Print 84 comment(s) - last by mindless1.. on Aug 9 at 6:45 PM

The new technology was tested on a Caterpilllar heavy duty diesel engine. It achieved a thermal efficiency of 53 percent much better than the most efficient auto diesel engines (about 45 percent) and better even than the most efficient diesel engine in the world -- a turbocharged maritime engine that is 50 percent efficient.  (Source: Caterpillar Equipment)

The new engine could cut U.S. oil consumption by 4 million barrels a day -- roughly the amount that the U.S. imports from the volatile Persian Gulf.  (Source: Flickr)
New engine could get better gas mileage than mild hybrids even

Diesel and gasoline are both great fuels from a chemical standpoint, each with its own unique advantages.  Diesel burns more completely, lubricates the engine better, produces less carbon monoxide, and is safer as it does not produce as much flammable vapors.  However it has its disadvantages -- older engines can have a greater danger of incomplete combustion, overall engine power is a bit lower, and diesel engines weigh more.

Gasoline on the other hand burns faster and produces more power (due to the faster burn, not the energetic content).  However, it also typically yields worse gas mileage than diesel, combusts less completely (in well-maintained engines), usually requires a spark to ignite, and produces more pollutants and flammable vapors.

Researchers at the University of Wisconsin-Madison, led by Professor Rolf Reitz have come up with an innovative solution -- an engine which blends diesel and gasoline fuels to get the best of both worlds.  They have designed an engine which they say will be 20 percent more efficient than traditional gas engines, while also lowering the emissions.  The new engine works via a technique called "fast-response fuel blending", which means that the engine mixes the diesel and gas to the perfect ratio for the current conditions.

Heavy loads (like that of commercial trucks) would warrant a 85 percent gasoline to 15 percent diesel mix, while light loads would typically induce a roughly 50-50 mix.  Normally the gas wouldn't combust in a diesel engine, but by adding just the right amount of diesel fuel, combustion is achieved.  In fact, the special mix lowers engine temperatures by as much as 40 percent drastically reducing the amount of energy lost to waste heat.  This allows the diesel engine to use cheaper low-pressure injection (typically in gas engines only), and burns the fuel more cleanly, producing less pollutants.

The researchers estimate that if all cars and trucks in the nation adopted the new engine, it would cut U.S. oil consumption by a third -- by 4 million barrels per day.  States Professor Reitz, "That's roughly the amount that we import from the Persian Gulf."

The engine was developed using theoretical models, then built using a Caterpillar heavy-duty diesel engine as a base.  The new engine achieved 53 percent thermal efficiency, an admirable result, considering the best diesel engine -- a massive turbocharged two-stroke used in the maritime shipping industry -- gets 50 percent.

Professor Reitz concludes, "For a small engine to even approach these massive engine efficiencies is remarkable.  Even more striking, the blending strategy could also be applied to automotive gasoline engines, which usually average a much lower 25 percent thermal efficiency. Here, the potential for fuel economy improvement would even be larger than in diesel truck engines.  What's more important than fuel efficiency, especially for the trucking industry, is that we are meeting the EPA's 2010 emissions regulations quite easily."

The one major downside is that the engine necessitates a second tank.  However, in order to meet EPA nitrous oxide emission regulations the only alternative for large diesel vehicles would be urea injection -- which would likely be more expensive, less efficient, and still require a second tank.  While there's no telling how soon the engine will start popping up in cars and trucks, it appears to be the best solution yet and the best alternative to mild hybrids.  Of course it could be combined with hybrid electric technologies for even great fuel efficiencies.

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RE: well but for vehicle usage
By tastyratz on 8/4/2009 10:58:03 AM , Rating: 5
Actually you bring up another VERY valid point without realizing it:

This engine actually opens up the possibility of using a 100% biofuel diesel.

The issue with a lot of fat based biodiesel is solidification at lower temperatures... but if the engine can start and warm up on gasoline every time they can run coolant lines parallel with the diesel fuel line and back to the tank to heat it up. Then when the engine is up to temperature they can switch over and begin blending. A lot of biodiesel conversions do this manually with switches... but this really opens up the possibility to do it from the factory intelligently.

RE: well but for vehicle usage
By AEvangel on 8/4/2009 12:07:06 PM , Rating: 5
Yeah it would be nice if this was pursued more as a viable option, I know of a couple of local Midwest based VW TDI owners that use 100% Bio-diesel, they have a small like 2.5 gallon tank installed in their trunk for regular diesel to start their car on then flip a switch and start running on the 100% Bio-diesel that they make in their basement for like half to a third of the price of regular diesel.

RE: well but for vehicle usage
By Lord 666 on 8/4/09, Rating: -1
RE: well but for vehicle usage
By quiksilvr on 8/4/2009 2:15:48 PM , Rating: 2
What does that have to do with anything? Did you think people would actually rate that up or do you get off posting stupid comments to see if the -2 rating exists?

RE: well but for vehicle usage
By FITCamaro on 8/4/2009 3:12:26 PM , Rating: 2
Given the poster, I would assume he was joking.

RE: well but for vehicle usage
By Lord 666 on 8/4/09, Rating: -1
RE: well but for vehicle usage
By RivuxGamma on 8/4/2009 9:54:10 PM , Rating: 3
Biodiesel sounds nice and all, but it does produce more CO2 and more nitrogen oxides when burned than normal diesel.

I'm a bit skeptical of the findings, anyway. There's just plain less energy in the mixture when diesel is mixed with gasoline, regardless of how it's burned. It's possible that it's only something that can work in gigantic engines and the article does say that it's expensive.

I'll wait until there's further proof of this technology before I hang my hat on it.

RE: well but for vehicle usage
By Samus on 8/5/2009 10:40:03 AM , Rating: 2
a golf tdi is 179lbs heavier than a golf 2.5, and the golf 2.5 doesn't even have a turbo.

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