226
General Engineering and Science
T
Qin
yq
&
0
condenser
0
I
S
(0)
(b)
Figure
2-36.
(a)
Schematic diagram
of
system.
(b)
T-S
diagram
of
process.
(text
continued
from
page
223)
The efficiency of power cycles such as the Rankine cycle is given by the ratio of
the net work out to the heat added. Thus from Figure
2-36
the efficiency is
(2-154)
The
H-S
plot
is
called a Mollier diagram and is particularly useful in analyzing
throttling devices, steam turbines, and other fluid flow devices.
A
Mollier diagram
for steam is presented in Figure
2-37
(standard engineering units) and in Figure
2-38
in
SI
units.
Thermodynamic properties may be presented in various ways, including:
Equations of state (e.g., perfect gas laws, Van der Waals equation, etc.).
Charts
or
graphs.
tables.
Tables
2-20-2-25
present thermodynamic properties for several pure substances
For further information
on
this subject, refer to References
15
through
26.
commonly encountered in petroleum engineering practice.
(text
continues
on
page
240)