Consider the air-standard Otto cycle described in Problem 9.94 operating with a compression ratio of 8 (= V_max/V_min). The air just prior to compression is at 293 K and 1 atm. The maximum cycle temperature is 2500 K. Assuming constant specific heats, determine the temperature (K) and pressure (atm) at the start of each process and the thermal efficiency for the cycle.

An air-standard Otto cycle is often used as a very simplified model of a sparkignition engine. The following sequence of processes applied to a fixed mass of air in a piston–cylinder assembly constitutes the Otto cycle:

Problem 9.94

1-2 : Internally reversible, adiabatic compression from the maximum volume V_max to the minimum volume V_min.

2-3 : Constant-volume heat addition to a peak cycle temperature T₃.

3-2 : Internally reversible, adiabatic expansion from V_min to V_max.

4-2 : Constant-volume heat rejection to return to the initial state.

Sketch this cycle using P–V and T–S coordinates, labeling each state point (1, 2, 3, and 4).