A More Accurate Method of Estimating Energy Saving by Variable-speed Control of Centrifugal Pump

Abstract

The basic method for estimating energy saving by variable-speed control of centrifugal pumps is byusing the pump affinity laws, which are easy to use. However, this method is erroneous if the pumpingsystem has static head or pressure head. This paper aims at providing a better method of estimation. Thismethod is based on a simplified mathematical model of centrifugal pumps using the minimum number ofpump and system parameters. This model yields dimensionless pump characteristics as functions ofdimensionless flow rate at an arbitrary pump speed. It is subsequently used to construct a pump powerconsumption chart. Computation of power consumption by variable-speed pumps using this chart showsthat the difference between results from the power consumption chart and the pump affinity laws increasesas the static head of the pumping system increases.