Measurement of Visible and Near-Infrared Optical Properties of Soot Produced from Laminar Flames PDF Download

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Languages : en
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Languages : en
Pages : 9

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Scattering to extinction cross section ratios, qse, were measured using the NIST Large Agglomerate Optics Facility for soot produced from ethene and acetylene laminar diffusion flames. Measurements were performed using light sources at 543.5 nm, 632.8 nm, and 856 nm. The average scattering to extinction cross section ratios for these wavelengths are equal to 0.245, 0.195, and 0.195 for ethene and 0.311, 0.228, and 0.237 for acetylene. The 856 nm measurements represent the longest wavelength for which accurate scattering measurements have been performed for soot. The size distribution and fractal properties of the two soots were determined to assess the effects of limited acceptance angle range, finite size of the sensor, and departure from cosine response on the uncertainty in the measurement of qse. The expanded relative uncertainty (95% confidence level) was found to be +/- 6% at the two visible wavelengths and +/- 8% at 856 nm. Both the magnitude and wavelength dependence of rho sub se for the present experiments are significantly different from those reported by Krishnan et al. for overfire soot produced using a turbulent flame. The results are compared with the predictions of fractal optics.

Author: Michael F. Modest
Publisher: Academic Press
ISBN: 032398407X
Category : Science
Languages : en
Pages : 1018

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Radiative Heat Transfer, Fourth Edition is a fully updated, revised and practical reference on the basic physics and computational tools scientists and researchers use to solve problems in the broad field of radiative heat transfer. This book is acknowledged as the core reference in the field, providing models, methodologies and calculations essential to solving research problems. It is applicable to a variety of industries, including nuclear, solar and combustion energy, aerospace, chemical and materials processing, as well as environmental, biomedical and nanotechnology fields. Contemporary examples and problems surrounding sustainable energy, materials and process engineering are an essential addition to this edition. Includes end-of-chapter problems and a solutions manual, providing a structured and coherent reference Presents many worked examples which have been brought fully up-to-date to reflect the latest research Details many computer codes, ranging from basic problem solving aids to sophisticated research tools

Author: Jill Marie Suo-Anttila
Publisher:
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Languages : en
Pages : 73

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The thermal hazard posed by large hydrocarbon fires is dominated by the radiative emission from high temperature soot. Since the optical properties of soot, especially in the infrared region of the electromagnetic spectrum, as well as its morphological properties, are not well known, efforts are underway to characterize these properties. Measurements of these soot properties in large fires are important for heat transfer calculations, for interpretation of laser-based diagnostics, and for developing soot property models for fire field models. This research uses extractive measurement diagnostics to characterize soot optical properties, morphology, and composition in 2 m pool fires. For measurement of the extinction coefficient, soot extracted from the flame zone is transported to a transmission cell where measurements are made using both visible and infrared lasers. Soot morphological properties are obtained by analysis via transmission electron microscopy of soot samples obtained thermophoretically within the flame zone, in the overfire region, and in the transmission cell. Soot composition, including carbon-to-hydrogen ratio and polycyclic aromatic hydrocarbon concentration, is obtained by analysis of soot collected on filters. Average dimensionless extinction coefficients of 8.4 {+-} 1.2 at 635 nm and 8.7 {+-} 1.1 at 1310 nm agree well with recent measurements in the overfire region of JP-8 and other fuels in lab-scale burners and fires. Average soot primary particle diameters, radius of gyration, and fractal dimensions agree with these recent studies. Rayleigh-Debye-Gans theory of scattering applied to the measured fractal parameters shows qualitative agreement with the trends in measured dimensionless extinction coefficients. Results of the density and chemistry are detailed in the report.

Author: Andrea D'Anna
Publisher: KIT Scientific Publishing
ISBN: 3866444419
Category : Technology & Engineering
Languages : en
Pages : 754

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Soot is of importance for its contribution to atmospheric particles with their adverse health impacts and for its contributions to heat transfer in furnaces and combustors, to luminosity from candles, and to smoke that hinders escape from buildings during fires and that impacts global warming or cooling. The different chapters of the book adress comprehensively the different aspects from fundamental approaches to applications in technical combustion devices.

Author: G. M. Faeth
Publisher:
ISBN:
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Languages : en
Pages : 130

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Measured soot optical properties were in good agreement with the predictions of RDG-PFA theory over a broad test range, as follows: soot from both the fuel-rich and fuel-lean regions of buoyant diffusion flames, wavelengths of 350-800 nm, primary particle size parameters as large as 0.46, and soot formed in diffusion flames burning in air for a variety of gaseous and liqud hydrocarbon fuels (acetylene, ethylene, propylene, butadiene, benzene, cyclohexane, toluene and n-heptane).

Author: Sivakumar Santhanakrishnan
Publisher:
ISBN:
Category :
Languages : en
Pages : 372

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Author: Mohammad Faghri
Publisher: WIT Press
ISBN: 1845641604
Category : Technology & Engineering
Languages : en
Pages : 497

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Controlled fires are beneficial for the generation of heat and power while uncontrolled fires, like fire incidents and wildfires, are detrimental and can cause enormous material damage and human suffering. This edited book presents the state-of-the-art of modeling and numerical simulation of the important transport phenomena in fires. It describes how computational procedures can be used in analysis and design of fire protection and fire safety. Computational fluid dynamics, turbulence modeling, combustion, soot formation, thermal radiation modeling are demonstrated and applied to pool fires, flame spread, wildfires, fires in buildings and other examples.

Author: Işil Ayranci Kilinç
Publisher:
ISBN:
Category :
Languages : en
Pages : 193

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A novel nonintrusive soot diagnostics methodology was developed, validated and applied for in-situ determination of temperature, volume fraction and refractive index of soot aggregates formed inside flames by using near-infrared emission spectrometry. Research was conducted in three main parts, first one addressing development and validation of a comprehensive direct model for simulation of line-of-sight radiative emission from axisymmetric sooty flames by coupling sub-models for radiative transfer, radiative properties and optical constants. Radiative property for soot agglomerates was investigated by experimentally validating DDA method against microwave measurements and using it as a reference to assess applicability of simpler RDG-FA approximation. Part two concerns experimental investigation of an axisymmetric ethylene/air diffusion flame by Fourier Transform Near-Infrared spectroscopy. Measurement of line-of-sight emission intensity spectra was performed along with analyses on calibration, noise, uncertainty and reproducibility. Final part focuses on development, evaluation and application of an inversion methodology that inputs spectral emission intensity measurements from optically thin flames, removes noise, identifies soot refractive index from spectral gradients and retrieves soot temperature and volume fraction fields by tomographic reconstruction. Validation with simulated data and favourable application to measurements indicate that proposed methodology is a promising option for nonintrusive soot diagnostics in flames.

Author: Jinyu Zhu
Publisher:
ISBN:
Category :
Languages : en
Pages : 272

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