A refrigerator is a heat transfer system. A popular misconception is that the component (the evaporator or holding plate) inside the box is radiating cold. It is more precise to say that the evaporator is absorbing heat from the inside of the closed cabinet or box. By absorbing heat the contents of the box are cooled.
Refrigeration systems have three major components connected in a recycling circuit. (Fig.1 )
1. The evaporator is the component that cools (absorbs heat) located inside the box
2. The compressor pumps the refrigerant – transfers the heat – around the system.
3. The condenser is a heat exchanger that transfers the collected heat from the refigerant to the air or water used to cool the system.
THE REFRIGERATION CYCLE
Liquid refrigerant is carried into the evaporator where it boils into a gas. Just as it takes a lot of heat to boil water, a lot of heat is absorbed from the box to boil the refrigerant. The main difference is the refrigerant boils at a much lower temperature than water.
The boiled refrigerant gas is pumped out of the evaporator by the compressor allowing the boiling process to continue. The heat is carried out of the box by the gas. As the gas passes through the compressor, its pressure and temperature increase.
This compressed and now hot gas then passes to the condensing unit, a heat exchanger that is cooled with either air or water. Because the refrigerant is now at a higher pressure and temperature, it is possible to trasnsfer the heat from the system into the cooling air or water which is at the ambient temperature (60°F-90° F). This cooling process converts the high pressure and temperature gas to a cool liquid that is carried to the evaporator and the cycle begins again….
The cooling medium used in Danfoss/SECOP systems is R134A, an ozone friendly refrigerant. This is commonly called “freon”. Freon was a brand name applied to an R12 product that has been phased out for environmental reasons.