Laser Ignition System

Submitted By:-

Himanshu Rajput6th Semester

Mechanical Engineering DepartmentNIT Hamirpur

Contents• INTRODUCTION• WHAT IS LASER?• TYPE OF LASERS• BATTERY IGNITION SYSTEM• LASER IGNITION SYSTEM• ADVANTAGES OF LASER IGNITION SYSTEM• DISADVANTAGES OF LASER IGNITION SYSTEM• CONCLUSION• REFERENCES

INTRODUCTION• It's widely accepted that the internal combustion engines will continue to power our

vehicles.• Hence, as the global mobilisation of people and goods increases, advances in

combustion and after-treatment are needed to reduce the environmental impact of the continued use of IC engine vehicles.

• Two critical aspects of engine performance are fuel economy and exhaust gas emissions.

• New engines are becoming increasingly complex, with advanced combustion mechanisms that burn an increasing variety of fuels to meet future goals on performance, fuel economy and emissions.

• The spark plug has remained largely unchanged since its invention, yet its poor ability to ignite highly dilute air-fuel mixtures limits the potential for improving combustion efficiency.

Continued….

• Spark ignition (SI) also restricts engine design, particularly in new engines, since the spark position is fixed by the cylinder head location of the plug, and the protruding electrode disturbs the cylinder geometry and may quench the combustion flame kernel.

• So, to counter these limitations an alternative is required one of the alternative is the laser ignition system (LIS).

• Compared to Spark ignition a LIS could prove to be better and help us increase engine efficiency.

WHAT IS LASER?• The term ‘laser’ is an acronym for Light Amplification by Stimulated Emission of

Radiation.

• A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation.

• A laser is created when the electrons in atoms in special glasses, crystals, or gases absorb energy from an electrical current or another laser and become “excited.”

• The excited electrons move from a lower-energy orbit to a higher-energy orbit around the atom’s nucleus. When they return to their normal or “ground” state, the electrons emit photons (particles of light).

• These photons are all at the same wavelength and are “coherent,” meaning the crests and troughs of the light waves are all in lockstep. In contrast, ordinary visible light comprises multiple wavelengths and is not coherent.

Types of Lasers• Gas

• A Helium-Neon (HeNe) used mostly for holograms such as laser printing.

• Solid-state• Uses a gain medium that is a solid (rather than a liquid medium as in dye or gas

lasers). Used for weaponry

• Semiconductor• Also known as laser diodes, a semiconductor laser is one where the active medium is

a semiconductor similar to that found in a light-emitting diode. • Applications include telecommunication and medicine

Standard Spark Plug Ignition in an IC Engine• Current internal combustion gasoline engines use spark plugs to ignite the air/fuel

mixture in each cylinder of a SI engine(located at the top of the combustion chamber).

Battery Ignition System

Laser Ignition System for an IC Engine• By tightly focusing the beam from a high-power pulse laser to form a combustion-

initiating spark in flammable mixtures including those used in engines, we accomplish what is called laser ignition.

• Technology drivers include the need for increased efficiency and reduced pollutant emissions, which are trending advanced engines toward lean (reduced emissions) and high- pressure (increased efficiency) operation.

• The laser beam is passed through a convex lens, this convex lens diverge the beam and make it immensely strong and sufficient enough to start combustion at that point. Hence the fuel is ignited, at the focal point, with the mechanism shown above. The focal point is adjusted where the ignition is required to have.

• Laser ignition encompasses the nanosecond domain of the laser pulse itself to the duration of the entire combustion lasting several hundreds of milliseconds.

• The laser energy is deposited in a few nanoseconds which leads to a shock wave generation. In the first milliseconds an ignition delay can be observed which has a duration between 5 – 100 ms depending on the mixture.

• Combustion can last between 100 ms up to several seconds again depending on the gas mixture, initial pressure, pulse energy, plasma size, position of the plasma in the combustion bomb and initial temperature.

Advantages of Laser ignition system•  It does not require maintenance to remove carbon deposits because of its self-

cleansing property.• a choice of arbitrary positioning of the ignition plasma in the combustion

cylinder.• absence of quenching effects by the spark plug electrodes.• ignition of leaner mixtures than with the spark plug => lower combustion

temperatures => less NOx emissions.• high load/ignition pressures possible => increase in efficiency.• precise ignition timing possible.

• no erosion effects as in the case of the spark plugs => lifetime of a laser ignition system expected to be significantly longer than that of a spark plug.

• exact regulation of the ignition energy deposited in the ignition plasma.• easier possibility of multipoint ignition.• shorter ignition delay time and shorter combustion time.• fuel-lean ignition possible.

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Disadvantages of laser ignition

Despite the advantages of the system there are a couple of disadvantages of laser ignition:• high system costs• concept proven, but no commercial system available yet.

Conclusion• The applicability of a laser-induced ignition system on direct injected

gasoline engine has been proven by many experiments conducted around the world.

• Main advantages are the almost free choice of the ignition location within the combustion chamber, even inside the fuel spray.

• Significant reductions in fuel consumption as well as reductions of exhaust gases show the potential of the laser ignition process.

• At present, a laser ignition plug is very expensive compared to a standard electrical spark plug ignition system and it is no where near ready for deployment. But the potential and advantages certainly make the laser ignition more attractive in many practical applications.

THANK YOU