 Hello students, myself Ganesh B. Aghlawe working as an assistant professor in Department of Mechanical Engineering, Balchanistop Technology, Sallapur. In this session of thermodynamics, we will study vapor power cycle in that Rankine cycle. Learning outcome. At the end of the session, students will be able to describe Rankine cycle and also evaluate Rankine cycle efficiency. In the Rankine cycle, first of all there is boiler. The function of boiler is to convert steam from the water. The generated steam will have the properties at state 1, our notation. This steam will be passed through the turbine, now the steam as is having the high temperature high pressure will rotate the turbine blades, these are the turbine blades and after rotating the turbine blades will be able to produce work. As turbine is connected to the generator, it will develop the electricity. Now, the notations used for the expansion process, assumption which type of process occurs in the turbine is isentropic expansion process, so 1 to 2 is the isentropic expansion process. At the outlet of the turbine, the steam will be either dry saturated or wet steam. As the Rankine cycle is closed, this steam is to be converted into water, so what we will do? We will pass this either wet steam or the dry saturated steam through the condenser, through the condenser. So what will happen? This steam will release the heat to the fluid which is passed through the condenser, that fluid may be water or may be air. So counter flowing water or air, this water will be surrounding water, we will take the heat from the steam and there will be condensation, condensation. So vapours are converted into liquid by rejecting heat to the surrounding fluid, it may be water or air, this is the phase change process. Now, this low pressure, low pressure liquid is pressurized by the liquid pump from condenser pressure to boiler pressure. So this hydraulic pump increases the water pressure from condenser pressure to boiler pressure and it supplies to the boiler, it supplies to the boiler, this is known as Rankine cycle. Rankine cycle, there is boiler, turbine, condenser and pump. You may use the storage tank also, if there is excess water is available, you could store it. Now, we will try to show this cycle on the TS plot, on the TS plot. So, this is temperature and trochial plot, in previous sessions we have studied the TS plot, this is the saturation curve. Now what I will do, I will show here the two isobaric lines, first of all. Now the boiler is generating steam at high pressure, high temperature and suppose it is super heated, suppose it is super heated, so consider point number 1 is here. This is the boiler pressure, isobaric line, this is the condenser pressure, low pressure line. So, when the steam undergoes the isentropic expansion, there is work development, the work will be developed during the process 1 to 2, which occurs in the turbine, this is called as turbine work done. At state 2, theoretically the saturated vapor gets converted into saturated liquid in the condenser. So, this is the location of the condenser on the TS plot, 3 to 4, 3 to 4 is the pressurization process. So, the drawback of two phase Carnot cycle is overcame in this Rankine cycle. So, what this pump does? This pump will pressurize this water from condenser pressure to boiler pressure. So, this is the work required to drive the pump, this is the heat required to be given to the boiler. This is the heat rejected by the condenser QR. Now, the Rankine efficiency, Rankine efficiency is the net work done divided by heat supplied. So, what is net work done? Net work done is work developed by turbine minus work consumed by pump divided by QS. As the pump work consumption is very very small, is very very small, sometimes you can neglect it also. So, this was the Rankine cycle, which is represented on the TS plot. Now, for the actual Rankine cycle, if we consider the irreversibility, then this will be polytropic expansion process from 1 to 2 dash and actual pressurization 3 to 4 dash, it becomes actual Rankine cycle, actual Rankine cycle. In that case, actual Rankine efficiency, actual Rankine efficiency can be written as actual net work done divided by actual heat supplied. So, this becomes equal to WT dash minus WP dash divided by QS dash. Now, here WT, theoretical case is nothing but H1 minus H2 minus WP is H4 minus H3 divided by, for theoretical Rankine cycle, heat supplied is H1 minus H4. For actual Rankine cycle, the notation, see here the notation H1 minus H, yes, think over, yes, it is H2 dash minus, this is H4, yes, H4 dash minus H3 divided by H1 minus, actual heat supply will be from 4 dash to 1, H1 minus H4 dash. We will find that after solving the numericals, the Carnot efficiency, Carnot efficiency is greater than theoretical Rankine efficiency, which is greater than actual Rankine efficiency and this is practical cycle, this is theoretical cycle and this is imaginary cycle. So, this was all about vapor power cycle, that is nothing but Rankine cycle. For more study, you can refer Fundamentals of Thermodynamics by Boranke Sontek and Fundamentals of Innering Thermodynamics by Moran Shapiro, thank you.