Centrifugal Compressors - Power Requirements

Power requirements for centrifugal chillers are the lowest of all chiller types currently available, and efficiencies have been improving even further over the years as a result of improved impeller designs, better unit configurations, enhanced heat transfer surfaces, and the increased utility emphasis on reducing energy requirements.

At ARI standard rating conditions centrifugal chiller's performance at full design capacity ranges from 0.53 kW per ton or lower to 0.68 kW per ton. This performance includes the semi-hermetic refrigerant cooled or open type compressor motors.

Open drive chiller power requirements are sometimes rated in shaft brake horsepower (bhp). To convert from bhp to electric input in kW, the efficiency of the motor must be considered (which is usually between 90 and 95 percent for centrifugal machines). For example, a rating of 1,000 bhp at 93 % motor efficiency would translate to 802 kilowatt input.