[Stoves] PM emissions from engines

[Crispin Pemberton-Pigott]

>>Huh? "The article is misleading in that very few spark ignition engines are
direct injection?" 

>When did you last have to tune a carburettor?

Most are indirect injection. I don't see that it can make much difference, but the article claims it does. Indirect injection is into the intake port just before the intake valve instead of into the combustion chamber at high pressure. ‎

I am willing to bet that with the addition of electronically controlled valves the hindrance can be overcome. They can't be far from market. My nephew did his PhD on them 10 years ago. Fully programmable valve timing, no cam shaft, no chain etc. Flat torque profile. 

Regards 
Crispin 


-----Original Message-----
From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of
Andrew Heggie
Sent: Tuesday, June 6, 2017 11:21 AM
To: Discussion of biomass cooking stoves
Subject: Re: [Stoves] PM emissions from engines

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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