Laser Ignition in Internal Combustion Engines By Jignesh Parmar

WHAT IS A LASER ?•A laser is a device that emits electromagnetic radiation through a process of optical amplification based on the stimulated emission of photons.

•The term ‘laser’ is an acronym for Light Amplification by Stimulated Emission of Radiation

STANDARD SPARK PLUG IGNITION IN AN INTERNAL COMBUSTION ENGINE

•Current internal combustion gasoline engines use spark plugs to ignite the air/fuel mixture in each cylinder (located at the top of the combustion chamber).

LASER IGNITION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE

•Laser ignition will replace the spark plug seen in current gasoline engines

•The laser ignition system has a laser transmitter with a fiber-optic cable powered by the car’s battery. • It shoots the laser beam to a focusing lens that would consume a much smaller space than current spark plugs. •The lenses focus the beams into an intense pinpoint of light, and when the fuel is injected into the engine, the laser is fired and produces enough energy (heat) to ignite the fuel. •Below is a diagram of the laser arrangement:

HOW LASER IGNITION WORKS

WHY LASER IGNITION?

1. Regulations on NOx emissions are pushing us toward leaner air/fuel ratios (higher ratio of air to fuel).

•These leaner air/fuel ratios are harder to ignite and require higher ignition energies.

• Spark plugs can ignite leaner fuel mixtures, but only by increasing spark energy.

•Unfortunately, these high voltages erode spark plug electrodes so fast, the solution is not economical. By contrast, lasers, which ignite the air-fuel mixture with concentrated optical energy, have no electrodes and are not affected.

2. Natural gas is more difficult to ignite than gasoline due to the strong carbon to hydrogen bond energy.

• Because of the requirement for an increase in ignition energy, spark plug life will decrease for natural gas engines.

• Lasers are monochromatic, so it will be much easier to ignite natural gases and direct the laser beam to an optimal ignition location.

3. Ignition sites for spark plugs are at a fixed location at the top of the 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 far better chance of ignition.

WHY LASER IGNITION?

4. The laser also produces more stable combustion so you need to put less fuel into the cylinder, therefore increasing efficiency.

5. Optical wire and laser setup is much smaller than the current sparkplug model, allowing for different design opportunities.6. Lasers can reflect back from inside the cylinders relaying information such as fuel type and level of ignition creating optimum performance.

WHY LASER IGNITION?

Future Research Needs1. Cost2. Concept proven, but no commercial

system yet available.3. Stability of optical window4. Beam Delivery/Laser induced optical

damage5. Particle Deposits6. Intelligent control7. Laser Distribution8. Multiple pulse ignition9. Multiple point ignition

1. Single Point Ignition:• Timing optimization (phasing) vs Thermal Efficiency• NOx tradeoffs• Knock margin

2. Multipoint Ignition:• Higher flame speed may provide additional knock

margin as well as a higher burn rate.

3. Multipulse Ignition:• May provide improved ignition, leaner combustion, and

lower emissions.

SHORTCOMINGS

Thank you