Project ForgeThermodynamics
First Law of Thermodynamics
GATE 2007
Medium
The stroke and bore of a four stroke spark ignition engine are 250 mm and 200 mm respectively. The clearance volume is 0.001 m³. If the specific heat ratio γ=1.4, the air-standard cycle efficiency of the engine is
- A46.40%
- B56.10%
- 58.20%
- D62.80%
Explanation
Swept volume Vs=(π/4)(0.2)²(0.25)=0.007854 m³. Compression ratio r=(Vs+Vc)/Vc=(0.007854+0.001)/0.001=8.854. Otto efficiency η=1−1/r^(γ−1)=1−1/8.854^0.4≈1−0.418=0.582=58.2%.
Source: GATE ME 2007 (2007)
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