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The World's Most Powerful Diesel Engine
trex279 writes "The Wartsila-Sulzer RTA96-C turbocharged two-stroke diesel engine is the world's most powerful diesel engine built to date. Each cylinder displaces a whopping 111,143 cubic inches (1,820 liters, equivalent to a cube 4 feet on a side) and produces 7,780 horsepower. The engine is about the size of a small building." The engine is intended for use in container ships.
From TFA:
/. so I guess I can't holler "Dupe!" It's in my bookmarks tho'.
Even at its most efficient power setting, the big 14 consumes 1,660 gallons of heavy fuel oil per hour.
I've seen this web site before, but probably not cited on
Mit der Dummheit kämpfen Götter selbst vergebens.
At least read the article before posting it:
The cylinder bore is just under 38" and the stroke is just over 98". Each cylinder displaces 111,143 cubic inches (1820 liters) and produces 7780 horsepower. Total displacement comes out to 1,556,002 cubic inches (25,480 liters) for the fourteen cylinder version.
Some facts on the 14 cylinder version:
Total engine weight: 2300 tons (The crankshaft alone weighs 300 tons.)
Length: 89 feet
Height: 44 feet
Maximum power: 108,920 hp at 102 rpm
Maximum torque: 5,608,312 lb/ft at 102rpm
Not even close to as bad as gas. Gas 2 cycles have nasty problems due to the lube oil being in the gas (doesn't burn well, otherwise it wouldn't lubricate) and the intake/exhaust ports being open at the same time (and hence you get unburned crap blowing right through). All of this is for simplicity, and it does work. A 2 cycle gas engine is an exceedingly simple contraption, and will almost run in spite of anything you do to it.
2 cycle engines are very common once you start moving up into the larger diesels. They're very different creatures, though they operate on similar principles. Diesel 2 cycles have separate lube oil in the crankcase, similar to 4-cyc gas engines. Thus, no continuous cloud of semi-burned lube oil coming out. Also, they're all (at least all that I've ever seen) direct injected, meaning fuel is delivered directly to the cylinder once the intake/exhaust ports are closed, thus no unburned fuel flows through.
Since diesel cylinder always get a full air charge, 2 cycle makes since - it's simple, and since you're only flowing air, you don't have the wasted fuel as in a gas 2cyc. As a by-product, you also get twice as much power from the same space as the equivalent 4 cycle at equal rpms. They do have more particulate problems, but these have been resolved well enough in the last few years to meet the new EPA Tier II diesel exhaust requirements.
vary the power output based on amount
No.
Two-stroke gasoline engines use the slightly pressurized fresh air/fuel mixture to force the previous combustion event's exhaust out of the cylinder. Some mixing of the fuel and exhaust is bound to occur, potentially resulting in unburned fuel escaping in the exhaust flow.
In a diesel engine, air and fuel aren't mixed until the actual combustion event, so there's no chance (assuming the engine is tuned properly) of fuel escaping in the exhaust.
this is pretty old and has been reposted on every automotive forum out there.
I know you were joking, but for those who haven't read the article, I found this interesting:
Even at its most efficient power setting, the big 14 consumes 1,660 gallons of heavy fuel oil per hour.
And the article also stated at the most efficient setting, the engine is >50% thermal efficient (more than 50% of energy is transferred to motion, rather than heat)
Of course, definitely not a consumer item!
Karnal
In a word, no.
Two stroke gasoline engines tend to pollute a lot for two reasons:
some
1. They use the incoming fuel/air mixture to push out the exhaust and inevitably some of the unburned fuel goes straight out the exhaust.
2. Most of them use the crankcase to pressurize the incoming fuel/air mixture. This necessitates adding oil to the incoming charge to lubricate the crank and piston.
These aren't issues for diesels because the fuel is injected directly to the combustion chamber after the intake and exhaust ports have closed, and the incoming charge is pressurized by a supercharger rather than the crankcase.
"Prefiero morir de pie que vivir siempre arrodillado!"
Would it run on biodiesel?
With the usual cuts in output, most likely, yes. (You take a really small cut in engine output when running it on biodiesel, something like 10% or so, but I don't have the figure right in front of me). It's still a diesel engine, just a hell of a lot bigger.
www.wavefront-av.com
The MAN B&W 14K98MC7 has nearly 8% more power (116,875 HP vs 108,920 HP for this Wartsila-Sulzer) http://www.manbw.com/engines/TwoStrokeLowSpeedProp Engines.asp?model=K98MC7
Great fact-checking to start 2007 with...
If you are talking diesel, one big engine, from my limited experience. This is due to the engine working at very low RPMS and in a ship, you are producing a steady load, not "start and stop" like driving a car in the city. Diesels also power down nicely and use fuel according to the load, so running at half of potential power uses much less fuel.
I also note the article does NOT say 7780 HP, it says 108,920 horsepower at 102 rpm and more importantly, 5,608,312 lb/ft at 102rpm. I knew that 7780 HP was wrong because you can tweak the fire out of a 6 litre chevy diesel and get 1000 HP and 1500 to 2000 lb/ft torque.
Most diesels have a 3/2 to 2/1 ratio of torque over HP, but then most peak in the 2400-3800RPM area, not 102. That is an absurd amount of torque, which is what is needed to twist a prop, after all. At 1,556,002 cubic inches, this is 3.6 lb/ft of torque for every cubic inch, which is similar to the above example of a 6.0L engine (364 cu. in.) getting 1310.4 lb/ft. (stock would be closer to 650-850 lb/ft).
In otherwords, a pretty efficient engine.
Tequila: It's not just for breakfast anymore!
The product page has a couple of PDFs with actual technical data and some nice photos. Oh, and in terms of real units, the power output is up to 80 MW for the largest model.
Displacement also sells cars, and a 2-stroke of a comparable power output will have about half the displacement so you have a consumer education curve as well. Prices for 2-strokes would also be higher until you make a lot of them and economies of scale start to take effect. Mazda's Wankel ("rotary") engine has the same problem.
DRM 'manages access' in the same way that a prison 'manages freedom'
You're wrong. Go read up on heat engines and the various thermodynamic cycles you can use. There are power plants in operation that achieve 59% thermal efficiency.
Suffice it to say, it is a very well established science, and all quite provable both theoretically and in practice.
Alcohol, Tobacco and Firearms should be the name of a store, not a government agency.
Now look at Diesels. The smallest working Diesels are the little glow plug engines that are used to power model aircraft - actually semi-Diesels whose spiritual big daddy is the classical single cylinder 9 litre like the Bolinder. The biggest are these marine monsters with their two-metre throws. But they all are constrained by a few parameters that are broadly the same - the MEP and the mean piston speed.
At the normal running speed of about 100rpm the engine in the article is doing about 6-7 metres per second. At its normal cruising rpm of about 2000, my car engine is doing 33 revs per second * 2 * 90mm stroke - or 6 metres/sec. I haven't checked, but I fully expect that the working MEPs are within the same ballpark. It's nice to see that engines ranging from grammes to kilotonnes are constrained by a simple law based in metallurgy and tribology.
The other nice thing is, that with the exception of the tiny toy engines, all Diesels work more or less the same way, and the direction of change is by downwards replacement - technologies developed for large marine engines find their way ultimately into small engines. Modern auto engines with their electronic solenoid operated injection systems are basically a shrink of the marine technology of the 80s and 90s. Turbochargers also undergo shrinkage as their technology moves from marine to auto use, so we get the variable vane turbocharger turning up on entry level cars.
It would be wrong to force too many analogies, but there are resemblances between Diesel systems development and computer development that are perhaps more than skin deep.
Pining for the fjords
"Jesus christ you fucktard. Those are turbojets."
Sure anonymous, mannerless fool and coward, they actually run on Diesel as their only fuel. http://www.shockwavejets.com/shockwave.cfm
The cylinder block yields less than 8K horsepower per cylinder, these jets 12K per turbine. Then mount 14 of them in a block and call it an engine, the jets will weight less and have more power.
--- Hindsight is 20/20, but walking backwards is not the answer.
What makes this work is that the chamber temperature is way higher than can be contained by any materials that we can make - so they cool the chamber walls (which would be an efficiency loss) but they cool them with propellants (so that the energy lost is put back into the system). So the engine itself has virtually no losses - and if you put a large enough nozzle on it, you can take it to just above the boiling point of water. So the engine can go from 3300 C (the SSME combustion temperature) to about 50 C (nozzle exit is way below atmospheric pressure, so the boiling point of water is lower). Efficiency = 1 - 350/3600, >90%. Several engines like this were designed, but since it would only make sense on a very long term deep space mission, I don't think anything this efficient was ever really built.
As a more concrete example, the Space Shuttle Main Engines (SSME) have a combustion efficiency of 99%. So the only thing that makes the total efficiency less than 99% is that the engines must operate in the atmosphere - so the nozzles cannot be too large (the exit pressure needs to be close to one atmosphere). The overall system efficiency of the SSME is 76%. More efficient engines have been made (look at the J-2 or any upper stage hydrogen engine), but this one everyone is familiar with.
Note that an inefficient rocket engine is a really bad idea - the SSME are 6.4 GW reactors, and are only a few meters long. Think about it - any losses in the engine (wasted heat) would need to be radiated away. What temperature would it have to be to radiate away 5% of 6.4 GW?!?
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So the engine can go from 3300 C (the SSME combustion temperature) to about 50 C (nozzle exit is way below atmospheric pressure, so the boiling point of water is lower). Efficiency = 1 - 350/3600, >90%.
No, this is just the limit on the efficiency from the laws of thermodynamics. The actual efficiency is certainly much, much lower. Also, there's no way that the exhaust is at 50 C at the point when it loses contact with the nozzle, so the real thermodynamic limit is going to be way less than 90%.
As a more concrete example, the Space Shuttle Main Engines (SSME) have a combustion efficiency of 99%.
No, this is definitely not the thermodynamic efficiency of the engines, considered as heat engines, because even according to your earlier (incorrect) calculation, the maximum possible efficiency based on the laws of thermodynamics is lower than 99%. This figure probably represents the fraction of the fuel that undergoes combustion.
Note that an inefficient rocket engine is a really bad idea - the SSME are 6.4 GW reactors, and are only a few meters long. Think about it - any losses in the engine (wasted heat) would need to be radiated away. What temperature would it have to be to radiate away 5% of 6.4 GW?!?
No, obviously the wasted energy isn't going away by radiation, which is a very slow process. The wasted energy is going into KE of the exhaust, heat of the exhaust, frictional heating of the atmosphere, and KE of the early stages of the rocket.
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The biggest difference between them is that two stroke diesels are positive displacement engines and ALL of them use some form of pressure charging: mechanical or exhaust driven, or both. Gasoline two-strokes nearly all use some form of crank case induction, where the change in volume of the crank case/underside of the piston is used to recharge the cylinder. That's what nececitates the lube oil in the fuel (keeping crankcase bearings lubricated). Positive displacement two stroke gas motors exist, but they sacrifice too much simplicity and weight to be very common. Most of the modern two stroke gas motors use some kind of direct injection, which eliminates oil in the fuel and dramatically reduces emissions.
You're certainly right about the basic simplicity of a two stroke gas motor. Piston port motors are incredibly simple though they're not exceptionally effecient, or tunable, over a broad RPM range. You're also 100% right about all diesels being direct injected. They have to be, since they use the heat of the compressed air charge for ignition.
Diesels overall are heavily built, simple, beasts; Until you get to the fuel injection system that is. Diesel fuel injection demands a level of precision that makes your average gas burner look downright sloppy and is usually the single most expensive component in the engine. At least for small to mid-sized (small marine through semi-truck) engines, and probably up through some of the larger static or marine applications.
Cheers,
Bagheera
(Side note: I've worked on two and four stroke race motors, a few aircraft engines, and several two and four stroke marine diesels. Give me a two-stroke reed-valve bike motor any day.)
Never attribute to malice what can as easily be the result of incompetence...