Handouts
LINK: Air Standard Power CyclesTopics:
Carnot Cycle
Otto Cycle
Diesel Cycle
Dual Combustion Cycle
Brayton Cycle
Stirling Cycle
Ericsson Cycle
Exercises
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1. In an air standard Otto cycle, the clearance volume is 10% of the displacement volume. Find the compression ratio and or thermal efficiency. a. 61.68 b. 72.68 c. 51.82 d. 81.50 2. A Carnot cycle has a maximum temperature of 200oC and a minimum temperature of 28oC. Find the cycle efficiency. a. 36.36 b. 46.46 c. 54.46 d. 32.21 3. A Carnot engine requires 45 kJ/sec from the hot source. The engine produces 25 kW of power and the temperature of the sink is 25oC. What is the temperature of the hot source? a. 285.1 b. 397.57 c. 352.22 d. 310.27 4. A Carnot engine receives 120 Btu of heat from a hot reservoir at 620oF and rejects 50 Btu of heat. Calculate the temperature of the cold reservoir. a. -10.01 b. -6.89 c. -9.96 d. -8.76 5. The maximum thermal efficiency possible for a power cycle operating between 1500oF and 300oF is: a. 61 b. 72 c. 51 d. 43 6. A heat engine is operated between temperature limits of 1300oC and 250oC. Engine supplied with 14000 kJ per kW-hr. Find the Carnot cycle efficiency in percent. a. 60.7 b. 63.7 c. 52.7 d. 66.7 7. An Otto engine has a clearance volume of 10%. It produces 320 kW power. What is the amount of heat rejected in kW? a. 200 b. 195 c. 190 d. 199 8. An air standard engine has a compression ratio of 16 and cut-off ratio of 4. If the intake air-pressure and temperature are 110 kPa and 32oC, find the work in kJ per kg. a. 1483.4 b. 1400.3 c. 1499.2 d. 1302.1 9. The thermal efficiency of a particular engine operating on an ideal cycle is 48%. Calculate the heat supplied per 1600 watt-hour of work developed in kJ. a. 11000 b. 12000 c. 13000 d. 10000 10. An Otto cycle has an initial condition of 100 kPa and 32oC. The compression ratio is 12 and the maximum temperature of the cycle is 1200oC. Find the heat added in kJ/kg. a. 555.45 b. 466.3 c. 405.8 d. 302.7 11. An Otto cycle has an initial condition of 101 kPa and 28oC. The compression ratio is 12 and the maximum temperature is 1300oC. Find the cycle mean effective pressure per kg of air. a. 418 b. 320 c. 422 d. 480 12. An Otto cycle has a heat added of 1200 Btu and work output of 610 Btu. Find the percent clearance. a. 20.41 b. 21.31 c. 22.45 d. 19.80 13. Air is compressed in an Otto cycle from 110 kPa to 760 kPa. Find the cycle efficiency. a. 38.30 b. 30.01 c.48.50 d. 42.43 14. A diesel cycle has a compression ratio of 10 and cut-off ratio of 3.0, find the cycle efficiency. a. 50.5 b. 60.3 c. 55.8 d. 48.02 15. A diesel cycle has a compression ratio of 8 and cut-off ratio of 2. If the heat added is 1450 kJ, find the heat rejected. a. 738.9 b. 638.4 c. 538.3 d. 434.5 16. A diesel cycle has an initial temperature of 28oC, compression ratio of 15 and cut-off ratio of 6. Find the maximum temperature of the cycle. a. 5000.9 b. 5062.2 c. 5082.3 d. 5042.1 17. In an air standard diesel cycle, compression starts at 110 kPa and 320 K. The compression ratio is 13 to 1. The maximum cycle temperature is 1800 K. Determine the cycle efficiency. a. 49 b. 45 c. 58 d. 60 18. Determine the air-standard efficiency of an engine operating on the diesel cycle with clearance of 7% when the suction pressure is 110 kPa and the fuel is injected for 6% of the stroke. Assume k=1.40. a. 55.3 b. 56.3 c. 61.4 d. 66.4 19. An Otto cycle has an efficiency of 70%. If the heat added is 450 kJ. Find the work done. a. 315 b. 421 c. 300 d. 320 20. An Otto cycle has an efficiency of 65%. If the work is 650 kJ, find the heat rejected. a. 350 b. 450 c. 380 d. 480 21. An Otto cycle has an efficiency of 50%. If the heat rejected is 1200 Btu, find the heat added. a. 2300 b. 2400 c. 2500 d. 2600 22. An Otto cycle has an initial condition of 30oC and 101 kPa. The compression ratio is 9 and the heat added during the process is 1100 kJ/kg. Find the mean effective pressure. a. 830.5 b. 840.5 c. 820.5 d. 880.3 23. The compression ratio of Otto cycle is 10. If the maximum temperature of the cycle is 1300oC, find the temperature after expansion. a. 363 b. 353 c. 340 d. 320 24. The initial temperature and pressure of Otto cycle are 30oC and 100 kPa, respectively. The compression ratio is 8 and the heat added during the process is 1400 kJ/kg. Find the maximum pressure of the cycle. a. 6981.7 b. 7891.6 c. 6781.4 d. 6641.3 25. A diesel cycle has a cycle efficiency of 60%. If heat added is 1700 kJ/kg, find the work a. 1020 b. 1030 c. 1040 d. 1050 26. A diesel cycle has a compression ratio of 10 and initial temperature of 35oC. If the maximum temperature of the cycle is 2200 K, find the cycle efficiency. a. 41.3 b. 48.2 c. 33.2 d. 48.8 27. A Brayton cycle has a pressure ratio of 12. Find the cycle efficiency. a. 43.3 b. 48.4 c. 50.83 d. 55.5 28. A Brayton cycle has an initial air temperature of 32oC. If the pressure ratio is 13, find the compressor work. a. 331.7 b. 542.7 c. 642.2 d. 578.3 29. A Brayton cycle has an initial temperature of 30oC and pressure ratio of 9. If the maximum temperature is 1500oC, find the heat added in the combustor. a. 1212.9 b. 1245.9 c. 1345.2 d. 1543.2 30. The maximum temperature of Brayton cycle is 1700oC and its pressure ratio is 8. Find the turbine work. a. 879.8 b. 889.8 c. 869.2 d. 856.3 31. The compression ratio of Brayton cycle is 12. Find the cycle efficiency. a. 53.2 b. 43.2 c. 62.9 d. 54.3 32. The temperature of four corners of Brayton cycle are t1=32oC, t2=420oC, t3=1320oC and t4=110oC. Find the cycle efficiency. a. 80.1 b. 99.0 c. 87.3 d. 91.3 33. A Brayton cycle has an initial condition of 30oC and maximum temperature of 1500oC. If the pressure ratio is 9, find the backwork ratio. a. 30.3 b. 29.3 c. 35.2 d. 32.0 |
Carnot Cycle
An air-standard Carnot cycle is executed in a closed system between the temperature limits of 350 and 1200 K. The pressures before and after the isothermal compression are 150 kPa and 300 kPa, respectively. If the net work output per cycle is 400 kJ, determine (a) The maximum pressure in the cycle, in kPa (b) The heat transfer to air.
SOLUTION:
Otto Cycle
An engine operates on the air standard Otto cycle. The cycle work us 900 kJ/kg, the maximum cycle temperature is 3000 deg C and the temperature at the end of isentropic compression is 600 deg C. Determine the engine’s compression ratio.
SOLUTION:
Diesel Cycle
The heat addition process in an air standard diesel cycle adds 800 kJ/kg. The cycle minimum temperature and pressure are 20 deg C and 100 kPa, and the maximum temperature is 1000 deg C. Determine the cycle thermal efficiency.
SOLUTION:
Brayton Cycle
A stationary power plant operating on a Brayton Cycle has a pressure ratio of 8. The gas temperature is 300 K at the compressor inlet an 1300 K at the turbine inlet. Utilizing the air standard assumptions. Determine (a) The gas temperature at the exits of the compressor and turbine (b) The back work ratio (c) The thermal efficiency.
SOLUTION:
