What is the Efficiency of a Centrifugal Pump Used as a Turbine?

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Discussion Overview

The discussion revolves around the efficiency of centrifugal pumps when used as turbines, comparing them to Francis turbines. Participants explore the manufacturing criteria, operational efficiency, and selection processes for optimizing performance in turbine mode.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants suggest that centrifugal pumps and Francis turbines share similar technologies but question whether their efficiencies are comparable when used in reverse roles.
  • It is noted that efficiency may vary based on whether the device is primarily designed as a pump or a motor, and how closely it operates to its design point.
  • One participant inquires about the selection criteria for a centrifugal pump to be used as a turbine, specifically regarding how to interpret pump curves for optimal efficiency under given operating conditions.
  • Another participant recommends consulting the engineering department of the pump manufacturer for guidance, citing a lack of sufficient published data for determining efficiency in turbine mode.
  • A reference is made to a 1977 study by the US Department of the Interior, which includes graphs but leaves open the question of whether optimization is achieved for either mode.

Areas of Agreement / Disagreement

Participants express differing views on the efficiency comparison between centrifugal pumps and Francis turbines, and there is no consensus on the best approach for selecting a centrifugal pump for turbine use. The discussion remains unresolved regarding the optimization of efficiency in this context.

Contextual Notes

Participants acknowledge limitations in available data and the need for manufacturer expertise, indicating that assumptions about efficiency may depend on specific operating conditions and design parameters.

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Centrifugal pump as turbine!

Dear Friends,

Francis turbine and centrifugal pump has got the same (reverse ofcourse) technologies rt. Have they both got the same manufacturing criterion? will centrifugal pumb, if used as a turbine, have the same efficiency as that of francis turbine?
 
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It is common in fluid power to use the same device as either a pump or a motor, sometimes alternately so in the same system. There would be some difference in efficiency depending on if the device was primarily designed as a pump or a motor, and upon how closely it is operating to its design point. It is possible to be more efficient as a pump at one design point and as a motor at another design point
 
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So, how to select a centrifugal pump to be used as a turbine to get the best efficiency.
From the pump curves how can we find that?
Say if the operating conditions are, 10 mtr head and discharge of 1 m3/sec.
 


I would contact the engineering department of the pump manufacturer. I've never seen enough information in the published data to figure that out. In some cases you will have to depend upon his intuitive opinion based upon his experience under similar conditions.
 


Someone has already studied and published in 1977 US Dept of the Interior
http://www.usbr.gov/pmts/hydraulics_lab/pubs/EM/EM39.pdf
A good friday night read - lots of graphs

although I do not know if optimization is reached for either turbine/pump mode in relation to what pkruse stated.
 
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