These complexes used subterranean storage spaces, a large thickly insulated above-ground domed structure, and outfitted with badgirs (wind-catchers) and series of qanats (aqueducts).

Cullen used a pump to create a partial vacuum over a container of diethyl ether, which then boiled, absorbing heat from the surrounding air.

In 1820, the British scientist Michael Faraday liquefied ammonia and other gases by using high pressures and low temperatures, and in 1834, an American expatriate in Great Britain, Jacob Perkins, built the first working vapor-compression refrigeration system.

Harrison also introduced commercial vapor-compression refrigeration to breweries and meat packing houses, and by 1861, a dozen of his systems were in operation.

Carl von Linde, an engineering professor at the Technological University Munich in Germany, patented an improved method of liquefying gases in 1876, creating the first reliable and efficient compressed-ammonia refrigerator.

[16] His new process made possible the use of gases such as ammonia (NH3), sulfur dioxide (SO2) and methyl chloride (CH3Cl) as refrigerants, which were widely used for that purpose until the late 1920s despite safety concerns.

In 1894, Hungarian inventor and industrialist István Röck started to manufacture a large industrial ammonia refrigerator which was powered by electric compressors (together with the Esslingen Machine Works).

In 1906, the first large Hungarian cold store (with a capacity of 3,000 tonnes, the largest in Europe) opened in Tóth Kálmán Street, Budapest, the machine was manufactured by the Ganz Works.

Doors, made of glass to allow inspection of contents, improve efficiency significantly over open display cases, which use 1.3 times the energy.

[19] In 1913, the first electric refrigerators for home and domestic use were invented and produced by Fred W. Wolf of Fort Wayne, Indiana, with models consisting of a unit that was mounted on top of an ice box.

[22][23] In 1914, engineer Nathaniel B. Wales of Detroit, Michigan, introduced an idea for a practical electric refrigeration unit, which later became the basis for the Kelvinator.

The absorption refrigerator was invented by Baltzar von Platen and Carl Munters from Sweden in 1922, while they were still students at the Royal Institute of Technology in Stockholm.

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 0.25-cubic-metre (9 cu ft) compartment, and cost $714.

During the latter part of the 1960s and the early 1970s, earth tone colors were popular, including Harvest Gold, Avocado Green and almond.

Safety regulations requires an emergency releases and employers should check to ensure no one will trapped inside when the unit gets locked as hypothermia is possible if one is in freezer for longer periods of time.

This liquid refrigerant is forced through a metering or throttling device, also known as an expansion valve (essentially a pin-hole sized constriction in the tubing) to an area of much lower pressure.

Refrigerant leaves the evaporator, now fully vaporized and slightly heated, and returns to the compressor inlet to continue the cycle.

Modern domestic refrigerators are extremely reliable because motor and compressor are integrated within a welded container, "sealed unit", with greatly reduced likelihood of leakage or contamination.

By comparison, externally-coupled refrigeration compressors, such as those in automobile air conditioning, inevitably leak fluid and lubricant past the shaft seals.

The Peltier effect uses electricity to pump heat directly; refrigerators employing this system are sometimes used for camping, or in situations where noise is not acceptable.

"Ultra-cold" or "ultra-low temperature (ULT)" (typically −80 or −86 °C [−112 or −123 °F]) freezers, as used for storing biological samples, also generally employ two stages of cooling, but in cascade.

Alternatives to the vapor-compression cycle not in current mass production include: Many modern refrigerator/freezers have the freezer on top and the refrigerator on the bottom.

Tier 1 refrigerators are those that are 20% to 24.9% more efficient than the Federal minimum standards set by the National Appliance Energy Conservation Act (NAECA).

This timer is set to shut off the compressor and fan and energize a heating element located near or around the evaporator for about 15 to 30 minutes at every 6 to 12 hours.

This allows consumers to leave food in the main refrigerator compartment uncovered, and also helps keep vegetables moist.

This method also helps reduce energy consumption, because the refrigerator is above freeze point and can pass the warmer-than-freezing air through the evaporator or cold plate to aid the defrosting cycle.

Refrigerators have significantly impacted various aspects of many individual's daily lives by providing food safety to people around the world spanning across a wide variety of cultural and socioeconomic backgrounds.

The most notable improvement is for meat and other highly perishable wares, which previously needed to be preserved or otherwise processed for long-term storage and transport.

If the coolant leaks into the refrigerator, at times when the door is not being opened (such as overnight) the concentration of coolant in the air within the refrigerator can build up to form an explosive mixture that can be ignited either by a spark from the thermostat or when the light comes on as the door is opened, resulting in documented cases of serious property damage and injury or even death from the resulting explosion.