Experimental Study of Nanometric Organic Carbon and Soot in a Methane Coflow Laminar Diffusion Flame (Contributo in atti di convegno)

Type
Label
  • Experimental Study of Nanometric Organic Carbon and Soot in a Methane Coflow Laminar Diffusion Flame (Contributo in atti di convegno) (literal)
Anno
  • 2006-01-01T00:00:00+01:00 (literal)
Alternative label
  • M. Commodo, S. Violi, A. D’Anna, C. Allouis, P. Minutolo (2006)
    Experimental Study of Nanometric Organic Carbon and Soot in a Methane Coflow Laminar Diffusion Flame
    in 29th Combustion Meeting, Pisa June 2006, Pisa
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • M. Commodo, S. Violi, A. D’Anna, C. Allouis, P. Minutolo (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • Dipartimento di Ingegneria Chimica - Università Federico II Napoli IRC-CNR (literal)
Titolo
  • Experimental Study of Nanometric Organic Carbon and Soot in a Methane Coflow Laminar Diffusion Flame (literal)
Abstract
  • Combustion-generated particles have gained significant interest because of their direct health and environmental effects [1]. In recent years, researchers have focused their attention on fine and ultrafine particles with sizes down to few nanometers, the most likely to cause the observed effects [2]. Broadly speaking, fine and ultrafine particles comprise two main classes of compounds: Nanoparticles of Organic Carbon (NOC) characterized by a size range of 1 - 10 nm and soot particles with sizes in the range 10 - 100 nm. NOC usually precedes and accompanies soot formation but it has also been found in flames operated in rich conditions well below the soot limit [3,4]. Most of the experimental studies on NOC and soot formation have been performed in laboratory laminar flames, which allows the formation and oxidation processes to be followed in detail [4-6]. Modelling of NOC evolution has also been carried out in a laminar non-premixed flame using a detailed chemical kinetic scheme [7]. In-situ laser light scattering and spectral absorption measurements are the optical techniques widely used for the experimental studies. Spectral absorption in particular allows the two broad classes of particles to be distinguished [8,5]. In recent years other techniques such as Differential Mobility Analysis (DMA) [8-11] and Atomic Force Microscopy (AFM) [9,12] have also become standard tools for the determination of size distributions of particulates formed in combustion systems. Light absorption, requiring a line-of-sight measurement, suffers from limited space resolution; the inversion procedure to obtain the local extinction coefficient in a non-uniform field for particle volume fraction has limited accuracy near the flame centreline. Point measurements are therefore more useful in axisymmetric, non-premixed systems. Laser Induced Incandescence (LII) is an answer [13,14] although it works only for soot particles; indeed, it fails to detect NOC which is much smaller and has a molecular character. Laser Induced Fluorescence (LIF) can provide relative concentration measurements of highly absorbing chromophoric groups within flames [15,16]. In the present work we explore the possibility of detecting combustion-formed NOC and soot simultaneously with a single-shot, point measurement. Laser induced emission (LIE) is measured by interaction of a pulsed Nd-YAG laser at 213 nm with the particles. The selected high energy enhances fluorescence from aromatic chromophoric groups within the flame and also allows soot particles to heat up and emit incandescent radiation. Coupled scattering measurements allow the evaluation of the mean size of the particles. This technique is used to examine the formation and growth of aromatic compounds and soot in coflow non-premixed methane and ethylene flames at atmospheric pressure. (literal)
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