Laser Ignition of Methane-Air Mixtures at High Pressures and Diagnostics

Journal of Engineering for Gas Turbines and Power - Tập 127 Số 1 - Trang 213-219 - 2005
Herbert Kopecek1, Soren Charareh1, Maximilian Lackner2, Christian Forsich2, Franz Winter2, Johann Klausner3, Gu ̈nther Herdin3, Martin Weinrotter1, E. Wintner1
1Technische Universita¨t Wien, Institut fu¨r Photonik, Gusshausstrasse 27/387, A1040 Wien, Austria
2Vienna University of Technology, Institute of Chemical Engineering, Getreidemarkt 9/166, A1060 Wien, Austria
3GE Jenbacher, A6200 Jenbach, Austria

Tóm tắt

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.

Từ khóa


Tài liệu tham khảo

Ronney, P. D. , 1994, “Laser Versus Conventional Ignition of Flames,” Opt. Eng., 33(2), pp. 510–520.

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.

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.

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.

Yablonovich, E. , 1974, “Self Phase Modulation of Light in a Laser Breakdown Plasma,” Phys. Rev. Lett., 32, pp. 1101–1104.

Yablonovich, E. , 1975, “Self Phase Modulation and Short Pulse Generation From Laser Breakdown Plasmas,” Phys. Rev. A, 10, pp. 1888–1895.

Ru¨disser, D., 2002, “Raum- und zeitaufgelo¨ste optische Diagnostik Laser-gezu¨ndeter Gasgemische mit planarer Laser-induzierter Fluoreszenz,” diploma thesis, Graz University of Technology, Graz.

Spiglanin, T. A., Mcilroy, A., Fournier, E. W., Cohen, R. B., and Syage, J. A., 1995, “Time-Resolved Imaging of Flame Kernels: Laser Spark Ignition of H2/O2/Ar Mixtures,” Combust. Flame, 102, pp. 310–328.

Chen, Y. L., and Lewis, J. W. L., 2001, “Visualization of Laser-Induced Breakdown and Ignition,” Opt. Express,9, pp. 360–372.

Weinberg, F. J., and Wilson, J. R., 1971, “A Preliminary Investigation of the use of Focused Beams for Minimum Ignition Energy Studies,” Proc. R. Soc. London, Ser. A, 321, pp. 41–52.

Ma, J. X., Ryan, T. W., and Buckingham, J. P., 1998, “Nd:YAG Laser Ignition of Natural Gas,” ASME, ICE 30-3, Paper No. 98-ICE–114.

Raffel, B., and Wolfrum, J., 1986, “Infrared Laser Induced Ignition of Gas Mixtures,” Ber. Bunsenges. Phys. Chem., 90, pp. 997–1001.

Lackner, M., Forsich, Ch., Winter, F., Kopecek, H., and Wintner, E., 2003, “In Situ Investigation of Laser-Induced Ignition and the Early Stages of Methane-Air Combustion at High Pressures Using a Rapidly Tuned Diode Laser at 2.55 μm,” Spectrochim. Acta, 59(13), pp. 2997–3018.

Kopecek, H., Wintner, E., Pischinger, H., Herdin, G., Klausner, J., and Jenbacher A. G., 2000, “Basics for a Future Laser Ignition System for Gas Engines,” Fall Technical Conference ASME, Preoria, US, ICE-35-2, Paper No. 2000-ICE-316.

Kopecek, H., Maier, H., Reider, G., Winter, F., and Wintner, E., 2003, “Laser Ignition of Methane-Air Mixtures at High Pressures,” Exp. Therm. Fluid Sci., 27, pp. 499–503.

Thông tin
Thông tin xuất bản

Journal of Engineering for Gas Turbines and Power

Tập 127 Số 1

213-219

Thông tin tác giả