The ability to accurately measure solid particulate levels in various applications ranging from engines to laboratory flames has become very important in the past few decades. A new approach to measuring soot levels called laser-induced incandescence was investigated. An apparatus was designed and built in order to measure soot levels in an atmospheric laminar diffusion flame with the intent of conducting proof-of-concept measurements. The apparatus utilized highly focussed optics while collecting time-resolved data using fast PMTs which allowed measurement of both time and spatial domains. Although noise and other technical problems proved to be a concern, measurements with reasonable agreement with published results for temperature (2800 K) and the primary particle soot size (6.3 +/- 2.5 nm) were achieved within the flame. Noise issues with the apparatus prevented accurate soot volume fraction measurements from being obtained. Numerous suggestions have been made as to how to improve the experiment for future use, potentially in a high pressure environment.

Accurate determination of soot emissions from combustion is of interest in both fundamental research and industries that rely on combustion. Laser-induced incandescence of soot particles is a young technique that allows unobtrusive measurements of both soot volume fraction and particulate size. An apparatus utilizing this technique has been brought to function for both atmospheric and high pressure measurements. Proof of concept measurements of an atmospheric ethylene-air laminar diffusion flame at 35, 42, and 47 mm above the burner exit correlate well with literature findings. Profile trends of a methane-air diffusion flame at 10, 20, and 40 atm at 6 mm above the burner are similar to reports in literature and are compared to trends from spectral soot emission measurements. Particle size is found to be roughly proportional to pressure. Discussion on the errors of laser-induced incandescence as well as recommendations for improving the apparatus are herein.

The ability to accurately measure solid particulate levels in various applications ranging from engines to laboratory flames has become very important in the past few decades. A new approach to measuring soot levels called laser-induced incandescence was investigated. An apparatus was designed and built in order to measure soot levels in an atmospheric laminar diffusion flame with the intent of conducting proof-of-concept measurements. The apparatus utilized highly focussed optics while collecting time-resolved data using fast PMTs which allowed measurement of both time and spatial domains. Although noise and other technical problems proved to be a concern, measurements with reasonable agreement with published results for temperature (2800 K) and the primary particle soot size (6.3 +/- 2.5 nm) were achieved within the flame. Noise issues with the apparatus prevented accurate soot volume fraction measurements from being obtained. Numerous suggestions have been made as to how to improve the experiment for future use, potentially in a high pressure environment.

Accurate determination of soot emissions from combustion is of interest in both fundamental research and industries that rely on combustion. Laser-induced incandescence of soot particles is a young technique that allows unobtrusive measurements of both soot volume fraction and particulate size. An apparatus utilizing this technique has been brought to function for both atmospheric and high pressure measurements. Proof of concept measurements of an atmospheric ethylene-air laminar diffusion flame at 35, 42, and 47 mm above the burner exit correlate well with literature findings. Profile trends of a methane-air diffusion flame at 10, 20, and 40 atm at 6 mm above the burner are similar to reports in literature and are compared to trends from spectral soot emission measurements. Particle size is found to be roughly proportional to pressure. Discussion on the errors of laser-induced incandescence as well as recommendations for improving the apparatus are herein.

Ce travail contribue à la quasi-in-situ détection des nanoparticules par la technique d’incandescence induite par laser (LII) pendant le dépôt chimique en phase vapeur avec catalyseur flottant (FCCVD) de nanotubes de carbone. Premièrement, la microscopie électronique en transmission (MET) à haute résolution était utilisé pour caractériser la nature et la taille des nanoparticules. Le signal théorique de LII a été simulé en considérant la densité des nanoparticules, la capacité thermique et la distribution de taille, etc. La sensibilité et l’incertitude concrètes des paramètres clés sur la taille évaluée des particules pour ce modelé ont été estimées. Le modèle LII a été validé par la comparaison des résultats évalués avec ceux obtenus par la MET. Ensuite, la technique mature LII combinée avec MET a été appliquée pour étudier l’évolution des nanoparticules dans la phase gazeuse le long de l’axe du réacteur. L’influence de la température, de la concentration de ferrocène, de la source de carbone et de la proportion hydrogène sur la taille des nanoparticules a également été démontrée. Enfin, les rôles des nanoparticules dans la phase gazeuse au cours du processus de synthèse des NTC ont été discutés en corrélant les informations sur l’évolution axiale des nanoparticules et la morphologie des NTC synthétisés sur le substrat le long de l’axe du réacteur. Un modèle basé sur la thermodynamique de la nucléation des nanoparticules a été proposé pour décrire le processus de formation des nanoparticules au cours du processus DCVCF. Il est constaté que les nanoparticules asformé en phase gazeuse présentent des structures cœur-coquille avec un noyau de α-Fe et la coque de carbone. Ainsi, les nanoparticules de fer en phase gazeuse ne pourraient pas contribuer à la croissance de NTC sur le substrat à cause de l’encapsulation de carbone. En même temps, la taille des nanoparticules évaluée par LII est en bon accord avec celle-ci déterminée par MET. Cette étude, montrant les relations potentielles entre les nanoparticules flottantes et les NTCs sur le substrat, révèle une perspective importante de l’application de LII pour comprendre et améliorer le processus DCVCF. / This work contributes to the quasi-in-situdetection of nanoparticles by laser induced incandescence(LII) technique during the floating catalytic chemicalvapor deposition (FCCVD) synthesis of Carbonnanotubes.First, high resolution transmission electron microscopy(TEM) was used to characterize the nanoparticlenature and size. The theoretical LII signal was simulatedby considering the nanoparticle density, heatcapacity and size distribution, etc. A detailed sensitivityand uncertainty of the key parameters on the evaluatedparticle size for this model was estimated. TheLII model was validated by a comparison of the evaluatedresults with the ones obtained by TEM measurements.Then, the developed LII technique combinedwith TEM was applied to investigate the evolutionof nanoparticles in the gas phase along thereactor axis. The influence of the temperature, ferroceneconcentration, carbon source and hydrogen ratioon the nanoparticle size was also demonstrated. Finally,the roles of nanoparticles in the gas phase duringCNT synthesis process were discussed by correlatinginformation on the axial nanoparticle evolutionand the morphology of CNTs synthesized on thesubstrate along the reactor axis. And a model basedon the thermodynamics of the nanoparticle nucleationwas proposed to describe the nanoparticle formationprocess during the FCCVD process. It is found thatthe as-formed nanoparticles in the gas phase exhibitcore-shell structures with an α-Fe core and a carbonshell. Hence iron nanoparticles in the gas phasecould not contribute to the CNT growth on the substratebecause of the carbon encapsulation. Meanwhilethe evaluated size of nanoparticles by LII is ingood agreement with the TEM determined one. Thisstudy, showing potential relations between the floatingnanoparticles and the CNTs on the substrate, revealsthe important LII application prospect to understandand to improve the FCCVD process.

Combustion-generated carbon black nano particles, or soot, have both positive and negative effects depending on the application. From a positive point of view, it is used as a reinforcing agent in tires, black pigment in inks, and surface coatings. From a negative point of view, it affects performance and durability of many combustion systems, it is a major contributor of global warming, and it is linked to respiratory illness and cancer. Laser-Induced Incandescence (LII) was used in this study to measure soot volume fractions in four steady and twenty-eight pulsed ethylene diffusion flames burning at atmospheric pressure. A laminar coflow diffusion burner combined with a very-high-speed solenoid valve and control circuit provided unsteady flows by forcing the fuel flow with frequencies between 10 Hz and 200 Hz. Periodic flame oscillations were captured by two-dimensional phase-locked LII images and broadband luminosity images for eight phases (0°- 360°) covering each period. A comparison between the steady and pulsed flames and the effect of the pulsation frequency on soot volume fraction in the flame region and the post flame region are presented. The most significant effect of pulsing frequency was observed at 10 Hz. At this frequency, the flame with the lowest mean flow rate had 1.77 times enhancement in peak soot volume fraction and 1.2 times enhancement in total soot volume fraction; whereas the flame with the highest mean flow rate had no significant change in the peak soot volume fraction and 1.4 times reduction in the total soot volume fraction. A correlation (ƒv Reˉ1 = a+b· Str) for the total soot volume fraction in the flame region for the unsteady laminar ethylene flames was obtained for the pulsation frequency between 10 Hz and 200 Hz, and the Reynolds number between 37 and 55. The soot primary particle size in steady and unsteady flames was measured using the Time-Resolved Laser-Induced Incandescence (TIRE-LII) and the double-exponential fit method. At maximum frequency (200 Hz), the soot particles were smaller in size by 15% compared to the steady case in the flame with the highest mean flow rate.

Dans une thématique de sécurité incendie, la prédiction de la propagation d’une flamme le long d’une paroi verticale solide nécessite la quantification du rayonnement. L’objectif de la thèse est de quantifier et caractériser les suies d’une flamme de PMMA. La flamme stationnaire d’un brûleur gaz sera également étudiée. La méthode optique de LII, une fois calibrée (extinction), permet d’obtenir des champs 2D de la fraction volumique ainsi que le taux de combustion en fonction de la hauteur pour la flamme de PMMA. Ensuite, la morphologie des agrégats de suie est déterminée grâce à des clichés MET et des mesures de la distribution en taille. Les propriétés optiques sont obtenues avec des mesures in-situ et ex-situ (effet de la température) de l’extinction spectrale, couplées avec une mesure de la concentration massique pour remonter à la fonction d’indice. Cette base de données permettra la perspective de calculer le rayonnement des suies et de l’utiliser dans un modèle de propagation. / In the field of fire safety, the propagation prediction of a flame along a solid vertical wall requires radiation quantification. The thesis objective is to quantify and characterize the PMMA flame soot. Gaseous burner steady flame will also be studied. The LII optical method, after calibration (extinction), provides 2D volume fraction fields and the combustion rate in function of the height for the PMMA flame. Then, the soot aggregate morphology is determined by TEM images and size distribution measurements. The optical properties are obtained with in-situ and ex-situ measurements (temperature effect) of the spectral extinction, coupled with a mass concentration measurement to obtain the index function. This database will allow the prospect to calculate the soot radiation and to use it in a propagation model.

This study is dedicated to investigation of soot formed during combustion in diesel engine. Measurements were performed in a high speed direct injection optical diesel engine. Initially soot particle size, size distribution and soot volume fraction were investigated using time resolved laser induced incandescence (TR-LII) technique. For this study standard diesel fuel was used and measurements were performed for various injection timing and two different engine loads. Investigation showed that TR-LII is a powerful tool that can be used for characterization of in-cylinder soot in the engines. Subsequently TR-LII technique was developed to measure in-cylinder soot in two dimensional plane (planar laser induced incandescence PLII) and technique was combined with high speed imaging to investigate soot processes for ultra-low sulfur diesel (ULSD) and bio-fuel (RME). Two injection strategies of single and double injection were applied during these measurements. A high speed imaging technique was used to study the soot formation and oxidation during the combustion process within the cylinder and PLII was applied later in the stroke to study qualitatively the relative amount of un-oxidised soot that was left in the combustion chamber. In addition to PLII, TR-LII technique was used simultaneously to explore crank angle resolved variation of primary soot particle size and their size distribution during the expansion stroke. The same measurements were repeated for fuels with different composition investigating the relationship between the fuel properties and soot emission. Finally mathematical model for soot particle size and distribution width was modified by introducing assumption of multi-lognormal in-cylinder soot particle size distribution.

Measurements of soot emission properties are of interest in both fundamental research and combustion-based industries. Laser-induced incandescence of soot particles is a novel technique that allows unobtrusive measurements of both soot volume fraction and particulate size with significant advantages. An apparatus utilizing this technique has been customized and used to provide measurements of soot concentration and particle sizing of a laminar, diffusion methane/air flame at pressures of 10, 20 and 40 atm at 6~mm above the burner. Soot volume fraction measurements correlate well with literature findings at all pressures. Despite similar trends, particle size values are found to be consistently larger than values reported in literature. Discussion on the errors of laser-induced incandescence as well as recommendations for improving the apparatus and results are herein.

Measurements of soot emission properties are of interest in both fundamental research and combustion-based industries. Laser-induced incandescence of soot particles is a novel technique that allows unobtrusive measurements of both soot volume fraction and particulate size with significant advantages. An apparatus utilizing this technique has been customized and used to provide measurements of soot concentration and particle sizing of a laminar, diffusion methane/air flame at pressures of 10, 20 and 40 atm at 6~mm above the burner. Soot volume fraction measurements correlate well with literature findings at all pressures. Despite similar trends, particle size values are found to be consistently larger than values reported in literature. Discussion on the errors of laser-induced incandescence as well as recommendations for improving the apparatus and results are herein.