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P=n*p*g*h*i Help

  1. May 2, 2008 #1
    P=n*p*g*h*i "Help"

    This is the power equation for a hydro turbine.
    P=power
    n=turbine efficiency
    p=density of watter (kg/m3)
    g=acceleration of gravity (9.81m/s2)
    h=head(m)
    i= flow rate (m3/s)

    What I want to know is how to change this for running a turbine with water pressure only

    P=r*g*h

    P=pressure
    r=water density
    h=head(m)

    Can anyone help with this so I can save the world
     
  2. jcsd
  3. May 3, 2008 #2

    HallsofIvy

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    I have no idea what you are asking. Your original formula b]is[/b] for a turbine run by water pressure. How do want to change it? In your second formula you've just taken out the "turbine efficiency" and "flow rate". It is not possible to build any 100% efficient machine so you must have some "efficiency" factor. And since "power" is "rate of doing work", you will have to have some measure of time- that's what the "flow rate" gave you.
     
  4. May 3, 2008 #3
    Sorry I'm not as good at this stuff as some of you people are. The numbers I'm using are
    P=1000MW
    n=90%
    p=1.03*1000
    h=100m
    i=?
    the second formula is for pressure and I don't know if thats needed?
     
  5. May 3, 2008 #4

    HallsofIvy

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    Oh, you are using "P" to mean two different things- that was confusing me. In the second equation r = density of water is the same as p (I suspect it was [itex]\rho[/itex]) in the first equation. So the second equation is incorporated into the first- that's another thing that was confusing me.

    Power= n*p*g*h*i = n*i*(pgh)= n*i*Pressure.
     
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