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 27°C to 800 kPa
2-3 v = constant heat addition to 1800 K
3-4 Isentropic expansion to 100 kPa
4-1 P =constant heat rejection to initial state