 Today, we are going to study regarding the introduction to diesel cycle, means we are going to observe the working of diesel cycle, how it works and as you know diesel is the name of the scientist. So, diesel is name of the scientist which is given to this cycle which is one of the prime thermodynamic cycle. At the end of this session students or you will be able to describe the working of diesel cycle. Now, the diesel cycle is an idealized thermodynamic cycle. What are the different types of the idealized thermodynamic cycle? Rankine cycle is there, Carnot cycle is there, Otto cycle is there, diesel cycle is there. So, these are the idealized thermodynamic cycle. In reality, in practical the actual cycle differs from this to some extent. So, this is the ideal cycle which is not possible to execute because of so many constraints in the field. So, but the base is there from which we are going to execute the cycle. So, diesel engines whatever atom mobile or the say electricity generation for the say diesel power plant or for so many applications diesel engines are used. So, diesel is the fuel which is used over there and the base taken is of the diesel cycle. So, that cycle works on that engine works on the diesel cycle. So, idealized thermodynamic cycles amongst this which that is one of the cycle. Then combustion process of reciprocating internal combustion engine. So, this is a reciprocating IC engine, this is not the roti engine, this works in the linear direction movement of the piston. In it, the fuel is ignited by the heat generated during the compression of the air. Means, here there is a no spark generation we are going to inject the fuel, inject the diesel at the end of the compression in the very fine particle form that is an atomizer form due to the heat and the pressure at the end of the compression. The heat generated in the air due to the compression that leads to automatic ignition of the fuel which is ignited which is injected in the very fine particle form through the injector fuel injectors or the diesel injectors. This is in contrast to igniting the fuel air mixture with the spark plug as in the atto cycle 4 stroke or 2 stroke whether it is a 4 stroke auto cycle engine or 2 stroke engine where the fuel air mixture is ignited with the help of the spark plug. This is not the case for the diesel engine whether it is a 2 stroke or the 4 stroke. Then diesel engines are used in aircrafts, automobiles, power generation, diesel electric locomotives, ships and submarines. So, nowadays most of the locomotives means Indian railways, those are to be shifted to the diesel, those are shifting from diesel engine to the electric, but still there is a much more number of the diesel engines which are used for the generation of electricity in that engine and then the electricity is used to rotate the compressors, sorry, rotate the engines, electric engines which are electric motors rather we can say that is the electric motors to drive the locomotives or the railways. So, these are the various applications of the diesel engine in the field. Now, the diesel engine cycle is in front of you, here the P indicates the pressure which is on the y axis, V indicates the pressure, sorry volume on the x axis, here V2 is the volume which can be called as the clearance volume, V3 is the volume when the fuel injection stops that is the cutoff of the fuel injection will be there at point number 3 and V1 is the total volume. When the piston is moving from the top dead center to the bottom dead center means those are the two extreme positions and those two extreme positions are indicated by point number 4 or 1 on x axis and the extreme left hand position is indicated with the V2 which is the top dead center position. Similarly, the pressures are different at these different positions, P1 is the pressure at point 1, P4 is at point 4, pressure 2 and 3 those are same because the process of heat addition takes place at constant process that is from 2 to 3. Now, we will discuss regarding the 4 processes which are there for diesel cycle. Now, the first process is the isentropic compression of the fluid which is indicated by the say that is a blue color, but here the compression takes place, but before that the suction of the air will be there from point number say 2 which is on this axis V2 to the V1. So, suction of the air from the atmospheric pressure will be atmosphere will be there. So, at this point the wall that intake wall or suction wall opens and the suction of the air will be there till the piston reaches the bottom dead center position. Then the process 1 to 2 is the compression at the adiabatic condition. We are calling the isentropic as adiabatic also. So, here the entropy remains same or the heat transfer through the wall of the engine is restricted. So, 1 to 2 is the adiabatic compression. Now, when the piston reaches the top dead center, compression takes place when the suction wall closes at point number 1 means suction and the exhaust or intake and the in outlet wall both are closed when the movement of the piston starts from point number 1 towards the 2 and here the compression takes place because of that pressure increases from point number 1 to the point number 2. So, the high pressure is generated in the air because of the compression because of the reduction in the volume and this pressure will be sufficient to ignite the fuel at its own because of say pressure and temperature which is increased. So, at 2 point there will be T2 pressure at point number 1 there will be T1 pressure. So, T1 temperature line can be indicated like this which is having the more slope as compared to this adiabatic. Then this line if we consider curve considered over here this will have the higher temperature as compared to point number 1. Now, during this 2-3 process 2-3 is reversible constant pressure heating which is indicated by that red color. So, this is idealized cycle. So, this is theoretical cycle for which we are indicating 2-3 process arrow will be from this side and here the heat addition will be there that is Q in is there Q supplied is there which takes place because of say combustion of the fuel. So, at the end of the compression then the fuel injection starts the fuel means diesel is injected in the cylinder in the very fine atomized form and this atomized form of the diesel will get ignited on its own without generation of any spark and due to that sudden blast or sudden heat addition is there and this heat addition or the supply of the diesel will be continued from point number 2 to 3. At 3 point the cutoff of the fuel injection will be there and we can have the cutoff ratio as a V3 divided by V2. V3 divided by V2 is the cutoff ratio whereas the compression ratio is V1 divided by V2. Now here when the piston reaches this point number 3 condition then there will be cutoff of the diesel and expansion of the burned gases will be there which is shown by the yellow color. So, 3 to 4 is the adiabatic expansion. During this the power is obtained from the engine we get the power from the diesel engine during this stroke only whereas the other strokes are ideal not generating any power those are the idle strokes. Those are the strokes in which we have to incur the energy to the piston for its movement through the crankshaft, crank and the connecting rod mechanism and for that purpose the flywheels are required and the here diesel engine requires the heavy flywheel because the compression ratio is higher as compared to the auto cycle. Auto cycle has got the compression ratio from 5 to 10 whereas the diesel engine requires the high compression ratio from 14 to 20. So, here the power is obtained from this engine diesel engine and this point number 4 is the point where the exhaust valve or the outlet valve opens and because of that burned gases in the cylinders are exhausted in the atmosphere as soon as the exhaust valve is open and due to that there is a drop of the pressure from point 4 to 1. So, this is reversible constant volume cooling or rather we can say that is a heat rejection process. So, heat is rejected to the atmosphere during this process and that is the process indicated by the 4 to 1 where the drop of the say pressure will be there from 4 to 1 and volume remains same. Now, when the exhaust valve is opened at point number 4, exhausted gases are expelled or the exhausted through the silencer the pressure reaches the point number 1 but still there are burned gases in the atmosphere those are to be rejected due to the movement of say piston from bottom dead center to the top dead center position from say even condition to the V2 condition there will be expelling of the burned gases which are still in that cylinder. So, that is the say process in practical this is not the theoretical. Theoretically cycle is comprising of 4 processes only 1, 2 compression at adiabatic condition 2, 3 heat addition at constant pressure 3, 2, 4 is the adiabatic or the isentropic expansion and 4, 1 is heat rejection at constant volume process. So, here it comprises of 2 adiabatic process 1 constant pressure and last as a constant volume process. So, this is regarding the say diesel cycle which is widely used for the engineering applications and applications were seen in the first slide itself. So, that is used for the aircraft, locomotive, power generation all the automobiles with the heavy capacity. So, that is for that purpose we are using this diesel cycle. Have you understood the working of this diesel cycle now? Is there any difficulty? Ok nice no difficulty. Thank you.