Topic: IC Engines
An air standard Otto cycle operates with a compression ratio of 9 and the ambient temperature is 300 K. If the adiabatic index of the medium is 1.5, what is the efficiency?
- A. 75%
- B. 66.67%
- C. 50%
- D. 33%
Answer: B. 66.67%
Explanation: The efficiency of an Otto cycle is given by eta = 1 - (1 / r^(gamma - 1)). Substituting r = 9 and gamma = 1.5 gives eta = 1 - (1 / 9^(1.5 - 1)) = 1 - (1 / 9^0.5) = 1 - (1/3) = 2/3 = 66.67%.