[FRIAM] Diesel OK?

[Steven A Smith]

I just read up a little on Selective Catalytic Reduction which seems to
characterize Bruce's Urea-injection system.

    https://en.wikipedia.org/wiki/Selective_catalytic_reduction

Which is similar but different to Air Injection:

    https://en.wikipedia.org/wiki/Secondary_air_injection

both in various combinations with two-way and three-way catalytic
converters:

    https://en.wikipedia.org/wiki/Catalytic_converter


I remember in the late 70s, early 80s when we imagined that an ICE
engine that could efficiently convert atmospheric oxygen and the
hydrocarbons of fossil fuels into pure CO2 and H20 would solve any and
all "pollution" problems.   Folks like Bill McKibbin were already trying
to alert us to Greenhouse Gas problems, but I know *I* wasn't listening
past my TechnoPhilic hearing aids.

As for Ed's apocryphal "peeing in the gas tank", urine being primarily
H20...  it seems highly unlikely that the <2% additive of Urea or Uric
Acid would be any benefit in emissions, though there have been systems
that injected water into the air-fuel charge which I believe (under very
limited conditions) increased power/efficiency by small margins, but I
think that was a result of cooling the incoming mixture effectively
increasing the difference between input/output temps resulting in
similar effects of increasing compression ration?


- Steve

> I seem to remember this as being associated with higher nitrogen oxide
emissions than richer-burning.  Has that long since been fixed?
> I believe that NO emissions are associated with the lean burn of
> Petrol... I'm not sure why Diesel is less apt to that... perhaps the
> longer chain hydrocarbons, the higher compressions (a different
> pointin the pressure/volume/temp space?) or the more "natural" or
> complete combustion conditions without a spark?