FORECASTING THE ENERGY-SAVING BENEFITS OF VARIABLE-SPEED PUMPS

Abstract

By calculating the energy-saving benefits of a variable-speed pump, the relation between back pressure and energy-saving benefits is analyzed. Based on the energy-saving benefit calculation for four different pump types using a non-dimensional method, it is shown that when the non-dimensional back pressure, h, and the non-dimensional flow, Q, are equal, then the corresponding non-dimensional energy-saving benefit Ω of variable-speed control are quite close each to other, thereby advancing a forecasting method of energy saving benefits of variable-speed control. When the method is used to forecast the energy-saving benefits of pumps whose specific speed is between 15 and 190 and the flow – between 5 and 200m³/h (subject to the condition h ≤ 0.9, Q ≥ 0.5), the error will not exceed 6.55% and thus the method proves to be of reference value for the evaluation of the variable-speed energy-saving benefits of other pumps.