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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.
Are two stroke diesels as dirty running as two stroke gas engines?
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In terms of fuel consumption, and air pollution, is it better to have one huge powerful engine, or two or more less powerful engines?
If they're now making desiel engines this size for cargo, I'm curious if perhaps it's time to switch to nuclear. The waste-return equation seems out of whack for petrochemical solutions.
In terms of mere size, this is comparable to steam engines of 1904. The Interborough Rapid Transit Company (the "IRT" to New Yorkers) built a plant in 1904 with a total output of 132,000 horsepower. The compound steam engines had bigger cylinders than this Diesel; 42 inches and 86 inches, compared to 38 inches for the new marine Diesel.
That was the high point of piston engines. Electrical generation was already converting from pistons to turbines, and even that 1904 IRT plant had a few smaller steam turbines.
There have been much more powerful marine powerplants than this, but they're usually multi-engine turbine systems. There's an annoying tendency in commercial shipping to have only one engine on large ships, which occasionally leads to accidents.
I know you're joking, but if you look at the cross-section in the article, you'll see that they wisely passed over the hemispherical head for a pent-roof head. They also made the engine incredibly undersquare - it has a 0.38 bore-to-stroke ratio. Diesels require very high compression ratios, and it's worth compromising a redneck's sense of aesthetics to get it.
Hnm...the article is a little disreputable. As far as I can tell, here's what happened. Some guy named Todd Walke scraped photos and diagrams out of the pdfs on this Wartsila web page. He made his own web page, which, AFAICT from Google, no longer exists, possibly because he got a take-down notice from Warsila. Meanwhile, a bunch of other people have mirrored the page. So in other words, the Slashdot story linked to somebody's copyright-violating copy of a copyright-violating copy of some of Wartsila's pics. As other people have pointed out, it's actually not the world's most powerful diesel engine, either. Oh well, the pics are cool!
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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.
This is more of an American attitude. Europe and Japan have a very large market for small city cars where the buyers aren't so concerned about power and really don't give a fig about engine size as long as it works well enough on a test drive. Fuel efficiency and reliability in this market are a lot more important. The costs of developing a new engine aren't prohibitive. Take the Smart car as an example - 3 cylinder engine and a paltry 698cc, but really quite popular.
But why are 2-strokes particularly desirable?
In fact, just FYI, there are several engines available now that convert heat energy into velocity at more than 90% efficiency - high expansion hydrogen based rocket engines! Really amazing devices, really.
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It wouldn't be useful from a commercial perspective of course. From a cultural one, it could be incredible. You could have an entire culture of nomads living on the ocean, never needing to make port. That whole international waters thing could be good too - casino ships?
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Um... all a rocket engine does is accelerate a high temperature gas - so the energy of the steam leaving the nozzle is not loss, it is the whole point of the engine.
Now, using that to accelarate am object may have useful or non-useful metrics. But it is hard to call that efficiency, though. (For example, accelarating a stationary object using a rocket engine takes more energy than picking the object up and throwing it. But we still don't try to throw the space shuttle into orbit for some reason...)
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I find it interesting that they're building engines like this, because it was my understanding that most new ships being constructed today are being built with diesel-electric systems. Inside the hull there's a turbine-driven electric generator, and then suspended below the hull are several "azipods," containing an electric motor connected to the propeller. The advantage over a conventional prop-shaft system is that there are fewer seals -- you don't have the big shaft going through the hull below the water line, just electrical connections -- and you don't need a rudder. Also, because you can rotate the azipods 90 degrees or more in each direction, you get more maneuverability than you do with a rudder; the azipod can basically act like a stern lateral thruster. In concert with bow thrusters, you can basically rotate a ship around on its axis, or pull it into a berth sideways without a tug. Also, I think that azipod systems take up less space inside the hull.
If this diesel really is the 60+% efficient that some people are quoting, I suppose it's probably more efficient than a turbine+generator+azipod system, but I'm surprised that the efficiency alone would be enough to make a designer give up the advantages of azimuth thrusters.
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