The three different phase transition processes for water are shown in p - T diagram (Fig. 2.8). All the waves (Fusion, sublimation and vaporization) meet at the Triple point. At the extreme of vaporization curve, there is another point called the Critical point. During the phase transition temperature is a function of pressure only.
Fig. 2.10 Phase diagram for a pure substance on p - T coordinates
Fusion
It is the solid to liquid phase transition.
|
(2.10) |
where lfu is the latent heat of fusion
' (Prime) indicates the saturated solid state
" ( Double prime) indicates the saturated liquid state
For water, v" < v' (Indicating contraction) ⇒
For most other substances v" > v' ( expansion) 
Vaporization
It is the liquid to vapor phase transformation.
|
(2.11) |
Usually, v"' > v"
Assuming vapor to behalf as an ideal gas
|
(2.12) |
|
(2.13) |
