Refrigerator

• 1. Introduction

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  The refrigerator reached widespread use with the General Electric Monitor-Top, introduced in 1927. The public named it after the gun turret on the ironclad warship USS Monitor of the 1860s. Its compressor sat on top of the cabinet, wrapped in a decorative ring, and over a million units were produced.

  The gas circulating inside that cabinet was either sulfur dioxide or methyl formate. Sulfur dioxide is corrosive to the eyes and can cause loss of vision. Methyl formate is highly flammable and toxic if inhaled or swallowed.

  A hazardous chemical in the kitchen did not stop the machine from selling. So how does a sealed box of insulation and gas push heat uphill? Who spent generations failing at the problem before a ring-topped cabinet could succeed? And what becomes of the machine once the hum finally stops?

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• 2. Cold Before Electricity

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  Long before anyone plugged in a compressor, ancient Iranians built cooling complexes called yakhchals. Each one combined an underground storage chamber with a thickly insulated dome above the ground. Wind-catchers known as badgirs and a series of qanats, which were aqueducts, completed the design. Together they used evaporative and radiative cooling to keep things cold.

  In more recent times, before the electric refrigerator, icehouses and iceboxes did the job for most of the year. People built them near freshwater lakes or packed them with snow and ice in winter. They were once very common, and the icebox stayed a household fixture for almost a century and a half.

  Natural cooling never fully disappeared. On mountainsides, runoff from melting snow still chills drinks. In winter, milk keeps fresh much longer simply by being left outdoors. The word "refrigeratory" was in use by at least the 17th century, long before anyone had built a machine to deserve it.

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• 3. The Inventors' Race

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  In 1755, the Scottish professor William Cullen designed a small refrigerating machine. He used a pump to create a partial vacuum over a container of diethyl ether. The ether boiled and drew heat from the surrounding air, and the experiment even produced a little ice. It had no practical use at the time.

  American inventor Oliver Evans described a closed vapor-compression cycle for making ice with ether in 1805. In 1820, the British scientist Michael Faraday liquefied ammonia and other gases using high pressure and low temperature. Then in 1834, Jacob Perkins, an American living in Great Britain, built the first working vapor-compression system. It was a closed-cycle device that could run continuously.

  Success did not come easily to everyone. In 1842, the American physician John Gorrie built a working prototype, but it failed commercially. Alexander Twining, an American engineer, took out a British patent in 1850 for an ether-based system.

  The first practical system came from James Harrison, a Scotsman. In 1851 he built a mechanical ice-making machine on the banks of the Barwon River at Rocky Point in Geelong, Victoria. His first commercial machine followed in 1854, and his patent arrived in 1856. It covered a system using ether, alcohol or ammonia. Harrison also brought the technology to breweries and meat packing houses, and by 1861 a dozen of his systems were running.

  Heat could drive cooling too. Edward Toussaint of France developed the first gas absorption system in 1859 and patented it in 1860. It had no compressor and used ammonia gas dissolved in water.

  In 1876, Carl von Linde, an engineering professor at the Technical University of Munich, patented an improved way of liquefying gases. The result was the first reliable and efficient compressed-ammonia refrigerator. It opened the way to refrigerants such as ammonia, which were widely used until the late 1920s despite safety concerns. In 1895 he discovered the refrigeration cycle.

  In Hungary, the inventor and industrialist István Röck began making a large industrial ammonia refrigerator in 1894. It was powered by electric compressors made by the Ganz Works. At the 1896 Millennium Exhibition, Röck and the Esslingen Machine Works showed an artificial ice plant with a capacity of 6 tonnes. In 1906, Budapest opened a cold store with a capacity of 3,000 tonnes in Tóth Kálmán Street, the largest in Europe. Large-scale refrigerator production in Hungary stayed in the hands of Röck and the Ganz Works until nationalisation after the Second World War.

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• 4. Cold Comes Home

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  In 1913, Fred W. Wolf of Fort Wayne, Indiana, produced the first electric refrigerators for home use. Each was a unit mounted on top of an ice box. His first model, called DOMELRE, was made in several hundred units over the next few years. In 1914, Nathaniel B. Wales, an engineer from Detroit, Michigan, proposed a practical electric unit that later became the basis for the Kelvinator.

  Alfred Mellowes invented a self-contained refrigerator with the compressor at the bottom of the cabinet in 1916. William C. Durant bought him out in 1918 and started the Frigidaire company to mass-produce them. That same year, Kelvinator introduced the first refrigerator with any kind of automatic control.

  In 1922, two Swedish students at the Royal Institute of Technology in Stockholm, Baltzar von Platen and Carl Munters, invented the absorption refrigerator. Electrolux commercialized it, and it became a worldwide success. Other pioneers included Charles Tellier, David Boyle and Raoul Pictet.

  Early home units usually needed the motor and compressor installed in the basement or an adjacent room, with only the cold box in the kitchen. A 1922 model with a wooden cold box, a water-cooled compressor, an ice cube tray and a 9 cubic foot compartment cost $714. A 1922 Model-T Ford cost about $476.

  By 1923, Kelvinator held 80 percent of the market for electric refrigerators. In the same year, Frigidaire introduced the first self-contained unit. Porcelain-covered metal cabinets began appearing around then as well.

  Safer gases arrived with Freon in the 1920s. It was a low-toxicity alternative to earlier refrigerants, and it expanded the market during the 1930s. Prices fell, and household refrigerators gained wider acceptance in the United States. Ice cube trays also spread through the 1920s. Until then, freezing had played no auxiliary role in the household refrigerator.

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• 5. The Cycle and Its Rivals

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  The United States Food and Drug Administration recommends keeping a refrigerator at or below 40 degrees Fahrenheit and a freezer at 0 degrees Fahrenheit. The ideal range for perishable food is 3 to 5 degrees Celsius. Low temperature slows the reproduction of bacteria, so food spoils more slowly.

  Most household refrigerators run on a vapor compression cycle. A refrigerant such as R134a enters the compressor as low-pressure vapor and leaves as high-pressure superheated vapor. It then passes through the condenser coils, which room air cools passively, and the vapor liquefies.

  Next comes the expansion valve, essentially a pin-hole sized constriction in the tubing. The pressure drops suddenly, and typically about half of the liquid flashes into vapor in an almost explosive way. The heat for that evaporation comes mostly from the remaining liquid, a phenomenon called auto-refrigeration.

  The cold refrigerant then moves through the evaporator, where a fan blows air from the compartment across the coils. The refrigerant vaporizes completely, and the chilled air returns to the cabinet. The refrigerant goes back to the compressor to start over.

  Modern domestic units are extremely reliable because the motor and compressor sit inside a welded container called a sealed unit. Automobile air conditioning compressors, by contrast, are coupled externally and inevitably leak fluid past the shaft seals. That leak creates a need for periodic recharging.

  Refrigerator-freezers with two compartments usually hide a trick. Typically the compressor and condenser coils sit at the top of the cabinet, with a single fan. Only the refrigerator compartment is properly thermostat-controlled. The freezer knob only adjusts a damper that sets how much air flows into the refrigerator. Changing one temperature therefore shifts the other the opposite way.

  Some manufacturers offer dual compressor models, where each compartment has its own compressor, coils, thermostat and door. A hybrid, the Dual Fan approach, gives each compartment its own fan on a single compressor. Modern computerized models skip the damper and let a computer manage fan speed for both compartments.

  Absorption refrigerators work differently. A heat source drives them, such as liquefied petroleum gas, solar thermal energy or an electric heating element. Those are much quieter than compressor motors. They have a long history on farms and rural cabins without electricity, and in caravans. Kerosene is a common fuel there. Larger absorption chillers cool a brine solution circulated through hospitals and universities.

  Peltier refrigerators use electricity to pump heat directly, typically from 12 volts of direct current. They can be totally silent if no fan is fitted, but they are inefficient. One 4 litre Peltier model was advertised as holding 6 cans of beer. Reversing the polarity makes the cell heat rather than cool.

  Other ideas have never reached domestic or commercial refrigerators. Magnetic refrigerators rely on the magnetocaloric effect, where placing a metal alloy in a magnetic field triggers cooling. Acoustic refrigerators use compressed helium gas and sound to move heat.

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• 6. The Freezer Frontier

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  In 1940, the United States saw home freezers introduced as separate compartments, larger than a tray of ice cubes would need. Frozen foods, until then a luxury, became commonplace. The popular term for these units in the 1940s was deep freeze. They did not reach mass production for the home until after the Second World War.

  Clarence Birdseye supplied the method behind much of that change. From the late 1920s, the Postum Company, forerunner of General Foods, successfully froze fresh vegetables after buying the rights to his techniques. In 1955, a domestic deep freezer went on sale. It was cold enough for owners to freeze fresh food themselves, instead of buying food already frozen by Birdseye's process.

  Early freezer compartments were tucked inside the main refrigerator and reached through the refrigerator door and a smaller inner door. They held only about minus 6 degrees Celsius, which suits food for a week. Models with an entirely separate freezer compartment arrived in the early 1960s and became the industry standard by the middle of that decade.

  Europe grades freezers with a four-star system. The lowest tier holds minus 6 degrees Celsius and keeps pre-frozen food for 1 week. The next holds minus 12 degrees and keeps food for 1 month. The upper tiers hold minus 18 degrees and store food for 3 to 12 months depending on whether it is meat, vegetables or fish.

  Only a four-star freezer is meant for freezing fresh food. It may offer a fast freeze function that runs the compressor continually, down to as low as minus 26 degrees Celsius. Food kept at or below minus 18 degrees Celsius is safe indefinitely.

  Combined units cannot go much colder than minus 23 degrees Celsius. The same coolant loop serves both compartments, and an excessively cold freezer makes it hard to keep the refrigerator above freezing. Chest freezers, which open from the top, give up some convenience for efficiency and partial immunity to power outages.

  Ice cream shows what the freezer changed. It became a popular commodity of the 20th century. Before the freezer, it could only be had by traveling to where it was made and eating it on the spot.

  Laboratories push far past any kitchen. Ultra-low temperature freezers for biological samples cool in two cascaded stages. The colder stage uses methane or a similar gas, with its condenser held near minus 40 degrees Celsius. For lower temperatures, labs buy liquid nitrogen at minus 196 degrees Celsius and suspend samples in a Dewar flask. Cryogenic chest freezers reach minus 150 degrees. At the extreme end, a dilution refrigerator goes down to minus 273.148 degrees Celsius.

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• 7. Watts, Colors and a Butter Heater

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  In a house without air conditioning, a refrigerator uses more energy than any other home device. Energy Star qualified models in the United States use 50 percent less energy than the average 1974 model. The most efficient unit made in the country uses about half a kilowatt-hour per day, equivalent to 20 watts continuously. Large units with big freezers and icemakers can use as much as 4 kilowatt-hours per day.

  The European Union uses a mandatory letter label, with A the most efficient. In the United States, the Consortium on Energy Efficiency splits Energy Star models into tiers. Tier 1 models beat the Federal minimum by 20 to 24.9 percent, and Tier 2 by 25 to 29.9 percent. Tier 3 requires at least 30 percent. About 82 percent of qualified refrigerators are Tier 1, 13 percent are Tier 2, and just 5 percent reach Tier 3.

  Efficiency once went backward. Many refrigerators made in the 1930s and 1940s were more efficient than most that followed, partly because later additions such as auto-defrost cost energy. After the Second World War, style mattered more than efficiency. In the 1970s, side-by-side American models with ice dispensers and water chillers became popular. Manufacturers often cut insulation to shrink the case and the cost.

  Style itself had a calendar. Most refrigerators were white in the early 1950s. Pastel pink and turquoise became popular in the late 1950s and early 1960s. Earth tones such as Harvest Gold, Avocado Green and almond followed in the late 1960s and early 1970s. Black was fashionable in the 1980s, and stainless steel came into vogue in the late 1990s. The Color Marketing Group has tried to coordinate appliance colors since 1961.

  Standards eventually reversed the slide. Twenty-first century refrigerators are typically three times more energy-efficient than those of the 1930s. Frost-free models use fans to cool each compartment. In cheaper or older ones, a mechanical timer switches off the compressor and fan. A heating element then warms for about 15 to 30 minutes every 6 to 12 hours. A small defrost limiter stops the heater if the ice melts early.

  Digital inverter compressors cut consumption further by running at varying speed instead of switching off and on. They typically run between 1200 and 4500 rpm, guided by at least 4 sensors. LG claims its linear inverter compressor reduces energy use by 32 percent and noise by 25 percent compared with its conventional compressors.

  Some features did not survive the rules. In the early 1950s, Nave Alfred E. filed a patent for a butter conditioner, a feature meant to keep butter easy to use. Companies in the UK, New Zealand and Australia built it into mass production, and it became a symbol of local culture. Makers later dropped it, saying it was the only way to meet new ecology regulations.

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• 8. Pantry and Aftermath

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  In the United States, an estimated 99.5 percent of households have a refrigerator. Ownership is lower elsewhere. Throughout Eastern Europe and the Middle East only 80 percent of the population own one, and in China the figure is 65 percent. Urban areas also show far higher ownership than rural ones.

  The ice trade, active in the 19th and 20th centuries, sold natural and artificial ice for refrigeration. Most of its ice came from North America and was shipped worldwide, with smaller operations in Norway. Cheaper home and large-scale refrigeration around the 1920s ended the need for that, and the trade shrank or vanished.

  The most notable gain from refrigeration was for meat and other highly perishable goods. The longer shelf life, together with growing global communication, increased cultural exchange through food from different regions. There have been claims that better food quality raised the height of United States citizens in the early 1900s. Refrigeration also made ultra-processed and convenience foods cheap to make and ship, which spread them widely, especially in lower-income regions known as food deserts.

  Then there is the question of what to do with an old machine. Freon-12, or R-12, proved damaging to the ozone layer, and in 1994 governments banned its use in new refrigerators and air-conditioning systems. Its replacement, R-134a, has been in common use since 1990, and it does not harm the ozone layer. It is still a potent greenhouse gas, and it is becoming rarer in Europe, where isobutane, known as R-600a, is now the main refrigerant.

  Isobutane carries its own hazard. If it leaks into the refrigerator overnight, it can build up into an explosive mixture. A spark from the thermostat, or the light coming on when the door opens, can ignite it. There are documented cases of serious property damage, injury and even death.

  Old refrigerators have killed in a quieter way. Children have been asphyxiated while playing with discarded units, particularly older ones with latching doors. Since the 1950s, many places have required doors that push open from the inside. Modern units use a magnetic door gasket that holds the door sealed but yields to a push from within. Max Baermann, who lived from 1903 to 1984 in Bergisch Gladbach, Germany, invented and manufactured it.

  Some governments pay to keep old units out of landfill. Australia's Phoenix program collected old refrigerators and paid owners for donating them. Each unit was refurbished with new door seals and a thorough cleaning. The cover strapped to the back of many old units was removed. The resulting refrigerators were more than 10 percent more efficient, and they were given to low-income families.

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