Project ForgeThermodynamics
First Law of Thermodynamics
GATE 2009
Hard
In an air-standard Otto cycle, the compression ratio is 10. The condition at the beginning of the compression process is 100 kPa and 27°C. Heat added at constant volume is 1500 kJ/kg, while 700 kJ/kg of heat is rejected during the other constant volume process in the cycle. Specific gas constant for air = 0.287 kJ/kgK. The mean effective pressure (in kPa) of the cycle is
- A103
- B310
- C515
- 1032
Explanation
Net work=Qin-Qout=1500-700=800 kJ/kg. v1=RT1/P1=0.287×300/100=0.861 m³/kg; v2=v1/r=0.0861 m³/kg. MEP=Wnet/(v1-v2)=800/(0.861-0.0861)=800/0.7749≈1032 kPa.
Source: GATE ME 2009 (2009)
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