Laser sparks revolution in internal combustion engines

[Shipkiller]

Read it here:

http://scienceblog.com/44560/laser-s...stion-engines/

[CrazyJoe]

nice find

[3lusive]

very interesting, thanks for sharing!

[jdl1pt]

Wow, that's very cool. Thanks for posting. Just dreaming about the better gas milage....

[VinnieAces]

pretty cool glimpse into the future

[kresh]

Everything is better with lasers.

[TotalPower]

That article mentions many statements that are incorrect starting with:

1. lean air/fuel ratio's produce less NOx.

Air is 80-81% nitrogen, so by introducing more air or having lean combustion you will have more nitrogen as a by-product.

2. spark plugs are affected inside the cylinders due to high heat (strong spark) and optics wouldn't be.

What happens if the optics get covered in soot, are moved due to the energy of combustion, or fall out of alignment (lose their concentration of energy)? They'd stop working or destroy your engine!

3.relatively cold metals absorb heat

What is colder, your warmed up engine or your fuel or air being sucked in? Clearly an engine that is up to temperatures although it is colder is meant to disapate heat through the cooling system. Heat is a sign of a chemical reaction, but instead of heat they should be worried about force (moving the piston faster).

4.the laser is not strong enough to light the mixture uniformly from a single spot, they need multiple lasers.

Multiple spark plugs are used on airplanes-good idea since they run on high energy magnetos which have to fire in a timely manner only once per ignition! but with lasers, they have to time EACH of their multiple 800 picosecond pulses inorder to be able to get enough energy to light a very lean mixture.



FYI: Not only do I work in the field of combustion correction technologies, my brother is the leading scientist on ultra fast lasers and laser pulse shaping in the US. He works at fempto seconds which is 10 to the -15 (can't do exponents) they are talking about pico which is 10 to the -12...and 800 pico at that which is about 8,000 times slower than what lasers are capable of doing today.

Yes the article sounds cool but it's a bunch of junk.

Myth-busted.

[jsublime]

Ok Mr. know it all. I think it sounds cool - lasers at full power!

[Sniz]

Sharks with friggin laser beams on top of their heads!

[E90SLAM]

Originally Posted by Sniz

Sharks with friggin laser beams on top of their friggin heads!

[TotalPower]

Sharks w/ laser beams will be fighting against boats w/ laser beams:

This article on the other hand- I think is pretty freaking cool:

http://latimesblogs.latimes.com/tech...pon-fire-.html

[Slops]

Originally Posted by Sniz

Sharks with friggin laser beams on top of their heads!

good read though

[Artmasterx]

Originally Posted by TotalPower

That article mentions many statements that are incorrect starting with:

1. lean air/fuel ratio's produce less NOx.

Air is 80-81% nitrogen, so by introducing more air or having lean combustion you will have more nitrogen as a by-product.

2. spark plugs are affected inside the cylinders due to high heat (strong spark) and optics wouldn't be.

What happens if the optics get covered in soot, are moved due to the energy of combustion, or fall out of alignment (lose their concentration of energy)? They'd stop working or destroy your engine!

3.relatively cold metals absorb heat

What is colder, your warmed up engine or your fuel or air being sucked in? Clearly an engine that is up to temperatures although it is colder is meant to disapate heat through the cooling system. Heat is a sign of a chemical reaction, but instead of heat they should be worried about force (moving the piston faster).

4.the laser is not strong enough to light the mixture uniformly from a single spot, they need multiple lasers.

Multiple spark plugs are used on airplanes-good idea since they run on high energy magnetos which have to fire in a timely manner only once per ignition! but with lasers, they have to time EACH of their multiple 800 picosecond pulses inorder to be able to get enough energy to light a very lean mixture.



FYI: Not only do I work in the field of combustion correction technologies, my brother is the leading scientist on ultra fast lasers and laser pulse shaping in the US. He works at fempto seconds which is 10 to the -15 (can't do exponents) they are talking about pico which is 10 to the -12...and 800 pico at that which is about 8,000 times slower than what lasers are capable of doing today.

Yes the article sounds cool but it's a bunch of junk.

Myth-busted.

I agree with a lot of what you said, but running lean can reduce NOx production. NOx is produced via two main mechanisms, thermal and prompt, both of which happen in IC engines. The main point of lean combustion is to lower combustion temperatures (because you are short of a stoichiometric ratio which generates the highest temperatures), which results in less NOx formation from the thermal pathway. Since reactions tend to be exponential with temperature, moderate decreases in T can significantly affect NOx levels. You will still have NOx via the "prompt" pathway. Here is an example of exhaust composition. You can see as you go leaner, you produce less NOx at the expense of more unburned hydrocarbons. The peak in NOx more or less corresponds with the peak temperature near stoichiometric conditions.

The relatively cold metal of nearby electrodes and cylinder walls absorbs heat from the explosion, quenching the flame front just as it starts to expand.

Lasers, Taira explains, can focus their beams directly into the center of the mixture. Without quenching, the flame front expands more symmetrically and up to three times faster than those produced by spark plugs.

This is pretty much BS. Sure, if you spark close to the wall the flame front will take longer to move across the cylinder than if you spark in the dead center, but heat transfer to the block isn't going to major factor.

Also, the laminar flame speed is basically a fixed value for a fuel depending on equivalence ratio, turbulence, and combustion conditions, and there is no way to speed up a flame speed by changing the ignition location. Maybe he means the fuel in the cylinder can burn 3x as fast, but its not going to be due to flame speed enhancements. Here is a flame speed plot...


As you go leaner (< 1) the flame speed drops significantly, so I wouldn't be surprised if the flame speed in a lean combustion like described is actually slower than in a normal engine running at closer to stoichiometric ratios.

[JoosyJoos]

Too much science... losing interest....

So back to the original point of this post.... LASERS!!!!

[TotalPower]

I am possitive that lean combustion will raise combustion temperatures since you are introducing more oxygen into the cylinder in order to more completely oxidize the fuel you are spraying-which is why you will see reduced fuel consumption and reduced CO/PM. Unfortunately, because air is mostly nitrogen, you raise NOx by going lean.
*Look after the vertical bar (stoich)...you see NOx go up, CO, PM go down. Since CO and PM go down that means you are getting more energy (heat and pressure) out of your fuel.

This is true only up until the point that the reaction is no longer stoich and you begin to be too lean and require more fuel.

Having richer combustion is a way to cool your engine down, because when fuel sprays into your combustion chamber it is in the form of a fine mist that is considerably colder than the internals and the spray will slightly vaporize but will dramatically reduce temperatures. This of course is not the best way to cool down an engine, but it works.

[AZCoyote]

Give me Plasma Arc plugs then we can talk...

[esqu1re]

Originally Posted by TotalPower

2. What happens if the optics get covered in soot, are moved due to the energy of combustion, or fall out of alignment (lose their concentration of energy)?

+1