Chapter 7, Problem 7.41P

Interpretation Introduction

Interpretation:

The compressor efficiency for the following inlet and outlet conditions should be determined.

T₁ = 300 K, P₁ = 2 bar, T₂ = 464K, P₂ = 6 Bar and C_p/R = 7/2

Concept Introduction:

The change in enthalpy and heat capacity at constant pressure are related to each other as follows:

$\text{ΔH = }\overrightarrow{\left[\text{Cp}\text{.}\left(T2-T1\right)\right]}$

Ideal gas having constant heat capacities. The actual enthalpy change is calculated as follows:

${\text{ΔH}}_S=\overrightarrow{\left[\text{Cp}\text{.T1}\left[{\left(\frac{\text{P2}}{P1}\right)}^{\frac{R}{Cp}}-1\right]\right]}$

The compressor efficiency is ratio of isotropic and actual enthalpy change as follows:

$\text{η = }\frac{\Delta {{\rm H}}_S}{\Delta {\rm H}}$