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In a compression ignition engine, the inlet air pressure is 1 bar and the pressure at the end of isentropic compression is 32.42 bar. The expansion ratio is 8. Assuming ratio of specific heats (γ) as 1.4, the air standard efficiency (in percent) is
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- 59.59%
- 59.699%
- 59.599%
- 59.99%
Correct Option: C
Compression ratio,
| rk= | = |  |  | 1/γ | ||
| v2 | p1 |
= (32.42) 1/1.4 = 11.9999 ≅ 12
| cutoff ratio,rk = | expansion ratio |
| = | = 1.5 | 8 |
| η = 1 - | | | ||||
| rcγ - 1 | γ(rc - 1) |
| η = 1 - | | | ||||
| 120.4 | 1.4(1.5 - 1) |
η = 59.599%.
