Anyone know much about Diesel fuel systems?? (Engineering/design problem)

[IwantMKIII]

Have a HW assignment for MAE454 class. Its a very very open ended HW so i'm trying to narrow down results.

Basically we have to design a fuel line from the diesel pump to the injector. We need to figure hose diameter and material to use. Assume engine speed to be at 1800RPM. That is all we get info wise besides the information on the engine in the below pics. Keep in mind, there is A LOT of information we have to assume, and we can go as deep into this as we want. Out biggest factors again though for the answer are diameter, pressure loss, material, fuel line wall thickness.


[thumb]http://img232.imageshack.us/img232/7755/p1zo1.jpg[/thumb]
[thumb]http://img232.imageshack.us/img232/1535/p2ue2.jpg[/thumb]
[thumb]http://img232.imageshack.us/img232/1527/p3hj6.jpg[/thumb]


To help narrow my results i'm taking another approach. Most car companys design around existing common size products. My question is what is a good common size injector for this 3.9L turbo engine of this nature. And if possible, what is the inlet size? I've tried to google this but don't know enough about diesels to really find any good info.


Cliff notes:
3.9L Turbo Diesel
1300 BAR max pressure
25l/hr at 1800RPM
-What's a common injector size for this engine? If possible whats the inlet size?

 

[popemobile]

25l/ hr Works out to about 6.5 Gallons/ hour. According to my SGII I can burn about that under WOT.

As a reference my golf tdi has the following injectors in it now. Obviously 4 cylinder 1.9. http://www.kermatdi.com/servlet/-strse-16/POWERPLUS-520/Detail
I can dig up a BSFC curve for it if that helps in any way.

I'd guess that the injection lines on my car are Steel; 1/4" od and 1/8" (or smaller id) with flared ends.

I'm Pump injection though. Not sure about your app . . .

 

[gaboonviper85]

is the motor a direct injection motor??? If so you'll obviously need some very good fuel line as it's under extream pressure.

 

[popemobile]

The motor is DI; however IDI Diesels have very similar fuel pressures.

1300 BAR =18,854.906 psi

I can't find my pumps peak pressure anyplace, but I can say my injectors primary pop pressures are all between 307 and 311 bar

 

[IwantMKIII]

is the motor a direct injection motor??? If so you'll obviously need some very good fuel line as it's under extream pressure.

tyler, its diesel...........of course its DI :nono::biglaugh:

 

[IJ.]

Ummm how about ya do your own work
(not going to learn much if you cheat like this)

 

[gaboonviper85]

tyler, its diesel...........of course its DI :nono::biglaugh:

Adam......not every diesel motor is direct inject!!! Stop thinking your smarter than me....orelse we will have another "forged 6m-7m crank" debait and you will loose.....again

Now do your homework and study with your own mind...so maybe someday you can teach me something....but as it stands I have forgotten more than you know.....burn

 

[IwantMKIII]

Ummm how about ya do your own work
(not going to learn much if you cheat like this)

This is far from cheating IJ. I'm taking a different approach as mentioned, i could design it without any of this information and base it clearly on pressure loss and pipe diameter as most have but i could do a better design with it. I don't know of anyone doing this, i was just trying to get a better answer, nothing wrong with that

 

[IwantMKIII]

Adam......not every diesel motor is direct inject!!! Stop thinking your smarter than me....orelse we will have another "forged 6m-7m crank" debait and you will loose.....again

Now do your homework and study with your own mind...so maybe someday you can teach me something....but as it stands I have forgotten more than you know.....burn

then come do my finite element hw smart guy :evil2:

either way, what other injection system is there, im curious. Like i said, i don't know much about diesels as it stands

 

[popemobile]

as previously stated there are both di (direct inject) and idi (indirect injection) diesels.
Both inject fuel in to compressed air in the combustion Chamber, the idi just has a preingntion chamber.

 

[IwantMKIII]

^so, how are diesel injectors rated vs. gasoline injectors size wise? any different?

 

[IJ.]

This is far from cheating IJ. I'm taking a different approach as mentioned, i could design it without any of this information and base it clearly on pressure loss and pipe diameter as most have but i could do a better design with it. I don't know of anyone doing this, i was just trying to get a better answer, nothing wrong with that

May not be cheating as such but it's damn lazy USE your brain give it a good workout!

 

[IwantMKIII]

^lazy? not really. Merely using a car oriented website to try to find out information about car related questions. Trying to be resourceful as i couldn't find anything on the web since i can't narrow results without more basic know-how of the system. Its not like we get a book for this kind of stuff handed to us as you won't later on either.

 

[tlo86]

he is trying to learn what the class failed to teach him jeeze guys cut him some slack.....
:biglaugh::biglaugh::biglaugh:

 

[IwantMKIII]

^at least im trying. And its not that they didn't teach it, its that they expect you to find out the information you need on your own. Its called Machine Design and Manufacturing for a reason . I know the concepts for the most part we need to use, just need to apply.

Im just trying to use my resources is all.


FTR: I assumed a 1/8" I.D.
Composite: Brass alloy CZ114 (mainly because its one of the few brass alloys i could find the right specs in time, brass over other metals because of its high corrosion tolerance)
Safety factor: 2
Tensile Strength: 500MPa
Proof Stress .2%: 250MPa
Wall thickness: .0625 (3/16" O.D.)

It worked out well, the wall thickness was based on Hoop Stress and material properties, it was just a coincidence it ended up being 3/16", which is good as it is a very common size. I used 1/128" increments in my calculations to find the wall thickness. I assumed no pressure drop even though there will be, just nothing very significant in a 18,854PSI fuel system.

 

[adampecush]

Brass alloy? I'd deduct you right there for that. Easier and cheaper to source a Q&T (>850MPa) steel line. Plus, steel is considerably stronger and less dense, resulting in a lighter part, not to mention you will have better fatigue resistance with a harder steel. Zinc dichromate coating for corrosion tolerance, and be done with it.

 

[IJ.]

My point is he know's the math why not crunch the numbers, as we all know what has been done in the real world will most times not be close to the theory.

I guess it comes down to what they mark on.

 

[IwantMKIII]

My point is he know's the math why not crunch the numbers, as we all know what has been done in the real world will most times not be close to the theory.

I guess it comes down to what they mark on.

No one has any idea what hell mark on. Again, there are no guidelines.

 

[IwantMKIII]

Brass alloy? I'd deduct you right there for that. Easier and cheaper to source a Q&T (>850MPa) steel line. Plus, steel is considerably stronger and less dense, resulting in a lighter part, not to mention you will have better fatigue resistance with a harder steel. Zinc dichromate coating for corrosion tolerance, and be done with it.

I don't know much about different materials and coating and what they do. its not somethign i have much experience with. I just knew brass has a very high resistance against corrosion vs. steel and most other metals

 

[IJ.]

You could blow em away by finding real world numbers then do a theoretical design to show any differences