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Today a refrigerator can be found in the majority of households within the industrialised world and is second only to cooking appliances in terms of market saturation. The first practical domestic refrigerator was developed in 1834, but it was not fully mass-produced until after World War II, causing a complete behavioural change in people's purchasing practices.
These early refrigerators used either a cycle of vapour compression or absorption of heat by a liquid or refrigerant to preserve food in cool conditions. Today's domestic refrigerators use a continuous vapour compression cycle as standard.
A compressor pressurises a refrigerant gas, raising its temperature. Serpentine or coiled heat exchanging pipes wind outside the appliance, allowing the refrigerant to dissipate the heat. As the refrigerant cools, it condenses to liquid form and moves from a high pressure to low pressure zone as it moves through on expansion valve, evaporating and absorbing heat as it passes through heat exchanging pipes within the refrigerator, thereby making it cold inside the appliance.
During the course of the domestic refrigerator's development, over 50 chemical substances have been used as a refrigerant, including poisonous sulphur dioxide and ethyl chloride in early models. In Europe the cooling agent commonly used is R600 (isobutene), but R134A HFC is used in Russian and Turkish refrigerators. In the USA and Japan refrigerators often use R410A HFC. Environmental issues, combustibility and toxicity levels, and the refrigerant compatibility of repair systems are among the reasons for the range of refrigerants developed.
The use of metals has, however, remained consistent within domestic refrigerators and looks unlikely to change. The cabinet or cell is formed of metal sheet, most commonly steel or sometimes aluminium, which is cut to size, formed in a press and welded into position. This material can either be pre-coated or lacquered after construction; for instance, international manufacturer Electrolux lacquer all their white goods within their factories.
Chino Mozzon, technical director of cooling for Italy-based manufacturer lndesit Company, says metals form...