LASER IGNITION SYSTEM: LASER IGNITION SYSTEM PRESENTED BY NAVEEN K S CONTENTS: Historical background Basic definitions Why laser ignition? Principle of laser ignition Working Comparison between sparkplug and laser ignition Advantages Disadvantages Scope Conclusions CONTENTS Historical background: The use of laser ignition to improve gas engine performance was initially demonstrated by J. D. Dale in 1978. However, with very few exceptions, work in this area has for the last 20 years been limited to laboratory experimentation employing large, expensive and relatively complicated lasers and laser beam delivery systems. Historical background BASIC DEFINITIONS: What is laser ignition system? Pulsed laser beam Optical breakdown Plasma Schlieren photography Detonation Multipoint ignition BASIC DEFINITIONS Laser ignition or Laser induced ignition: It is the process of starting combustion by the stimulus of a laser light source. Laser ignition or Laser induced ignition Pulsed laser : These lasers operate in a pulse mode i.e. they switch ON and OFF very quickly. The current record for the shortest laser pulse is just under 4 femtoseconds, or 0.000000000000004 of a single second . Pulsed laser Optical breakdown: The phenomenon is observed when a material is subjected to very powerful laser pulses. Optical breakdown Plasma: Heating a gas may ionize the molecules or atoms thus turning it into a plasma . Plasma Schlieren photography : a visual process used to view the flow of fluids of varying density. It is used to view the various stages of flame propagation after laser ignition as shown below: Schlieren photography Detonation: It is a term describing supersonic combustion propagating through a medium resulting in a shock wave. Detonation Multipoint ignition : The laser beam generated will be divided two or more beams by means of diffraction grating. Each beam is directed by optic fiber and focused into their respective laser spark plugs. Multipoint ignition Why laser ignition?: Regulations on NO X emissions are pushing us towards 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 he spark energy. Unfortunately those high voltages erodes sparkplug electrodes so fast the solution is not economical . Why laser ignition? Cont……: 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 . 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 . Cont…… Cont………: 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 better chance of ignition . Cont……… Laser induced spark ignition theory: There are four methods in which laser light can interact with a combustible gaseous mixture for ignition they are:- Thermal initiation Resonant breakdown Non-resonant breakdown Photochemical ignition Laser induced spark ignition theory Thermal initiation: Ignition occurs without the generation of an electrical breakdown. a laser beam is used to raise the kinetic energy of target molecules. molecular bonds are broken and chemical reaction occurs leading to ignition . Long ignition delay times. Best suited for solid fuels. Thermal initiation Non-Resonant breakdown: 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. Energy is transferred to the combustion gases from the spark and starts the reaction Commonly used technique because of the freedom in selection of laser wavelength and implementation. Non-Resonant breakdown Resonant breakdown: Similar to non-resonant breakdown in that the end result is a plasma spark. The wavelength of the laser must be tuned to the particular resonance. This lowers the number of photons required for photo ionization, and hence the amount of energy required to cause breakdown. Resonant breakdown Photochemical ignition: This method starts ignition by creating radicals, and in general does not heat the gas as do the previous three methods. If the production rate of the radicals is higher than the neutralizing radicals then the highly active species will reach a threshold value, leading to an ignition event Photochemical ignition PowerPoint Presentation: PRINCIPLE OF LASER IGNITION PowerPoint Presentation: 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 Working : Working PowerPoint Presentation: 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. Comparison between sparkplug and laser ignition : Comparison between sparkplug and laser ignition PowerPoint Presentation: Ignition reliability between spark ignition and laser spark ignition PowerPoint Presentation: Ignition delay and burning behavior – laser ignition and spark ignition PowerPoint Presentation: Comparison of NOX emissions of different ignition PowerPoint Presentation: graph of excess pressure vs. time taken for ignition at different air fuel ratio Advantages: Lasers promise less pollution 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 . Advantages Cont…….: easier possibility of multipoint ignition . shorter ignition delay time and shorter combustion time. absence of quenching effects by the spark plug electrodes. Lasers can reflect back from inside the cylinders relaying information such as fuel type and level of ignition creating optimum performance . Cont……. Disadvantages: high system costs concept proven, but no commercial system available yet . Disadvantages Recent developments………: 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, 11mm length) high powered laser made out of ceramics that produces bursts of pulses less than a nanosecond in duration . Recent developments……… Cont……………: Ford Motor Co. and researchers at the University of Liverpool are developing a car ignition system that swaps spark plugs for a laser beam to start vehicles while generating fewer greenhouse gas emissions. The team has just received nearly £200,000 (US$320,000) in grants to test the technology from the Carbon Trust , a government funded entity charged with helping businesses in the transition to a low carbon economy. The award is part of the Carbon Trust’s Applied Research grant that supports the development of low carbon technologies. Cont…………… Scope: From the perspective of dwindling oil resources laser ignition system is good as it reduces the fuel consumption. From the environmental point of view it is very significant since it considerably reduces the emission. Seen as the current best alternative to conventional sparkplug ignition system. Scope CONCLUSION: At present, a laser ignition plug is very expensive compared to a standard electrical spark plug ignition system and it is nowhere near ready for deployment. But the potential and advantages certainly make the laser ignition more attractive in many practical applications . CONCLUSION THE END……………..: THE END……………..