• Oct 4th 2010 at 1:02PM
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What do you get when you cross a diesel engine with its gasoline counterpart? If Steve Ciatti (pictured), a mechanical engineer at Argonne National Laboratory has anything to say about it, it'd be an offspring that is genetically superior to its parents. Taking the best features of diesel engines (high efficiency) and gasoline engines (lower particulate matter and nitrogen oxide emissions), a blend of the two might be the holy grail of modern, liquid-fueled engine design.

There are different ways to merge the two, and homogeneous charge compression ignition (HCCI) is one of these technologies we've reported on in the past. Ciatti, though, is taking a slightly different approach by burning a lower octane fuel (80 to 85 RON, or Research Octane Number). This gasoline is easier to ignite than regular pump gas, but no where near the level of diesel fuel. Using a modified diesel engine (still no spark plugs or throttle) the diesel fuel injectors are able to spray fuel two or three times before ignition occurs at top dead center. The multiple fuel injections spread the fuel more evenly in the combustion chamber, which lowers particulate matter and NOx emissions compared to traditional diesel.

The added benefit of a lower octane fuel is that its easier to refine, making it very attractive to oil companies and BP and ConocoPhilips have taken notice of Ciatti's work. There is a downside, however, to this technology. Peak power drops approximately 25 percent, so this technology wouldn't be useful where ultimate power density is needed. However, since the torque curve stays essentially the same, we're willing to bet many people will trade a little top end power for a more efficient gas burning engine.

[Source: Wired | Image: Argonne National Laboratory]

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    • 1 Second Ago
      • 8 Months Ago
      ehhhhhhh....... back to the drawing board.
      • 8 Months Ago
      You should check out the original Wired story, which has greater detail about the research.

      • 8 Months Ago
      I think RON stands for Reynolds Octane Number.
      • 8 Months Ago
      Don't blog about this! This reeks of "oil industry research." This is just another way to extend our uses of petroleum. There are so many existing blends of petrol in use and research today that all of this crack science does is add oil to the fire.

      Is this innovative research? Sure, but it doesn't deserve praise.
      • 8 Months Ago
      If the peak power is decreased, the torque curve neccessarily changes. It's not a debate. It's just simple multiplication.
      • 8 Months Ago
      So ... what's the actual efficiency here?

      BTW, engine out gasoline does not have lower NOx emissions. It has lower NOx emissions post-catalytic converter. In the cat NOx is reduced to N2 by excess incompletely burned hydrocarbons. If you improve combustion efficiency to diesel levels you won't have those HCs and your cat won't work (and you'll have to find another source of electrons, like urea).

      Secondly, gasoline PM is lower than diesel by mass, not by number. That's because gasoline is far more volatile and gasoline PM is much smaller in size.

      Where gasoline could have an advantage is higher flame temperature, if this engine is running stoichiometric (is it? Handy detail to have, that) Efficiency-wise, at least, though that's bad for NOx. The ability to run lower octane is significant, however, as that improves well-to-tank efficiency, especially given that crude is getting progressively heavier and sourer.

      This is a remarkably detail-free entry. C'mon ABG, you can do better.
      • 8 Months Ago
      but - they won't sell it as they are sure people won't buy it.

      sometimes I think the best thing we could do to get more efficient cars to market would be to outlaw the publication of hp numbers for engines.

      same for megapixels for cameras for that matter.

      maybe then we could get down to making machines that actually functioned better and not worrying so much about machines which market better.
      • 8 Months Ago
      It seems very similar to the "Gasoline Partially Premixed Combustion" that may bring great advances as reported in the links below.

      Extracting real work from ICE with such higher thermal efficiencies and low emissions is really excellent news. Gas engines with efficiencies nearing diesel and fuel cells!

      Could not read all the thesis, but it seems to rely on current technology using gasoline in diesel-strength engines with direct injection an a more sophisticated engine control to allow for a more efficient combustion and energy transfer to real work.

      High hopes!

      Lund Team Shows 57% Thermodynamic Efficiency in a Gasoline-Fueled Heavy-Duty Diesel Engine Using PPC:

      Vittorio Manente (2010) Gasoline Partially Premixed Combustion: An Advanced Internal Combustion Engine Concept Aimed to High Efficiency, Low Emissions and Low Acoustic Noise in the Whole Load Range (PhD Thesis)

      Scania, Lund, Chalmers and KTH Collaborating in Research on More Efficient, Lower-Emitting Heavy-Duty Engine Fueled by Biofuels

      • 8 Months Ago
      With modern computer controls, Direct Injection, VVT, etc....there is great potential to modify fuels for better emissions and efficiency. For example, typical diesel fuels blended with other cleaner fuels might reduce the need for particulate filters or urea injection.

      And adding ethanol to standard gasoline increases octane allowing much higher compression, torque, and efficiency with cleaner emissions.

      These engines ultimately could have multiple fuel injectors in the same cylinder and multilple fuel tanks. And there could be more than 4 strokes per cycle with computer controls. For example, engine might "start" on gasoline, switch to ethanol blended with diesel and veggie oil at optimum conditions, and squirt in a shot of water on the 5th or 6th stroke, exiting through a "Steam Turbo" that drives the alternator, ac, and charge compressor, and water pump if needed.
        • 8 Months Ago
        Cool, i want a rube goldberg engine!
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