Handouts
LINK: Thermodynamic Processes
Topics:
Isobaric Process
Isochoric Process
Isothermal Process
Isentropic Process
Polytropic Process
Exercises
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Air initially at 100 kPa and 300 K undergoes a constant pressure process until it reaches a final temperature of 620 K. Determine: 1. The work per kilogram of air a. 80 kJ/kg b. 103 kJ/kg c. 65 kJ/kg d. 92 kJ/kg 2. The heat required per kilogram of air a. 209 kJ/kg b. 350 kJ/kg c. 332 kJ/kg d. 322 kJ/kg 3. The change in internal energy, in kJ/kg a. 210 kJ/kg b. 255 kJ/kg c. 230 kJ/kg d. 260 kJ/kg 4. The change in entropy, in kJ/kg-K a. 0.61 b. 0.73 c. 0.88 d. 0.92 An ideal gas undergoing an isobaric process initially occupies a volume of 1500-L, pressure of 450 kPa and temperature of 320oC to a final temperature of 530oC. Let R=0.280 kJ/kg-k and Cp=1.0 kJ/kg-K. Determine: 5. The mass of the ideal gas, in kg a. 6 b. 5 c. 4 d. 3 6. The final volume occupied by the ideal gas, in m3 a. 2 b. 3 c. 4 d. 5 7. The change in internal energy and enthalpy, in kJ a. 614 and 853 b. 620 and 822 c. 610 and 845 d. 618 and 800 8. The heat and the work required in kJ a. 200 b. 243 c. 221 d. 239 Nitrogen is cooled at a constant pressure of 1.20 kPa from an initial specific volume of 1.80 m3/kg to a final specific volume of 0.76 m3/kg. If the mass of nitrogen undergoing the process is 2.20 kgs, determine: 9. The work, in kJ a. -4.5 b. -3.2 c. -2.7 d. -3.8 10. The change in entropy, in kJ/K a. -1.20 b. -1.97 c. -2.21 d. -1.52 11. The change in enthalpy and internal energies, in kJ a. -9.6 and –6.8 b. -10.1 and -5.3 c. -8.5 and –6.5 d. -7.3 and -4.2 Five kilograms of air is contained closed rigid container. An amount of 1200 kJ of heat is added until the air reaches 650 K. Determine: 12. The initial temperature of air, in K a. 320 b. 300 c. 345 d. 316 13. The final pressure, in kPa if the initial pressure of air is 300 kPa. a. 610 b. 622 c. 617 d. 636 14. A rigid insulated tank contains nitrogen at 85oF. The tank is continuously heated until the temperature reaches a limit of 300oF. Determine the amount of heat added, in Btu, if the mass of nitrogen contained inside the tank is 0.12 lbm. a. 3.3211 b. 4.5795 c. 5.5512 d. 2.8721 15. An unknown ideal gas with a molecular mass of 32 kg/kgmol undergoes an isochoric process. The initial and final temperature of the tank is 220oC and 800oC, respectively. If the change in internal energy of the system is 170 kJ per kg of gas, determine the change in enthalpy, in kJ/kg and the change in entropy, in kJ/kg-K. a. 320.7 and 0.2279 b. b. 333.3 and 0.2361 c. 305.1 and 0.3412 d. 345.7 and 0.2781 16. Two kilograms air is compressed isothermally from an initial temperature of 300 K and 100 kPa to a pressure limit of 400 kPa. Determine the work done on the system. a. -220.8 kJ b. -238.7 kJ c. -253.1 kJ d. -262.1 kJ Air expands in a water-cooled piston cylinder, maintaining a constant temperature of 320 K. The initial state of air is P1=520 kPa and V1=10L. If the final pressure is P2=100 kPa, determine: 17. The mass of air, in kg a. 0.0876 b.0.0566 c. 0.1211 d. 0.0661 18. The final volume of air inside the system, in liters a. 48 b. 52 c. 65 d. 58 19. The work, in kJ. a. 7.60 b. 8.57 c. 6.38 d. 5.55 20. 10 kJ of heat is added isothermally to a piston-cylinder arrangement containing 0.5 kg nitrogen. The initial pressure of the gas is 440 kPa and the temperature of the system is maintained to 400 K. Determine the pressure, in kPa at the final state. a. 232.76 b. 422.12 c. 320.11 d. 371.78 Air with an initially at: P1=920 kPa, T1=800 K and V1=0.13m3, expands in a reversible adiabatic manner. If the work produced is 130 kJ, determine: 21. The mass of air, in kg a. 0.52 b. 0.67 c. 0.44 d. 0.72 22. The final pressure and temperature, in kPa and K a. 120.88 and 442.18 b. 124.89 and 452.17 c. 128.11 and 410.12 d. 130.11 and 40023. Helium is compressed isentropically from a pressure of 100 kPa and volume of 0.24m3, until it reach a peak pressure of 560 kPa. Determine the work required, in kJ and the volume of the compressed helium, in m3. a. -30.2 and 0.0331 b. -32.4 and 0.0521 c. -35.7 and 0.0853 d. -38.3 and 0.0772 24. One kilogram of ethane is contained in a piston-cylinder and expands in a reversible adiabatic manner from 1100oC to 38oC. Determine the work done in the process, in kJ. a. 1320.11 b. 1531.28 c. 1452.87 d. 1570.28 300 kJ of heat is added in a piston-cylinder arrangement containing air causing it to expand in a polytropic manner. If the polytropic exponent throughout the process is 1.2, determine: 25. The change in enthalpy and internal energy, in kJ a. -410 and -280 b. -400 and -310 c. -380 and -330 d. -420 and -300 26. The work produced, in kJ a. 500 b. 400 c. 600 d. 700 Nitrogen expands in polytropically through a turbine. At the inlet of the turbine: P1=900 kPa, T1=1500K and v1= 98 m/s. At the exit, the pressure and velocity is 180 kPa and 175 m/s. If the turbine produces 45 MW and letting n=1.3, determine: 27. The exit temperature, in K a. 1000.0 b. 1034.6 c. 1055.3 d. 1120.1 28. The heat transferred, in kJ/s a. 9405 b. 9504 c. 9450 d. 9540 Helium expands polytropically in a piston-cylinder arrangement from an initial pressure and volume of 3800 kPa and 0.75 m3, respectively. If the final pressure is 120 kPa, determine 29. The work done, in kJ, a. 5220.12 b. 5022.21 c. 5311.12 d. 5202.13 30. The heat transferred, in kJ a. 2868.33 b. 2754.12 c. 2886.31 d. 2553.12 31. The change in entropy, in kJ/kg-K. Let n=1.3. a. 3.0330 b. 4.0313 c. 2.022 d. 5.0121 |
Isobaric Process
Air enters a combustion chamber at 28 deg C. Consider the combustion as adding 1600 kJ/kg of heat to the air. What is the ratio of the volume of hot air V2 to the initial volume V1?
SOLUTION:
Isometric Process
A closed rigid container has a volume of 1 m3 and holds air initially at 273 K and 350 kPa. Heat is added until the temperature is 630 K. Find (a) The heat added, kJ/kg (b) The final pressure, kPa (c) The change in entropy, kJ/kg-K.
SOLUTION:
Isothermal Process
If 0.15 kg/s of air are compressed isothermally from P1 = 98 kPa and V1 = 0.10 m3/s to P2 = 650 kPa, find the work for (a) A nonflow process (b) A steady flow process with v1 = 10 m/s and v2 = 60 m/s.
SOLUTION:
