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Homework Help: T-v diagram at constant volume

  1. Dec 29, 2011 #1
    1. The problem statement, all variables and given/known data
    5 kg of a mixture of saturated liquid-vapor water is in a container of fixed volume 2,5 m3. Initially the temperature is 75 ºC and then the water is heated.
    a) Find the temperature at which the water is completely vaporized.
    b) Draw the temperature-specific volume diagram.

    3. The attempt at a solution
    a) Is easily solved from the tables and I've found a temperature of 140,7 ºC.

    b) Here I am completely at a loss... From what I can understand from the problem, initially the process begins somewhere inside the "dome shaped" region.
    The specific volume is constant and equals 0,5 m3/kg, which lies between Vf and Vg for 75ºC. I put a red dot where I think the process begins... is it right?
    But now... how can we get to the final state? I think the final state is a saturated vapor state... is it right?
    Because specific volume is constant, I put a blue dot where I think the final state is... but how can the temperature change inside the dome shaped region??

    Many thanks!
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution

    Attached Files:

    • 1.jpg
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  2. jcsd
  3. Dec 29, 2011 #2
    oh... I think I got it! Temperature changes because pressure is not constant... So the diagram should be a straight line from red to blue dot. Is this okay?
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