Evolution of the Refrigorator by: Leia Watson

Refrigerator 

              Before the refrigerator was invented, people dug holes in the ground and lined them with wood and packed snow to keep their food cold. The very first known artificial refrigerator was invented in 1748 by William Cullen at the University of Glasgow, bu he did not use it for any practical use. From that point on people kept trying to make his invention better but nobody had rally figured out the right way to do it.

               The first person to figure out the basic artificial refrigerator technology was German engineer Carl von Linden who discovered how the process of liquifying gas worked in 1876. From the late 1800s to 1929 inventors started to use toxic gases in their refrigerator systems. Such as: ammonia, methyl chloride, and sulfur dioxide, which they believed kept the food cold. Soon fatal accidents started to happen in 1929 when the chemicals started to leak into he food. They realized they they had to figure out another way.

                As soon as Freon was discovered everyone started to use it in their refrigeration systems. Soon enough Freon was used in almost every home kitchen, until they found out that the chlorofluorocarbons were messing with the ozone layer. Now we have figure out the exact technology of how to refrigerate our food safely and successfully. It all has to do with physics and evaporation. It took us a long time to find out how to keep food cold and fresh, but it was worth all the years of hard work.

source:

http://inventors.about.com/library/inventors/blrefrigerator.htm 
http://www.youtube.com/watch?v=JwVJ4pvIbG8