Market demands for lower fueling costs and higher specific powers in stationary natural gas engines have engine designs trending toward higher in-cylinder pressures and leaner combustion operation. However, ignition remains as the main limiting factor in achieving further performance improvements in these engines. Addressing this concern, while incorporating various recent advances in optics and laser technologies, laser igniters were designed and developed through numerous iterations. Final designs incorporated water-cooled, passively Q-switched, Nd:YAG microlasers that were optimized for stable operation under harsh engine conditions. Subsequently, the microlasers were installed in the individual cylinders of a lean-burn, 350 kW, inline six-cylinder, open-chamber, spark ignited engine, and tests were conducted. The engine was operated at high-load (298 kW) and rated speed (1800 rpm) conditions. Ignition timing (IT) sweeps and excess-air ratio (λ) sweeps were performed while keeping the NOx emissions below the United States Environmental Protection Agency (USEPA) regulated value (brake-specific NOx (BSNOx) < 1.34 g/kW h), and while maintaining ignition stability at industry acceptable values (coefficient of variation of integrated mean effective pressure (COV_IMEP) < 5%). Through such engine tests, the relative merits of (i) standard electrical ignition system and (ii) laser ignition system were determined. A rigorous combustion data analysis was performed and the main reasons leading to improved performance in the case of laser ignition were identified.
Performance of a Laser Ignited Multicylinder Lean Burn Natural Gas Engine
Contributed by the Combustion and Fuels Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received October 3, 2016; final manuscript received April 19, 2017; published online June 6, 2017. Assoc. Editor: Eric Petersen.The United States Government retains, and by accepting the article for publication, the publisher acknowledges that the United States Government retains, a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for United States government purposes.
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Almansour, B., Vasu, S., Gupta, S. B., Wang, Q., Van Leeuwen, R., and Ghosh, C. (June 6, 2017). "Performance of a Laser Ignited Multicylinder Lean Burn Natural Gas Engine." ASME. J. Eng. Gas Turbines Power. November 2017; 139(11): 111501. https://doi.org/10.1115/1.4036621
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