AET Question Bank for AUC R2017 Unit 1 2018 0717 S PDF

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Unit 1 Question Bank...

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Srinivasan Engineering College, Perambalur – 621 212.

AUC R2017

Srinivasan Engineering College (Approved by AICTE, New Delhi & Affiliated to Anna University, Chennai)

Perambalur – 621 212

Department of Aeronautical Engineering AE 8301 | Aero Engineering Thermodynamics Question Bank

Unit – I

Fundamental Concept and First Law 2 Marks

1. Discuss briefly about thermodynamic system and its types. (or) What is meant by Thermodynamics system? How do you classify it? 2. When a system is said to be in “Thermodynamic Equilibrium”? 3. What is thermodynamic temperature scale and why is it significant? (R13, Apr/May 2015) 4. Compare Heat and Work. (R08, Apr/May 2015), (R08, Nov/Dec 2016) 5. What is meant by a thermal energy reservoir? (R08, Apr/May 2015), (R08, Nov/Dec 2016) 6. When is work said to be done by a system? 7. Define: Internal energy. (R08, Apr/May 2017) 8. What are point and path functions? Give examples. (R13, Apr/May 2015) 9. State: Zeroth law of thermodynamics. Also give its importance. (R08, Nov/Dec 2015) (or) Define Zeroth law of thermodynamics. (R08, Apr/May 2017) 10. Define extensive and intensive property. 11. What are the limitations of the first law of thermodynamics? (R13, Nov/Dec 2016) 12. What are the deficiencies of the first law of thermodynamics? (R08, Apr/May 2017) 13. Indicate the practical application of steady flow energy equation. (R13, Nov/Dec 2016) 14. What is Nozzle? Write its energy flow equation. (R08, Nov/Dec 2015), (R08, Apr/May 2017) 15. Write the steady flow energy equation for steam turbine by considering heat lost to the surrounding. (R13, Apr/May 2017) (Additional) 16. Derive specific heat capacity at constant pressure and constant volume. 17. What is meant by Thermodynamic Substance and Thermometric Property? 18. Define indicated power and brake power of an engine.

Gurunath Kaliyaperumal – AE 8301 Aero Engineering Thermodynamics | 1

Srinivasan Engineering College, Perambalur – 621 212.

AUC R2017

13 or 15 or 16 Marks

1. i. ii.

2. i. ii.

What is polytropic process? How the work done is calculated in this process? Three grams of nitrogen gas at 6 atm and 160 °C in a frictionless piston cylinder arrangement is expanded adiabatically to double its initial volume, then compressed at constant pressure to its initial volume and then compressed again at constant volume to its initial state. Calculate the net work done on the gas. Draw the p-V diagram for the processes. (R13, Apr/May 2015), (R13, Nov/Dec 2016) What is an unsteady flow process? Give two examples. An insulated rigid tank having 5 kg of air at 3 atm and 30 °C is connected to an air supply line at 8 atm and 50 °C through a valve. The valve is now slowly opened to allow the air from the supply line to flow into the tank until the tank pressure reaches 8 atm, and then the valves is closed. Determine the final temperature of the air in the tank and find the amount of air added to the tank. (R13, Apr/May 2015)

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3. 0.4 m3 of air at 5 bar and 130 °C is contained in a system. A reversible adiabatic expansion takes place till the pressure falls to 1.02 bar. The gas is then heated at constant pressure till enthalpy increases by 72.5 kJ. Calculate: i.

The work done.

ii.

The index of expansion, if the above processes are replaced by a single reversible polytropic process giving the same work between the same initial and final states. (R08, Apr/May 2015), (R08, Apr/May 2017)

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4. 1 m3 of air is heated reversibly at constant pressure from 15 °C to 300 °C, and is then cooled reversibly at constant volume back to the initial temperature. The initial pressure is 1.03 bar. Calculate the net heat flow and overall change of entropy, and sketch the process on a T-s diagram. (R08, Nov/Dec 2015), (R08, Nov/Dec 2016) 5. i. ii.

6. i. ii.

Show that heat is a path function and not a property.

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A stationary mass of gas is compressed without friction from an initial state of 0.3 m3 and 0.105 MPa to a final state of 0.15 m3 and 0.105 MPa, the pressure remaining constant during the process. There is a transfer of 37.6 kJ of heat from the gas during the process. How much does the internal energy of the Gas change.

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Derive the expression for the work done in an adiabatic process for a closed system.

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An insulated and evacuated rigid tank of 15 litres capacity contains a 0.5 litre balloon containing water at 500 kPa and 150 °C. The balloon bursts and its contents occupy the entire volume of the tank. Find out the end pressure and also the temperature.

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Gurunath Kaliyaperumal – AE 8301 Aero Engineering Thermodynamics | 2

Srinivasan Engineering College, Perambalur – 621 212.

AUC R2017

7. 1500 kJ of heat transferred to 1 m3 of air at 15 bar and 220 °C. Find i. the final temperature and pressure if the volume remains constant, ii. the final temperature and volume if the pressure remains constant. After which process, the internal energy of the air has the greater value? iii. After the heating process, if the air is expanded isothermally to a pressure of p3 = 5 bar, what is the final volume in each case. Take Cp = 1005 J/kg-K, Cv = 718 J/kg-K and R = 287 J/kg-K. 8. 85 kJ of heat is supplied to a system at constant volume. The system rejects 90 kJ of heat at constant pressure and 20 kJ of work is done on it. The system is bought to its original state by adiabatic process. Determine the adiabatic work. Determine also the value of internal energy at all end states if initial value is 100 kJ. (R13, Apr/May 2017)

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9. Derive the steady flow energy equation and deduce it for a heater and a nozzle. 10. Air flows steadily at the rate of 0.4 kg/s through an air compressor, entering at 6 m/s with a pressure of 1 bar and a specific volume of 0.85 m3/kg, and leaving at 4.5 m/s with a pressure of 6.9 bar and a specific volume of 0.16 m3/kg. The internal energy of the air leaving is 88 kJ/kg greater than that of the air entering. Cooling water in a jacket surrounding the cyclinder absorbs heat from the air at the rate of 59 kJ/s. Calculate the power required to drive the compressor and the inlet and outlet pipe cross sectional areas. (R13, Apr/May 2017)

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11. Air flows steadily at the rate of 0.5 kg/s through an air compressor, entering at 7 m/s velocity, 100 kPa pressure and 0.95 m3/kg volume and leaving at 5 m/s, 700 kPa and 0.19 m3/kg. The internal energy of the air leaving is 90 kJ/kg greater than that of the air entering. Cooling water in the compressor jackets absorbs heat from the air at the rate of 58 kW. i. Compute the rate of shaft work input to the air in kW. ii. Find the ratio of the inlet pipe diameter to outlet pipe diameter. 12. In an air compressor, air flows steadily at the rate of 0.5 kg/s. At entry to the compressor, air has a pressure of 105 kPa and specific volume of 0.86 m3/kg and at exit of the compressor those corresponding values are 705 kPa and 0.16 m3/kg. Neglect kinetic and potential energy change. The internal energy of air leaking the compressor is 95 kJ/kg greater than that of air entering. The cooling water in the compressor absorbs 60 kJ/s of heat from the air. Find power required to drive the compressor. (R13, Nov/Dec 2016) 13. A turbine operating under steady flow conditions receives steam at the following state: pressure 13.8 bar; specific volume 0.143 m3/kg; internal energy 2590 kJ/kg; velocity 30 m/s. The state of the steam leaving the turbine is: pressure 0.35 bar; specific volume 4.37 m3/kg; internal energy 2360 kJ/kg; velocity 90 m/s. Heat is lost to the surroundings at the rate of 0.25 kJ/s. If the rate of steam flow is 0.38 kg/s. What is the power developed by the turbine? (R08, Nov/Dec 2015), (R08, Nov/Dec 2016)

Gurunath Kaliyaperumal – AE 8301 Aero Engineering Thermodynamics | 3

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