Concept explainers
Steam at 75 kPa and 8 percent quality is contained in a spring-loaded piston–cylinder device, as shown in Fig. P4–40, with an initial volume of 2 m3. Steam is now heated until its volume is 5 m3 and its pressure is 225 kPa. Determine the heat transferred to and the work produced by the steam during this process.
FIGURE P4–40
The heat transfer of the spring-loaded piston cylinder device.
The work done of the spring-loaded piston cylinder device.
Answer to Problem 40P
The heat transfer of the spring-loaded piston cylinder device is
The work done of the spring-loaded piston cylinder device is
Explanation of Solution
Write the expression for the energy balance equation.
Here, the total energy entering the system is
Substitute
Here, the mass of the piston cylinder device is
Calculate the specific volume of the spring-loaded piston cylinder device.
Here, the specific volume of saturated liquid is
Calculate the specific internal energy of the spring-loaded piston cylinder device.
Here, the specific internal energy of saturated liquid is
Write the expression for the mass of the system.
Here, the initial volume of the system is
Determine the final specific volume of the piston cylinder device.
The final volume of the piston cylinder device is
Determine the work done during the constant pressure process.
Here, the initial pressure is
Conclusion:
From the Table A-5, to obtain the value of the specific volume of saturated liquid is
Substitute 0.08 for
Substitute 0.08 for
Substitute
Substitute
From the Table A-5, to obtain the value of the specific volume of saturated liquid is
Determine the quality of final state for the spring-loaded piston-cylinder device.
Here, the specific volume of saturated liquid is
Substitute
Substitute 0.561375 for
Substitute
Thus, the heat transfer of the spring-loaded piston cylinder device is
Substitute
Thus, the work done of the spring-loaded piston cylinder device is
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Chapter 4 Solutions
Thermodynamics: An Engineering Approach
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