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Control system reduces emissions and increases fuel economy

Many of the alternative fuels on the market require vehicles with very specialized engines and fuel systems to operate. Biodiesel is different in that it can be burned in existing diesel engines with existing fuel systems and technologies. There are a few issues with existing biodiesel blends causing it to produce more of certain emissions that conventional diesel fuels.

Researchers at Purdue University have developed a new advanced closed-loop control system which prevents biodiesel fuel blends from producing more nitrogen oxides that conventional diesel fuels. Nitrogen oxides are the component of burnt diesel fuel that contributes to smog. According to the researchers, vehicles burning biodiesel can produce as much as 40% more nitrogen oxides at some operating conditions and fuel economy declines by as much as 20% compared to conventional diesel fuel.

The reason biodiesel produces more nitrogen oxides during the combustion process is because the fuel has oxygen in it whereas conventional diesel fuel doesn't. One key innovation that the new engine control system uses to help reduce nitrogen oxides produced when burning biodiesel is exhaust gas recirculation. The technique reroutes a portion of the exhaust gases back into the cylinders of the engine to reduce the amount of emissions that are released. Using the exhaust gas recycling method the researchers were able to reduce the amount of nitrogen oxides produced and increase fuel economy.

"We were able to improve the fuel economy with a biodiesel blend while reducing nitrogen oxides to where they were with conventional diesel," Gregory Shaver, assistant professor of mechanical engineering said. "At the same time, we were able to maintain the customary biodiesel reductions in particulate matter emissions compared to ordinary diesel fuel while not increasing noise emissions."

Using the closed-loop control system and exhaust gas recirculation the team was able to reduce the nitrogen oxide emissions produced by the vehicles burning biodiesel to the same level produced by vehicle burning conventional diesel. However, while the new techniques did improve the fuel economy of biodiesel vehicles, the fuel economy is still not as great as that of traditional diesel fuel.

"This means you get lower mileage for biodiesel compared to ordinary diesel fuel," Shaver said. "We improved the combustion efficiency and were able to get better mileage than before, but still not as good as conventional diesel fuel."

The reason that fuel economy with biodiesel is lower than that of conventional diesel is because biodiesel has 10 to 12% lower energy density than conventional diesel when burned during the combustion process. The closed-loop control technique uses advanced models to adjust the engine automatically as it senses what blend of fuel I being used in the engine. The software in the control system adjusts fuel injection timing and the air-to-fuel ratio along with the amount of exhaust gasses returned to the cylinders depending on the type of fuel being used in the vehicle.

"You need to be able to estimate what the blend ratio is so you know what's going on in the engine," Shaver said. "Is it 20 percent biodiesel fuel mixed with 80 percent regular fuel? Then we can do something to reduce the nitrogen oxides to levels consistent with a conventional fuel that didn't have oxygen in it."

The technology needed to implement the new control system into existing diesel vehicles is already here. Shaver says that it only adds an "extra wrinkle or two" to what is already used inside a vehicles control module. The future of biodiesel production itself is in question as companies producing the fuel have gone out of business after tax credits supporting the industry were ended.



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what a waste of resources
By drewidgho5t on 1/26/2010 3:16:00 PM , Rating: 1
So an entire article that tells us...??

This smells of something more along the lines of a reporter calling and asking one of the professors to "just give me something, anything to write about".

Truly the senior ed's @ dailytech should seriously reprimand this article author for putting together a last minute piece.




RE: what a waste of resources
By GTVic on 1/26/2010 4:00:22 PM , Rating: 4
The referenced paper was published online so your main argument has no merit.

Of more importance is the number of bio-diesel companies going belly-up due to the elimination of tax-credits and possibly the increased opposition to using biological matter for fuel.


RE: what a waste of resources
By XIAOYI on 1/26/10, Rating: 0
RE: what a waste of resources
By ZHENZHEN on 1/27/10, Rating: -1
RE: what a waste of resources
By geddarkstorm on 1/26/2010 4:20:25 PM , Rating: 3
This is a sci/tech site, and this is tech information: news about tech developments with some more advanced details than a generic news sites.

If you wanted random news fluff, go read CNN.


RE: what a waste of resources
By Calin on 1/27/2010 2:00:26 AM , Rating: 2
There are some things I didn't knew about:
-biodiesel has higher nitrogen oxide ratio in exhaust gasses
-biodiesel has lower energy density
-biodiesel has lower particulate in exhaust

So, I think that (for me) this article is interesting

Of course, biodiesel have other issues:
-vegetal oil will gel much more easily
-vegetal oil (or at least some of them) typically needs to be heated to be as fluid as diesel fuel


in defense of me
By drewidgho5t on 1/27/2010 2:44:30 PM , Rating: 2
I don't need to read cnn for random news fluff. I got it here.

What part was NEW AND INFORMATIVE?? The part about using egr's? The part about higher nitro oxides when utilizing bio/diesal? The part about optimizing the engine control system for the fuel being used?

There is NOTHING new and informative in this article. Maybe you should go read CNN and get the news when it occurs, in this case about 5-10 yrs ago.

"One key innovation is using an egr..."--certainly NOT new.

"uses advanced models to adjust... as it senses"--Brazil has been doing it for years with regards to their use of bio-fuel in cars. You can purchase cars with these advanced sensors and mapping systems.

So if these advanced techniques are already in use in other countries then they are certainly not new.

If this article provided some knowledge as one of you stated, then good. But just because YOU recently learned that 2+2=4, does not make it new. (That 2+2=4 comment is NOT intended to be a diss concerning anyones level of knowledge. It is meant to make the point that learning something does not make that particular fact someone just learned new.

In fact I would not be surprised to learn that this article was recycled from one written several years ago. Apparently some magazines have been doing exactly that.




RE: in defense of me
By Veerappan on 1/28/2010 1:37:44 PM , Rating: 2
Settle down. Some of the combinations of technologies here might be new, and it definitely informed me.

Yes, it's true that EGR systems have been around for a while. My car (2001 Jetta 1.8t) uses an EGR during a cold-start to reduce emissions while the engine is cold. However, the EGR on my car shuts off after a minute or two (when the coolant reaches a certain temperature). This model seems to employ an EGR at all times in a varying manner to reduce emissions. Sounds like a good idea to me.

I also was unaware of the differing energy contents of the average biodiesel as compared to normal diesel, while I was aware of the nitrogen oxide and particulate matter differences.

Just because you happen to know all of these things does not mean that everyone else does.


Biodiesel Progress
By Paperdoc on 1/27/2010 11:54:46 AM , Rating: 2
I do some consulting / advising with firms interested in production of fuels from bio-resources as an alternative to fossil fuel (oil) reserves. It's a relatively new field with some problems emerging. Those problems do become barriers to widespread acceptance of these replacements, whether for real technical reasons or just because they are misused as excuses for resisting change. So any good solution to some of the problems is worthwhile noting and using if is proves reliable. The article explains in reasonably simple terms what the problems are in this area, and what the solutions offered can do, and what they can't. Seems like a good item to me!




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posts are late
By AstroGuardian on 1/27/2010 2:43:51 AM , Rating: 1
Posts @ Dailytech are couple of days late. I read this article @ www.physorg.com couple of days ago. I will check tomorrow whether they are just copied.




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