Repeat Prob. 9-164 using constant specific heats at room temperature.

Prob. 9-164:

Consider a simple ideal Brayton cycle with air as the working fluid. The pressure ratio of the cycle is 6, and the minimum and maximum temperatures are 300 and 1300 K, respectively. Now the pressure ratio is doubled without changing the minimum and maximum temperatures in the cycle. Determine the change in

(a) the net work output per unit mass and

(b) the thermal efficiency of the cycle as a result of this modification. Assume variable specific heats for air.