 Ganesh Bihagalave working as an assistant professor in Department of Mechanical Engineering, Valchinist of Technology, Sallapur. In this session of thermodynamics, we will see steam properties second part in that Moliar diagram. Learning outcome. At the end of this session, students will be able to evaluate steam properties from Moliar's diagram. In previous sessions, we have studied the temperature and property diagram. Now, this is the temperature-specific volume diagram. There is a change in the saturation dome shape. Now, here point number one to this process is isobaric process. The point one EFGS is isobaric process. So water is in the liquid phase. Remember, the saturated liquid curve left hand region is the liquid region. The area below inside this dome shape is wet region and this upper region is the super heated vapor region. So, when we start heating the water from point number one, it is a sensible heat. We will follow the isobaric as discussed previously. Then from EF to G point is the latent heat process. Now, as the pressure is taken as 1 bar, the saturation temperature is 100 degree Celsius. The point number G is on the saturated liquid and point number EFGS is in the super heated form. Now, if we try to join all the saturated points, then we will be getting the saturated liquid curve. This is the critical point and this is the saturated vapor curve. Now, you can see here the saturated, sorry, this critical point has the properties for water. Pressure, critical pressure is 22.09 megapascal, ok. At a critical point, the latent heat is 0, remember, ok. Now, after this, we will move to the Mollier's chart. Mollier's chart or diagram is very useful for solving the numericals for a steam nozzle, ok. So, now, we will see the Mollier's diagram. So, Mollier's diagram is plotted on specific enthalpy versus specific entropy chart. On x-axis, there is a specific entropy, on y-axis, there is specific enthalpy. The saturated curve is having such type of nature. The critical point is somewhere here, this is the critical point. Then, this becomes saturated liquid curve and this is the saturated vapor curve. So, the drainage fraction of the saturated vapor curve is 1 and the drainage fraction of saturated liquid is 0. Then, I can show the drainage fraction curves having suppose 0.1 value and 0.95. So, in between that, there will be 0.2, 0.3 and so on, ok. So, this is the nature of drainage fraction lines. The isothermal lines, constant temperature lines is having this nature. These are the isothermal lines. The temperature along these lines is constant. In the study of moisture, it is observed that isothermal lines and isenthalpic lines. Almost coincide, they coincide each other, ok. Isothermal line and isenthalpic lines are coinciding. Now, the isobaric lines, the nature of isobaric lines on the Mollier's diagram having such type of slope. These are the isobaric lines. Along these isobaric lines, the pressure remains constant. At the same time, there are specific volume curves are also present. So, these are the specific volume lines. This is the nature of the specific volume lines. So, this is all about the Mollier's diagram. Now, what we will do? We will try to locate the points if we know any two inlet properties of the steam nozzle. So, consider this is the Mollier's diagram, HS diagram. And now, I will show only the saturated vapor curve. This is the saturated vapor curve. Suppose, you know the temperature, inlet temperature to suppose the steam nozzle. Steam nozzle inlet properties are 1, steam is flowing through the nozzle and suppose the exit state is represented by point number 2. If I know the inlet temperature is 300 degree Celsius, assumption is there. And pressure is suppose 20 bar, inlet temperature T 1, inlet pressure T 1 as the nature of the isothermal lines are these and consider this is 300 degree Celsius. And the pressure line is 20 bar, then the intersection point is point number 1. The flow through steam nozzle is isentropic. The flow through the steam is isentropic. And if the exit pressure is around 5 bar assumption once again, then what I will be doing? This pressure line is 20 bar pressure line. I will search the 5 bar pressure line. So, it is the 5 bar pressure line. And I will draw the parallel line to the y axis, parallel line to the y axis. So, the intersection of this isentropic expansion to the isobaric line occurs at this state represented by 2. Now, Mollier's chart is very useful. If you know the inlet any two properties and outlet one property, you could represent the process on the Mollier's diagram and corresponding properties. Corresponding properties like suppose if I take the projection from point number 1, I will get the h 1 enthalpy. If I will draw such type of line, I will get h 2. Remember, this is the graphical method of solving the numericals on the steam nozzle. Similarly, the specific volume, I will get specific volume of steam at point number 2 in this fashion. So, this is the use of Mollier's diagram. Now, I will try to show the Mollier's diagram, which is given in the. So, I have taken from the moron. So, this is the Mollier's diagram. As we have discussed, it is enthalpy versus entropy. This is the saturation curve. This region will be the weight region. This is the superheated region. Whereas, this is the critical point. These are the drainage fraction curve. These are the isothermal lines. These are the isobaric lines. So, if suppose this is the inlet to the convergent nozzle, taking the vertical projection will be isentropic expansion and you could locate point number 2, that is that exit at exit of the steam. Here, we will see the references. For a further study, you could refer the fundamentals of thermodynamics by Boranke and Sontek. And second book, Fundamentals of Inheriting Thermodynamics by Moran Shapiro. Thank you.