What is a chiller?

A chiller is basically a central means of heat exchange between inside and outside the building. A chiller performs two basic functions: to cool the air in the building and to provide dehumidification. Water enters the evaporator and condenser via external piping. The piping inside the tubing is surrounded by a chiller medium, which is a compressible gas such as Freon. As water circulates in the tubing, heat is transferred between the water and the chiller medium. The chiller comes in two stages of media pressure. First, the medium is fed to the condenser at high pressure by a compressor. When a medium is compressed, its temperature rises. The chiller medium then leaves the condenser through an expansion device that depressurizes the medium suddenly before entering the evaporator. When a medium expands in this way, its temperature decreases. The pressure change between these two phases is the key to the cooling provided by the chiller. Heat is removed from the air in the building as the air passes through coils in the air ducts through which the cooling water flows. This water flows into the evaporator where the heat is transferred to the chiller medium. The chiller medium is compressed in the compressor, after which the resulting heat energy, which is a combination of building heat taken from the evaporator and the effects of compression, transfers to water in the condenser circuit. Condenser water is pumped to a cooling tower where the heat given off from the compressor is dissipated to the outside air. Effectively, the evaporator acts as a device to absorb heat from the air in the building while the condenser acts as a device to remove that heat from the building after it is picked up.