[ Themodynamics
Table of Contents ]
A P-h diagram exhibits the same features
as a P-n diagram. Figure11
is the P-h diagram for purewater.
A P-h diagram can beconstructed
for any pure substance.Like
the P-n diagram, there areregions
on a P-h diagram in whichtwo
phases exist together. In theliquid-vapor
region in Figure 11,water
and steam exist together.For
example, at point A, waterwith
an enthalpy (hf),
given bypoint B, exists
together with steamwith
an enthalpy (hg),
given bypoint C. The
quality of themixture at
any point in theliquid-vapor
region can be foundusing
the following relationship.

