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Homework Help: Head of fluids & Engine Efficieny.

  1. Apr 2, 2009 #1
    1. The problem statement, all variables and given/known data
    A pump delivers water at a rate of 60L/s with a head of 65m. It runs for 8 hours per day. The efficiency of the pump is 75%. The efficiency of the electric motor driving the pump is 80%.

    i) What is the value of the head in kPa
    ii) Calculate the input power kW that is required to enable pump to supply the pressure as determined in part (i) above.

    2. Relevant equations
    pressure = density x gravity x height (take gravity as 9.81 meters per second)

    3. The attempt at a solution

    I know to find efficiency of the system you multiply the efficiency of both the pump and the motor - but the 'head' has stumped me - I know about head LOSS, but when it says 'a head of 65m' i'm lost. I've looked all through my handouts and can only find information about head loss. Not sure what this 65m head is referring to.

  2. jcsd
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