[ Themodynamics Table of Contents ]

An h-T diagram exhibits the same features as on the previous property diagrams. Figure 12 isthe h-T diagram for pure water. An h-T diagram can be constructed for any pure substance. Asin the previous property diagrams, there are regions on the h-T diagram in which two phasesexist together. The region between the saturated liquid line and the saturated vapor linerepresents the area of two phases existing at the same time. The vertical distance between thetwo saturation lines represents the latent heat of vaporization. If pure water existed at point Aon the saturated liquid line and an amount of heat was added equal to the latent heat ofvaporization, then the water would change phase from a saturated liquid to a saturated vapor(point B), while maintaining a constant temperature. As shown in Figure 12, operation outsidethe saturation lines results in a subcooled liquid or superheated steam.