Physics Curiosities

How do refrigerators work?

There is evidence that human beings, from the very beginning, noticed that the simple cooling of food was able to preserve it for a longer time. Most likely, the appropriation of territories was responsible for the dissemination of this knowledge to civilizations.

However, it was only in the 19th century that Jacob Perkins, an English inventor, developed a compressor capable of solidifying water, producing ice artificially. And, of course, this discovery made it possible for some industries, such as breweries, for example, to thrive. In addition, the commercial sector was also very favored, since it became possible to send the products to several distant countries.

At the beginning of the 20th century, Willis Carrier, an American, installed the first air-conditioning unit in a New York press, which was able to control the humidity of the environment and cool it.

The first domestic refrigerators (better known as refrigerators) appeared in the United States in the early 1920s, becoming popular very quickly. Nowadays, in Brazil, it is estimated that more than 80% of households have a refrigerator.


Basically, a refrigerator is made up of the following elements:

  • Refrigerant fluid: which must have low vaporization pressure and high condensation pressure, as is the case with freon – the most used fluid for refrigeration.
  • Compressor: it works like a suction pump that removes the fluid from the branch of the pipe that precedes it (reducing the pressure) and injects this fluid in the branch of the pipe that succeeds it (increasing the pressure).
  • Condenser: it is an external coil, located at the back of the refrigerator, in which the steam liquefies, and which is responsible for releasing heat to the environment.
  • Capillary tube: it is responsible for decreasing the pressure of the fluid vapor.
  • Evaporator: consists of a serpentine-shaped tube attached to the freezer. To change to a gaseous state, the fluid absorbs energy in the form of heat from the freezer and, when leaving the evaporator, reaches the compressor, restarting the cycle.
  • Freezer: it is located at the top of the refrigerator to facilitate the formation of internal convection currents, allowing the mixing of air at low temperature in the freezer and its vicinity with air at the highest temperature of the other parts.

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