Boss, even our lecturers are showing your video clips, that explains itself. Being so senior and expert, still humble, Thank you. Kindly increase your frequency of making videos, just a recommendation.
sir firstly thank you so much sir ,kindly please make the videos on fuel pumps also so that we learn much more in details ,knowledge is expanding in nature ,what we learned is very less in fuel pump.
A comprehensive and in-depth explanation about vit sir. Thank you for the video. I would like to add something. The main difference between VIT and SUPER VIT is that in Super VIT, the breakpoint is adjustable where as in VIT, it is fixed.
Bada sab ....your RU-vid video were verymuch useful for my class2 preparation,no matter how much time I study few subject like rudder carrier bearing cannot be understand when surveyer ask question I just used say what ever I memmories off course when he ask cross question I could not answer I belive after watching your video I will be more confident...as I'm start understanding thank you ...love to see lot of video from you bada sab
Firstly, excellent way explaining the topic sir. Regarding the super vit,i read somewhere,if i am right,that breakpoint ( 85% usually) can be varied by governor output signal 4-20mA,which vary the air pressure to the vit index,basis scavenge pressure and fuel quality setting.
I want to add few lines , please do not take it otherwise, there is engineering principle , pmax/ pmean is inversely proportinal to SFOC , also if we see the propulsion engine sfoc curve with percentage load ....sfoc comes low at near 80 percent to 90 percent load as per different engine, thats why we used to run engine at NCR( economical RPM).so we try to get the break point near 85 percent. Another point of not engaging the VIT below 40 percent load is one is manovering RPM is there, continuous engaging the VIT rack leads to wear and tear of parts and another is in marine diesel engine inertia force is directly proportional to rpm square. if we increase the peak max more it will give more load to crosshead bearing ,as gas pressure will increase due to more p max but RPM is less, it will affect crosshead lubrication and we need to manufacture bigger bearings etc.
keep up the good work Amar..Actually I dont get enough time to get into the nitty gritty of all these topics . I am busy with content creation and workshop conduction for Hydraulic Failuure Management of Deck Equipments for various companies..Trouble shooting etc... So obviusly I find it difficult to catch up with ALL topics at a decent level...So Please add on your knowledge and point out any gaps in whatever I Make.... I am aware that my stuff is not 100 %...and may be lacking in many places..
Very nice sir. I had great confusion with VIT & Super VIT. I was thinking VIT for sulzer engine and Super VIT for MAN B&W engine. even I didn't had clarification on double helix. thank you so much for explaining this sir 🙏
Sulzer Engine VIT VIT = Variable beginning of injection + Variable ending of injection = Adjustable timing of injection. the maximum combustion pressure reaches a load range of 75-100%. MAN B&W Super VIT Super VIT = Adjustable Timings + Adjustable Break Point(85%) the maximum combustion pressure reaches a load range of 85-100%.
Genearlly to counter ignition delay , we used to do setting of FQS , fuel oil quality setting and ofcourse for doing that we need to have VIT arrangenment.
Downloaded video watched super easy made by Ramesh sir. I have a request sir please make a video regarding fuel injectors(2 stroke)working,circulation during standby and test,howw the internal part function at 350bar and 7to8 bar. Thank you sir
I have even sailed on modern MAN BW engines ( MC engine) where VIT was not there....so we can see that fitting all arrangements are viable as cost wise as reduction in SFOC is about 2gm/kwhour approx
Hi sir, your videos are very help full , lot of things i learned. Pls update m.e governor videos, y limiters are there . Automation parts like pid controllers
sir thank you sooo much for this video and the effort you put This video was very excellent like your previous videos' request you to please do a vide on sulzer vit
Thank you for making this topic look so easy. Sir, I have a doubt, what is the effect of piston speed on rate of compression?. If the rate of compression increases with increase in piston speed then why do we need to advance the timing on increasing load. Increased rate of compression will lead to increased temp. And the fuel should burn at the correct place Without altering the timing.
Higher speed means more load... means more amount of fuel needs to burn.So fuels burns away from TDC thereby increasing inefficiency. If you advance it ..we improve this
thank you very much for your efforts sir! please make videos on maintenance of machineries. important checks to be done while overhauling an equipment. please explain earthing system onboard ship.
Badasaab....ur explanation of vit is awesome ..it has cleared my many of doubts... One more doubt sir... U said start of fuel injection ll be after plunger covering spill ports?? I studied some where that start of injection ll be after plunger covering the suction port n end of injection opening of spill ports. I request you to clear my doubt... Thank you sir..
they are not port that are suction and spill valves in sulzer fuel pump whose opening and closing is controlled by push rod which are resting on ecentric rocker arm.VIT is controlled the changing the position of ecentric for suction valve and FQS is controlled by spill valve ecentric postion.
Sir this video was very helpful for understanding the role of vit at loads above 40 percent mcr. But nowhere could i find a clear concept as to the reason of vit being inactive below that load. Sir kindly provide me with a clear answer so that i can sleep. You are the best.
Ha ha..the answer is very much in the video..I am sure u must have seen it in high speed mode...below 40 % the termination of combustion does not continue beyond 10 degrees.. so minimum. Wastage of heat...If you advance and start the combustion process earlier. The engine may stall bcoz it may not have the momentum to compress burning gas and cross TDC.
@@rmetcvideos Sir I partially agree with this answer....in propulsion engine power is directly propulsion to rpm cube. lets us assume 100 percent MCR is at 100 RPM. At 40 percent MCR it will come around 70 RPM ....which is not less....
another point i think of generator engines having not VIT provided....they r 4 strokes engine...medium speed engines...RPM 720.etc....in 4 tsroke engine compression ratio is more compare to 2 stroke engine...we supply 300 percent air in modern 4 stoke engine compare to 2 stroke engine where we provide 200 percent....higher fuel injection pressure compare to 2 stroke engine...also time for cooling is less as RPM is more....
Sir super big thank u for this video..! I have a tiny doubt sir that just arised, when the load of engine increases does it mean that the rpm of engine has increased or decreased ?
Heya! Wanted to confirm in electronic engines, Is the advancing and retarding fuel injection timing already incorporated with electronic injection profile cam as per load in ECU... Or VIT happening is not there... Please answer this
I dont think there is any big change as far as timing is concerned. Timing is about the orientation of cam wrt camshaft and position of spill port at the Firing angle.In VIT the only difference is that advancement happens after say 50 % load.Timing is checked with Engine stopped. So...there shud be no difference
Every movement of the piston towards TDC acts like a brake on the shaft.But the Flywheel has enough energy stored up PLUS thanks to the PUSH of the firing piston s--the Piston can overcome the obstacles and reach TDC
Inertia stored in flywheel and firing push from some other unit do overcome this break. Also small Con rod angle just before TDC make this break very much ineffective.
We get more output at 85% because we are increasing the amount of fuel injected, we are burning more and more fuel, not because we start retarding the injection timing. We retard the injection timing because with the amount of fuel delivered the pressure will be already at maximum value therefore we cannot advance the injection further as it will cause excessive mechanical stress. Marine diesel engines are designed and optimized to operate with maximum thermal efficiency within a certain range, and this range depends on the normal cruise speed of the vessel, Ships during sailing will mostly operate near 85% load, thus at this load we should expect maximum efficiency which happens when we achieve maximum pressure. Therefore when we achieve this maximum pressure we start reducing the VIT index .
so many videos i have watched even this video is not doig justice to th e topic VIT- variable injection timing- double helix or by changin the barrel position super vit - variable injection + breakpoint shift by controlling scavange pressure the graph says VIT INDEX not super vit index even after mcr 80 the vit index can be reducked by the barrel shifting method that why they called thr line VIT INDEX not super vit wihhc you said in the video
The graph copied from Internet..Have you heard people using the term Super VIT Index..may be they dont..The index I guess is always called VIT..Super VIT being the ABILITY to vary the index basis influence of multiple parameters like. Scav Pressure,Fuel Quality, etc apart from Engine Load. Anyway..Getting into definitions is not an area of interest to me 😄
Thank you very much sir for the topic., Surveyor asked me why break point cannot be set beyond 85%, But I was blank, Then one of my fellow told me due to mechanical lever limitation break point cannot going beyond 85%. Is that true sir?
your fellower was right but he is explaining in term of vit construction(mechanical vit) the location of pivot point restraining the movement of linkage controling pressing of pressure regulating valve in vit