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Refrigeration is a process of removing heat, which means cooling an
area or a substance below the environmental temperature. Mechanical
refrigeration makes use of (he evaporation of a liquid refrigerant, which
goes through a cycle so that it can be reused. The main cycles include
vapour-compression, absorption steam-jet or steam-ejector, and airing. The
term ‘refrigerator’ was first introduced by a Maryland farmer Thomas Moore
in 1803, but it is in the 20th century that the appliance we know today
first appeared
People used to find various ways to preserve their food before the
advent of mechanical refrigeration systems. Some preferred using cooling
systems of ice or snow, which meant that diets would have consisted of very
little fresh food or fruits and vegetables, but mostly of bread, cheese and
salted meals. For milk and cheeses, it was very difficult to keep them
fresh, so such foods were usually stored in a cellar or window box. In
spite of those measures, they could not survive rapid spoilage. Later on,
people discovered that adding such chemical as sodium nitrate or potassium
nitrate to water could lead to a lower temperature. In 1550 when this
technique was first recorded, people used it to cool wine, as was the term
‘to refrigerate’. Cooling drinks grew very popular in Europe by 1600,
particularly in Spain, France, and Italy. Instead of cooling water at
night, people used a new technique: rotating long-necked bottles of water
which held dissolved saltpeter. The solution was intended to create very
low temperatures and even to make ice. By the end of the 17th century, iced
drink including frozen juices and liquors tad become extremely fashionable
in France.
People’s demand for ice soon became strong. Consumers’ soaring
requirement for fresh food, especially for green vegetables, resulted in
reform in people’s dieting habits between 1830 and the American Civil War,
accelerated by a drastic expansion of the urban areas arid the rapid
amelioration in an economy of the populace. With the growth of the cities
and towns, he distance between the consumer and the source of food was
enlarged. In 1799s as a commercial product, ice was first transported out
of Canal Street in New York City to Charleston, South Carolina. Unfortunately,
this transportation was not successful because when the ship reached the
destination, little ice left. Frederick Tudor and Nathaniel Wyeth, two New
England’ businessmen, grasped the great potential opportunities for ice
business and managed to improve the storage method of ice in the process of
shipment. The acknowledged ‘Ice King’ in that time, Tudor concentrated his
efforts on bringing he ice to the tropica1 areas. In order to achieve his
goal and guarantee the ice to arrive at the destination safely he tried
many insulating materials in an experiment and successfully constructed the
ice containers, which reduce the ice loss from 66 per cent to less than 8
per cent at drastically. Wyeth invented an economical and speedy method to
cut the ice into uniform blocks, which had a tremendous positive influence
on the ice industry. Also, he improved the processing techniques for
storing, transporting and distributing ice with less waste.
When people realised that the ice transported from the distance was
not as clean as previously thought and gradually caused many health
problems, it was more demanding to seek the clean natural sources of ice.
To make it worse, by the 1890s water pollution and sewage dumping made
clean ice even more unavailable. The adverse effect first appeared in the
blowing industry, and then seriously spread to such sectors as meat packing
and dairy industries. As a result, the clean, mechanical refrigeration was
considerately in need.
Many inventors with creative ideas took part in the process of
inventing refrigeration, and each version was built on the previous
discoveries. Dr William Cullen initiated to study the evaporation of liquid
under the vacuum conditions in 1720. He soon invented the first man-made
refrigerator at the University of Glasgow in 1748 with the employment of
ethyl ether boiling into a partial vacuum. American inventor Oliver Evans
designed the refrigerator firstly using vapour rather than liquid in 1805.
Although his conception was not put into practice in the end the mechanism
was adopted by an American physician John Gorrie, who made one cooling
machine similar to Evans' in 1842 with the purpose of reducing the
temperature of the patient with yellow fever in a Florida hospital. Until
1851, Evans obtained the first patent for mechanical refrigeration in the
USA. In 1820, Michael Faraday, a Londoner, first liquefied ammonia to cause
cooling. In 1859, Ferdinand Carre from France invented the first version of
the ammonia water cooling machine. In 1873, Carl von Linde designed the
first practical and portable compressor refrigerator in Munich, and in 1876
he abandoned the methyl ether system and began using ammonia cycle. Linde
later created a new method (‘Linde technique') for liquefying large amounts
of air in 1894. Nearly a decade later, this mechanical refrigerating method
was adopted subsequently by he meat packing industry in Chicago.
Since 1840, cars with the refrigerating system had been utilised to
deliver and distribute milk and butter. Until 1860, most seafood and dairy
products were transported with cold-chain logistics. In 1867, refrigerated,
railroad cars are patented to J.B, Sutherland from Detroit, Michigan, who
invented insulated cars by installing the ice bunkers at the end of the
cars: air came in from the top, passed through the bunkers, circulated
through the cars by gravity and controlled by different quantities of
hanging flaps which caused different air temperatures. Depending on the
cargo (such as meat, fruits etc.) transported by the cars, different car
designs came into existence. In 1867, the first refrigerated car to carry
fresh fruit was manufactured by Parker Earle of Illinois, who shipped
strawberries on the Illinois Central Railroad. Each chest was freighted
with 100 pounds of ice and 200 quarts of strawberries. Until 1949, the
trucking industry began to be equipped with the refrigeration system with a
roof-mounted cooling device, invented by Fred Jones.
From the late 1800s to 1929, the refrigerators employed toxic gases -
methyl chloride, ammonia, and sulfur dioxide - as refrigerants. But in the
1920s, a great number of lethal accidents took place due to the leakage of
methyl chloride out of refrigerators. Therefore, some American companies started
to seek some secure methods of refrigeration. Frigidaire detected a new
class of synthetic, refrigerants called halocarbons or CFCs
(chlorofluorocarbons) in 1928. this research led to the discovery of
chlorofluorocarbons (Freon), which quickly became the prevailing material
in compressor refrigerators. Freon was safer for the people in the
vicinity, but in 1973 it was discovered to have detrimental effects on the
ozone layer. After that, new improvements were made, and
Hydrofluorocarbons, with no known harmful effects, was used in the cooling
system. Simultaneously, nowadays, Chlorofluorocarbons (CFS) are no longer
used; they are announced illegal in several places, making the
refrigeration far safer than before.
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