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Refrigeration Theory

Most people associate refrigeration with cold and cooling, yet the practice of refrigeration engineering deals almost entirely with the transfer of heat. A good definition of refrigeration is the removal of heat energy so that a space or material is colder than its surroundings. Heat is an energy which cannot be created, destroyed or seen however it can be moved. 

This is one of the most fundamental concepts that must be understood. Cold is really only the absence of heat, just as darkness is the absence of light, and dryness is the absence of moisture.

"Cold is just the absence of heat"

Below is a basic diagram of how heat is displaced in a household refrigerator.  The heat energy is drawn via the evaporator, it is then displaced at the external part of the fridge via the condenser into the cooler air.