Food spoils because bacteria eat it. When the internal temperature of the food drops below 32 degrees Fahrenheit, these microorganisms are stunted or killed. Basically, it freezes the water molecules inside the product. This slows down the rate of decomposition.
The science behind this didn’t come out of thin air. It was born at the beginning of the 19th century, when scientists mapped out the laws of thermodynamics and heat. This frame allows for artificial temperature control.
American inventor Jacob Perkins built a machine based on Oliver Evans’ concept of vapor absorption. Perkins specializes in vapor compression. He invented a loop. Certain chemicals (called refrigerants ) absorb heat when they change from liquid to vapor due to changes in pressure. It then releases heat as it condenses. It is a heat transfer system.
Perkins received the first patent for a refrigeration device. But it never made any money. It stayed a lab curiosity.
In the late 1840s, a Florida doctor tried a different approach. His device produces ice by pressurizing and lowering the refrigerant. It keeps leaking. This is not reliable.
Ferdinand Carre changed the game in 1860. He replaced the ether used by Perkins with ammonia. It is poisonous. It is also very stable. It worked.
In the 1920s, electricity was common. The technology was mature enough to sell crude, expensive freezers in the US and Europe. They are very inefficient. Outside air enters through openings that are not tightly sealed. You often had to keep them in ice houses to maintain the cold.
Modern refrigerators have come a long way since then. better machines. Safer chemicals. Tighter seals.
“Perkins discovered that certain chemicals can lower the temperature of the air by absorbing all the heat.”
The next page takes a closer look at how this cycle works in your kitchen appliances.
