Chapter 5, Problem 5.10NP

Interpretation Introduction

Interpretation:

The maximum theoretical efficiency of an internal combustion engine operating in the Otto cycle for a fuel-air mixture at 273 K at a compression ratio of 6.9 and 15 needs to be calculated

Concept Introduction:

The efficiency (e) of a Carnot engine is a function of the reservoir temperatures and can be expressed as:

  $\text{ε = 1}-\frac{{\text{T}}_{\text{cold}}}{{\text{T}}_{\text{hot}}}\text{ ------(1)}$

For the expansion of an ideal gas mixture from an initial temperature and volume of T_i and V_i to a final temperature and volume of T_fand V_f respectively, the various parameters are related by the following equation:

  $\begin{array}{l}\frac{{\text{T}}_{\text{f}}}{{\text{T}}_{\text{i}}}\text{ = }{\left(\frac{{\text{V}}_{\text{f}}}{{\text{V}}_{\text{i}}}\right)}^{1-\gamma }\text{ ------(2)}\\ \text{γ = }\frac{{\text{C}}_{\text{p}}}{{\text{C}}_{\text{v}}}\text{ and }\frac{{\text{V}}_{\text{i}}}{{\text{V}}_{\text{f}}}=\text{ compression ratio}\end{array}$