
Lasers to replace spark plugs in gasoline engines - iwwr
http://scienceblog.com/44560/laser-sparks-revolution-in-internal-combustion-engines/
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nickpinkston
Wow - 9x11mm YAG laser as a spark plug to reduce emissions and increase
performance - sounds cool, but I can't help but think that this is like
building a carbon fiber stagecoach: cool improvement to what should be a dying
technology. We can't produce a damn fuel cell cheaply, but mini YAG lasers are
possible? What are you doing science?!?

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jerf
They aren't sexy and few people talk about them, but if you do an engineering
and economic analysis, some form of carbon-neutral liquid fuel is still very
much on the table as a reasonably long-term energy transport solution. The
characteristics of liquid hydrocarbon fuel are pretty good in most ways, which
is why we still use them. For instance, have you ever worked the math on the
amount of energy being moved when you pump ten gallons of gas in one minute
and converted that back to Watts? There isn't an immediately obvious
replacement for them that actually works as well. If the problems of the
particular way we obtain them can be solved, then it's worth it to continue to
figure out how to use them more efficiently.

And while 20 years ago you might have thought it would "just be easier" to
switch away entirely to something like electric vehicles, research on that
front has not proceeded as satisfactorily as would have been nice (batteries,
oh batteries, why can't you just be an order of magnitude better?), and "fix
the problems that liquid hydrocarbons have" has started to look less like a
stupid idea.

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ugh
What about changing out the whole battery? (You no more own a battery but you
rent one from the gas station.) The infrastructure is hard to build, it's not
easy to standardize in a future proof way (The same battery or at least very
few different models of battery have to fit every car and they should be
replaceable within minutes in some automatable way.) but I still think that
the idea is very appealing.

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Natsu
> What about changing out the whole battery? (You no more own a battery but
> you rent one from the gas station.)

People already steal copper wires and screw up our infrastructure that way. I
honestly can't imagine a world in which greedy idiots don't screw everyone
over given how expensive those batteries are and that makes me sad.

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ugh
If you are doing it right I can see very few scenarios for screwing the system
— not more than exist now when it comes to, say, manipulating the odometer.

Such systems must already allow you to keep the battery as long as you want
and to use it as often as you want (for as long as you have a contract), they
must allow you to charge yourself, otherwise they wouldn't make all that much
sense. The idea is that you don't have to change batteries for daily commutes
or short trips (you charge at night), only for longer trips. (This is
something that works much better in densely populated countries with little
sprawl — the US might not be a very good candidate. I think Israel is trying
out such a system in some way, its smallness makes it ideal.)

It's like a flat rate, some drive little, some drive more, but just because
the battery is rented doesn't mean that driving behavior will change all that
much. There is only so much you can drive and charge.

I also think that it would be somewhat involved to sell the battery on the
black market. You have to at least get a replacement battery before your
contract is up, so where's the advantage in selling your old battery on the
black market? You might be able to profit a little, but you would also need
scale, you need know how (how to manipulate the data those batteries would no
doubt be collecting) and you need to be able to hide from the police. Nothing
unheard of, but also no show-stopper. (People already do this with odometers
and hardly anyone cares.)

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lutorm
_If engines ran leaner — burnt more air and less fuel — they would produce
significantly smaller NOx emissions._

This doesn't sound right to me. I'm pretty sure engines can run lambda>1 right
now, and this gives better fuel economy, but it is not allowed due to
emissions requirements. lambda>1 might give less inherent NOx, but lambda=1 is
required for catalytic converters to work and the decrease in NOx from higher
lambda is not enough to outweigh the loss of the catalytic converter.

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ajays
It's all fine and dandy till a speck of soot blocks the optics, and the engine
dies.

A better solution (IMHO) would be to have multiple spark plugs.

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lutorm
Yeah that seems like an obvious problem to anyone who's looked inside a
combustion chamber. I wish they'd mentioned something about how they think
this is not a problem.

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jimmyk
It seems to me like that kind of concentrated power would be capable of
vaporizing any small particles (or even turning them into plasma briefly) in
the way.

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lutorm
Maybe, but they say that it's focused in the center of the chamber because
that's where you want ignition to start. In that case, you might not have that
high flux at the entry aperture (you might not want this for other material
reasons, too). In any case, I don't think you want to start combustion at the
edge because that's the least efficient place to do it.

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mhb
Maybe the beam is wide enough before it is focused so that the soot wouldn't
block enough of it to be a problem before the soot is blown out of the
chamber.

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lutorm
_... before the soot is blown out of the chamber._

You've never looked inside an old engine, have you?

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mhb
No. But I only intended to address the point that if the beam is focused in
the center then it would take more than a speck of soot to block the wider,
lower flux, defocused beam where it enters the cylinder.

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jackfoxy
I possibly overlooked it, but I didn't see how much leaner the fuel mix could
be for the same power output. Seems like a pretty important consideration.

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jasongullickson
I have to wonder how much further electric vehicles (battery technology in
particular) would be if we half as much resources on EV that is spent trying
to improve the internal combustion engine?

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hugh3
I wonder how much worse our internal combustion engines would be if we'd spent
half the money that we spent on improving them on batteries instead.

