Re: OT: 216 Billion Americans Squirrels Are Scientifically Illiterate (Part 36)

Andrew wrote:
On 11 Apr, 00:35, "Dr. Dweeb" <s...@xxxxxxxxx> wrote:
Bill Todd wrote:
Bob Koehler wrote:
In article <56v7fnF29prb...@xxxxxxxxxxxxxxxxxx>, b...@xxxxxxxxxxx
(Bill Gunshannon) writes:
Supposedly, diesels polute less than cars.

Burning less fuel gives them a significant advantage here. But
burning diesel fuel has caused them to emit much higher levels
of NO. Recent tehnoogy, including new fuel blends, have
significantly cut down the NO, but not as low as gas engines.

My dim recollection from around 40 years ago is that increased NO in
gasoline engines is a by-product of higher compression ratios and,
perhaps specifically, increases in 'quench area' used to make them
feasible (by increasing turbulence just before combustion and thus
better mixing the fuel and air). A quick look now does not make it
clear whether the NO increase comes from compression ratio alone or
is related to the relative coolness of the quench area during
combustion (which was said to cause increases in other pollutants).

Since diesel engines run far higher compression ratios than gasoline
engines, their NO problem may be to some degree endemic.
Fortunately, exhaust processing seems to have been fairly effective
in reducing NO at the tailpipe for gas engines, and presumably
could work well for diesels too.

IIRC the "environmental" issue with diesel engines is more with
"particulate mass" and its elimintaion than gas emissions (NO, CO2
etc)

C02 is not a pollutant, particulate mass is, and the stuff that
comes out of diesel engines is nasty stuff.


That's 1990's thinking or perhaps you could describe it as US
thinking. Environmental science is changing all the time, CO2 has
moved from being a benign side effect of burning fossil fuel to an
environmental pollutant. Someone and it may have been you posted a
reference to an organization that is still trying yo describe CO2 as a
bountiful plant growth accelerator (only in the US).

The definition of Pollution is where something is where it is not
supposed to be, and causes some sort of damage or problem.

Many naturally occurring substances are necessary in small quantities
for life to occur, these same substances can cause serious problems in
larger quantities. CO2 was considered benign we now know that in
larger than normal quantities it isn't.

You are sort of right about Diesel. Older Diesel engines produce more
particles and combined with higher Sulphur Diesel fuel do produce more
pollutants (other than CO2) than petrol engines.

However low Sulphur Diesel and newer Diesel engine designs such as the
latest Mercedes Diesel engines have reduced these emissions
dramatically.


Last time I looked, I was a major shareholder of a large fleet of Mercedes,
MAN, HINO etc diesel engined vehicles. This is an issue that transport
idustry has been following quite closely for many years.

Newer fuels and better engines have reduced the size of the particulate
mass, not its toxicity, and in fact the smaller particles are a severe
problem, because larger particles tended to land somewhere and get washed
away, the smaller particles are pervasive and it is essentially impossible
to avoid them, short of living in a bubble Also, being smaller
(microscopic), they are more easily absorbed into biological organisms and
are for this reason even more problematic.

There have been various suggestions as to how to gather them so they are not
emitted, but one of the issues is that the container of material is so
severely toxic that there are in fact very few facilities capable of
correctly dealing with them.

There is plenty of literature available on this matter that is not written
by marketing droids. In this case, less is not actually better.

Dweeb

Regards
Andrew
Dweeb.

- bill


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