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| 1 | |
An Otto cycle has a compression ratio of 8 and maximum temperature of 627°C. At the beginning of the compression stroke, the pressure and temperature of the working fluid are 100 kPa and 27°C. Based upon the cold air standard analysis assumptions, how much work is produced per cycle completion? |
| | A) | 43.7 kJ/kg |
| | B) | 85.6 kJ/kg |
| | C) | 97.4 kJ/kg |
| | D) | 114.2 kJ/kg |
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| 2 | |
A 4-liter (2 liter per revolution at standard P and T) spark ignition engine has a compression ratio of 8 and 2000 kJ/kg heat addition by the fluid combustion. How much power will this engine produce when operating at 2500 RPM? |
| | A) | 50.2 hp |
| | B) | 73.1 hp |
| | C) | 97.4 hp |
| | D) | 148 hp |
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| 3 | |
An Otto cycle has a compression ratio of 9 and a heat input of 1004 kJ/kg. At the start of the compression stroke, the air is at 95 kPa, 22°C. The thermodynamic efficiency of this cycle, based on hot-air standard analysis assumptions, is |
| | A) | 0.248 |
| | B) | 0.361 |
| | C) | 0.482 |
| | D) | 0.531 |
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| 4 | |
A pure Diesel cycle operates with a compression ratio of 15, and a cutoff ratio of 2.5. What is the rate of heat input required for this cycle to produce 300 hp? |
| | A) | 227 kJ/s |
| | B) | 386 kJ/s |
| | C) | 438 kJ/s |
| | D) | 556 kJ/s |
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| 5 | |
At the start of the compression stroke of a Diesel cycle, the air is at 100 kPa, 27°C. This cycle has a compression ratio of 16, and a heat input of 400 kJ/kg. Using hot-air standard analysis, what is the cut-off ratio for this cycle? |
| | A) | 1.4 |
| | B) | 1.6 |
| | C) | 1.8 |
| | D) | 2.0 |
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| 6 | |
A Sterling engine uses an energy source whose temperature is 727°C and an energy sink whose temperature is 27°C. How much heat must be added to the engine to produce 1 unit of work? |
| | A) | 1.0 |
| | B) | 1.19 |
| | C) | 1.43 |
| | D) | 2.01 |
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| 7 | |
A simple Brayton cycle uses helium as the working fluid, has a maximum temperature of 1000 K, and a pressure ratio of 4. At the start of the compression, the helium pressure and temperature are 50 kPa and 250 K. Based upon cold-air standard analysis assumptions, the thermal efficiency of the cycle is: |
| | A) | 0.13 |
| | B) | 0.23 |
| | C) | 0.33 |
| | D) | 0.43 |
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| 8 | |
A simple Brayton cycle has a pressure ratio of 5 and a maximum temperature of 900 K. Air enters the compressor at 100 kPa, 300 K. Based upon cold-air standard analysis assumptions, the back-work ratio of this cycle is: |
| | A) | 0.22 |
| | B) | 0.36 |
| | C) | 0.42 |
| | D) | 0.53 |
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| 9 | |
A gas turbine utilizes two stages of compression, two stages of expansion, intercooling, reheating, and regeneration. The pressure ratio for both compressors is 4, the temperature at the outlet of all combustion processes is 1200 K, the regenerator and intercooler operate ideally, and air enters the first compressor at 100 kPa, 300 K and the second compressor at 300 K. What is the thermal efficiency of this gas turbine using cold air standard analysis assumptions? |
| | A) | 0.22 |
| | B) | 0.41 |
| | C) | 0.63 |
| | D) | 0.72 |
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| 10 | |
A simple Brayton cycle has a pressure ratio of 6, a maximum cycle temperature of 1100 K, and air enters the compressor at 100 kPa, 300 K. The isentropic efficiency of the compressor is 0.80 and that of the turbine is 0.90. Using hot-air standard analysis assumptions, what is the thermal efficiency of this cycle? |
| | A) | 0.27 |
| | B) | 0.37 |
| | C) | 0.42 |
| | D) | 0.55 |
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