Concept explainers
Two tanks (Tank A and Tank B) are separated by a partition. Initially Tank A contains 2 kg of steam at 1 MPa and 300°C while Tank B contains 3 kg of saturated liquid–vapor mixture at 150°C with a vapor mass fraction of 50 percent. The partition is now removed and the two sides are allowed to mix until
FIGURE P4–44
(a)
The final temperature of the steam for a tank.
The quality of the steam at the final state for a tank.
Answer to Problem 44P
The final temperature of the steam is
The quality of the steam at the final state is
Explanation of Solution
Write the expression for the energy balance equation.
Here, the total energy entering the system is
Simplify Equation (I) and write energy balance relation of two tanks.
Here, the boundary work to be done into the system is
Substitute 0 for
Here, the initial mass of tank A is
Write the expression for volume of tank A.
Here, the volume of the tank A is
Write the expression for volume of tank B.
Here, the volume of the tank B is
Write the expression for total mass of tank.
Write the expression for total volume contained in both tanks.
Write the expression for final specific volume of tank.
Conclusion:
Convert the unit of pressure from kPa to MPa.
From the Table A-6, “Superheated water”, obtain the value of initial specific volume
From the Table A-4, “Superheated water”, obtain the value of initial specific volume and specific internal energy for tank B.
At the initial temperature and quality of the steam at the final state of tank B as 150 C and 0.50.
Determine the specific volume of a two-phase system for tank B.
Here, the specific volume of saturated liquid for tank B is
Here, the specific internal energy of saturated liquid for tank B is
Substitute
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Substitute
Refer Table A-5, “Saturated water-pressure”, obtain the final temperature of the steam.
At final pressure of the steam is
Thus, the final temperature of the steam is
From the Table A-5, “Saturated water-pressure”, obtain the value of quality of the steam at the final state and final specific internal energy for tank B.
At the final pressure and specific volume at the final state as 300 kPa and
Determine the specific volume of a two-phase system for steam.
Here, the specific volume of saturated liquid for steam is
Here, the specific internal energy of saturated liquid for steam is
Substitute
Thus, the quality of the steam at the final state is
Substitute
(b)
The amount of heat lost from the tanks.
Answer to Problem 44P
The amount of heat lost from the tanks is
Explanation of Solution
Conclusion:
Substitute
Thus, the amount of heat lost from the tanks is
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Chapter 4 Solutions
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