Estimation of Power Consumption by Centrifugal Pump with Reduced Impeller Size

Abstract

Energy saving in centrifugal pumps by impeller size reduction is an efficient method. It is popular to estimate energy saving of this method by using the affinity laws. However, using the affinity laws alone to estimate energy saving without considering the characteristics of the individual pump and the pumping system may yield erroneous results. This paper is aimed at presenting a better method by using actual pump performance curves and incorporating the pumping system into the analysis. It is shown that both head and efficiency can be approximated by quadratic functions of flow rate. Together with the assumption that the system curve is also a quadratic function, the presented method is capable of computing pump power input at given values of flow rate and static head. Results from this method suggest a simple and more accurate formula for estimating energy saving in centrifugal pumps by impeller size reduction.

Keywords: pump characteristics, energy efficiency, impeller trimming,
affinity laws