Performance Analysis Of Centrifugal Pump Operating As Turbine For Identified Micropico Hydro Site Of Ethiopia

In many countries, the supply of electricity in rural areas has always been challenge due to thernrelative isolation from the national electricity grid. The single most important solution tornovercome this problem is through the development of the Micro/Pico hydro power generation.rnBy using a Pump as Turbine (PAT) on particular Micro/Pico hydro sites, the required electricityrndemand can be more or less fulfilled.rnThis thesis presents performance analysis of PAT for Dabis Hydro site which is located in WestrnShewa zone. The numerical study of a centrifugal pump running as turbine at different operationrnconditions was achieved using commercial CFD software Ansys CFX. 3D Navier–Stokesrnequations were solved using Ansys CFX. The standard k   turbulence model was chosen forrnturbulence model. Using results from simulation, complete characteristic curves of the pump inrnnormal and reverse modes were obtained. After that, the performance of PAT was estimatedrnusing various methods proposed by different researchers. The pump mode simulated results wasrnin good agreement with the performance of centrifugal pump evaluated experimentally. Thernturbine mode performance of the pump was simulated and results showed that when the PAT isrnmade to operate from low to high head condition, the required flow rate at the site increases. Andrnthe simulation result of the PAT at best efficiency point (BEP) was compared with resultsrnobtained using published empirical formulas and the prediction method proposed by Stephanoffrn[15] showed acceptable result.rnIn this thesis, the pump was also simulated in reverse modes to evaluate the effect of impeller tiprnrounding. The result shows that the efficiency of the pump is greatly improved beyond the BEPrnwhen the impeller tips is made round. The effects of PAT speed were also studied consideringrnconstant flow rate/head conditions and the results indicate that as the impeller speed increase,rnimpeller torque decreases. Whereas as the rotational speed of the PAT increases, the powerrnoutput as well as the efficiency of the PAT increases till the impeller speed reaches 1400 RPM.rnLastly, the effect of draft tube on PAT was simulated and studied. The results show that the PATrnhead increase when draft tube is added to the system. The result also shows that the systemrnefficiency of the PAT with draft tube drops down due to the increase in head.

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