An air standard cycle with variable specific heats is executed in a closed system and is composed of the following four processes:
1-2 isentropic compression from 100 kPa and 22 degrees C to 600 kPa
2-3 volume is constant and heat addition is 1500 K
3-4 isentropic expansion to 100 K
4-1 pressure is constant and heat rejection to initial state
Show the cycle on at P-v and T-s diagrams. Calculate the net work output per unit mass. Determine the thermal efficiency.