 Rassan Naikhande, working as an assistant professor in Department of Mechanical Engineering at Walsh Institute of Technology, Solapur. Now, today we are going to see regarding the introduction to the Kelvin Planck statement. Means, we will see what is Kelvin Planck statement. Kelvin Planck is the scientist name who has described this second statement which comes under the second law of thermodynamics. Thus one other statement is there which is a Clausius statement that is related to the refrigeration effect whereas this Kelvin Planck statement is related to the IC engine. Now, at the end of this session you will be able to describe regarding the Kelvin Planck statement what is the meaning of that where it is used, for which application it is used all those things you will be able to understand, you will be able to describe. Now, Kelvin Planck statement it is also called as a heat engine statement of second law of thermodynamics. Just now I had told you that for thermodynamics second law of second law there are two statements. One is by Kelvin Planck statement which is widely used for the heat engine. Second that is the heat engine is device that consumes heat energy to produce the desire work. So, to produce the mechanical energy to produce the mechanical work we are going to consume the heat energy and that is under the Kelvin Planck statement which we are going to see in the short while. Now, heat engine cannot have the thermal efficiency and as you know in the universe there is no engine which has got the 100 percent efficiency and the statement is like this. It is impossible to construct a device operating in the cycle it is impossible to construct a device operating in a cycle which produces no other effect than the extraction of the heat energy from the single thermal reservoir and delivers an equivalent amount of work. So, this is impossible to construct this type of the engine is impossible to construct which takes the energy from one reservoir and converts that all amount of the energy into the useful work. So, that statement is the second law of statement second law of thermodynamics statement given by the Kelvin Planck according to that it is impossible means what? It is possible to construct the engine with some amount of the heat rejection. So, that is the meaning of that now with this figure it is better it can be better understood. Now, Kelvin Planck statement according to that we have seen that it is impossible to construct the engine. Suppose this circular portion is indicating the engine which takes the heat from the reservoir which is at high temperature or which is supplying some heat energy and all that amount of the heat energy gets converted into useful work. So, this is a hypothetical engine this is a hypothetical cycle which is impossible it is impossible to construct the engine which converts all the amount of the heat energy into all the amount of the work means here we have the 100 percent efficiency because there is no heat rejection at all all the heat is getting converted into useful work. So, this is ideal condition which is not possible to have in the existence this is rather we can call this as a PMM 2 perpetual motion machine of second kind which is impossible to construct because all the amount of the heat is getting converted into useful work means 100 percent efficiency is there and PMM 1 engine is an engine which converts all the heat amount of the engine energy into the useful work means it has got the 100 percent efficiency which is impossible to construct. So, this Kelvin Planck statement is useful in that way here in the reality what is happening it is stated by the Kelvin Planck we can generate the mechanical energy by addition of the heat energy from some thermal reservoir. So, thermal reservoir which is at say temperature T 1 which is at high temperature and reservoir means what is that is known to you reservoir is the unit which supplies the heat energy to the some system without drop in the temperature the temperature remains the same as it is and it is same as that of the sea. If you take certain amount of the water from the sea whether there will be any change in the sea it does not have any change similar to that the reservoir is the name given to this source which remains at temperature T 1 in spite of supplying the heat energy to this engine. So, how much is the quantity of heat supplied over here that is Q 1 and that is from thermal reservoir which is at T 1 temperature. Now, what happens over here this heat energy supplied that is Q 1 will get converted into useful amount of the work. So, how much is the heat energy absorbed for this purpose that is Q 1 minus Q 2 means the maximum amount can be converted to obtain the useful work, but certain amount of the heat energy must be rejected to the sink portions must be rejected to some say area where the rejection will be in the atmosphere in the actual engine in actual actual atom well what happens the heat supplied will be there useful work will be obtained from the engine and that burnt gases are expelled in the atmosphere. So, that is nothing, but the working substance which is taking the heat energy from the through that say burnt gas burnt gas possess certain amount of the heat energy and those burnt gases are exhausted in the atmosphere. So, here we can call that as a sink. So, atmosphere is again one sort of the reservoir if you expel any amount of the heat energy into that from the engine it does not have any effect on the temperature. So, temperature of the atmosphere at that instant remains same there will not be any rise of the temperature because of say expelling heat into into the atmosphere. So, this act as a reservoir which is at temperature T 2 means what is the understanding from this Kelvin Planck's statement here the total amount of the heat energy cannot be converted into useful work certain amount of the heat rejection should be there. So, here q 1 is q supplied q 2 is heat rejection and the effective work obtained from the engine is W yes have you understood this concept regarding means here this is not possible to existence to to manufacture whereas, this is possible to have the manufacturing which were usually we are manufacturing for so many applications diesel engine is there petrol engine is there gas engine is there CNG is there. So, all those are working on the principle principle of the Kelvin Planck's statement which is coming under the second law of thermodynamics. So, I think there is no difficulty all of you understood this yes nice thank you for this purpose the reference book I have used is thermal engineering by Danpat Rai and company which is of Domkundar Domkundwar and one more author is Kotharnar Raman thank you thank you very much.