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Using Bernoulli's Equation to find Power Requirement

  1. Apr 24, 2017 #1
    1. The problem statement, all variables and given/known data

    Calculate head required for the pump and then its power requirement assuming 70% efficiency.
    The lower storage vessel is vented to atmosphere (assume 1 bar pressure) .

    I have the following given information:
    Pipe Area = 0.00636m^3.
    Flow(Q)= 0.01m^3/s
    Average Velocity = 1.57m/s
    Density of Fluid = 960kg/m^-3.
    Liquid viscosity = 0.081 Pa/s

    I have calculated the head losses of the whole system, using firstly the Equivalent Head (Hm) to be 1.03m and Number Velocity head (Hf) to be 0.54m.


    2. Relevant equations

    Bernoullis img00094.gif

    3. The attempt at a solution

    Pump inlet
    ## \frac {0} { 960 * 9.81 } + \frac {1.57^2} { 2 * 9.81 \ } + 0 = \frac {P2 }{\ 960 * 9.81 \ } + \frac {1.57^2} { \ 2 * 9.81 \ } + 4 + 0.38 ##

    P2 = -41249 Pa
    = -0.41Bar

    Pump Outlet

    ## \frac {P1} { 960 * 9.81 } + \frac {1.57^2} { 2 * 9.81 \ } = \frac {200000 }{\ 960 * 9.81 \ } + \frac {1.57^2} { \ 2 * 9.81 \ } + 15 + 1.19 ##

    P1= 352470 Pa
    P1 = 3.5 Bar + 2 Bar(Pressurised Cylinder)


    Power = qpgh
    = 0.01 x 960 x 9.81 x 19.57
    = 1.84 kW
    Assuming 70% = ## \frac { 1.84 } { \ 0.7 \ } ##
    = 2.63 kW



    Is my method correct so I can say the pump required is an 2.63 kW to overcome the 5.5 bar.


    Any help would be great

    Thanks
     

    Attached Files:

    Last edited: Apr 24, 2017
  2. jcsd
  3. Apr 29, 2017 #2
    Thanks for the thread! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post? The more details the better.
     
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