Repeat Prob. 9–57, but replace the isentropic expansion process with a polytropic expansion process with the polytropic exponent n = 1.35. Use variable specific heats.

Data From Q#57:

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 20°C. 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.