Laser-induced spark ignition of CH4/air mixtures

Phuoc, Tran X.; White, Fredrick P.

doi:10.1016/s0010-2180(99)00051-6

Cited by 215 publications

(99 citation statements)

References 29 publications

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“…A large amount of work has been undertaken on the laser ignition of gas phase fuel-air premixtures for a variety of fuels that include hydrogen and methane (Spiglanin, 1995;Phuoc and White, 1999). Laser intensities of the order of 200 GW/cm 2 for air at 100 kPa and 300 K are required to generate a plasma in a gas (Bradley et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Laser Ignition of Iso-Octane Air Aerosols

Lawes

Lee

Mokhtar

et al. 2007

Combustion Science and Technology

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Iso-octane aerosols in air have been ignited with a focused Nd:YAG laser at pressures and temperatures of 100 kPa and 270 K and imaged using schlieren photography. The aerosol was generated using the Wilson cloud chamber technique. The droplet diameter, gas phase equivalence ratio and droplet number density were determined. The input laser energy and overall equivalence ratio were varied. For 270 mJ pulse energies initial breakdown occurred at a number of sites along the laser beam axis. From measurements of the shock wave velocity it was found that energy was not deposited into the sites evenly. At pulse energies of 32 mJ a single ignition site was observed. Overall fuel lean flames were observed to locally extinguish, however both stoichiometric and fuel rich flames were ignited. The minimum ignition energy was found to depend on the likelihood of a droplet existing at the focus of the laser beam.3

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Section: Introductionmentioning

confidence: 99%

Laser Ignition of Iso-Octane Air Aerosols

Lawes

Lee

Mokhtar

et al. 2007

Combustion Science and Technology

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“…In the beginning, experiments were performed with sized and robust, commercial available lasers that delivered pulses with energy in the range of tens to a few hundreds of mJ and several ns pulse duration (Ma et al, 1998;Phuoc & White, 1999;Weinrotter et al 2005a;Weinrotter at al. 2005b).…”

Section: Introductionmentioning

confidence: 99%

All-Poly-Crystalline Ceramics Nd:YAG/Cr4+:YAG Monolithic Micro-Lasers with Multiple-Beam Output

Pavel¹,

Tsunekane²,

Taira³

2011

Laser Systems for Applications

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“…By tightly focusing the beam from a high-power pulsed laser in a flammable mixture, a combustion-initiating spark can be created. While several modes of ignition are possible, the most widely used process for laser ignition has been nonresonant breakdown [2,[5][6][7]. For commonly used nanosecond pulsed lasers (pulse duration ~5-10 ns), the non-resonant breakdown sequence is initiated by initial seed electrons, which are accelerated by the electric field and create new electrons in collisions.…”

Section: Introductionmentioning

confidence: 99%

Fundamental Studies of Ignition Process in Large Natural Gas Engines Using Laser Spark Ignition

Yalin¹,

Willson²

2008

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Past research has shown that laser ignition provides a potential means to reduce emissions and improve engine efficiency of gas-fired engines to meet longer-term DOE ARES (Advanced Reciprocating Engine Systems) targets. Despite the potential advantages of laser ignition, the technology is not seeing practical or commercial use. A major impediment in this regard has been the "open-path" beam delivery used in much of the past research. This mode of delivery is not considered industrially practical owing to safety factors, as well as susceptibility to vibrations, thermal effects etc. The overall goal of our project has been to develop technologies and approaches for practical laser ignition systems. To this end, we are pursuing fiber optically coupled laser ignition system and multiplexing methods for multiple cylinder engine operation. This report summarizes our progress in this regard. A partial summary of our progress includes: development of a figure of merit to guide fiber selection, identification of hollow-core fibers as a potential means of fiber delivery, demonstration of bench-top sparking through hollow-core fibers, single-cylinder engine operation with fiber delivered laser ignition, demonstration of bench-top multiplexing, dual-cylinder engine operation via multiplexed fiber delivered laser ignition, and sparking with fiber lasers. To the best of our knowledge, each of these accomplishments was a first. 3 List of Tables Executive SummaryPast research has shown that laser ignition is a potential means to reduce emissions and improve engine efficiency of gas-fired engines to meet longer-term DOE ARES (Advanced Reciprocating Engine Systems) targets. From a fundamental point of view, the benefits of laser ignition (over conventional ignition) are due to: 1) the freedom to locate the laser spark in the middle of the combustion volume away from electrodes and walls which act as heat sinks; and 2) the higher power density of laser sparks, which lead to faster early flame growth and more robust early flame kernels. Additionally, laser ignition avoids limitations of conventional spark including erosion and dielectric breakdown, both of which become increasingly problematic as engine motored pressures increase. Past laser ignition efforts have generally employed "open-path" beam delivery, which is not considered industrially practical owing to safety factors, as well as susceptibility to vibrations, thermal effects etc. The overall goal of our project has been to develop technologies and approaches for practical laser ignition systems. (The project goal is inconsistent with the title of the project; however, very early in the life of the project the goals and milestones were re-scoped by DOE and the research team.) To enable practical systems we have pursued fiber optically coupled laser ignition systems and multiplexing methods for multiplecylinder engine operation. The approaches are selected in order to be compact, rugged, reliable and with the potential for low-cost. For multi-cylinder operation w...

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Laser-induced spark ignition of CH4/air mixtures

Cited by 215 publications

References 29 publications

Laser Ignition of Iso-Octane Air Aerosols

Laser Ignition of Iso-Octane Air Aerosols

All-Poly-Crystalline Ceramics Nd:YAG/Cr4+:YAG Monolithic Micro-Lasers with Multiple-Beam Output

Fundamental Studies of Ignition Process in Large Natural Gas Engines Using Laser Spark Ignition

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