PowerPoint Presentation

A SEMINAR ON :A comparative study of laser ignition and spark ignition with gasolineair mixtures. Presented By :Amiya Kumar SahooReg. no. : 11012227648Group : 7ME-1A

1

INTRODUCTIONAn ignition system is a system for igniting a fuel-air mixtureThe process of combustion of fuel is initiated by the ignition systemIn IC engines there are 2 types of ignition based on the fuelSpark Ignition (petrol engine)Compression Ignition (diesel engine)2

2

DRAWBACKS OF CONVENTIONAL SPARK IGNITION Location of spark plug is not flexible as it require shielding of plug from immense heat and fuel spray. It requires frequent maintenance to remove carbon deposits.Leaner air-fuel mixtures cannot be ignited.Degradation of electrodes at high pressure and temp.Multi point fuel ignition is not feasible.Flame propagation is slow.Higher turbulence levels are required.

3

ADVANCE IGNITION METHODSSome of the Advance ignition methods are :Ion sensing ignitionPlasma jet ignitionRail-plugs ignitionLaser induced spark ignition First demonstrated by J. D. Dale in 1978.Laser Ignition is the process of starting combustion by the stimulus of a laser source.

4

LASERThe acronym LASER stands for Light Amplification by Stimulated Emission of Radiations.

It is Intense & Unidirectional beam of light.

It is Monochromatic & Coherent.

A Q-switched Nd:YAG laser of 532 or 1064nm wavelength and with 6.6 or 7.9ns pulse width is used for laser ignition.5

LASER GENERATION6

WORKING OF Nd:YAG LASER7

PRINCIPLE OF LASER IGNITION8Laser ignition begins with the initial seed electrons produced from impurities in the gas mixture by focused laser beam.

Initial electrons readily absorb more photons and increase their kinetic energy.

When the electrons gain sufficient energy ,they collide with other molecules and ionize them, leading to an electron avalanche, And optical breakdown the gas occurs .

This results in a well localized plasma with temperatures in the order of 106K and pressures in the order of 102 Mpa is formed.

This extreme condition leads to the development of a rapidly expanding shock wave that is of sufficient strength to ignite flammable mixtures

ADVANTAGES OF LASER IGNITION

Leaner mixtures can be ignited inside combustion chamber. Lower combustion temperatures & less NOx emissions.High pressure and temperature does not affect the performance allowing the use of high compression ratios.

9

ADVANTAGES OF LASER IGNITION

Lifetime is high.Precise ignition timing possible. It does not require maintenance to remove carbon deposits because of its Self cleaning property.

(1) (2)1. After 20 h operation with spark plug ignition, heavily polluted 2. Immediately after 100 laser pulses. Beam area is cleaned by the laser beam.

10

ADVANTAGES OF LASERIGNITION

Shorter ignition delay time and shorter combustion time.Flame propagation is fast as multi-point fuel ignition is also possible.

11

Fig. Multi-point Ignition

12ParametersLaser IgnitionSpark IgnitionIgnition LocationFlexibleFixedMulti-Point IgnitionPossibleNot feasibleIgnition of lean Mix.Can be ignitedCannot be ignitedEmission of NOxVery lessMoreIgnition TimingPrecise(No misfire)Not PreciseMaintenanceLow(Self-cleaning)HghLifetimeHighLow

COMPARISON BETWEEN LASER & SPARK IGNITION

COMBUSTION CHAMBER EXPERIMENT

13Fig. Experimental SetupComponents :1.Nd:YAG Laser 5.Convex lens 9.Laser Energy Sensor2.Beam attenuator 6.Mirror 10.Laser Energy Sensor3.Beam Splitter 7.Convex lens( Focusing Lens) 11.Laser Energy Power 4.Concave lens 8.CVCC Meter

IGNTION PROBABILITY OF LASER IGNITION

14

The probability of ignition is defined as the ratio of effective trails and number of shots.The absorbed energy is exactly the energy necessary to yield ignition inside the combustion chamber.

IGNTION PROBABILITY OF LASER AND SPARK IGNITION15

Spark ignition failed to ignite mixture of equivalence ratio 0.6 regardless of ignition energyIn laser ignition maximum probability of ignition of equivalence ratio 0.6 was 65% for 532nm and 70% for 1064nm

MINIMUM ENERGY REQUIRED FOR IGNITION The minimum ignition energy required for laser ignition is more than that for electric spark ignition because of following reasons:

The efficiency of energy transfer to near-threshold laser sparks is substantially lower than to electrical sparks, so more power is required to heat laser sparks.Energy in the form of photons is wasted before the beam reach the focal point.16

NOx EMISSION POTENTIALS 17NOx in [mg/m]

Direct Pre ChamberSpark IgnitionLaser Ignition Direct Pre ChamberDiesel Pilot Ignition

RESULT COMPARISON18

CONCLUSION

The applicability of a laser-induced ignition system on engine has been proven.Main advantages are the free choice of the ignition location within the combustion chamber, even leaner mixtures can be burned and Significant reductions in fuel consumption & exhaust gases.At present, a laser ignition plug is very expensive as compared to spark plugs.But potential advantages will surely bring it in to market for many practical applications.

19

THANK YOU

20

ANY QUERY

21