Repeat Prob. 9-54, but replace the isentropic expansion process by polytropic expansion process with the polytropic exponent n = 1.35. Use variable specific heats.
Prob. 9-54
An ideal diesel engine has a compression ratio of 20 and uses air as the working fluid. The state of air at the beginning of the compression process is 95 kPa and 20oC. If the maximum temperature in the cycle is not to exceed 2200 K, determine
(a) The thermal efficiency
(b) The mean effective pressure.
Assume constant specific heats for air at room temperature.