Wartsila RTA 96C 1

[dicer]

I would like to know what injection advance is used and how turbulent the combustion chamber is on these engines?
Hp/cu in seems very low as compaired to automotive engines, yet effciency is high?

 

[JRMacGregor]

Stroke is very long. RPM is VERY low.

 

[dicer]

Yeah I know. That should cause efficiency to drop. Lot of area to heat.

 

[romke]

You can find a lot of information here:

http://www.wartsila.com/,en,product...B676C68-5794-4765-AB44-4077CD1BF36F,,8000.htm

The engine may be slow revving but is equipped with a very "modern" common rail injection system with three injectors per cylinder.

 

[JRMacGregor]

Another thing about these engines is that they are designed for applications where the vessel spends most of its time at one speed. That means that the engine can be optimised for that duty. No need for the engine to be efficient across a wide RPM range.

I suspect that has something to do with the efficiency quoted.

 

[dicer]

Thanks guys, but all that I've been through.
That sites been in favorites for years.

Again there are two things that don't make sense.

1 The high efficiency yet low HP per Cubic inch.
2 The low speed and alot of surface area, meaning this engine is not even close to an adiabatic type engine.
Thus lots of heat transfer, look at the oil cooled (bore cooled) piston.
You have to remember this engine uses very little fuel per hp produced. The BSFC figures are great.
If memory serves I think its in the .25/BHP hour it maybe a bit less than that.

 

[waross]

It may not be accurate to compare a turbo charged engine with a 38 inch bore and an 8 foot stroke, running at 102 RPM with an automotive engine.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[dicer]

I'm not looking for accuracy, I'm looking for a good explanation of why?

 

[GregLocock]

Ask a proper question, you'll get a proper answer. What is you exact question?

Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[L4189]

The bsfc on those engines are probably based on using bunker C fuel. With constant load (prop rpm), when the engine switches from no. 2 to bunker C the fuel rate goes down.

 

[dicer]

Proper question,
(1) What is total combustion space heat rejection ?
(2) What is the injection advance in piston position to TDC?
(3) Why the high effciency as compaired to smaller engines yet less horse power density per cubic inch displacement?

 

[GregLocock]

(3) Efficiency is high because the losses are low. Presumably the gain in less heat loss to the cylinder walls (etc) outweighs the losses in ring friction and bearing friction.

I doubt power/cubic inch really featured as a design requirement. I'd guess they could have doubled the piston area without noticing, if power was a big deal in itself.




Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[dicer]

Yeah but large area and even larger area means more heat loss. I think there is something else that is not so readily apparent going on.

 

[GregLocock]

Ratio of combustion chamber volume to combustion chamber surface area improves a syou scale the design up.

Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[GregLocock]

Oh, and of course ring friction increases even more slowly

Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[chief]

The modern slow speed diesel engine (100rpm) is the most fuel efficient power system available. The engine exhaust powers a Turbocharger, generates steam via an exhaust boiler, and the engine coolant system supplies heat to a vacuum distiller to convert sea water to fresh water. Truly you get more bang for your buck from Doctor Diesels invention.

Offshore Engineering&Design

 

[GregLocock]

Once you add a turbo or preferably a turbogenerator then I'd agree.



Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[chief]

Greglocock,
These slow speed diesels are mostly used in the marine industry. The steam generated has many variations of use. To drive a turbo gen, turbo pump. cargo heating, accomodation heating,et al. The engine coolant can also be diverted to cargo or accomodation heating.
In all, i have seen efficiencies quoted above 80% overall per lb of fuel energy burned.
Also of course they can burn the crudest and cheapest fuel Bunker C.
Doctor Diesel in his early experiments used pulverised coal in his first engine ,built by MAN.

Offshore Engineering&Design

 

[chief]

check out this link and let your eyes pop. It currently is installed in the EMMA MAERSK. The worlds largest container ship, but that is another story.

http://people.bath.ac.uk/ccsshb/12cyl/

Offshore Engineering&Design

 

[GregLocock]

Heat recovery is one thing, cost effective shaft efficiency is another. MAN turbodiesels have a better shaft efficiency than the Wartsila.

Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.