Air enters a dual cycle at 100 kPa and 20C. Using a cold-air analysis, determine the thermal

Question:

Air enters a dual cycle at 100 kPa and 20°C. Using a cold-air analysis, determine the thermal efficiency, the required specific heat input, and the net work output of this engine if:
a) r = 18, rc = 2, and rp = 2
b) r = 20, rc = 2, and rp = 2
c) r = 18, rc = 1.8, and rp = 2.2