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Applying the Entropy Balance: Control VolumesAir at 400
Chapter 6, Problem 90P(choose chapter or problem)
Air at 400 kPa, 970 K enters a turbine operating at steady state and exits at 100 kPa, 670 K. Heat transfer from the turbine occurs at an average outer surface temperature of 315 K at the rate of 30 kJ per kg of air flowing. Kinetic and potential energy effects are negligible. For air as an ideal gas with \(c_{p}=1.1 \mathrm{\ kJ} / \mathrm{kg} \cdot \mathrm{K}\), determine (a) the rate power is developed, in kJ per kg of air flowing, and (b) the rate of entropy production within the turbine, in kJ/K per kg of air flowing.
Questions & Answers
QUESTION:
Air at 400 kPa, 970 K enters a turbine operating at steady state and exits at 100 kPa, 670 K. Heat transfer from the turbine occurs at an average outer surface temperature of 315 K at the rate of 30 kJ per kg of air flowing. Kinetic and potential energy effects are negligible. For air as an ideal gas with \(c_{p}=1.1 \mathrm{\ kJ} / \mathrm{kg} \cdot \mathrm{K}\), determine (a) the rate power is developed, in kJ per kg of air flowing, and (b) the rate of entropy production within the turbine, in kJ/K per kg of air flowing.
ANSWER:Solution 90P:
Step 1 of 2:-
The initial air pressure is: .
The initial temperature is: .
The pressure while leaving the turbine is: .
The average surface temperature is: .
Air flow rate is: .
a)
The energy rate balance equation can write as,
Implies,
