SECOND LAW OF THERMODYNAMICS
Thermodynamics
It is sometimes useful to plot on the Mollier diagram the processes that occur during the cycle.
This is done on Figure 38. The numbered points on Figure 38 correspond to the numbered points
on Figures 35 and 36. Because the Mollier diagram is a plot of the conditions existing for water
in vapor form, the portions of the plot which fall into the region of liquid water do not show up
on the Mollier diagram. The following conditions were used in plotting the curves on Figure 38.
Point 1:
Saturated steam at 540oF
Point 2:
82.5% quality at exit of HP turbine
Point 3:
Temperature of superheated steam is 440oF
Point 4:
Condenser vacuum is 1 psia
The solid lines on Figure 38 represent the conditions for a cycle which uses ideal turbines as
verified by the fact that no entropy change is shown across the turbines. The dotted lines on
Figure 38 represent the path taken if real turbines were considered, in which case an increase in
entropy is evident.
HT-01
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