On a Mollier chart, the constant pressure lines 

Explanation:

Mollier diagram:

• Mollier chart is drawn between enthalpy (h) and entropy (s).
• The turbine output on the Mollier diagram represented by the vertical straight line in ideal conditions.
• On Mollier diagram constant pressure line diverge from one another as shown in the figure.

From the first and second laws of thermodynamics, the following property relation was obtained,

Tds = dh – vdp

\({\left( {\frac{{\partial h}}{{\partial s}}} \right)_p} = T\)

This equation forms the basis of the h-s diagram of a pure substance, also called the Mollier diagram. The slope of an isobar on the h-s coordinates is equal to the absolute saturation temperature ( tsat + 273) at that pressure.

Mollier diagram is enthalpy (h) versus entropy (s) plot.

It consists of a family of constant pressure lines, constant temperature lines and constant volume lines plotted on enthalpy versus entropy coordinates.

The slope of the constant pressure line on an h-s curve is equal to absolute temperature and due to this reason, the constant pressure lines are of diverging nature in the superheated region.