# Consider the air-standard Otto cycle described in Problem 9.94 operating with a compression ratio of 8 (=

## Question:

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 T_{3}.

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).

## Step by Step Answer:

**Related Book For**

## Thermodynamics Concepts And Applications

**ISBN:** 9781107179714

2nd Edition

**Authors:** Stephen R. Turns, Laura L. Pauley