New Laser Ignition System

8/10/2019 New Laser Ignition System

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Presented By:

Manjunath Gowda.M

M.TECH in THERMAL POWERENGINEERING


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Historical background Basic definitionsWhy laser ignition? Principle of laser ignitionWorkingComparison between sparkplug and laser

ignitionAdvantagesDisadvantagesConclusions


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The use of laser ignition to improve gasengine performance was initiallydemonstrated by J. D. Dale in 1978 by CO2laser.

However, with very few exceptions, work inthis area has for the last 20 years beenlimited to laboratory experimentation.

Concerns about cost, safety,reliability have thus far kept

laser ignition out of the market.


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What is laser ignition system?

It is the process of starting combustion by the

stimulus of a laser light source.

Laser Spark Plug ignition Multipoint ignition


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These lasers operate in a pulse mode i.e. they switch ONand OFF very quickly.

The current record for the shortest laser pulse is just under

4 femtoseconds (1015), or 0.000000000000004 of a single

second.

lasma

Heating a gasmay ionize the molecules or atoms

thus turning it into a plasma.


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a visual process used to view the flow offluids of varying density. It is used to view thevarious stages of flame propagation afterlaser ignition as shown below:


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The laser beam generated will be divided twoor more beams by means of diffractiongrating. Each beam is directed by optic fiberand focused into their respective laser spark

plugs.


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Regulations on NOXemissions are pushing ustowards leaner air-fuel ratio.

The leaner air-fuel ratio are harder to ignite and require higher ignition energies.Sparkplugs can ignite leaner fuel mixtures but only by increasing the spark energy.

Unfortunately those high voltages erodes sparkplug electrodes so fast the solutionis not economical.

Natural gas is more difficult to ignite than gasoline

due to strong carbon to hydrogen to bond energy.

Lasers are monochromatic, so it will be much easier to ignite natural gas.


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Because of the requirement for increase in ignition energy, spark

plug life will decrease for natural gas engines.Laser sparkplug ignition system will require less power than traditional sparkplugs,

therefore outlasting spark plugs.

Ignition sites for spark plugs are at a fixed location at the top ofthe combustion chamber that only allows for ignition of the air-

fuel mixture closest to them.

Lasers can be focused and split into multiple beams to give multiple ignition

points, which means it can give a better chance of ignition.


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Laser light is tightly focused so that the intensity exceeds the

breakdown threshold of the gas.

Once breakdown is achieved, a plasma spark is formed which

absorbs the laser energy

Once breakdown has occurred and the laser pulse has

stopped inserting energy into the focal volume, the plasma

begins to decay.

The energy released in this decay is responsible for

developing the flame kernel, which ultimately leads to

combustion and the consumption of the fuel air mixture


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Nd:YAG(neodymium-doped yttriumaluminum garnet laser)


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The laser ignition system has a laser transmitter with a fiber

optic cable powered by a battery.

It shoots the laser beam to a focusing lens that would consume a

much smaller space than the current sparkplugs

The lenses focuses the beams into an intense pinpoint of light

When the fuel is injected into the engine, the laser is fired and

produces enough energy to ignite the fuel.


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Ignition reliability between spark ignition and laser spark ignition

ignition reliability of spark plug ignition

A/Frel( )

1,40 1,50 1,60 1,70 1,80 1,90 2,00 2,10 2,20 2,30

pinit

(bar)

10

15

20

25

30

35

40

0,000,250,500,751,00

ignition reliability of laser ignition

A/Frel( )

1,40 1,50 1,60 1,70 1,80 1,90 2,00 2,10 2,20 2,30

pinit

(bar)

10

1520

25

30

35

40

0,000,250,500,751,00

Comparison between sparkplug and

laser ignition


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Comparison of NOX emissions of different ignition


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graph of excess pressure vs. time taken for ignition at different air fuel ratio


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Possibility ofignition of very lean gas mixtures

The laser also produces more stable combustion

so you need to put less fuel into the cylinder,

therefore increasing efficiency.

Optical wire and laser setup is much smaller than

the current sparkplug model, allowing for different

design opportunities.

Lasers will reduce erosion.


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Easier possibility ofmultipoint ignition.

Shorter ignition delay time and shorter combustion

time.

Absence of quenching effectsby the spark plug

electrodes.

Lasers promise less pollution


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High system costs.

Concept proven, but no commercialsystem available yet.


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Japanese researchers working for Toyota have created a

prototype laser that brings laser ignition much closer to

reality. The laser is a small(9mm diameter, 11mmlength) high powered laser made out of ceramics that

produces bursts of pulses less than a nanosecond in

duration.


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At present, a laser ignition plug is very expensivecompared to a standard electrical spark plugignition system and it is nowhere near ready fordistribution.

But the potential and advantages certainly makethe laser ignition more attractive in many practical

applications.


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New Laser Ignition System