h-s Diagram or mollier chart

h-s DIAGRAM OR MOLLIER CHART

It is also called Mollier chart. In h-s diagram, the vertical ordinate represents the enthalpy while the base represents the entropy as shown in Figure 4.7. In h-s diagram, the dry steam line divides this chart into two regions. The region which is below the dry steam line represents the wet condition of steam. Here, the dryness fraction lines are shown parallel to dry steam line. The region above the dry steam line represents the superheated condition of steam. In this region, the constant temperature lines are shown.

At the same time, the lines at constant pressure are straight in the wet steam region but it is curved in the superheated region.

An adiabatic process is represented by a vertical line on h-s diagram. Throttling process in which enthalpy remains constant is represented by a horizontal line. With the help of this diagram, the heat drop during the adiabatic expansion can be directly read.

Constant volume process, constant pressure process and constant temperature process can be represented on the lines already plotted.