The purpose of the condenser is to provide a way of dumping unwanted heat.  The condenser actually performs two functions.  It cools the hot, superheated gas from the compression cycle and then condenses the vapor back into a liquid.  Most systems are equipped with one of the two following:


1.    Air Cooled Condenser

The air cooled condenser is the simplest, but also the least efficient ype of condenser.  The condensing temperature of the refrigerant vapor is usually 15 to 20oF above the ambient air.  If it happens to be 105oF outside it would not be unusual to see the condensing temperature at 125oF with its corresponding higher pressure.  More horsepower is required to achieve this higher pressure and less heat is absorbed by each pound of refrigerant on the low side.  Hot weather is when refrigeration is generally needed the most, but with an air cooled condenser the capacity of the system drops during this time.


2.    Evaporative Condenser

The evaporative condenser works on the same principles as a swamp cooler.  As long as there is good water supply and the we-bulb temperature of the air outside is low, this type of condenser works well.  If the ambient temperature outside is at 100oF and the relative humidity is at 21%, the we-bulb temperature will be at about 70oF.  With water sprayed on the condenser tubes and air flowing through to evaporate this water the effective heat-sink temperature will be at the we-bulb temperature.  Typically, condensers are sized to allow the refrigerant vapor to condense around 80 to 95oF.  This lower condensing temperature reduces the amount of heat-energy required during the compression cycle.