Hello friends here in this video we will see how many types of gas power cycles are there for an IC engine.Gas power cycles for IC engines now here I'll mention how many types of gas power cycles are there one by one the types of gas power cycles in IC engines are the first type of cycle it is Carnot cycle second Otto cycle third diesel cycle fourth dual cycle and fifth Brayton cycle so these five cycles are there in case of gas power cycles now I will start explaining them one by one that is starting with the Carnot cycle first Carnot cycle out of all the cycles which we have Carlos cycle will give us the maximum efficiency so it is a reversible cycle which gives maximum efficiency when compared with other types of cycles so Carlos cycle it is a reversible cycle which will give maximum efficiency when compared with the other types of gas power cycles next in this cycle all the processes are reversible in case of Carnot cycle the processes are reversible and here I'll mention the processes the processes which take place in [Music] Carnot cycle on there are basically four processes so starting with the first one process one to two that is it will go from state one to state two so process one to two is reversible adiabatic reversible adiabatic is also called as isentropic compression that is the process one to two having reversible isentropic reversible adiabatic the other name is isentropic compression second process two to three it is reversible isothermal heat addition then process three to four it is reversible adiabatic which is again isentropic expansion after compression heat addition there will be expansion then at last during process four to one there will be reversible isothermal heat rejection so here I have mentioned the processes which take place in Carnot cycle and as we can see all the processes are reversible and it consists of isentropic compression isentropic expansion then isothermal heat addition and isothermal heat rejection so we can even simplify Carnot cycle that it is made up of reversible adiabatic processes that is isentropic and reversible isothermal so it is a combination of isentropic and isothermal processes now I will draw some diagram which is called as the PV and TS diagram for Carnot cycle so here we have PV that is pressure and volume and TS temperature entropy diagram for Carnot cycle so now while I am drawing the diagram this diagram is nothing but a graph of pressure versus volume and temperature versus entropy that is PV and TS diagram now I look at the first process the first process is reversible adiabatic compression that is isentropic compression so isentropic compression will be shown on PV diagram with the help of a curve now this curve which I have drawn it will have two states state one and state two and this curve indicates a compression process because if we see volume at point number one that is V 1 is greater than the volume at point number 2 that is V 2 so V 2 value is less V 1 is more it means compression process has taken place air has been brought inside the engine and then compressed so its volume decreases and pressure increases as we see here initially the pressure was P 1 and after compression the pressure has gone up to P 2 so volume decreases and pressure increases during the compression process now the second process is reversible isothermal heat addition so isothermal line again it is shown with the help of a curve here as I have drawn this curve from two to three this indicates the heat addition process and heat addition is isothermal so we are getting a curve here next process three to four is reversible adiabatic that is isentropic expansion so after the heat addition process there will be expansion process so now process two to three is heat addition and this is isothermal curve because the process is reversible isothermal heat addition next after that process three to four is reversible adiabatic that is isentropic expansion previously we have seen isentropic compression now expansion so after point number three that is once the heat has been added there will be expansion process so like we had drawn it for the compression process parallel to that will draw a curve for expansion process so here this curve which I have drawn that is three to four indicates expansion process so when the heat was added up to point number three here the volume was v3 and after the expansion has taken place volume has increased because during expansion the volume increases and pressure drops so here this graph or this curve is going down because volume should increase and pressure should drop next the last process which is reversible isothermal heat rejection so once the expansion has taken place now the heat would be rejected so again the process is isothermal from four to one that is isothermal heat rejection next similarly as I have drawn the PV diagram that is the pressure-volume diagram I'll draw the temperature entropy diagram the first process is reversible isentropic compression so on the TS diagram entropy should remain constant because it is isentropic process so here I'll denote this is process 1 to 2 and since the process is isentropic isentropic means entropy should remain constant so if we see here the entropy is s 1 is equal to s 2 entropy remains constant and during compression process pressure increases and even that temperature increases so here from 1 to 2 the temperature will go on increasing next heat addition is from 2 to 3 and that was isothermal heat addition so isothermal means temperature should remain constant so your 2 to 3 Here I am drawing a horizontal line which indicates constant temperature that is T 2 is equal to t 3 isothermal heat addition then there is isentropic expansion from 3 to 4 again the entropy will remain constant and since it is expansion temperature should drop so your the temperature is dropping from 0.32 for entropy remains constant that is s 3 is equal to s 4 and the temperature has dropped because in compression process temperature increases but in expansion process temperature decreases so this is isentropic expansion then 4 to 1 it is again isothermal heat rejection that is temperature remains constant so temperature at point 1 is equal to temperature at point 4 isothermal heat rejection so now here on this PV and DL diagram I will mark that first of all during process 1 to 2 since it is a compression process and during compression work is done on the engine or work is done we can say on the gases which are present inside so your I'll denote I will show an arrow which goes inside the cycle that is work is input and this work would be denoted as W suffix C that is work which is done on the gases or on air during compression next after the isentropic compression process from 2 to 3 we had heat addition so here heat is added that is Q suffix a heat added next once the heat was added from 2 to 3 then from point number 3 the gases will start expanding and we will be getting work from the engine so work is getting away that is we are get moving away from this cycle so work I will denote it as W suffix e that is work which we are getting during the expansion process now from 3 to 4 the work during expansion gets completed and now from 4 to 1 the heat rejection starts that is after the completion of work the L or we can say air fuel mixture which is present inside the engine will be taken away from the engine so that is heat rejection process so your heat is removed or rejected from the system so that is Q suffix are the same thing I will denote it here from 1 to 2 the work is done during compression from 2 to 3 heat is added into the engine cylinder then 3 to 4 there is expansion work has been developed by the engine and from 4 to 1 there is heat rejection that is the heat goes out of the engine so your the Carnot cycle we have seen on PV and TS diagram I will write some important points here that during compression process because the first process is reversible isentropic compression so during the compression process air as we are using air as a walking medium for the air standard cycles or gas power cycles in that the working medium assumed is air so air is compressed increasing its pressure and temperature by reducing its volume so during the compression process as we can see here in the diagram air is compressed increasing its pressure and temperature by reducing its volume next after the compression process heat is added that is heat addition takes place and the process is reversible isothermal process so when the compression process has been done or completed after that the heat addition starts so here as we can see at point number two the compression is completed and after that the heat addition starts from two to three as we can see on both PV as well as on TS diagram the heat addition starts after the compression and it's it ends on point number three and the process is reversible isothermal next after the expansion or we can say after the heat addition has been completed after the heat addition process expansion of air takes place thereby reducing walk output that is W suffix e work which is produced during the expansion process so now as I have written the forth point that after getting the work output that is w suffix E from the engine the air should be or the air should air should reject the heat from the engine and that heat rejection is at constant temperature that is isothermal heat rejection so for that I will explain it with the help of a diagram that how a Carnot engine looks like Here I am drawing the diagram for the Carnot engine these are the cylinder walls and this is the cylinder head No this is the cylinder wall and here we have cylinder head cylinder wall in case of Carnot engine is a perfect insulator whereas the cylinder head is a perfect conductor so this is the diagram of the Carnot engine so here when we have air inside the Carnot engine and that air will be compressed with the help of a piston here I have not shown that piston so when the piston is compressing the air suppose here the piston is there now when this piston would be compressing the air after the compression as we know there is heat addition process so since the cylinder head is made a perfect conductor at that time the heat source would be brought close to the cylinder head that is the heat source here we have the heat source which will be at high temperature that heat source will be giving heat to the air inside the engine through the perfect conductor and this is the heat addition process taking place inside the Carnot engine next once the heat has been added the heat source would be removed and then there will be expansion that is piston will be moving behind and we will be getting the work output now after the work output has been reached we need to remove or we need to reject the heat which is there inside the engine so for that purpose we have another reservoir like heat source there is a reservoir called as heat sink now that heat sink which is at low temperature will be brought close to the cylinder head and the heat which is there inside the air that heat will get transferred to the heat sink because heat sink has low temperature and here in this way the heat rejection process that is q/r takes place so this is the diagram of a Carnot engine and because the walls are perfectly insulated the heat transfer is zero heat transfer is zero through the walls that is Q value is zero only a transfer which takes place that takes place through the head of the cylinder next as we have seen there is Carnot engine now I will write down the efficiency formula therefore efficiency of Carnot engine is given by efficiency of Carnot engine is it is maximum temperature minus minimum temperature upon maximum temperature so here we have written the formula of Carnot efficiency it has maximum temperature minimum temperature maximum minus minimum upon the maximum temperature now let me write down some of the limitations of Carnot cycle limitations of Carlos title the first one is Carnot cycle is not restricted by the type of fuel Carnot cycle does not take into account the kind of fail used means we can use Carnot cycle everywhere because the fuel is not mentioned specifically then as we see that in the processes which we have seen process 1 to 2 was reversible isentropic process that is reversible isentropic compression 3 to 4 reversible isentropic expansion so both the processes are isentropic that is heat transfer is 0 and for that purpose if we want an engine such that the heat transfer is 0 we should not give the time for the working medium that is air to exchange heat it means the piston in the engine the piston in the engine should move very very fast so that there is no heat transfer so I will write down that for reversible adiabatic processes that is both compression as well as expansion processes piston should move at a very high speed so that there is no time for air to exchange heat so that the heat transfer process is zero the piston should move at a very high speed so now here as I have written that for the reversible adiabatic processes that is both reversible adiabatic compression and reversible adiabatic expansion piston should move at a very high speed so that there is no time for the air to exchange heat with the surroundings then for isothermal processes that is isothermal heat addition and isothermal heat rejection piston should move at a very low speed so that temperature cannot change quickly so during the isothermal processes piston should move really slowly that is the piston should move slowly so that there is no sudden change in temperature and previously we have seen for isentropic compression and expansion the piston should move really fast so that there is no heat transfer next here I will write down that hence to make such an engine in which the piston speed increases suddenly during compression and expansion and piston speed reduces that is piston moves very slowly during heat addition and heat rejection processes so hence to make such an engine in which the piston speed increases suddenly during compression and expansion process and piston speed reduces that is piston moves very slow during heat addition and heat rejection processes so in two processes the piston moves at a very fast speed and for the remaining two processes it moves at really really slow speed so hence to make such an engine is impossible so this is the limitation of Carnot engine that it is not an actual engine or this cycle is not an actual cycle it is only a theoretical concept then we can say that to attain reversible processes in actual is extremely difficult so that is why Carnot cycle is not an actual cycle and I can say that hence for all the above reasons for all the above reasons Carnot cycle is not a practical cycle the Carnot cycle is not a practical cycle and for that I have given some of the reasons and with this we complete the description regarding not cycle