Constant Pressure Addition Consider the plot on the Figure 7, TV Diagram temperaturevolume diagram of Figure 7, viewing the constantpressure line that represents the states through which the water of the previous discussion passes as it is heated from the initial state of 14.7 psia and 60F. Let state A represent the initial state and state B represent the start of the saturated liquid line (212F). Therefore, line AB represents the process in which the liquid is heated from the initial temperature to the saturation temperature.
Point C is the saturated vapor state, and line BC is the constanttemperature process in which the change of phase from liquid to vapor occurs. Line CD represents the process in which the steam is superheated at constant pressure. Temperature and volume both increase during the process. Now let the process take place at a constant pressure of 100 psia, beginning from an initial temperature of 60F. Point E represents the initial state, the specific volume being slightly less than 14.7 psia and 60F. Vaporization now begins at point F, where the temperature is 327.8F. Point G is the saturatedvapor state, and line GH is the constantpressure process in which the steam is superheated.In a similar manner, a constant pressure of 1000 psia is represented by line IJKL, the saturation temperature being 544.6F.
