Find the specific flow exergy into and out of the steam turbine in Example 7.1, assuming a...

Find the specific flow exergy into and out of the steam turbine in Example 7.1, assuming an ambient at 293 K. Use the exergy balance equation to find the reversible specific work. Does this calculation of specific work depend on T0?

Example 7.1

Steam enters a steam turbine at a pressure of 1 MPa, a temperature of 300°C, and a velocity of 50 m/s. The steam leaves the turbine at a pressure of 150 kPa and a velocity of 200 m/s. Determine the work per kilogram of steam flowing through the turbine, assuming the process to be reversible and adiabatic.

Control volume: Turbine.

Sketch: Fig. 7.2.

Inlet state: Fixed (Fig.).

Exit state: Pe, Veknown.

Process: Steady state, reversible and adiabatic.

Model: Steam tables.

FIGURE 7.2 Sketch for Example 7.1.

Analysis

The continuity equation gives us

From the energy equation we have

and the second law is

se = si