[Vwdiesel] environmental concerns

[Jonbonbart at aol.com]

In a message dated 7/1/02 9:47:50 PM Eastern Daylight Time, steve at dropkin.net
writes:

<< Find out what misinformation they've heard about modern diesels
 and work from there. <snip> it's the invisible stuff (NOx and the like)
 that kills, and diesels produce much less of that. >>

That is misinformation.

Diesels have higher combustion temperatures than gasoline engines. This is
part of why they have higher efficiency. Diesels have no throttle plate to
create a vacuum. They pull in the full displacement of air each stroke. These
lower pumping losses also improve the efficiency.
The bad side is that the higher temperatures and more residual oxygen once
the meager fuel has burned means that more, not less, NOx compounds are
produced. The oxygen that remains once the fuel is consumed combines with
nitrogen due to the higher pressure and temperature into the smog producing
compounds collectively called NOx. Exhaust Gas Recirculation goes a long way
in reducing the excess O2 available for combining, but the relatively high
sulfur content in petroleum diesel fuel limits the amount of EGR before the
SO2 condenses and begins eating the intake. Once the US joins the rest of the
world and forbids the use of high sulfur diesel fuel then this last argument
against diesels will be moot.
Oh, Did I mention? Biodiesel, unlike petroleum diesel, contains NO Sulfur! No
limits to the amount of EGR for NOx reduction. Retarding injection timing by
2 degrees will do the same reduction without EGR.
Jonathan Bartlett