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Wartsila RTA 96C

Wartsila RTA 96C

Wartsila RTA 96C

(OP)
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?  

RE: Wartsila RTA 96C

Stroke is very long. RPM is VERY low.

RE: Wartsila RTA 96C

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

RE: Wartsila RTA 96C

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.

RE: Wartsila RTA 96C

(OP)
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.  

RE: Wartsila RTA 96C

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

RE: Wartsila RTA 96C

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

RE: Wartsila RTA 96C

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

Cheers

Greg Locock

SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.

RE: Wartsila RTA 96C

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.

RE: Wartsila RTA 96C

(OP)
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?


 

RE: Wartsila RTA 96C

(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

SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.

RE: Wartsila RTA 96C

(OP)
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.  

RE: Wartsila RTA 96C

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

Cheers

Greg Locock

SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.

RE: Wartsila RTA 96C

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

RE: Wartsila RTA 96C

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

 

Cheers

Greg Locock

SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.

RE: Wartsila RTA 96C


 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

RE: Wartsila RTA 96C


 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

RE: Wartsila RTA 96C

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

Cheers

Greg Locock

SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.

RE: Wartsila RTA 96C

(OP)
Yeah after compairing cylinder capacity to surface area, it is suprisingly better than an average auto engine.
I should have done that in the begining.
There are many things that add to make these engines effcient. Thanks for all the posts

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