Centrifugal chillers are used for cooling large buildings in a centralized air conditioning system. There are other types of chillers using screw compressors and reciprocating compressors. These are usually smaller in size. Today's topic is about centrifugal chillers - ultimate choice for any air conditioning installations higher than 500 RT (refrigeration tons)
Basically, centrifugal chillers use centrifugal fans to move refrigerant within chiller circuit. As with any refrigeration circuit, there must be a compressor, a condenser, an expansion device, and evaporator.
In case of centrifugal chiller, fan is compressor. Rotating at very high speeds, it is capable of pressurizing refrigerant gas so as to increase its temperature. Because pressure is so dependent on efficiency of impeller of compressor, impeller is very carefully designed to match system.
The clearances between impeller and housing at mouth ring (impeller suction) are made very small so as to reduce leaks back to discharge.
Usually inlet vanes that throttle gas control flow of gas, and thus chiller load. The expansion of liquid to gas is usually made through a fixed orifice.