The History Of The Refrigerator And Freezers

In early history, people were known to cool their food with ice and snow that was either found locally or brought down from mountains

. The first cellars were simply holes dug into the ground, lined with wood or straw and packed with snow and ice. These holes were generally north facing (so the sun would not heat them), and for a long time were the only means of preserving food.

Refrigeration is the process of removing heat from an enclosed space, or from a substance, so as to lower its temperature. A fridge uses the evaporation of liquid to remove excess heat energy. The liquid used in a fridge evaporates at a very low temperature, thus creating near freezing temperatures in the fridge. So, as a liquid is rapidly evaporated, this vapour then requires kinetic energy which it draws from the immediate area (the fridge), which then in turn loses energy and gets colder. All modern refrigerators depend on the rapid expansion of gases to keep them cold.

The first known record of artificial refrigeration is of William Cullen at the University of Glasgow in 1748. In 1805 Oliver Evans, an American inventor, designed the first refrigerator. Jacob Perkins then built the first refrigerator just less than 30 years later in 1834 it used ether in a vapour compression cycle. Following this, John Gorrie built a refrigerator based on Evans design in 1844 to cool the air for his yellow fever patients. Then, in 1876, a German engineer by the name of Carl von Linden patented the process of liquefying gas, an integral part of modern refrigeration technology.

From the late 1800s until 1929, refrigerators used toxic gases such as ammonia (NH3), methyl chloride (CH3Cl) and sulphur dioxide (SO2). Not surprisingly, there were several fatal accidents involving methyl chloride leaking out from refrigerators. Following this, three American corporations launched collaborative research into the development of less dangerous methods of refrigeration. The research eventually lead to the discovery of Freon or CFCs (chlorofluorocarbons), these are colourless odourless, non-flammable, non-corrosive gases or liquids. Compressor refrigerators using CFCs would become the norm in a matter of years until people discovered that CFCs damaged the ozone layer of the whole planet.

Modern refrigerators now use HFC-134a, also known as tetrafluoroethane. HFC turns into a liquid when it is cooled to -15.9 degrees Fahrenheit (-26.6 degrees Celsius). This new gas is not harmful to the ozone layer and is certainly not as dangerous as using ammonia, methyl chloride or sulphur dioxide.

by: Amy

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