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Homework Help: Thermodynamics Entropy Help Please

  1. Feb 24, 2017 #1
    1. The problem statement, all variables and given/known data
    A flue gas is cooled from 1100 C to 150 C and the heat is used to generate saturated steam at 100 C in a boiler. The flue gas has a heat capacity given by CP/R = 3.83 + 0.000551 T, where T is in K. Water enters the boiler at 100 C and is vaporized at this temperature. Its latent heat of vaporisation is 2256.9 kJ/kg. What is the lost work of this process

    2. Relevant equations

    3. The attempt at a solution
    Basically i think i only need help in finding the rate of entropy generation of this qn. I believe i can finish the qn once i get that :)

    I managed to equate mdot(steam) x ndot(gas) = -15.13g/mol by doing a simple energy balance
    Tried to sub that into equation for summation of entropy but cant seem to solve it.
    Sdot(g) = Sdotg(steam) + Sdotg(gas)
    I have calculated ΔS(gas) and ΔS(steam) to be -41.835 and 6048 J/kgK but still cant seem to sub it in.

    Appreciate the help!! Thks!!
    Last edited by a moderator: Feb 24, 2017
  2. jcsd
  3. Mar 1, 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.
  4. Mar 2, 2017 #3
    Using the first law of thermodynamics, what do you get for the heat load?
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