Similar articles

Abstract: laser-induced incandescence (LII) has received increasing attention as a potentially powerful technique for in-situ measuring of the volume fraction and primary size of soot particles in combustion systems. In this study, a 3D Monte Carlo simulation combined with a Mie equation was developed to analyze the influence of spectral absorption and scattering on the measured LII flux emitted by soot particles. This paper represents a first attempt to analyze soot measurement using the LII technique in coal combustion products. The combustion products of gases (CO₂, N₂), soot, and fly-ash particles, present between the location of laser-excited soot and the LII flux receiver. The simulation results indicated that an almost Beer-Lambert exponential decrease in LII flux occurred with an increase in the volume fraction of soot particles, while a nearly linear decrease occurred with an increase in the volume fraction of fly-ash particles. The results also showed that scattering effects of both soot and fly-ash particles on the LII flux could be neglected. Compared with the absorption of gases, a decrease of 20% of LII flux was observed with soot particles, and a decrease of 10% with fly-ash particles.

[1] Axelsson, B., Collin, R., Bengtsson, P.E., 2001. Laser-induced incandescence for soot particle size and volume fraction measurements using on-line extinction calibration. Applied Physics B: Lasers and Optics, 72(3):367-372.

[2] Charalampopoulous, T.T., Chang, H., 1988. In situ optical properties of soot particles in wavelength range from 340 nm to 600 nm. Combustion Science and Technology, 59:401-421.

[3] Chen, L.H., 2005. Study by Numerical Simulation of Impact of Multiple Scattering on Participating Media. PhD Thesis, Rouen University, France.

[4] Chen, L.H., Garo, A., Cen, K.F., Grehan, G., 2007. Numerical simulation of soot optical diagnostics in non-optically thin media. Applied Physics B: Lasers and Optics, 87(4):739-747.

[5] Dalzell, W.H., Sarofim, A.F., 1969. Optical constants of soot and their application to heat flux calculations. Journal of Heat Transfer, 91:100-104.

[6] Dasch, C.J., 1984. New Soot Diagnostics if Flames Based on Laser Vaporization of Soot. 20th Symposium (International) on Combustion, p.1231-1237.

[7] Dauen, K.J., Thomson, K.A., Liu, F., 2008. Simulation of laser-induced incandescence measurements in an anisotropically scattering aerosol through backward Monte Carlo. Journal of Heat Transfer, 130:112701.1-12701.10.

[8] Howell, J.R., 1998. The Monte Carlo method in radiative heat transfer. Journal of Heat Transfer, 120(3):547-560.

[9] Knutson, E.O., Whitby, K.T., 1975. Aerosol classification by electric mobility: Apparatus, theory, and application. Journal of Aerosol Science, 6(6):443-451.

[10] Krishnan, S.S., Lin, K.C., Faeth, G.M., 2001. Extinction and scattering properties of soot emitted from turbulent diffusion flames. Journal of Heat Transfer, 123:331-339.

[11] Lee, S.C., Tien, C.L., 1980. Optical Constants of Soot in Hydrocarbon Flames. Proceeding of the 18th Symposium (International) on Combustion, the Combustion Institute, Pittsburg, USA, p.1159-1166.

[12] Li, N., Sioutas, C., Froines, J.R., Cho, A., Misra, C., Nel, A., 2003. Ultrafine particulate pollutants induce oxidative stress and mitochondrial damage. Environmental Health Perspectives, 111(4):455-460.

[13] Modest, M.F., 1992. The Monte Carlo method applied to gases with spectral line structure developments in radiative heat transfer. American Society of Mechanical Engineers, HTD 203:79-84.

[14] Murphy, J.J., Shaddix, C.R., 2005. Influence of scattering and probe-volume heterogeneity on soot measurements using optical pyrometry. Pyrolysis and Flame, 143:1-10.

[15] Roth, P., Filippov, A.V., 1996. In situ ultrafine particle sizing by a combination of pulsed laser heat up and particle thermal emission. Journal of Aerosol Science, 27(1):95-104.

[16] Schulz, C., Kock, B.F., Hofmann, M., Michelsen, H.A., Will, S., Bougie, B., Suntz, R., Smallwood, G., 2006. Laser-induced incandescence: recent trends and current questions. Applied Physics B: Lasers and Optics, 83(3):333-354.

[17] Siegel, R., Howell, J.R., 1981. Thermal Radiative Heat Transfer. Hemisphere Publishing Corporation, McGraw-Hill.

[18] Snelling, D.R., Smallwood, G.J., Campbell, I.G., Medlock, J.E., Gülder, Ö.L., 1997. Development and Application of Laser-induced Incandescence (LII) as a Diagnostic for Soot Particulate Measurements. AGARD Conference Proceedings 598, Advanced Non-intrusive Instrumentation for Propulsion Engines, Brussels, Belgium, 23:1-9.

[19] Snelling, D.R., Smallwood, G.J., Sawchuck, R.A., Neill Gareau, S.W., Chippior, W.L., Liu, F., Gülder, Ö.L., Bachalo, W.D., 2000. In-situ Real-time Characterization of Particulate Emissions from a Diesel Engine Exhaust by Laser-induced Incandescence. SAE Paper No. 2000-01-1994.

[20] Stanmore, B.R., Brilhac, J.F., Gilot, P., 2001. The oxidation of soot: review of experiments, mechanisms and models. Carbon, 39(15):2247-2268.

[21] Veranth, J.M., Fletcher, T.H., Pershing, D.W., Sarofim, A.F., 2000. Measurement of soot and char in pulverized coal fly-ash. Fuel, 79(9):1067-1075.

[22] Zheng, C.G., Yan, R., Zhou, Y.B., Ma, Y.Y., 1993. The radiative properties of suspended particles during pulverized-coal combustion. Journal of Engineering Thermophysics, 14(3):317-321.