Thermal Engineering 1 Important Questions
Unit 1
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We have added Thermal Engineering 1 Important Questions, Thermal Engineering 1 Diploma N Scheme Important questions – for second year 3rd semester Diploma. You can download the Thermal Engineering 1 Important Questions pdf Thermal Engineering 1 Diploma N Scheme Important questions pdf
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Year: II Semester: 3 Subject Code:4020340 Subject: Thermal Engineering 1
Note:
- The following questions are collected from board exam question papers (from april 2014) of the previous scheme (L and M )
- The highlighted questions are asked more than two times in Board Exam
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Unit 1 BASICS OF THERMODYNAMICS AND THERMODYNAMIC PROCESSES OF PERFECT GASES
- 5 kg of air at 180 ° C expands adiabatically to 3 times its original volume during the expansion the temperature is decreased to 20 ° C. Work done during expansion is 53 KNm. Find cv, cp, and R.
- 2 kg of an ideal gas is compressed polytropically from a pressure of 1.5 bar and at 16o C to a pressure of 7.5 bar according of the law pv3=C. Determine (i) the initial volume, (ii) final temperature (iii) workdone (iv) change in internal energy (V) heat transferred (vi) change in enthalpy and (vii) change in entropy. Assume R=0.280kJ/kgK and Cp=1.0 kJ/kgK
- 25 kg of air at a pressure of 1 bar occupies a volume of 0.3m3. if this air expands isothermally to a volume of 0.9 m3 determine (i) the initial temperature (ii) the final temperature (iii) external workdone (iv) change in internal energy (v) heat absorbed by the air (vi) change in entropy. Assume R= 0.29 kJ/kgK
- A quantity of air occupies a volume of 30 liters at a temperature of 38o C and a pressure of 104 kN/m2. The temperature of the air is raised by adiabatic compression until the volume becomes 6 litres. Find (i) the final temperature (ii) the external work done (iii) change in internal energy (iv) the heat transferred (v) the change in enthalpy and (vi) the change in entropy. Take R = 0.29 kJ/kgK and ɣ = 1.4
- A perfect gas of molecular weight 28 and specific heat at constant pressure 1.016 kJ/kgK is compressed according to the law PV2 = C from an initial volume of 0.1 m3, temperature 35oC and pressure 98 kN/m2 to find final temperature of 145o C. Determine the final pressure of the gas, work done, heat transfer and change of entropy
- 1 kg of air at 11 bar and 80oC is expanded to 10 times to its original volume by (i) isothermal process and (ii) isentropic process. Determine the workdone in each of the cases. Plot these two on a common p-V diagram. Take R = 287 J/kgK γ = 1.4
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7. 25 kg of air at a pressure of 140 kN/m2 occupies 0.15m3 and from this condition, it is compressed to 1.4 MN/m2 according to the law pv1.25=C. Determine (|i) the change in internal energy (ii) the workdone on or by the air. (iii) the heat received by the air and (iv) the change in Entropy. Assume Cp =1.005 kJ/kgK and Cv = 0.718 kJ/kgK.
8. A gas occupies 4.5 bar and temperature 30o C occupies a volume of 3.1m3. if the mass is 1.25 kg, determine the gas constant
9.A gas is compressed hyberpolically from a pressure and volume of 100 kN/m2 and 0.056 m3 respectivelly to a volume of 0.007m3. Determine the final pressure and the workdone on the gas
10. Explain any two types of thermodynamic systems with 6 examples
11. Prove that universal gas constant Ru = 8.314 kJ/kgmoleK (4 marks)
12. During the compression stroke of an engine, the workdone on the gas is 75 kJ/kg and the heat rejected to the surroundings is 45 kJ/kg. determine the change in internal energy and state whether it is an increase or decrease
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13. A gas having molecular weight 28 occupies a volume of 0.15 m3 at a pressure of 2 bar and a temperature of 200 Find the mass of the gas. Also determine the volume and density of the gas at 00 C and 1 bar. Take RU = 8.314 kJ/kgmoleK
14. Prove the adiabatic process follows PV2 = C (6 Marks)
15. The initial volume of 0.18 kg of a gas was 0.15 m3 at a temperature of 150 C and a pressure of 100 kN/m2. After adiabatic compression to 0.056m3, the final pressure was 400 kN/m2. Find (a) Ratio of specific heat ‘γ’ and (b) change of internal energy
16. Derive the relation Cp –Cv = R
17. A mass of air has an initial pressure 1.3 MN/m3, volume of 0.014 m3 and temperature of 1350 It is expanded until its final pressure is 275 kN/m2 and its volume becomes 0.056 m3. Determine (a) mass of air and (b) the final temperature of the air. Take r = 0.237 kJ/kgK
18. Derive the formula for work done during polytropic process PVn = C
19. 5 Kg of an ideal gas is expanded from a pressure of 7 bar and volume of 1.5 m3 to a pressure of 1.4 bar and volume 4.5 m3. Determine (a) Index of polytropic expansion and (b) Work done
20. What are intrinsic and extrinsic properties? Give examples for each
21. 5 kg gas occupies 0.3 m3 at 200C and 140 kN/m2 and after adiabatic compression to 0.15 m3 the pressure is 370 kN/m2. Determine the value of compression, characteristic gas constant and the two principal specific heat capacities of the gas.
22. A gas is compressed hyberpolically from a pressure and volume of 105 kN/m2 and 0.05 m3 respectivelly to a volume of 0.005m3. Determine the final pressure and the workdone on the gas
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23. 35 m3 of air at 220C and under atmospheric pressure is heated at constant volume to a temperature of 1000C. Determine (a) Mass of air (b) the final pressure (c) heat transfer (d) the change in internal energy (e) the work done (f) the change in enthalpy and (g) the change in entropy. Assume Cp = 1.0 kJ/kgK and Cv=0.71kJ/kgK
24. State and explain the Clausius statement of second law of thermodynamics
25. 2 kg of air at a pressure of 1.1 bar and 150C is compressed isothermally to a pressure of 5.5 bar. Determine (a) the final volume (b) heat rejected (c) chanfe in entropy and (d) change in internal energy. Assume R=0.292 kJ/kgK.
26. A gas whose original pressure, volume and temperature were 120 kN/m2, 0.125 m3 and 300 C respectively is compressed such that its pressure and temperature are raised to 600 kN/m2 and 700C respectively. Determine the new volume of gas.
Thermal Engineering – 1 3 Marks Questions and answers | |
Unit 1 | Click here |
Unit 2 Part 1 | Click here |
Unit 2 Part 2 | Click here |
Unit 3 | Click here |
Unit 4 | Click here |
Unit 5 | Click here |