- #7223 of 8145
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Re: ... Diesel Design Thoughts [roland3]
by winter2
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Nov 28, 2008 (7:44 pm)
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Replying to: roland3 (Nov 27, 2008 2:10 am)
Interesting comments. An interesting issue here. As gasoline engine compression ratios increase, and more of them are moving toward direct gasoline injection, they are starting to run into some of the same issues diesels have had, namely particulate and NOx. Higher compression ratios are more conducive to the formation of NOx. Particulate in direct injection gasoline just may become a problem. Particulate comes from the incomplete combustion of fuel. In gassers, add the fact that sulfur content is 30 PPM versus less than 10 PPM for U.S. diesel fuel, you add to the particulate issue. Granted 30 PPM is pretty small, but considering that 97% of vehicles in the U.S. are gasoline powered, it adds up.
In the newer diesels, piezo-electric injectors are becoming more mainstream. They can inject seven plus injections quickly to cool the air charge and produce a very clean burn. As for particulate, there are self-regenerating particulate exhaust filters and appropriate catalysts and urea spray systems to reduce NOx.
Does anyone in the forum know how effectively the urea injection system reduces NOx?
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- #7224 of 8145
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Re: ... Diesel Design Thoughts [winter2]
by ruking1
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Nov 28, 2008 (7:54 pm)
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Replying to: winter2 (Nov 28, 2008 7:44 pm)
Here's a start.
link title
link title
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- #7225 of 8145
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Re: ... Diesel Design Thoughts [winter2]
by roland3
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Nov 28, 2008 (8:46 pm)
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Replying to: winter2 (Nov 28, 2008 7:44 pm)
... As far as I know the piezo-ceramic, CR injection systems have a max of five pulses. Because they are injected into the combustion chamber and instantaneously ignite, the systems have no effect on the intake air temperature.
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... The urea after-treatment systems are very effective on reducing NOx; however it is my opinion that the entire infrastructure will have to work, almost without problems, for two years, after implementation, just to cover, the carbon footprint, from building, the hundreds of millions of dollars, infrastructure, where upon, I expect the whole system to be obsolete. At least, it does not appear to be outright poisonous, as the MTBE debacle was. The reduced carbon output is a trade off in that urea treated engines are more efficient, because they can be tuned and built to a higher state and make more heat. Of course, that is if you ignore the three percent liquid penalty of the urea, and what it took, to get it, in your car.
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- #7226 of 8145
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Re: ... Diesel Design Thoughts [roland3]
by winter2
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Nov 29, 2008 (5:32 pm)
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Replying to: roland3 (Nov 28, 2008 8:46 pm)
Here are links showing piezo injection with seven pulses.
http://www.greencarcongress.com/2008/09/delphi-launches.html
Here is another.
http://www.springerlink.com/content/h5g70142565u5131/
Here is yet a third showing up to seven injections/cycle
http://www.theengineer.co.uk/Articles/268707/Perfect+piezo.htm
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- #7227 of 8145
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Re: ... Diesel Design Thoughts [ruking1]
by winter2
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Nov 29, 2008 (5:42 pm)
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Replying to: ruking1 (Nov 28, 2008 7:54 pm)
Based on the first link, NOx cannot exceed 0.05 gm/mile. If I could retrofit such a system onto my Jeep Liberty CRD, then it would reduce NOx by 88% and for the new Jetta TDI by 82% to meet the 0.05 gm/mile.
On the British version of our EPA website, a brief search shows no diesel using AdBlue or equivalent. Many do have DPF though.
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- #7228 of 8145
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Re: ... Diesel Design Thoughts [winter2]
by gagrice
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Nov 29, 2008 (8:03 pm)
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Replying to: winter2 (Nov 29, 2008 5:42 pm)
The Jetta TDI passes all emissions without adblue. Only the V6 diesels coming from BMW and Mercedes use adblue to get 50 state approval. Honda tried without it and failed the test. So I've read. Honda claims it would cost $5000 more for the diesel than gas engine to pass California emissions. VW is doing it for about $1200.
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- #7229 of 8145
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Re: ... Diesel Design Thoughts [winter2]
by roland3
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Nov 30, 2008 (3:21 am)
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Replying to: winter2 (Nov 29, 2008 5:32 pm)
... Winter, thank you for the links. It might be a case similar to Audi, in that they test above thirty thousand pounds of fuel pressure in their racing program but their street cars run less than thirty thou. So you are right there are some systems that are capable of seven pulses but there are very few that have made it on-highway.
..
... What I find even more surprising (and hopefully true) is that one system claims a significant drop in NOx production, especially considering that most attempts at more complete combustion increase NOx. Read, more compression, more boost, more heat, sharper timing. It is one of Mother Nature's CRUEL ironies.
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- #7230 of 8145
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Re: ... Diesel Design Thoughts [gagrice]
by ruking1
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Nov 30, 2008 (8:16 am)
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Replying to: gagrice (Nov 29, 2008 8:03 pm)
This is a tad confusing. Not too long ago Honda went from concept to market for a diesel engine cTDI and transmission/s in not only the shortest time, but with a clean sheet. By all reports it is/remains one of the more sophisticated diesel designs.(tuneable/scale able LOW emissions being one of the HIGHEST priorities)
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- #7231 of 8145
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Re: ... Diesel Design Thoughts [ruking1]
by roland3
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Nov 30, 2008 (9:20 am)
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Replying to: ruking1 (Nov 30, 2008 8:16 am)
... It appears very hard to outdo the "World, Bosch, Common Rail" engine template. I guess Honda might be using Nippon Denso injection. That's one of the reasons that I find Green Diesel Corp's injection so amazing.
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- #7232 of 8145
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Re: ... Diesel Design Thoughts [roland3]
by winter2
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Nov 30, 2008 (9:53 am)
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Replying to: roland3 (Nov 30, 2008 3:21 am)
I get a magazine devoted to diesel and I find that there are Bosch CP3 pumps out there that will deliver 40,000 PSI (2666 Bar) reliably over the long term including the one on my Jeep Liberty CRD. In fact, V.M. Motori, the manufacturer of the engine in my Jeep has a version of my engine with piezo injection.
http://www.vmmotori.it/en/01/00/01/dettaglio.jsp?id=56
It uses the same Bosch CP3 pump at 1600 Bar but delivers 60 more Newton-Meters ( 44.25 lb-ft) of torque over the version I have.
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