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Homework Help: Head added and final pressure

  1. Oct 15, 2013 #1
    1. The problem statement, all variables and given/known data

    Given: A sealed, rigid container (cannot change shape or size) containing steam at the shown conditions has heat added until it reaches the final shown state.

    Determine: a) heat added, b) work performed, c) change in internal energy of the system, and d) final system pressure

    2. Relevant equations

    Q = W + Δu

    Also given: T1= 200 deg C, mass = 10kg, volume = 1m^3 (for initial conditions)
    T2 = 350 C (for final conditions)

    The pressures I found in the thermo tables for the corresponding temperatures are:
    P1 = 1554.9 KPa
    P2 = 16529 KPa

    3. The attempt at a solution

    What I know is it's a saturated vapor system since it stated steam in the problem statement and closed system so no work is done.

    From that I was able to answer b) W = 0 and c) Q = 0 + m(u1-u2) --> 10Kg(2594.2-2418.3) KJ/kg = 1759 KJ of internal energy. The u's I got from thermo tables.

    The two I'm having a hard time with is a) the heat added to the system and d) final system pressure.
  2. jcsd
  3. Oct 15, 2013 #2
    You already found the answer to a. Look at what you put for c. You also already found the final pressure.
  4. Oct 15, 2013 #3
    Also I can tell the quality is not going to be 100%. You can use the volume and mass to find the specific volume. Than use that specific volume and the specific volumes from the table for state 1 and 2 to find the quality.
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