 1930s. Separate freezers became common during the 1940s, the popular term at the time for the unit was a "deep freeze". But home units of these devices or "appliances" did not go into mass production until after WWII. The 1950s and 1960s saw technical advances like automatic defrosting and automatic ice making. Developments of the 1970s and 80s brought about more efficient refrigerators, even though environmental issues led to the banning of very effective (Freon) refrigerants. Early refrigerator models (1916 and on) featured a cold compartment for ice cube trays. Successful processing of fresh vegetables through freezing began in the late 1920s by the Postum Company (the forerunner of General Foods) which had acquired the technology when it bought the rights to Clarence Birdseye's successful fresh freezing methods.The first successful example of the benefits of frozen foods occurred when General Foods heiress Marjorie Merriweather Post (then wife of Joseph E. Davies, United States Ambassador to the Soviet Union) deployed commercial-grade freezers to Spaso House, the US Embassy in Moscow in advance of the Davies’ arrival. Post, fearful of the food processing safety observed in the USSR, then fully stocked the freezers with products from General Foods' Birdseye unit. The frozen food stores allowed the Davies to lavishly entertain and serve fresh frozen foods that would otherwise be out of season. Upon returning from Moscow, Post (who resumed her maiden name after divorcing Davies) directed General Foods to market frozen product to upscale restaurants.Introduction of home freezers as separate compartments (larger than necessary just for ice cubes), or as separate units, occurred in the United States in 1940. Frozen foods then began to make the transition from luxury to commonplace.
In the 11th century, the Persian physicist and chemist, Ibn Sina (Avicenna), invented the refrigerated coil, which condenses aromatic vapours.This was a breakthrough in distillation technology and he made use of it in his steam distillation process, which requires refrigerated tubing, to produce essential oils.
The first known artificial refrigeration was demonstrated by William Cullen at the University of Glasgow in 1748. Between 1805, when Oliver Evans designed the first refrigeration machine that used vapor instead of liquid, and 1902 when Willis Haviland Carrier demonstrated the first air conditioner, scores of inventors contributed many small advances in cooling machinery. In 1850 or 1851, Dr. John Gorrie demonstrated an ice maker. In 1857, Australian James Harrison introduced vapor-compression refrigeration to the brewing and meat packing industries. Ferdinand Carré of France developed a somewhat more complex system in 1859. Unlike earlier compression-compression machines, which used air as a coolant, Carré's equipment contained rapidly expanding ammonia. The absorption refrigerator was invented by Baltzar von Platen and Carl Munters in 1922, while they were still students at the Royal Institute of Technology in Stockholm, Sweden. It became a worldwide success and was commercialized by Electrolux. Other pioneers included Charles Tellier, David Boyle, and Raoul Pictet. Carl von Linde was the first to patent and make a practical , and compact refrigerator.In a few exceptional cases, mechanical refrigeration systems had been adapted by the start of the 20th century for use in the homes of the very wealthy, and might be used for cooling both living and food storage areas. One early system was installed at the mansion of Walter Pierce, an oil company executive.General Electric sought to develop refrigerators of its own, and in 1915 the first Guardian unit was assembled in a back yard wash house as a predecessor to the Frigidaire. In 1916 Kelvinator and Servel introduced two units among a field of competing models. This number increased to 200 by 1920. In 1918, Kelvinator had a model with automatic controls.These home units usually required the installation of the mechanical parts, motor and compressor, in the basement or an adjacent room while the cold box was located in the kitchen. There was a 1922 model that consisted of a wooden cold box, water-cooled compressor, an ice cube tray and a 9 cubic foot compartment for $714. (A 1922 Model-T Ford cost about
$450.) In 1923 Frigidaire introduced the first self-contained unit. About this same time porcelain covered metal cabinets began to appear. Ice cube trays were introduced more and more during the 1920s; up to this time freezing was not an auxiliary function of the modern refrigerator.The introduction of Freon expanded the refrigerator market during the 1930s. Separate freezers became common during the 1940s, the popular term at the time for the unit was a "deep freeze". But home units of these devices or "appliances" did not go into mass production until after WWII. The 1950s and 1960s saw technical advances like automatic defrosting and automatic ice making. Developments of the 1970s and 80s brought about more efficient refrigerators, even though environmental issues led to the banning of very effective (Freon) refrigerants. Early refrigerator models (1916 and on) featured a cold compartment for ice cube trays. Successful processing of fresh vegetables through freezing began in the late 1920s by the Postum Company (the forerunner of General Foods) which had acquired the technology when it bought the rights to Clarence Birdseye's successful fresh freezing methods.The first successful example of the benefits of frozen foods occurred when General Foods heiress Marjorie Merriweather Post (then wife of Joseph E. Davies, United States Ambassador to the Soviet Union) deployed commercial-grade freezers to Spaso House, the US Embassy in Moscow in advance of the Davies’ arrival. Post, fearful of the food processing safety observed in the USSR, then fully stocked the freezers with products from General Foods' Birdseye unit. The frozen food stores allowed the Davies to lavishly entertain and serve fresh frozen foods that would otherwise be out of season. Upon returning from Moscow, Post (who resumed her maiden name after divorcing Davies) directed General Foods to market frozen product to upscale restaurants.Introduction of home freezers as separate compartments (larger than necessary just for ice cubes), or as separate units, occurred in the United States in 1940. Frozen foods then began to make the transition from luxury to commonplace. 
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