A chiller works by compressing refrigerant gas and condensing it into a liquid, which then triggers the metering device to decrease pressure. Once the pressure drops, the liquid evaporates and pulls heat out of the water.
The functioning of a chiller depends on the type of chiller. The vapor compressor has four different components: compressor, condenser, metering device and evaporator. Once the warmed refrigerant liquid pulls heat from the water, it evaporates back into warm gas that then goes through the entire process all over again.
Another type of chiller is the absorption chiller, which substitutes the compressor with heat. This process starts when water and an absorbent combine. The mixture is put under pressure and heats. The water evaporates, becomes water vapor and condenses. The resulting super-pressurized liquid flows through an evaporator where it turns into a gas. While evaporating, it pulls heat from the water. The gas returns to repeat the cycle and recombines with the absorbent.
Both types of chillers contain liquid refrigerant, a necessity in the cooling process, an evaporator and a condenser. Cooling towers are sometimes used in large chillers. These devices help the chillers to release the heat that builds up in the system.