Chapter 5, Problem 5.39P

Interpretation Introduction

Interpretation:

For per mole of gas $W$, $W_{\text{ideal}}$, $W_{\text{lost}}$ and $S_G$ for a gas flowing in a steady-flow adiabatic turbine with given conditions should be determined.

Concept Introduction:

The shaft work done by turbine is calculated as:

  $\Delta H=Q+Q_{\sigma }+W_S$

For adiabatic conditions and no heat transfer to the cold reservoir

  $\Delta H=W_S$

   .....(1)

The work done by an ideal gas is calculated by following formula:

  $W_{\text{ideal}}=\Delta H-T_{\sigma }\Delta S$   .....(2)

The work lost is calculated by following formula:

$W_{\text{lost}}=\left|W_S-W_{\text{ideal}}\right|$   .....(3)

And

The entropy generation in the surrounding is calculated by following formula

$S_G=\frac{W_{\text{lost}}}{T_{\sigma }}$

   .....(4)

Where $W_{\text{lost}}$ is the work lost by turbine to the surrounding and $T_{\sigma }$ is the surrounding temperature.