Could Spark Plugs be Replaced by Lasers?

[N2NH]

Something new that can help lower emissions by internal combustion engines...

A team at the Conference on Lasers and Electro-Optics will report on 1 May that they have designed lasers that could ignite the fuel/air mixture in combustion engines.

The approach would increase efficiency of engines, and reduce their pollution, by igniting more of the mixture.

Be interesting to see how this technology can be tweaked to increase mileage or to bring acceleration times down...


Lasers could replace spark plugs in car engines

[W5RB]

Stick 'em in some medallion taxis in NY , and in a few hundred race cars for a coupla seasons , and let me know how it works out .

[KG4CGC]

Lasers can only convert energy in ONES and ZEROS. A percentage of the energy will be lost.
Picture a board laid down across a set of stairs. The laser will only covert gas at the points where the board touches the stair corners. The rest of the gas is not ignited.

[NQ6U]

Lasers can only convert energy in ONES and ZEROS. A percentage of the energy will be lost.
Picture a board laid down across a set of stairs. The laser will only covert gas at the points where the board touches the stair corners. The rest of the gas is not ignited.

Makes for a bumpy ride. Hard on crankshafts, too.

[n2ize]

Makes for a bumpy ride. Hard on crankshafts, too.

Not you too !!!!

[rot]

Lasers can only convert energy in ONES and ZEROS. A percentage of the energy will be lost.
Picture a board laid down across a set of stairs. The laser will only covert gas at the points where the board touches the stair corners. The rest of the gas is not ignited.

Lost me here bro.
Are you saying gas as in octane or gas as in state of matter?
Seems to me gas(as in octane) only needs enough drive (activation energy) to yield a reacted gas(state of matter) and thus a pressure in cylinder rise from an entropyy change....assuming the gas(octane)/air is OK.
Damn...I think I've confused myself...here.
rot

ps could be that combustion eff thingy I don't get...

[ab1ga]

Lasers can only convert energy in ONES and ZEROS. A percentage of the energy will be lost.
Picture a board laid down across a set of stairs. The laser will only covert gas at the points where the board touches the stair corners. The rest of the gas is not ignited.

The rest of the gas is not ignited by the lasers, but is ignited as the flame front progresses away from the original ignition site.

It's been too long since I took thermo, and automotive combustion wasn't a focus of my interest, but if I remember correctly Otto-cycle engines extract P-V work, so the higher the pressure attained at top dead center the better, provided the increases don't destroy the physical structure. But once the piston starts to travel beyond TDC, crank shaft rotation will increase the combustion volume and decrease the pressure, which reduces the pressure increase attained by combustion, reducing efficiency.

I remember seeing sonograms of cylinder combustion, and you could see the flame front progressing from the location of the spark across the cylinder; the objective for cleanest burn was an even, consistent burn with a slight excess of oxygen to make sure you got CO2 out of the pot instead of a lot of CO. But the flame front progression takes time, and during that time the combustion volume is being increased by crank inertia, i.e. energy paid for by the previous combustion event.

Using a laser with multiple spots (that's the magic), you can light the mix in multiple places at the same time, shortening the distance the flame front has to travel to burn all the fuel, which shortens the combustion time, which increases chamber pressure and efficiency.

You could almost simulate the process with multiple spark plugs, but they always ignite the mixture at the electrodes - the lasers, if properly focused, can light the mixture in the middle of the combustion volume as well. Since all that nasty chemistry is happening away from the "plug", it only needs to withstand temperature and pressure, not electrical discharge products as well. The only downside I can see is that if you have a badly mistuned engine, combustion residue may land on the laser, preventing necessary focusing or absorbing too much of the light used.

My guess is that the whole high-energy ignition system salad would fly out the window as well, replaced by drivers in the body of the "plug" itself.

A fascinating idea, be nice to see how it pans out.

73,

[rot]

It's been too long since I took thermo, and automotive combustion wasn't a focus of my interest, but if I remember correctly Otto-cycle engines extract P-V work, so the higher the pressure attained at top dead center the better, provided the increases don't destroy the physical structure. But once the piston starts to travel beyond TDC, crank shaft rotation will increase the combustion volume and decrease the pressure, which reduces the pressure increase attained by combustion, reducing efficiency.

Puck..I did not know that and I searched the webz for stuffs.
Kewlba...
Thanks fer throwing it up.
rot

[ab1ga]

Puck..I did not know that and I searched the webz for stuffs.
Kewlba...
Thanks fer throwing it up.
rot

rot,

As I said, it's been a while, and further Websearch has revealed that although my explanation was on the right track, the interplay between engine rotation speed, flame front propagation, engine torque and efficiency is a lot more complicated than even my bloated post indicates.

I think I've found a very nice explanation of the physics of automotive engines. The page is long, the print is small, but it seems accessible and complete. I started reading it, but there's a printer installation on the honey-do list today, so I won't get to it today. You might enjoy it:

http://mb-soft.com/public2/engine.html

73,

[rot]

rot,

As I said, it's been a while, and further Websearch has revealed that although my explanation was on the right track, the interplay between engine rotation speed, flame front propagation, engine torque and efficiency is a lot more complicated than even my bloated post indicates.

I think I've found a very nice explanation of the physics of automotive engines. The page is long, the print is small, but it seems accessible and complete. I started reading it, but there's a printer installation on the honey-do list today, so I won't get to it today. You might enjoy it:

http://mb-soft.com/public2/engine.html

73,

Wowsa...lots of goodies....Thanks.
Ya know...the service around this place (Island University) is top notch.
Toolness.
rot