Lasers set to zap engines into running more efficiently

new scientist ^ | 20 February 2015 | by Hal Hodson

[ckilmer]

PEW pew! For a week last November an internal combustion engine hummed away in a lab near Chicago. Why the excitement? This particular engine sets fire to fuel with lasers instead of spark plugs, burning fuel more efficiently than normal. Laser-fired engines could lead to cleaner, greener cars.

[ckilmer]

The new technology is desirable because you get more energy out of a given amount of fuel. It’s less clear that it is cleaner.
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The more complete the burn the smaller the pollution.

[Red Badger]

Rest In Peace, old friend, your work is finished.....

[tacticalogic]

And I've often wondered about injecting gasoline VAPOR into the combustion chamber instead of particulate (atomized) gasoline. Liquid gasoline doesn't burn; it only ignites at the liquid-gas boundary of the atomized droplets. Wouldn't a proper air/gas mixture of vapor be much more explosive and avoid the loss of energy required for the state change from liquid to gas?

Superchargers tend to do that.

[ckilmer]

I don’t know if this will work. But it looks promising for internal combustion engines.

[ckilmer]

I remember reading about this a few years ago.

If it ever happens, I wonder if you will be able to retrofit an existing engine?
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Hmmm if this has been around for a couple years—then there are likely some problems with the tech that they’re not talking about. One poster above mention carbon degredation over time

[Red Badger]

Rest In Peace, old friend, your work is finished.....

If you want ON or OFF the DIESEL ”KnOcK” LIST jut FReepmail me..... This is a fairly HIGH VOLUME ping list on some days.....

[thackney]

I think it might be solution looking for a non-existent problem.

[CopperTop]

"..his particular engine sets fire to fuel with lasers instead of spark plugs.."

Sounds like a nice way to make future "spark plugs" cost $100 each.
Geezes I'm cynical in my old age. d:^)

[lacrew]

I don’t know how they would get vapor into the cylinders. Seems like it would be compressible and hard to ‘pump’ into the fuel rail.

[Red Badger]

Just think, no more ignition coils, HV wires or burnt plugs. However the lasers can still go bad eventually...............

[ckilmer]

Power needs to be high enough to ignite fuel in ms and optics would malfunction with carbon buildup in cylinders.

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Another poster mentioned that he’d seen this a couple years ago. might be the carbon buildup that has prevented this tech from going to prime time.

[Arthur McGowan]

If you get more energy out of the fuel, then presumably you need to burn less fuel to drive a given distance. No?

[Freeport]

Doesn’t this simply change the proportion of different waste products?

Yes and no. If one can burn the fuel/air mixture at a lower temperature, but faster, less NO2 is formed, but you get an increase in overall thermal efficiency from the shorter burn time.

Even in current generation engines, the single point ignition at the to of a cylinder is the least efficient way to burn fuel.

For maximum efficiency, one wants to burn all the fuel at the same instant. This generates the greatest thermal efficiency.

A plug initiated burn takes quite a while, relative to the piston cycle time.

So initiating burning over a larger volume does two things:

1) Reduces the burn time to increase thermal efficiency

2) Burns more of the available fuel that would otherwise go out the tailpipe unburned.

So yes, I believe the fuel efficiency numbers. What I have an issue with is keeping the laser path free of post combustion products over the life of the engine. Gunk & carbon buildup will kill this system if they are not addressed.

[Lake Living]

From the article:

Back-up generators and ships’ engines could benefit too. “There is a lot of pressure on the shipping companies to reduce the pollution from their ships,” says Ghosh. “One shipping company we are talking to is interested in retrofitting their existing engines with laser ignition.”

[Red Badger]

Back during the 70’s, I remember some people were working on that idea by heating the gasoline in a sealed container to several hundred degrees and high pressure, and then spraying it into the cylinders. IIRC, it worked well but was too dangerous to actually use.............

[NorthMountain]

More miles per gallon == less gallons per mile == less emissions per mile.

[Arthur McGowan]

Maybe somebody could invent a device that would mix the gasoline with air before it reached the cylinder.

[reed13k]

I’m unsure what you mean by “a workable rotary engine”. My RX-7 in the 80’s had a working rotary engine that was very nice to me ;)

[Arthur McGowan]

How about using optical fiber, keeping the laser a safe distance from the cylinder?

[nascarnation]

Sounds challenging....