In an air-standard Otto cycle, the pressure and temperature of air just before the compression stroke are 200 kPa and 26.85 °C, respectively. The combustion process is assumed to be a constant volume process, where 1.02 MJ/kg heat is added. The cycle efficiency is 50%. The adiabatic index $γ$ and specific heat at constant volume $C_v$ can be considered to be constant during the process (corresponding values taken at the mean cycle temperature). Assuming that the ideal gas law is applicable, $γ = \frac 43$ and $c_v= 0.85\ kJ/kg-K$ , the maximum pressure (in MPa) reached during the cycle is _____ . (Rounded off to 1 decimal place)

Question

In an air-standard Otto cycle, the pressure and temperature of air just before the compression stroke are 200 kPa and 26.85 °C, respectively. The combustion process is assumed to be a constant volume process, where 1.02 MJ/kg heat is added. The cycle efficiency is 50%. The adiabatic index $γ$  and specific heat at constant volume  $C_v$  can be considered to be constant during the process (corresponding values taken at the mean cycle temperature). Assuming that the ideal gas law is applicable,  $γ = \frac 43$  and  $c_v= 0.85\ kJ/kg-K$ , the maximum pressure (in MPa) reached during the cycle is _____ . (Rounded off to 1 decimal place)

cdquestions Admin · Accepted Answer

The answer is: 9.5 or 9.7 (approx.)

List-I (Process)		List-II (Conditions)
(A)	Isothermal process	(I)	No heat exchange
(B)	Isochoric process	(II)	Carried out at constant temperature
(C)	Isobaric process	(III)	Carried out at constant volume
(D)	Adiabatic process	(IV)	Carried out at constant pressure

Correct Answer: 9.5

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