The experiment even created a small amount of ice, but had no practical application at that time. 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 history of artificial refrigeration began when Scottish professor William Cullen designed a small refrigerating machine in 1755. The word "refrigeratory" was used at least as early as the 17th century. On mountainsides, runoff from melting snow is a convenient way to cool drinks, and during the winter one can keep milk fresh much longer just by keeping it outdoors. Natural means are still used to cool foods today. Placed near freshwater lakes or packed with snow and ice during the winter, they were once very common. In modern times, before the invention of the modern electric refrigerator, icehouses and iceboxes were used to provide cool storage for most of the year. See also: Refrigeration and Timeline of low-temperature technologyĪncient Iranians were among the first to invent a form of large evaporative cooler called yakhchāls using subterranean storage spaces, a large domed above-ground structure made with thick walls and outfitted with wind catchers (called " badgirs"), walled off further into a series of "qanats", a kind of aqueduct used in Ancient Iran. Freezers allow people to buy perishable food in bulk and eat it at leisure, and make bulk purchases. The refrigerator allows the modern household to keep food fresh for longer than before. Refrigerators and freezers may be free-standing, or built into a kitchen. A large domestic refrigerator stands as tall as a person and may be about one metre (3 ft 3 in) wide with a capacity of 0.6 m 3 (21 cu ft). Among the smallest are Peltier-type refrigerators designed to chill beverages. Newer refrigerators may include automatic defrosting, chilled water, and ice from a dispenser in the door.ĭomestic refrigerators and freezers for food storage are made in a range of sizes. A vapor compression cycle is used in most household refrigerators, refrigerator–freezers and freezers. The freezer-over-refrigerator style had been the basic style since the 1940s, until modern, side-by-side refrigerators broke the trend. Commercial refrigerator and freezer units were in use for almost 40 years prior to the common home models. Frozen foods, previously a luxury item, became commonplace.įreezer units are used in households as well as in industry and commerce. Home freezers as separate compartments (larger than necessary just for ice cubes) were introduced in 1940. The introduction of Freon in the 1920s expanded the refrigerator market during the 1930s. In 1923 Frigidaire introduced the first self-contained unit. In 1913, refrigerators for home use were invented. The first commercial ice-making machine was invented in 1854. In 1834, the first working vapor-compression refrigeration system was built. Artificial refrigeration began in the mid-1750s, and developed in the early 1800s. The first cooling systems for food involved ice. The United States Food and Drug Administration recommends that the refrigerator be kept at or below 4 ☌ (40 ☏) and that the freezer be regulated at −18 ☌ (0 ☏). The refrigerator replaced the icebox, which had been a common household appliance for almost a century and a half. A similar device that maintains a temperature below the freezing point of water is called a freezer. The optimal temperature range for perishable food storage is 3 to 5 ☌ (37 to 41 ☏). A refrigerator maintains a temperature a few degrees above the freezing point of water. The lower temperature lowers the reproduction rate of bacteria, so the refrigerator reduces the rate of spoilage. Refrigeration is an essential food storage technique around the world. A refrigerator, colloquially fridge, is a commercial and home appliance consisting of a thermally insulated compartment and a heat pump (mechanical, electronic or chemical) that transfers heat from its inside to its external environment so that its inside is cooled to a temperature below the room temperature.
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