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20. The moment of inertia of a flywheel is 0.54 kg-m? and it rotates at a speed of 3000 r.p.m. in a large heat insulated system, the temperature of which is 15°C. If the kinetic energy of the flywheel is dissipated as frictional heat at the shaft bearings which have a water equivalent of 2 kg, find the rise in the temperature of the bearings when the flywheel has come to rest. Calculate the greatest possible amount of the above heat which may be returned to the flywheel as high- grade energy, showing how much of the original kinetic energy is now unavailable. What would be the final r.p.m. of the flywheel, if it is set in motion with this available energy ? (Ans. 3.19°C ; 0.1459 kJ ; 222 r.p.m.)

20. The moment of inertia of a flywheel is 0.54 kg-m? and it rotates at a speed of 3000 r.p.m. in a large heat insulated system, the temperature of which is 15°C. If the kinetic energy of the flywheel is dissipated as frictional heat at the shaft bearings which have a water equivalent of 2 kg, find the rise in the temperature of the bearings when the flywheel has come to rest. Calculate the greatest possible amount of the above heat which may be returned to the flywheel as high- grade energy, showing how much of the original kinetic energy is now unavailable. What would be the final r.p.m. of the flywheel, if it is set in motion with this available energy ? (Ans. 3.19°C ; 0.1459 kJ ; 222 r.p.m.)

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)
Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)
8th Edition
ISBN:9781305387102
Author:Kreith, Frank; Manglik, Raj M.
Publisher:Kreith, Frank; Manglik, Raj M.
Chapter3: Transient Heat Conduction
Section: Chapter Questions
Problem 3.37P
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Please answer the two questions under item no.20. Answers are given i want the solutions Thank you. Love u

20. The moment of inertia of a flywheel is 0.54 kg-m² and it rotates at a speed of 3000 r.p.m. in a large heat insulated system, the temperature of which is 15°C. If the kinetic energy of the flywheel is dissipated as frictional heat at the shaft bearings which have a water equivalent of 2 kg, find the rise in the temperature of the bearings when the flywheel has come to rest. Calculate the greatest possible amount of the above heat which may be returned to the flywheel as high- grade energy, showing how much of the original kinetic energy is now unavailable. What would be the final r.p.m. of the flywheel, if it is set in motion with this available energy ? [Ans. 3.19°C ; 0.1459 kJ ; 222 r.p.m.] In a steady flow air enters the system at a pressure of 10 bar and 200°C with a velocity of 100 m/s and leaves at 1.5 bar and 25°C with a velocity of 50 m/s. The temperature of the surroundings is 25°C and pressure is 1 bar. Determine reversible work and actual work assuming the process to be adiabatic. Determine also the irreversibility and effectiveness of the system on the basis of one kg of air flow. Take for air : c, = 1 kJ/kg K ; R = 287 J/kg K. (Ans. 200.65 kJ ; 178.75 kJ/kg, 21.90 kJ/kg ; 0.894]
Transcribed Image Text:20. The moment of inertia of a flywheel is 0.54 kg-m² and it rotates at a speed of 3000 r.p.m. in a large heat insulated system, the temperature of which is 15°C. If the kinetic energy of the flywheel is dissipated as frictional heat at the shaft bearings which have a water equivalent of 2 kg, find the rise in the temperature of the bearings when the flywheel has come to rest. Calculate the greatest possible amount of the above heat which may be returned to the flywheel as high- grade energy, showing how much of the original kinetic energy is now unavailable. What would be the final r.p.m. of the flywheel, if it is set in motion with this available energy ? [Ans. 3.19°C ; 0.1459 kJ ; 222 r.p.m.] In a steady flow air enters the system at a pressure of 10 bar and 200°C with a velocity of 100 m/s and leaves at 1.5 bar and 25°C with a velocity of 50 m/s. The temperature of the surroundings is 25°C and pressure is 1 bar. Determine reversible work and actual work assuming the process to be adiabatic. Determine also the irreversibility and effectiveness of the system on the basis of one kg of air flow. Take for air : c, = 1 kJ/kg K ; R = 287 J/kg K. (Ans. 200.65 kJ ; 178.75 kJ/kg, 21.90 kJ/kg ; 0.894]
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