[Stoves] PM emissions from engines

[Crispin Pemberton-Pigott]

Dear Andrew

A set of good points. I won't tackle all of them.

Most articles are misleading, somehow. We will store and filter...

Direct injection is going to save the planet by reducing fuel consumption, didn't you hear? It may kill us along the way.

Harold Annegarn would caution that when you measure the PM will provide different answers. The total mass emitted ‎is one number. If measured immediately, the size is so small they are, traditionally, counted, not weighed. If measured after ten seconds, they will have grown into large enough particles to be reported as having mass.

If measured after 1 km the particles will have agglomerated into giant dendritic particles composed of thousands of tiny globs and be so large as to count as PM4. After that they will bump into each other and gain enough mass to fall to the ground.

Thus size exposure depends upon distance and time.

The number of nanoparticles produced by other gasoline engines depends of the throttle setting at the time with the n compounds in particular varying enormously‎ with power. PM per g of fuel burned might be higher at low power.

This also applies to stoves which produce very different products at high and low power, and it is hard to predict which will be better. Stoves often have poor secondary air control leading to high excess air conditions at low power and far worse combustion.

These days, fireplaces are using O2 sensors in the flue to control the air supply in order to get the PM under control. If they were powered by TEGs or TAGs we might see them on off-grid household stoves.

Crispin

‎

 On Tue, 6 Jun 2017 03:03:23 +0000,Crispin Pemberton-Pigott
<crispinpigott at outlook.com> wrote:

>
>This throws even more confusion on the subject, gasoline engines produce more PM than diesel engines, presumably running on standard fuels.

The article is misleading in that very few spark ignition engines are
direct injection, though the proportion may be rising. Also
particulates are not small molecules but rather large agglomerations
of compunds.

It does lead to another  question though and that is what is more
significant, the number of particles or their mass? Plainly if we
restrict our attention to PM4, as perceived wisdom is larger particles
are efectively filtered out by the nasal passage, then as particle
mass goes up with the cube of it's dimensiones then a device producing
many small pm1 particles can emit 8 times as many particles as one
emitting pm4 before it reaches the same mass.

>
>"The laboratory studied the emissions of 7 gas engine vehicles equipped with direct-fuel-injection systems. The research found that they emit from 10 to 100 times more particulates than modern diesel engines. In fact, they have higher particulate emissions than older diesel without particulate filters.?"

In this country all diesel vehicles have to have particulate traps and
many have urea injection to reduce NOx (itself a precursor of
particulates amongs other associated problems)


Therein lies another worry: Nikhil's scepticism  does raise the
question about premature death in that many of the people affected
will have spent most of their lives exposed to higher levels of
particulates, in UK the majority of adults smoked in the 50s, we had
lead in fuel and open burning much of which has decreased to
negligible amounts. Surely we won't see an improvemt in life
expectancy for a generation?

Don't let this drift too far as vehicles are not a pertinent subject
though particulate emmissions are but using Nikhils equitoxity concept
what are the differences between fine fly ash (50% silica) and black
carbon with Poly Cyclic Aromatic compounds adsorbed on their surface?

Andrew (in the good enough camp)

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