The effects of flow rate on the performance of centrifugal pump as turbine based on entropy production theory

Abstract Centrifugal pumps as turbines (PATs), economically feasible and energy-saving technologies, are commonly used in energy-intensive industrial operations. The entropy production theory was applied to study a forward-curved blade PAT by experimental and numerical simulation techniques. The findings demonstrate that the hydraulic efficiency reaches 75.65% at the design flow rate. The impeller and volute are where the majority of the energy loss occurs. In the low-flow condition, the shear force and the significant velocity gradient are the primary causes of energy loss in the low-flow condition. In the high-flow condition, the shock loss is greater, increasing turbulent entropy production power. There is very little correlation between flow rate and entropy production in the draft tube, the loss is mainly from the incoming flow state and the viscosity effect of the tube wall. This study helps understand the energy conversion mechanism of PAT, which has reference value for the efficient and economical operation of the PAT.