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Thermodynamics exhaust power question

  1. Feb 10, 2009 #1
    1. The problem statement, all variables and given/known data
    An electric generating station is designed to have an electric output power 1.20 MW using a turbine with two-thirds the efficiency of a Carnot engine. The exhaust energy is transferred by heat into a cooling tower at 98°C.
    (a) Find the rate at which the station exhausts energy by heat, as a function of the fuel combustion temperature Th.

    If the firebox is modified to run hotter by using more advanced combustion technology, how does the amount of energy exhaust change?

    (b) Find the exhaust power for Th = 838°C.

    (c) Find the value of Th for which the exhaust power would be only half as large as in part (b).
    ----- K

    (d) Explain why no value for Th would give an exhaust power one quarter as large as in part (b).

    2. Relevant equations
    e= 1-Tc/Th

    3. The attempt at a solution
    i have no idea where to start..all i know is that the outpot power = 1.40MW and that Tc is 110 C??..what do i do with this info..please help
  2. jcsd
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