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Homework Help: Finding Turbine Inlet State - Thermodynamics

  1. Aug 2, 2015 #1
    1. The problem statement, all variables and given/known data
    max. Turbine work output rate: 6.0MW
    Turbine isentropic efficiency: 90%
    Turbine exit state (isentropic): 40KPa, x=92%
    Turbine and pump actual process are assumed adiabatic

    Find turbine inlet state: Pinlet, Tinlet, Sinlet

    2. Relevant equations
    W = ΔH
    h = hf + xhfg

    3. The attempt at a solution
    I find hexit = hf + 0.92hfg

    where hf = hf @ 40KPa = 317.62 on sat. liquid table and hfg=2318.4. So then I find hexit = 2450.18 kj/kg.

    Then I do Wturbine = h1 - h2' to find h1 = hinlet = 8636.1 kj/kg. I then tried to look up that h on the superheated table to find the pressure and temperature and stuff but that's way too high of a number. I need help!
  2. jcsd
  3. Aug 3, 2015 #2


    User Avatar
    Science Advisor

    How? Where did you get Wturbine ? (units of kW/kg/s) You don't have a a mass flow rate to find Wturbine.
    Have you included the entire problem statement?
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