 ರವ್ತೆ ಟಿತಂು ಎೋומಂತ್ರ್ ಜವವಿಲತ猿ಲೈದ್ ಪೀವಿಕ inne percentbane problem between vapor absorption and vapor compression system. In my previous video riddle I have discussed simple vapor absorption system, also called practical vapor absorption , today we are going to compare the vapor absorption system & compression strength. at the end of this video session students will be able to compare the vapor absorption and vapor compression system on the basis of various criteria as well as they will be able to state the merits and demerits of each system that is vapor absorption and vapor compression system. the contents of this video session are comparison between vapor absorption and vapor compression system and what are the merits and demerits of vapor absorption system. now let us see what is the difference between vapor absorption and vapor compression system. now in this table as we have already seen the working of both vapor compression as well as vapor absorption system the major change as compared to the vapor compression and compared to the vapor compression system in vapor absorption system is that in vapor absorption system we do not use the compressor. whereas in case of vapor compression system we use the compressor for compressing the refrigerant coming out of the evaporator so the function of compressor is carried out by three devices namely absorber pump and generator so absorber pump generator assembly carried out the function of compressor in case of vapor absorption system. and therefore there are certain advantages in case of vapor absorption system so the first point is that if you see here the vapor compression system will have more wear and tear as well as it will produce more noise due to the moving parts of the compressor particularly when you use the reciprocating compressor. ok there are vibrations which produces the voice noise as well as there is going to be wear and tear between the piston cylinder so in case of vapor compression system due to the presence of compressor it will be noisy as you can experience particularly in case of our domestic refrigerator which works on the principle of vapor compression cycle. ok so every time we find that there are vibrations and it produces the noise whereas in case of vapor absorption system the compressor is absent so only moving part in this system is an aquapump but it is of very small size and therefore the vapor absorption system is quieter in operation compared to vapor compression as well as it will have less wear and tear. now second thing is that the vapor compression system in case of vapor compression system you supply the electric power to run the compressor because compressor is usually driven by electric motor and so you need electric power to be supplied in case of vapor compression system. whereas in vapor absorption system though we are using pump the pump work is usually very negligible and majorly what we supply our major input in case of vapor absorption system is the heat supplied in the generator so that heat which we supply in the generator for separating the refrigerant vapor from the strong solution the heat which is used can be waste heat which is low grade heat that is compared to the electric power heat is the low grade energy so waste heat low grade heat or even we can use solar power that is solar heat can be used so no need of electric power because some of the vapor absorption system they do not even use pump they are pump less so in absence of total electric power still the vapor absorption system can work now but the COP of vapor compression system is more whereas the COP of vapor absorption system is less the major reason here is that because your input which you are supplying is a low grade now COP already we know the definition is the refrigerating effect upon input so for vapor compression system in both the system the output desired is nothing but the cooling effect or refrigerating effect but the denominator is different in case of vapor compression system it is the compressor work whereas in case of vapor absorption system because pump work is negligible it is the heat supplied in the generator that is the denominator so COP in this case is refrigerating effect divided by heat supplied in the generator now because the heat is a low grade energy you require to supply the large amount of heat in case of generator therefore as compared to the vapor compression system COP of vapor absorption system is less usually the COP of vapor absorption system is less than one whereas in case of vapor compression it is more than one up till now the HHS COP of the order of 1.4 has been achieved with the help of vapor absorption system now the another disadvantage of vapor compression system is that at part load the performance is over means if it is not operated at full load condition then the problem is that the refrigerant doesn't get the required heat in the evaporator so there are chances that the vaporization of liquid refrigerant may not be complete in the evaporator and you need to compress the wet vapor so that is why the performance of this system deteriorates at part load whereas in case of vapor absorption system as we have seen already the refrigerant vapor coming out of the evaporator is absorbed in the absorber so even though the load is less and the vapor along with liquid enters into the absorber there is no much issue because in absorber this is going to be absorbed with the water so the performance of vapor absorption system is not much affected due to the load means partial load at part load also it will be performance will remain same but whereas here it will decrease now let us see the another comparison here you can see now in case of vapor compression system we are supplying the mechanical energy through the compressor means electric power and then it is given in the form of mechanical energy for running the compressor whereas in vapor absorption system we are giving the heat as the input heat energy is utilized but the major issue with vapor absorption system is that charging of refrigerant is difficult now in case of vapor compression system the charging of the refrigerant to the system is easy the reason is that in vapor compression system usually the refrigerant is charged into the compressor using the compressor compressor is provided with the charging line so once you open the charging line wall the refrigerant vapor from the refrigerant cylinder can be taken inside the compressor and it will pass into the system so charging is that way very easy but here because we do not have compressor we need to charge the refrigerant in the evaporator okay so liquid charging will be done in this case here it is vapor charging here it will be liquid charging so this charging of refrigerant is difficult particularly in vapor absorption system next here because as we have seen in the previous slide the input is electrical power so energy supplied is a high grade energy electric power so this energy supplied is one full to one half of the refrigerating effect so this energy supplied is much less so COP is higher performance is better whereas in case of vapor absorption system we are supplying low grade energy that is heat so energy supplied is heat energy in case of vapor absorption system it is more than about one and half times the refrigerating effect therefore the COP of this system is comparatively very less now in case of vapor absorption compression system because we have a compressor we require some preventive measure since liquid refrigerant accumulated in the cylinder may damage the cylinder cylinder so entry of liquid refrigerant particularly with reciprocating compressor is not desirable in vapor compression system whereas liquid refrigerant though it comes out of the evaporator and going to the absorber it has got no bad effect on the system now let us see compared with vapor compression system VARS that is vapor absorption refrigeration system have one major advantage we are compressing the liquid liquid is compressing instead of vapor and as a result work input is very small let us think for a while that why the work input will be less in case of vapor absorption system now already we know that liquid specific volume is very small compared to the vapor specific volume therefore the pump work is negligible as compared to the compressor work and that is why we get the advantage in case of vapor absorption system and the pump work is very small so work input in VARS is of the order of 1% of the heat supplied in the generator it is very negligible and so we it is often neglected in the cycle analysis VARS are more expensive than VCRS because absorption system they are complex and they occupy more space bulky so they are more expensive remember compared to vapor compression system which are compact in nature and also we have seen COP is much less so they are less efficient also and vapor absorption systems require much larger cooling tower to reject waste heat and they are more difficult to service since they are less common so large amount of heat is to be rejected in case of vapor absorption system in the condenser and absorber so you require larger cooling towers and servicing is also difficult because they are not used much widely compared to vapor compression system therefore vapor absorption systems are considered only when the unit cost of thermal energy is low means the waste heat is available in large quantity or it is projected that it will have low cost heat available in that low cost compared to the electricity these are the references thank you