Inviromental Impact of catalytic converters vs EV batteries

[Logic]

This a write-up by Andrew Moore aka: ademonrower here, comparing the environmental impact of the metals in catalytic converters vs the constituents in EV batteries.

"...An average EV Li-NMC battery requires more than 7.4 times as much energy for the
production of its electrically-vital components as an average catalytic converter for the
production of its chemically-vital components..."

IMHO:
That last bit of unburned HC that: 'isn't a problem' according to most here..!
Yet everyone is driving around with a 'solution' to this 'non problem' in the form of Catalytic Converters..!

ie: That last bit of unburned HC is worth going after!
Especially if we can get to the point of doing away with expensive Catalytic Converters completely.

It seems that these HCs 'hide' from combustion in the area between the piston side above the 1st ring and the cylinder wall.
"Nonesense! That's a tiny volume!"
Yes it is, but during combustion there is a HUGE pressure spike,
That pressure is in the burned volume behind the flame front and is compressing the hell out of the unburned volume ahead of the flame front!
The density of the AF mixture is said to be as high as that of water in the squish area and that means it's the 'same' in that dead area!
ie: Tiny volume yes, but surprisingly high density and thus mass.

That pressure drops fast, resulting in some of that AF 'squirting out of the gap into the combustion chamber, late in the power stroke.
It will then burn, but too late to be of much use and fuel will have coalesced on the surface, diluting the oil.

Also there is some HC hiding in the dead still boundary layer that is that very first (and ~2nd etc) layer of molecules on the walls of the combustion chamber.

Any ideas on how one might ameliorate those??
One or 2 things come to my mind, but more research reqd before saying anything.

[Ecky]

My Insight is a JDM model, and while it still meets LEV standards, it has no upstream catalyst. It does, however, still have the "secondary" catalyst which functions as a NOx trap. You can 100% smell that the car has no catalyst. I'm aware of anecdotal evidence about areas which are prone to inversion layers, which have had their air quality improve dramatically due to the introduction of catalytic converters.

How to achieve the same result without a catalyst? Well, I don't think you can really replace a catalyst with anything else. You can improve combustion with prechambers or other techniques, but they're not functionally equivalent. Of course, where to draw the line for "Good Enough" is entirely subjective.

[Logic]

Originally Posted by Ecky

My Insight is a JDM model, and while it still meets LEV standards, it has no upstream catalyst. It does, however, still have the "secondary" catalyst which functions as a NOx trap. You can 100% smell that the car has no catalyst. I'm aware of anecdotal evidence about areas which are prone to inversion layers, which have had their air quality improve dramatically due to the introduction of catalytic converters.

How to achieve the same result without a catalyst? Well, I don't think you can really replace a catalyst with anything else. You can improve combustion with prechambers or other techniques, but they're not functionally equivalent. Of course, where to draw the line for "Good Enough" is entirely subjective.

Thx for 'giving it a think' and a reply Ecky'.

What I am wondering here is if there is, or was, any 'outside the box' thinking or 'Inventions' on how to further ameliorate this problem..?

Your engine sounds interesting.
Googling it now.

[Logic]

I think I may have had an idea or 2. Need to research more and think it over.


I NB the huge increase in surface to molecule contact with water like densities during combustion.

Blowby adds to that 'taken out of play' volume...
To get the gap to zero would take something; preferably, both frangible and lubricious...

[Ecky]

I would guess one way to make the burn more complete would be to increase the time spent inside the combustion chamber - which is precisely opposite of what manufacturers have been trying to do in recent years, as its one of the few low-hanging efficiency fruits still left. Fast combustion sheds less heat to pistons and cylinder walls, and also allows combustion to be started later (more retarded timing) resulting in less negative work being done on the rising piston. Retaining a design that keeps combustion speed high, but holds the charge in the cylinder longer, would give more complete combustion.

This might even be done already during startup/warmup, as the extra energy loss is all into the cooling system.

[Piotrsko]

What about the old fashioned long timey favorite: extra long stroke? Get relatively more time before you have to ignite. Just won't rev as fast

[Logic]

Originally Posted by Piotrsko

What about the old fashioned long timey favorite: extra long stroke? Get relatively more time before you have to ignite. Just won't rev as fast

Ye the old engines did it that way.
Large stroke + Looong conrod = 'No' side thrust and no burn lost out the exhaust.
Little to no pumping losses either if AF moves through tracts and valves slowly..?
Big and heavy means great stationary engines, that outlive people..!

They seem to run very economically too..?

https://www.youtube.com/watch?v=cbQz5T-VA8s&t=7s

"Electricity...4X the cost of the diesel... Interesting isn't it..."

They do not make nearly as much or as irritating a noise as small, high rpm engines.

So what happens with new high pressure injection and other tweaks like heating the diesel and using the waste heat.

[Isaac Zachary]

One way of burning most everything up in a combustion chamber is by means of a stratified charged. In simple words: take a cylinder full of air (or maybe a very lean mix) and make a pocket of fuel mixed with air around the spark plug (either with direct injection or with special valving systems like in the original Honda CVCC engine).

The result is that more of the fuel burns up because it isn't homogeneous, so you don't have lots of fuel near the cylinder walls and piston tops and combustion chamber surfaces that end up quenching the flame before it comes up completely to that metal.

Note that this is one reason why diesels tend to be more efficient.

Another way would be to have really hot or extremely thermally insulated combustion chamber surfaces. Maybe some sort of ceramic coating, as metal conducts heat very well.

[Ecky]

Originally Posted by Piotrsko

What about the old fashioned long timey favorite: extra long stroke? Get relatively more time before you have to ignite. Just won't rev as fast

It isn't the stroke that increases the time, a long stroke just moves the powerband down the rev range. However we're taking a few percent, or tens of percent at most. Lowering RPM requires upsizing the engine to maintain power.

A long stroke engine and a short stroke engine both take the exact same amount of time for a stroke at the same RPM.

The long stroke engine has higher piston speed.

[Logic]

Originally Posted by Ecky

It isn't the stroke that increases the time, a long stroke just moves the powerband down the rev range. However we're taking a few percent, or tens of percent at most. Lowering RPM requires upsizing the engine to maintain power.

A long stroke engine and a short stroke engine both take the exact same amount of time for a stroke at the same RPM.

The long stroke engine has higher piston speed.

Yep; its the long conrods and low rpm of the old Listers etc IMHO,
but lets not forget that low rpm powerband from the long stroke.

Those looong conrods cut down on piston to sleeve side thrust=friction and wear dramatically.

While the long stroke enables low rpm powerband/efficiency.

I'm thinking that the low rpm (600-ish) means that air in intake and exhaust tracts is nowhere near the supersonic flow speeds one sees on modern engines, so way less pumping losses etc.
Also the valves don't have to open early and close late (overlap) so much more time for all the fuel to burn.

BUT!

All this has nothing to with the issue of a lot of AF getting into that U shaped piston-ring-sleeve gap (and below it) due to the flame front compressing the yet unburned AF down to ~'the density of water'!

One way I can think of is a solid lubricant that builds up in that U gap as the ring, scraping against the sleeve, moves upward..?
Preferably something that doesn't 'rust' like MoS2 does.
Any ideas..!?

The other is a catalytic surface, similar to an exhaust catalyst, so that the very dense, AF in contact with it, changes into smaller gas molecules.
eg: One ~C4H12 gets broken down into four ~CH4s with 4 times the volume, so 3 quarters of that new gas has no choice but to head back into the chamber.

NB that there will be an effect on all the surfaces where there is normally a quenched, still, boundary layer.

It was found that catalytic activation is more effective with lean fuel-air mixtures and at higher compression ratios.
Among the different catalysts investigated, copper was found very effective in reducing both HS and CO emissions, and brake thermal efficiency was also improved.
At a high CR of 9:l and with a lean mixture (A/F=I5.7), copper catalyst increases the absolute brake thermal efficiency from 17.7% to 22.8%,
decreases HC emissions from 3200 to 2300 ppm,
and lowers CO emissions from 3.6 to 0.25% by volume when compared
to the normal engine.
https://www.dragonfly75.com/moto/ImproveEngine.pdf

NB this:
Heat dull rusted copper and it reduces to nice shiny Copper..!
No other metal does that as far as I know. Why..?

IMHO the whole head should be copper plated. Valves, sparkplug, pistons and all!
Even that top 4mm of sleeve that the rings never touch, but where the main combustion event actually happens... (and because)

NB that pgfpro is going to try copper pre-chambers.
Wish I was there!