TITLE.PM5

156 ENGINEERING THERMODYNAMICS

dharm

/M-therm/Th4-4.pm5

∴ pv Z g

C pv Z g C

111

2

222

2

++ 22

F

HG

I

KJ

=++

F

HG

I

KJ + W ...(4.54)

Z 1

Z 2 = 0

Water turbine

W

Turbine shaft

Generator

Boundary

Fig. 4.32. Water turbine.

W is positive because work is done by the system (or work comes out of the boundary).

4.12.2. Steam or gas turbine

In a steam or gas turbine steam or gas is passed through the turbine and part of its energy
is converted into work in the turbine. This output of the turbine runs a generator to produce
electricity as shown in Fig. 4.33. The steam or gas leaves the turbine at lower pressure or temperature.

W

Turbine

2

1

Generator

Gas or steam out

Q

Gas or steam in

Boundary

Fig. 4.33. Steam or gas turbine.