Concept explainers
a)
The maximum work potential
a)
Answer to Problem 75P
The maximum work potential
Explanation of Solution
Write the expression for the initial mass
Here, initial pressure is
Write the expression for the final mass
Here, exit mass of helium from the cylinder is
Write the expression for the initial specific volume
Write the expression for the dead-state volume
Here, dead-state temperature is
Write the expression for the difference between initial entropy
Here, specific heats of helium is
Write the expression for the maximum work potential
Conclusion:
From the Table A-2, “Ideal-gas specific heats of various common gases table”, select the value of
Substitute
Substitute
Substitute
Substitute
From the Table A-2, “Ideal-gas specific heats of various common gases table”, select the value of
Substitute
Substitute
Thus, the maximum work potential
b)
The exergy destroyed during the process
b)
Answer to Problem 75P
The exergy destroyed during the process
Explanation of Solution
Write the mass balance equation for the system as,
Here, mass of the helium at the inlet of cylinder is
Write the Energy balance for the uniform flow system as;
Here, net energy transfer in to the control volume is
Combine Equation (VII) and Equation (VIII) to get,
Write the expression for the entropy balance for helium.
Here, entropy generation is
Substitute
Write the expression for the exergy destroyed during the process
Conclusion:
Substitute
Thus, the exergy destroyed during the process
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Chapter 8 Solutions
Thermodynamics: An Engineering Approach
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