Assessment of Specific Speed Influence on Pump-as-Turbine Operation

article in a collection out of WoS and Scopus

English

Pumps operating in reverse mode, often named Pumpas-Turbines (PaTs), are gaining interest in small-scale hydropower applications. Due to low investment costs and simple design, this technology is considered a good alternative to typical turbines. PaTs are mainly used in energy recovery applications, especially in drinking water pipeline systems where they replace Pressure Reducing Valves (PRVs). This work presents the assessment of three different centrifugal pumps used in reverse mode. The goal is to compare the PaTs’ performance by investigating machines having different specific speeds, namely a pump with very low specific speed nq = 9, a pump with a common value of specific speed nq = 35, and a pump with relatively high specific speed nq = 90. Measurements, as well as results from CFD simulations, are presented to verify the usability of each of the pump, and quantify the effect of specific speed on PaTs’ performance in reverse mode operation. In particular, not only integral values and characteristic curves are compared, but also flow patterns at different operating points, which are origin of hydraulic losses and other important features (e.g., the shift of the Best Efficiency Point (BEP) for pump and turbine modes) are presented and discussed.

pump as turbine; specific speed; energy recovery

ŠTEFAN, D.; HUDEC, M.; ROSSI, M.; NIGRO, A.; RENZI, M.; POCHYLÝ, F.; BEZDÍČEK, J.; RUDOLF, P.

9. 11. 2022

TU Wien

Wien

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