Laser Ignition of Methane-Air Mixtures at High Pressures and Diagnostics
Author:
Kopecek Herbert1, Charareh Soren1, Lackner Maximilian2, Forsich Christian2, Winter Franz2, Klausner Johann3, Herdin Gu¨nther3, Weinrotter Martin1, Wintner Ernst1
Affiliation:
1. Technische Universita¨t Wien, Institut fu¨r Photonik, Gusshausstrasse 27/387, A1040 Wien, Austria 2. Vienna University of Technology, Institute of Chemical Engineering, Getreidemarkt 9/166, A1060 Wien, Austria 3. GE Jenbacher, A6200 Jenbach, Austria
Abstract
Methane-air mixtures at high fill pressures up to 30 bar and high temperatures up to 200°C were ignited in a high-pressure chamber with automated fill control by a 5 ns pulsed Nd:YAG laser at 1064 nm wavelength. Both, the minimum input laser pulse energy for ignition and the transmitted fraction of energy through the generated plasma were measured as a function of the air/fuel-equivalence ratio (λ). The lean-side ignition limit of methane-air mixtures was found to be λ=2.2. However, only λ<2.1 seems to be practically usable. As a comparison, the limit for conventional spark plug ignition of commercial natural gas engines is λ=1.8. Only with excessive efforts λ=2.0 can be spark ignited. The transmitted pulse shape through the laser-generated plasma was determined temporally as well as its dependence on input laser energy and properties of the specific gases interacting. For a first demonstration of the practical applicability of laser ignition, one cylinder of a 1 MW natural gas engine was ignited by a similar 5 ns pulsed Nd:YAG laser at 1064 nm. The engine worked successfully at λ=1.8 for a first test period of 100 hr without any interruption due to window fouling and other disturbances. Lowest values for NOx emission were achieved at λ=2.05 NOx=0.22 g/KWh. Three parameters obtained from accompanying spectroscopic measurements, namely, water absorbance, flame emission, and the gas inhomogeneity index have proven to be powerful tools to judge laser-induced ignition of methane-air mixtures. The following effects were determined by the absorption spectroscopic technique: formation of water in the vicinity of the laser spark (semi-quantitative); characterization of ignition (ignition delay, incomplete ignition, failed ignition); homogeneity of the gas phase in the vicinity of the ignition; and the progress of combustion.
Publisher
ASME International
Subject
Mechanical Engineering,Energy Engineering and Power Technology,Aerospace Engineering,Fuel Technology,Nuclear Energy and Engineering
Reference15 articles.
1. Ronney, P. D.
, 1994, “Laser Versus Conventional Ignition of Flames,” Opt. Eng., 33(2), pp. 510–520. 2. Forch, B. E., and Miziolek, A. W., 1991, “Laser-Based Ignition of H2/O2 and D2/O2 Premixed Gases Through Resonant Multiphoton Excitation of H and D Atoms Near 243 nm,” Combust. Flame, 85, pp. 254–262. 3. Morsy, M. H., Ko, Y. S., and Chung, S. H., 1999, “Laser-Induced Ignition Using a Conical Cavity in CH4-Air Mixtures,” Combust. Flame, 119, pp. 473–482. 4. Heitzmann, T., and Wolfrum, J., 1995, “Experimental and Modeling Studies on the Ignition of CH3OH/O2-Mixtures With a CO2-Laser System,” Z. Phys. Chem. (Munich), 188, pp. 177–196. 5. Yablonovich, E.
, 1974, “Self Phase Modulation of Light in a Laser Breakdown Plasma,” Phys. Rev. Lett., 32, pp. 1101–1104.
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