In this video, I explain Rankine Cycle. So first I explain the basic of Rankine Cycles, then various components of the Rankine Cycles and its arrangement, then after PV and TS diagram of the Rankine Cycles and at last we find out the equation of efficiency for the Rankine Cycles. So first we understand the basic of Rankine Cycles. The heat energy of the fuel is converted into the mechanical work or a power in a steam turbine power plant means steam turbine power plant is work on the Rankine cycles so we supplied the heat energy in the boiler this heat energy is converted into the mechanical work in the steam turbines so there are a main four component of the cycle first one is the boiler second one is the turbine third one is the condensers and fourth one is the pit pump now we understand the one by one components okay so first we understand what is functions of boilers which process is carried out in the boilers and then after we draw this process on the pv diagram then we move towards the second component okay so it is a easy for you to understand okay so that is a process one to two it is the constant pressure heat addition in the boiler means in a rank time cycle first component is the boiler okay so here you see this is the boiler and in the boiler which process is carried out that is a heat addition okay so you already know that in the boiler we burn the fuels and this burning fuel is really some amount of the heat energy okay and this heat energy is added into the water okay that's why its name is given that is a heat addition and this heat addition process is done at the constant pressures okay means during this heat addition process in the boiler the pressure of the working fluid is remains constants so in a boiler We supplied the water from the feed pump and this water is absorbed the Q as quantity of the heat energy. Q means heat and S means supply.
Okay. And this water is converted into the steam. So, it is called as the process 1 to 2. The water is heated at the constant pressure P1 in the boiler until the saturation temperature is reached.
So saturated water is converted into saturated steam at the constant pressures. So in this process you see that is a at the inlet of the boiler one condition at the outlet of the boiler two condition is there okay. So pressure remains constant means this P1 and P2 are constants okay.
So when we draw the process on the PV diagram it's coming to the horizontal lines okay. Now during 2-2 process the steam is superheated in a superheater that I explained on this PV diagram okay. and the heat supply value is find out that is a qs is equal to h2 minus h1 so first we draw this process on the pv diagram on the y axis pressure is there on the x axis volume is there and in this pv diagram one curve is drawn it is called as the saturation curve okay in this saturation curve this point is called as the critical point okay and from the critical point the line left side is indicate saturated liquid line means this line is indicated it is a saturated liquid line means at this point suppose we take here point it's indicate the water suppose we take the point here it's indicate the water means in this line the we putting the point that is the water okay means liquid and the right side from this critical point this is the critical point means right side means this line is indicate the saturated vapor means any point on this line it's the indicate the vapor states okay and this region is indicate the superheated region this region means region right side to the saturated vapor line is indicate the superheated region same way region left side to the saturated liquid line is indicate the saturated liquid and the area under this cow line is indicate the mixing of liquid plus vapor so it is called as the weight regions okay so where is the point number one is coming so we know that it is a constant pressure process okay at the when the water is entering the boiler it have the high pressure means point number one is coming in this upper region okay because here the value of the pressure is zero when we moving in upper direction the pressure is increased okay so we know that at the entry of the boiler the state of the working substance is the liquid means point number one is coming somewhere here on these lines or either the left side of this line okay and this water is converted into the vapor means it is converted into the steam means point number two is coming on this higher region but on this right side line because from the critical point line is indicate the vapor line okay so point number two is coming here okay so this is the complete line that is a one to two okay so here at the two days point this point is indicate two days at this point it is the saturated streams okay and at the two point is indicate the superheated means the any point right side to this saturated vapor light is indicate the superheated okay so here we mentioned during the two dash to two so this is the two dash point and this is the two point this process the steam is superheated in the superheater means from the boiler the steam is coming is the saturated okay but we need to convert the saturated steam into the superheated we require the superheater so this is the point number two so we can draw the point number two anywhere okay that is a two days point here or a two point here same way one point is coming also on this lab point or either it is also commonly saturated liquid lines okay it is depending on the conditions and what amount of the heat is added so when we here at the heat this h2 is higher than the h1 so it is we written that is h2 minus h1 now the second process it is the process two to three it is the isentropic expansion in the turbine means second component is the turbine okay and isentropic expansion means isentropic means entropy remains constant during the expansion process okay so when the expansion is done what happened the pressure is reduced means high pressure high temperature superheated dry saturated or a wet steam generated in the boiler at the p1 and p1 is supplied to the steam turbine means at the point number two there is a high pressure high temperatures superheated steam is there or a dry and saturated or a wet steam is there okay means it is depending on that means suppose there is two two point is here that is indicated it is a superheated steam suppose it is two dash point it is indicated dry and saturated and suppose wet steam is that and this point is coming here under this wet region means any steam is there okay it is supplied to the boiler and the p1 and t1 is supplied to the steam turbine so here this turbine is there not it is p1 and t1 but it is a p2 and t2 means here the two point is there okay and at the three point the steam is coming out from the turbine and this turbine is produced from work done and this work done is denoted as the wt that is a w means work and t means turbine steam is expand isentropically means entropy is remains constant during the expansion process okay so this steam is expand isentropically into a steam turbine up to the condenser pressure means during the expansion we know that the pressure is reduced and the volume is increased and the entropy remains as it is steam turbine developed mechanical work wt due to the expansion of the steam so turbine work wt is equal to h2 minus a3 okay now how we draw this isentropic expansion line on this pv diagram okay so we know that the pressure is reduced means point number three is coming on there below side to the point two okay and we know that volume is increased and the point number three is coming right side to the point number two okay so point number three is coming somewhere here it is the point number three so here the it is the weight region okay so it is not necessary that the steam outlet from the turbine is the weight steam it may be dry and saturated it may be superheated depending on the condition means point number three is coming either in weight region on these lines or this line depending on the types of turbines and depending on the process and the turbine work is the h2 minus a3 then after the third process it is the process three to four that is the constant pressure heat rejection in the condenser means the third component is the condensers okay so condenser is a one type of heat exchangers okay and it is used to reject the heat to the atmosphere here we also mentioned that is a heat rejection process okay so you simply remember that the heat addition in a boiler qs and the heat rejection the condensers are occur at the constant pressures means we need to draw the horizontal line okay for this one to two process in the boiler and process three to four in the condensers the exhaust steam from the turbine enters into the condenser here you see the exhaust steam coming out from the turbine is supplied to the condenser where it is condensed at the constant pressure by circulating the cooling water into the tubes the heat rejected by the exhaust steam is denoted as the qr okay so in this condenser number of tube is there okay and the cooling water is required so you know what is the meaning of condensed process condensation condensation means the steam is converted into the water it is called as the condensation process that why its name is given the condenser and in this condenser the steam is converted into the vapor at the constant pressure so point number four is coming under each size okay so here we reject the qr quantity means its temperature is reduced okay not temperature is written but its phase is change from the steam to water so we here it is a constant pressure process that means we need to draw the horizontal line means the p3 and p4 are same but which side we draw the horizontal line either left side or either right side okay so we know that this line is indicate the water line and this line is indicate the vapor line so we know that at the outlet of the condenser water is there so means point number four is coming on this line okay so it is the this line so it is a point number four okay and how amount of the heat is rejected how we find out so heat rejected qr is the h3 minus h4 now the next process is the process four to one that is isentropic compression in the pump or it is called as the pumping process isentropic means the entropy is remains constant compression means the pressure is increased and the volume is reduced but in a pump what water is there so water volume is not reduced okay so we need to draw these one vertical lines and the isentropic means entropy is remains constant and the pressure is increased so here we putting the component pump the condensed water coming from the condenser you is pumped into the boiler at the boiler pressure with the help of the feed pump means here the lowers pressure in these condensers okay and the boiler pressure is higher here you see that the one to two it is boiler line so here the higher pressure and at the entry of the pump it is the lower pressure so function of the pump is to increase the pressures okay so here you see this is the water coming out from the condenser is supplied to pump its pressure is increased and it is supplied to the boiler to do so to do this increase the pressures we need to supply some work done this work done is indicated as the wp quantity of the work done so wp is applied to the feed pump so pump work is denoted wp is equal to h1 minus h4 so how we draw this line on this pv diagram so it is just go to the simply vertical line so here you see this the pressure is increased from p4 to p1 now we draw the ts diagram okay so here you see this is the ts diagram okay now that is the same type line this is the critical point left side is indicate liquid right side is indicate saturated vapor line so point number one is draw here okay so it is the liquid line means its temperature is increased first okay this means sensible heat then after at the constant temperature at the constant temperature its phase is changed from water to vapor and then it is go to the superheated means this line is indicated it is the constant pressure second process that is isentropic expansion means entropy remains constant so here on the x-axis entropy is there okay means s2 is equal to s3 so here we take the projection of the two to three line okay what we did x2 is equal to s3 means we need to draw the vertical line okay then after three to four is the condenser means the steam is converted into the water so we need to draw this type line and this process is done at the constant temperature but its phase is 10 means that is the latent heat rejection is there then 4 to 1 it is the pumping so here we draw this pumping line so it is also isentropic means we need to draw the vertical line okay so this is the pv and ts diagram understanding now we find out the efficiency for the rankine cycles before moving ahead i request to like the video and subscribe my channels for watching the more video related to the bme subject or power plant engineering okay for other subject the I request to visit the playlist for the BME subject the various link is provided in the descriptions as well as in a car.
So we take these equations okay we already discussed this equation that is a heat supplied in boiler so Qs is equal to h2 minus h1 so somewhere you see here the outlet point minus inlet point is written h2 minus h1 because here the one input is there second heat input is there means this value is higher okay two values are that why we mention h2 minus h1 in a turbine the steam is loss is energy okay means the value of 2 is higher and some work is output so it's enthalpy at the three point is reduced same way heat is rejected from this three point means h4 is lower that's why it is f3 minus h4 is written in a pump we had some work done so here the h4 is coming and in this h4 we add some work means h1 is higher that's why here the h1 minus h4 is mentioned now we find out the network developed So, network developed is denoted as the Wnet. Okay. Means what work is produced and what work is supplied. So, here you see in this diagram.
Turbine is produced some work done. And in a pump we supply some work done. So, Wt is positive.
When the system is produced work done, it is denoted as the positive. When we supply work done to the system, it is indicated negative. So, it is the Wt minus Wp.
So, we have the value of Wt that is H2 minus H3. We have the value of Wp that is H1 minus. h4 now what is the equations of the efficiency so efficiency of the rankine cycle is denoted by these symbols okay so network developed divided by heat supply in the boiler means what is the output and what is the input okay so in the rankine cycle or the steam power plant the output is the wt but at the same time we supply some work done to the pump so we consider network then and input is the heat energy supply to the boiler that is the us so we have a network developed that is h2 minus f3 minus h1 minus h4 divided by heat supply that is h2 minus h1 now we do the small correction in this upper part of this equation that is h2 minus h1 means this h1 is coming in these sides and this f3 is supplied on these sides okay so it is written h2 minus h1 minus another bracket h3 minus h4 divided by h2 minus h1 now we divide this equation in the two parts that is h2 minus h1 divided by h2 minus h1 so this f2 minus h1 is cancelled so we return 1 minus f3 minus h4 upon h2 minus h1 so this is the equations for the rank and cycle efficiency now what is the f3 minus h4 so here you see this is the heat rejections okay so instance of this h3 minus h4 we are also written it is a qr what is h2 minus h1 so you see it is a heat supply okay so rankine cycle efficiency is 1 minus qr upon qs now suppose we neglect the pump work so usually pump work is very small hence it is a negative or we can neglect it not negative but we can neglect it so when we neglect the pump work okay means only the turbine work is our output so in upper part turbine work is there that is h2 minus h3 and heat supply that is h2 minus h1.
So, this is the final equations for the efficiency of Rankine cycle. This is the equation of the efficiency when we consider the pump work and this equation is when we neglect the pump work. So, thank you for watching this video. If you learn something then like the video, subscribe my channel and don't forget to share with your friends.