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.

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