A refrigerator, commonly called a fridge, is a device both used commercially and domestically that consists essentially of a thermally insulated compartment and a heat pump, mechanical, electronic, or chemical, which transfers the heat from its inside to the external environment, so that inside is cooled to a temperature below the initial room temperature.[1] Refrigeration is one of the essential techniques of food storage globally.[2] The low temperature lowers the rate of reproduction of bacteria, so the refrigerator reduces spoilage. A refrigerator maintains temperatures only a few degrees above the freezing point of water. The optimum temperature range for the storage of perishable foods is from 3 to 5 °C or 37 to 41 °F. [3] A freezer is essentially a specialized refrigerator or compartment of a refrigerator that should be kept at a lower temperature than a conventional refrigerator, usually below the freezing point of water. [4] The refrigerator was an improvement on the icebox, which was a standard home appliance for nearly a century and a half. The United States Food and Drug Administration recommends that the refrigerator should be maintained at or below 4 °C, and the freezer is to be regulated at −18 °C.
Texpanded the refrigerator market during the 1930s. Home freezers as separate compartments, larger than necessary just for ice cubes, were introduced in 1940.
the smallest are of Peltier-type refrigerators, which are designed to cool drinks only. A large domestic refrigerator stands as tall as a person and may be about one metre (3 ft 3 in) wide, with a volume of 0.6 m3 (21 cu ft). Refrigerators and freezers can stand alone independently or be embedded into the kitchen. The refrigerator enables the modern household to keep its foodstuffs fresh for a longer period than has ever been possible before. Freezers allow users to buy perishable food in bulk and eat at leisure; they also make bulk purchases.Technological development
See also: Refrigeration and Low-temperature technology timeline
Ancient origins
Main article: Yakhchāl
Ancient Iranians were among the first to invent a form of cooler utilizing the principles of evaporative cooling and radiative cooling called yakhchāls. 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).
In modern times, this task was accomplished by chili pine [sic] before the coming of the modern electric fridge. Icehouses and iceboxes preceded the artificial ice and spring tainting of cooling foods in temperate climates. Packed with snow and ice during the winter or situated near fresh-water lakes, they were formerly common. Cooling foods by natural means finds application in these modern times also. On mountainsides runoff from melting snow is just what one wants to cool drinks, and in the winter it’s quite practicable to keep milk fresh by sitting it in pans out of doors. The word “refrigeratory” was used at least as early as the 17th century.[12]
Artificial refrigeration
Mechanical drawing
Schematic of Dr. John Gorrie’s 1841 mechanical ice machine
Mechanical drawing
Ferdinand Carré’s ice-making device
The history of artificial refrigeration began when Scottish professor William Cullen designed a small refrigerating machine in 1755. Cullen made a pump to create a partial vacuum over a container of diethyl ether, which then boiled, absorbing heat from the surrounding air.[13] The experiment even created a small amount of ice, but had no practical application at that time.
In 1805, the first closed vapor-compression cycle for the production of ice by ether under vacuum was described by the American inventor Oliver Evans. In 1820, the British scientist Michael Faraday liquefied ammonia and other gases by using high pressures and low temperatures, and in 1834 built the first working vapor-compression refrigeration system. It was a closed-cycle apparatus that could operate continuously.[14] A similar attempt was made in 1842, by American physician, John Gorrie,[15] who built a working model, but it was a commercial failure. American engineer Alexander Twining obtained a British patent in 1850 for a vapor compression system using ether.
The first truly practical vapor compression refrigeration system was built by James Harrison, a Scottish Australian. His 1856 patent was for a vapor compression system using ether, alcohol or ammonia. He built a mechanical ice-making machine in 1851 on the banks of the Barwon River at Rocky Point in Geelong, Victoria, and his first commercial ice-making machine followed in 1854. By 1861 a dozen of his systems were in operation. Harrison introduced commercial vapor-compression refrigeration to breweries and meat packing houses.
Edward Toussaint, a Frenchman, patented the first gas absorption refrigeration system in 1860; the invention was developed in 1859. It is a compressor-less system that is heat-source-driven and uses gaseous ammonia dissolved in water—commercially available as “aqua ammonia”.
Carl von Linde was a professor in engineering at the Technological University Munich, Germany. He patented a new method for the liquefaction of gases in 1876, and from this developed the first reliable and efficient compressed-ammonia refrigerator.[16] His invention has allowed the usage of such gases as ammonia (NH3), sulfur dioxide (SO2) and methyl chloride (CH3Cl) as refrigerants to be used for the thirty years, until the late 1920s, despite the risk of them being toxic and/or flammable,[17] In 1895 he discovered the refrigeration cycle.
Electric refrigerators
Manufacturing of refrigerators in France, approx. 1950
In 1894 began the production of a big, industrial ammonia refrigerator, at the initiative of aristo-entrepreneur István Röck, chairman of The Hungarian Fridge Co. Ltd. in Budapest, which took part in production – together with the Esslingen Machine Works. The electric compressors were produced by the Ganz Works. During the 1896 Millennium Exhibition, Röck and The Hungarian Fridge and Stockraising Co. displayed a 6-ton capacity artificial ice producing plant. The first large Hungarian cold store, 3,000 tonnes, the largest in Europe, was opened in 1906 in Tóth Kálmán Street, Budapest and the machine was made by the Ganz Works. Until nationalisation after the Second World War, large-scale industrial refrigerator production in Hungary was in the hands of Röck and Ganz Works.
Commercial refrigerator and freezer units (they also go by many other names) have been in common use for close to 40 years before the home models gained acceptance. They used gas systems, such as ammonia (R-717) or sulfur dioxide (R-764), on which some occasional leaks occurred, hence risky to use at home. Practical household refrigerators became quite available in 1915 but were only well-accepted in the United States in the 1930s when the prize lowered and non-toxic, non-flammable synthetic refrigerants such as Freon-12 (R-12) were introduced. However, R-12 proved to be damaging to the ozone layer and was thus banned on its use in new refrigerators and new air-conditioning systems in 1994 by governments. Its less harmful replacement, R-134a (tetrafluoroethane), is in common use from 1990, but R-12 is still found in many old systems.
The glass-fronted beverage cooler is mainly used in commercial refrigeration. Typically, these kinds of appliances are normally catered to individual loading requirements, leading to a bigger cooling system. This stands them in much better capacity to take heavy traffic of drinks and frequent door opening. Therefore, these kinds of commercial refrigeration can easily compromise 50% of the energy usage of the supermarket. These particulars can be seen in the fact that;
Residential refrigerators
DOMELRE refrigerator.
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 mounted on top of an icebox. His first machine, produced over the next several years in several hundred units, was entitled DOMELRE. In 1914, engineer Nathaniel B. Wales of Detroit, Michigan, unveiled an idea for a practical electric refrigeration unit, which later became the basis for the Kelvinator. A self-contained refrigerator, with a compressor on the bottom of the cabinet was invented by Alfred Mellowes in 1916. Mellowes commercially produced this refrigerator but was bought out by William C. Durant in 1918, who started the Frigidaire company to mass-produce refrigerators. In 1918, Kelvinator company introduced the first refrigerator with any style of auto control. The absorption refrigerator was invented in 1922 by the Swedes Baltzar von Platen and Carl Munters, both still being students at the Royal Institute of Technology at Stockholm. It became a worldwide success and was commercialized by Electrolux. Other pioneers were Charles Tellier, David Boyle, and Raoul Pictet. Carl von Linde was the first to patent and make a practical and compact refrigerator.
The first refrigerator which gained wide use was the General Electric “Monitor-Top” refrigerator, introduced in 1927, so-named, by the public, because of its resemblance to the gun turret on the ironclad warship USS Monitor of the 1860s.[25] The compressor assembly, which emitted a great deal of heat, was placed above the cabinet, and enclosed by a decorative ring. Over a million units were produced.
Introduced in the 1920s, Freon helped popularize the refrigerator during the 1930s and provided a safer, low-toxicity alternative to previously used refrigerants. defrosting and automatic ice making. More efficient refrigerators were designed in the 1970s and 1980s, even though environmental concerns caused very effective refrigerants to be banned. The early models of refrigerators from 1916 had a compartment that was cold for ice cube trays. From the late 1920s fresh vegetables were successfully treated by freezing by the Postum Company, the forerunner of General Foods, which had acquired the process when it purchased.
Styles of refrigerators
The late-1950s/early-1960s introduced pastel colors, such as turquoise and pink. Brushed chrome-plating, which is very similar to a stainless steel finish, was also an option on some models during this time period. The late 1960s and all of the 1970s embraced earth tone colors like Harvest Gold, Avocado Green, and almond. The 1980s were all about black. The late 1990s brought about a greater use of stainless steel. Since 1961 the Color Marketing Group has attempted to standardize the colours of appliances and other consumer goods.
Freezer
“Freezer” redirects here. For other uses, see Freezer (disambiguation).
Freezer units are used both by individual households and by industry and commerce. Foods frozen at 0 °F or below are completely safe. For the most part, the temperatures for frozen storage in normal home freezers are in the range of −18 to −23 °C, though many reach as low as −29 °F and some even −34 °F or lower. In general, however, refrigerator freezers maintain a temperature no lower than −23 °C −9 °F, since the same coolant loop is used for the entire unit; if the freezer compartment is lowered too far, it becomes difficult to maintain a temperature above freezing in the refrigerator compartment. Domestic freezers may be a separate compartment within a refrigerator, or a separate appliance. Many modern upright freezers come with an ice dispenser built into their door.
As separate compartments, larger than necessary just for ice cubes, or as separate units, home freezers were introduced in the United States in 1940.
Walk-in freezer
There are walk in freezers, as the name implies, they allow for one to walk into the freezer. 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.[32]
Refrigerator technologies
See also: Heat pump and refrigeration cycle
Basic functioning of a refrigerator
Process and components of a traditional refrigerator
An Embraco compressor and fan-assisted condenser coil
Compressor refrigerators
The vapor is then compressed and exits the compressor as high-pressure superheated vapor. The vapor is liquefied by the condenser. As the refrigerant leaves the condenser, it’s still under pressure, but is now only slightly above room temperature. This liquid refrigerant is forced through a metering or throttling device, known as an expansion valve, which is essentially a pinhole-sized constriction in the tubing to an area of much lower pressure. This sudden drop in pressure forces the flash evaporation of part of the liquid—usually about half. Much of the latent heat that is necessary for this flash evaporation is taken from adjoining still-liquid refrigerant, causing auto-refrigeration. This cold, partially vaporized refrigerant then passes through the coils or tubes of the evaporator unit.
Modern domestic refrigerators are very reliable due to the motor and compressor being hermetically sealed inside a welded container, called a “sealed unit”, which vastly reduces the chance of leakage or contamination. In contrast, externally-connected refrigeration compressors, like those in automobile air conditioning, necessarily leak fluid past the shaft seals. This demands periodic fluid recharging and, if neglected, can lead to compressor failure.
Dual-compartment designs
Special design is required for refrigerators with two compartments to control the cooling of refrigerator or freezer compartments. Mounted at the top of the cabinet are usually the compressors and condenser coils, cooled by a single fan. This arrangement has a few downsides: each compartment cannot be controlled independently and the more humid refrigerator air is mixed with the dry freezer air.[33]
Some manufacturers offer dual compressor models. The separate freezer and refrigerator compartments can be housed inside a single cabinet; they run independently of each other, with their separate own compressor, condenser and evaporator coils, insulation, thermostat, and door.
A hybrid of the two designs is to have a separate fan for each compartment, the Dual Fan approach. This allows for separate control and airflow on a single compressor system.[citation needed]
Absorption refrigerators
An absorption refrigerator runs differently from a compressor refrigerator, using a source of heat—like combustion of liquefied petroleum gas, solar thermal energy, or an electric heating element. All these heat sources are much quieter than the compressor motor in a typical refrigerator. A fan or pump might be the only mechanical moving parts; reliance on convection is considered impractical.
Other uses for an absorption refrigerator, or “chiller”, are large systems used in office buildings or complexes, such as hospitals and universities. These large systems are used to chill a brine solution that is piped through the building.
Peltier effect refrigeratorsThey can be totally silent but are less energy-efficient than other methods.
Ultra-low temperature refrigerators
“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 use two stages of cooling, but in cascade.
For much lower temperatures, liquid nitrogen (−196 °C [−320.8 °F]), held in a Dewar flask, is typically purchased by laboratories into which the samples are suspended. Cryogenic chest freezers are capable of −150 °C (−238 °F), and may have a liquid nitrogen backup.
Other refrigerators
Alternatives to the vapor-compression cycle not in current mass production include:
Acoustic cooling
Air cycle
Magnetic cooling
Malone engine
Pulse tube
Stirling cycle
Thermoelectric cooling
Thermionic cooling
Vortex tube
Water cycle systems.[34]
Architecture
Exclamation mark with arrows pointing at each other
Please see the talk page for details. (May 2024)
Most refrigerator/freezers sold today have the freezer on top and the refrigerator on the bottom. Most refrigerator-freezers—excluding manual defrost models or less expensive units—make use of what visually appears as two thermostats. Only the fresh food compartment is actually temperature controlled. When the refrigerator gets too warm, a thermostat turns on the cooling process, and a fan blows some of that cold air around the freezer; at the same time, the refrigerator becomes colder. The freezer control knob only affects the volume of air that enters the refrigerator through a damper system.[35] Adjusting the refrigerator temperature will unintentionally affect the freezer temperature in the reverse direction.[citation needed] A change in the freezer temperature will not affect the refrigerator temperature. The freezer control can also be used to offset any adjustment made to the refrigerator.[citation needed]
Because of this, the refrigerator can end up too warm. However, as only enough air is diverted to the refrigerator compartment, the freezer generally re-acquires the set temperature quickly, unless a door is opened. coil, as this coil is cooling two areas.
Features
Inside of a household refrigerator with a diverse array of common foodstuffs
Newer refrigerators may have the following features:
Automatic defrosting
A power failure warning, which flashes a temperature display to alert the user. It is capable of displaying the maximum temperature reached during the power failure and whether the temperature allows for frozen food to have defrosted or possibly contain harmful bacteria.
In some refrigerators, the process of making ice is build in so the user doesn’t have to manually use ice trays. Some refrigerators have water chillers and water filtration systems.
Adjustable shelves and trays
A status indicator that alerts when it is time to replace the water filterIt is also removable, and helps to avoid the accumulation of ice-maker dust.
A Fast Freeze function which quickly cools foods down by running the compressor for a fixed period of time, hence temporarily lowering the freezer temperature below normal operating levels. It should be engaged several hours before loading more than 1 kg of unfrozen food into the freezer. For freezers that lack this facility, setting the thermostat to its coldest point will achieve the same result.
Advances in auto-defrost, which did away with the chore of thawing the product because of its improved performance and energy cost, were introduced into the market in the 1950s but still are not universal.
Compressor refrigerators
Portable compressor refrigerators for RV and camping use are expensive but effective and reliable. Refrigeration units for commercial and industrial applications can be made in various sizes, shapes and styles to fit customer needs economically. In its most general form, commercial and industrial refrigerators may have the compressor away from the cabinet, similar to split system air conditioners. This again reduces noise nuisance and reduces the load on air conditioning in hot weather .
Absorption refrigerator
Absorption refrigerators are made for a number of different applications, such as in caravans and trailers, and at places with no electricity where they have a long history, like on farms, and rural cabins. They may be powered with any heat source, but the more common ones use gas (natural or propane) or kerosene.
DISCLAIMED
Most Peltier refrigerators use electricity, usually 12 V DC, but some wine coolers can be powered directly from the mains. Peltier refrigerators are inexpensive but inefficient and become progressively more inefficient with increased cooling effect, much of the reason being the enormous temperature differential across the short distance between the ‘hot’ and ‘cold’ side of the Peltier cell. Peltier refrigerators generally use heat sinks and fans to reduce this differential; the only sound produced is from the fan. Reversing the polarity of the voltage applied to the Peltier cells results in a heating rather cooling effect.
Magnetic refrigerator
Magnetic refrigerators operate on the magnetocaloric effect. When a metal alloy is exposed to a magnetic field, it can induce a cooling effect.[37]
Acoustic refrigerators create a form of heat and cold by producing a resonant linear reciprocating motor/alternator that compresses helium gas to facilitate heat creation from the gas and cold creation with the oscillating power mechanism. The heat is then dissipated, and the cold air is routed to achieve refrigeration.
Energy efficiency
A European energy label for refrigerator
The refrigerators in a house without air-conditioning (space heating and/or cooling) used more energy than any other home device. In the early 1990s, a competition was held among the major manufacturers to encourage energy efficiency. Current US models that are Energy Star qualified use 50% less energy than the average models made in 1974. But even ordinary units are quite efficient; some smaller units use less than 0.2 kWh per day. Larger units, especially those that have large freezers and icemakers, can have electricity use as high as 4 kW·h per day. The European Union, rather than using Energy Star, projects a mandatory energy efficiency rating label based on the alphabet; thus, EU refrigerators at the point of sale are labelled as per their energy performance.
For US refrigerators, the Consortium on Energy Efficiency (CEE) further categorizes the Energy Star. Tier 1 refrigerators are those that are 20% to 24.9% more efficient than the Federal minimum standards set by the NAECA. Tier 2 are those that are 25% to 29.9% more efficient. Tier 3 is the highest qualification, for those refrigerators that are at least 30% more efficient than Federal standards.[42] About 82% of the Energy Star qualified refrigerators are Tier 1, with 13% qualifying as Tier 2, and just 5% at Tier 3.
Besides the standard-style compressor refrigeration, other forms exist, which include but are not limited to, absorption refrigeration and magnetic refrigeration. Although they generally use up energy many times over the amount a standard compressor unit requires, other qualities such as silent operation or the ability to use gas can
Many home refrigerators of the 1930s and 1940s were in most ways much more efficient than most later refrigerators. Reasons for this include the addition of new features that took away from efficiency, such as auto-defrost. Plus, after the War, style became more important than efficiency. This proved particularly true in the US in the 1970s, when side-by-side models with ice dispensers and water chillers became popular.
The new energy-efficiency standards apply to today’s fridges and the ones made in the 1930s: they are three times larger in size but consume the same amount of energy. [43][44]
The efficiency of older refrigerators can be improved by defrosting (if the unit is a manual defrost) and cleaning it regularly, replacing old and worn door seals with new ones, adjusting the thermostat to accommodate the actual contents (a refrigerator needn’t be cooler than 4 °C (39 °F) to store drinks and non-perishable items) and replacing insulation where applicable. Some sites recommend cleaning condenser coils monthly or so on units with coils on the rear, to add life to the coils and not suffer an unnoticeable deterioration in efficiency over an extended period, the unit should be able to ventilate or “breathe” with adequate spaces around the front, back, sides, and above the unit. If the refrigerator uses a fan to keep the condenser cool, then this must be cleaned or serviced, at per individual manufactures recommendations.[citation needed]
Auto defrosting
Main article: Auto-defrost
Frost-free refrigerators or freezers use electric fans to cool the appropriate compartment.[45] This could be called a “fan forced” refrigerator, whereas manual defrost units rely on ycling on and off.
Frost-free refrigerators, which include early frost-free refrigerators/freezers, do not turn off the refrigerator fans while in defrost. This allows food to be left uncovered in the main refrigerator compartment and also keeps vegetables moist by not allowing them to dry out. This method also helps reduce energy consumption, as the refrigerator operates above freeze point and can run the warmer-than-freezing air through the evaporator or cold plate to aid the defrosting cycle.[citation needed]
Another factor that determines the energy consumption of a refrigerator is the type of refrigeration. For example, Inverter Refrigerators consume comparatively less energy than a usual non-inverter refrigerator. In an inverter refrigerator, the compressor is used according to the need. For example, an inverter refrigerator may use lesser energy during winters than it does during summers. This is because the compressor works for a lesser period than it does during summers.
Moreover, the inverter compressor refrigerator automatically modulates the speed of the compressor after considering the external and internal conditions to assure optimized cooling and energy consumption. Most of them use at least 4 sensors, which help detect variance in external temperature, internal temperature owing to the opening of the refrigerator door or keeping new food inside, humidity, and usage patterns. The compressor changes its speed depending on the sensor inputs. Suppose the door is opened or new food is kept, the sensor detects an increase in temperature inside the cabin and signals the compressor to increase its speed till a pre-determined temperature is attained. Typically, the compressor runs between 1200 and 4500 rpm. An inverter compressor is also superior in respect of two important parameters: durability and energy efficiency. Never switching itself off and running at different speed instead of always running at the same speed minimizes wear and tear as well as energy usage. LG contributed much to improving the inverter compressors as we know it by reducing the friction points in the compressor and thus introducing Linear Inverter Compressors. The drive connected to the piston in conventional domestic refrigerators is a reciprocating one. The AC wobbles magnetic poles of the electromagnet to create the push and pull that compresses the refrigerant. This, according to LG, reduces energy consumption by 32% and noise by 25% compared to its conventional compressors.
Form Factor
The most efficient is the chest-style freezer, as its top-opening design minimizes convection when opening the doors, thus reducing the amount of warm moist air entering the freezer. Conversely, in-door ice dispensers cause more heat leakage, hence adding to an increase in energy consumption.[49]
Impact
Global adoption
The gradual global adoption of refrigerators marks a transformation age for food preservation and household convenience. In the 20th century alone, refrigerators have changed from luxury items to common commodities, changing the concepts and awareness regarding food storage practices. By and large, refrigerators have had deep impacts on several aspects of the daily lives of most people, from food safety to people who cut across vast cultural and socio-economic backgrounds around the world.
Global adoption of the refrigerator has also altered the way societies treat their food supply. In fact, the introduction of the refrigerator to various societies has led to systems of monetization and industrialized mass food production, generally associated with increased food waste, animal wastes, and dangerous chemical wastes traced back into various ecosystems. Beyond that, refrigerators have also given people around the world easier access to food, where many options that commercialization has pushed tend to be low in nutrient density. [50]
The presence of these refrigerators in a majority of homes worldwide became much more common once consumer refrigerators became economically feasible to produce and sell in high quantities.developing countries despite its growing popularity. Throughout Eastern Europe and the Middle East, only 80% of its population own refrigerators. Moreover, it is stated that 65% of the population in China are owning refrigerators.
Displacement of the Ice Trade
. Most of the ice used for trade was harvested from North America and transported globally with some smaller operations working out of Norway.[53] With the introduction of more affordable large and home scale refrigeration around the 1920’s, there was no longer a need for large scale ice harvest and transportation, and the Ice Trade subsequently slowed and shrank to smaller scale local services or disappeared altogether.[54]
Effect on diet and lifestyle
The refrigerator makes it possible for households to store food fresh for many more days than what was previously possible. The most marked improvement is that for meat and other highly perishable wares, which today need not be preserved or otherwise processed for long term storage and transport.[55].
Early frost-free refrigerators/freezers, including the early frost-free refrigerators, have left the fridge fans on while in defrost. This means food can even be left uncovered in the main cold space. Also, vegetables are kept moist and not allowed to dry out. This method is also a way of the ones that prevent the energy consumption by the refrigerator keeping above freezing point and able to draw cold air through the evaporator or cold plate in order to aid in the defrost process.
Inverter
Refrigerator in a rural store
In the case of digital inverter compressors, energy consumption is reduced even further than in single-speed induction motor compressors, and therefore contributes far less in terms of greenhouse gases.
Type of refrigeration is another factor which determines how much energy the refrigerator will be consuming. For example, inverter refrigerators consume comparatively less energy than usual non-inverter refrigerators. In an inverter refrigerator, the compressor is used according to need. For example, an inverter refrigerator may consume lesser energy during winters than it does in summers. This is because the compressor works for a lesser period than it does during summers.
Moreover, the refrigerator with an inverter compressor would adjust to the compressor’s speed. This is upon the consideration of the outer and inner conditions so that it serves cooling and at the same time consume energy as is demanded. Most of them use at least 4 sensors which help them detect variance in the external temperature, internal temperature due to the opening of the refrigerator door or keeping new food inside, the humidity, and usage patterns. The compressor varies its speed according to the sensor inputs. For example, the opening of the door or introducing new food will result in the temperature increasing in the cabin; the compressor must then increase its speed until it reaches a pre-determined temperature, after which the compressor will run in the minimum speed just to maintain the temperature within. In general, the compressor actually runs in the range of 1200 to 4500 rpm. An inverter compressor is also far superior with respect to two important parameters: durability and energy efficiency. But with an inverter compressor, it never switches itself off; it runs at different speeds rather than always running at the same speed, minimized wear and tear, as well as effectively using energy. LG contributed a lot to improving the inverter compressors with the reduction in the points that friction can occur in the compressor and therefore came up with the Linear Inverter Compressors. The drive connected to the piston in conventional domestic refrigerators is the reciprocating one, but in the linear inverter compressor, the permanent magnet piston is suspended between two electromagnets. It wobbles magnetic poles of the electromagnet, therefore, creating the push-pull that compresses the refrigerant. This, according to LG, reduces energy consumption by 32 percent and noise by 25 percent compared to its conventional compressors.
Form Factor
Design-wise, the physical layout of the refrigerators plays a large part in its energy efficiency. The chest-style freezer is touted to be the most efficient, as its top-opening design reduces convection at door openings, therefore lessens the inflow of warm moist air into the fridge. The inversely proportional in-door ice dispensing leads to more heat leakage, hence adding to an increase in energy consumption.[49]
The spread of refrigerators around the globe marks the dawning of a new age of transformation in food preservation and household convenience. In one century, refrigerators have transformed from elite commodities to something common, hence changing the concepts and awareness of food storage practices. Generally, refrigerators have had deep impacts on most aspects of the daily life of most people around the world, across vast cultural and socio-economic backgrounds, from food safety to people.
The global acceptance of the refrigerator has had another ripple effect in that the means towards which society treats its food supply has also been changed forever. In fact, the manner in which the refrigerator affected society was such that entire systems of monetization and industrialized mass food production, generally associated with increased food waste, animal wastes, and dangerous chemical wastes traced back into various ecosystems. Beyond that, refrigerators have also given people around the world easier access to food, where many options that commercialization has pushed tend to be low in nutrient density. [50]
The presence of these refrigerators in a majority of homes worldwide became much more common once consumer refrigerators became economically feasible to produce and sell in high quantities. It is estimated that 99.5 percent of American households have a refrigerator.[51] Developed western countries tend to have a higher percentage of refrigerator ownership, however it has been relatively low in eastern and developing countries even if its popularity keeps rising. For instance, in Eastern Europe and the Middle East, only 80% of the population own refrigerators. In China alone, 65% of the population are owning refrigerators.
Today, most of the ice making trade harvested from North America and transported to worldwide was done in Norway on a large commercial basis.[53] The Ice Trade, however, has slowed and, with the introduction of more affordable large and home scale refrigeration around the 1920’s, subsequently disappeared, shrinking to a much smaller scale of local services.
Effect on diet and lifestyle
The refrigerator allows households to keep food fresh for many more days than what was otherwise could. The most important factor is that in the case of meat and other highly perishable wares which today do not have to be pickled or otherwise made imperishable for long term storage and transportation.[55] This
