Theoretical and Numerical Study of Performance Prediction of Centrifugal Pumps as Turbines

Pumps as turbines (PAT) is an attractive alternative for recovering the pressure-energy. Establishing an external characteristic correlation between pumps and turbines is essential in selecting the proper machine. In this study, a theoretical method was presented to predict the performance of PAT at best efficiency point based on pump's characteristics (geometric and hydraulic). In order to verify the theoretical results, the pumps with specific speed 55, 86,128,180,200 were simulated in direct and reverse modes by FLUENT12.0. Using theoretical and numerical results, the characteristic correlation curves of pumps in direct and reverse modes were obtained. Deviations of theoretical results s in higher flow rate and head than pump mode, the best efficiency of PAT was 2%similar to 6% lower than pump mode.