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Finding the internal energy using a steam table

  1. May 7, 2015 #1
    1. The problem statement, all variables and given/known data
    What is entropy of water at 5 Bar and an internal energy of 2724 kJkg-1?

    3. The attempt at a solution
    I have looked at the steam tables, i found where the pressure is 500kpa, then i do not know where to go from there.

    Thank You
     
    Last edited: May 7, 2015
  2. jcsd
  3. May 7, 2015 #2

    phinds

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    So you will be supplied with tables that no one has told you how to use? Really?
     
  4. May 7, 2015 #3
    i have changed the question around
     
    Last edited: May 7, 2015
  5. May 7, 2015 #4
    sorry for double post, i pressed something wrong by accident.
     
    Last edited: May 7, 2015
  6. May 7, 2015 #5
    Let me understand correctly. You have steam tables, and you know that you have water at 5 bars with an internal energy of 2724 kJ/kg, and you are asked to determine its entropy. Is that right?

    Chet
     
  7. May 7, 2015 #6
    Yes, thats exactly what i'm trying to do, i didnt know how to change the title and i didnt want to start a new thread.
     
    Last edited: May 7, 2015
  8. May 7, 2015 #7
    You found a place in the tables where the pressure is 500 kPa. What is the heading on the top of the page (e.g., saturated steam or superheated steam)?

    Chet
     
  9. May 7, 2015 #8
    Superheated Steam
     
  10. May 7, 2015 #9
    OK. Now there are columns of numbers on the page. What are the headings on the columns of numbers?

    Chet
     
  11. May 7, 2015 #10
    They are all temperatures from 100°c to 700°c
     
  12. May 7, 2015 #11
    What are the headings on the other columns (or rows?)?

    Chet
     
  13. May 7, 2015 #12
    there is t(sat), then h and s for all the temperatures above. also hg and sg for saturation
     
  14. May 7, 2015 #13
    I thought you said that the part of the table you were open to was for superheated steam. This table is for saturated steam. What gives?

    Chet
     
  15. May 7, 2015 #14
    i have two tables and i didn't notice, i have one with h and s, another with u and v, i just realized that i have to find the value for temperature in the u and v table using internal energy, then use that temperature to find the value of entropy in the h and s table. I got the value of entropy to be 7.272.

    Thank you very much!!!
     
  16. May 7, 2015 #15
    Sounds about right.

    Chet
     
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