It works a bit like this; A pump (A) - the compressor, moves a refrigerant through a closed system of pipes.You remove heat from this refrigerant by blowing cold air or passing cold water over this section of the pipes (the condenser) and you add heat to the refrigerant by blowing warm air or passing warm water over this section of the pipes (the evaporator - C). The cycle is continuous, adding or removing heat as long as the pump is running.

Think of the cycle in two halves; One half has heat added to it (the evaporator) this heat comes from the product you wish to remove heat from.The other has heat removed from it (the condenser) this heat is usually removed by a fan and wasted to outside air. There is a pump between the two to keep the flow continuous.

tip: roll your mouse over the diagram.

Here comes the science bit: The cycle relies on one other important factor and this is the change from a liquid to a gas, this requires an input of energy.The energy used is the heat from the item you wish to cool. This heat transfer is done in the evaporator by blowing the heat from the product over the pipes containing liquid refrigerant. The liquid refrigerant absorbs this heat and boils off the liquid, it is aided by the expansion device (B) which helps the liquid to expand into a gas. So now we have removed heat from the product by transferring it into the refrigerant.The compressor pushes the refrigerant gas through the pipes adding its own heat from the electric motor. The refrigerant is now a hot gas.The energy gained (heat) has to be removed. To remove this heat and return the refrigerant to the evaporator to be used again we have to pump it through the pipes and condense the refrigerant into a liquid. This heat transfer is done in the condenser by blowing ambient air over the pipes containing the hot gas. This cools the gas into a liquid and so the cycle starts again.

Welcome, you are now a fridge engineer!