Combustion

Warnatz, Jürgen; Maas, Ulrich; Dibble, Robert W.

doi:10.1007/978-3-642-98027-5

Cited by 218 publications

(224 citation statements)

References 124 publications

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“…The phenomenon induces local temperature drops due to increasing heat removal rates from convection and diffusion along with decreasing chemical reaction rates [22].…”

Section: Localized Extinctionmentioning

confidence: 99%

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On the structure of the near field of oxy-fuel jet flames using Raman/Rayleigh laser diagnostics

Sevault

Dunn

Ditaranto

2012

Combustion and Flame

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An experimental study on turbulent non-premixed jet flames is presented with focus on CO 2 -diluted oxy-fuel combustion using a coflow burner. Measurements of local temperatures and concentrations of the main species CO 2 , O 2 , CO, N 2 , CH 4 , H 2 O and H 2 were achieved using the simultaneous line-imaged Raman/Rayleigh laser diagnostics setup at Sandia National Laboratories. Two series of flames burning mixtures of methane and hydrogen were investigated. In the first series, the hydrogen molar fraction in the fuel was varied from 37 to 55 %, with a constant jet exit Reynolds number Re Fuel of 15,000. In the second series the jet exit Reynolds number was varied from 12,000 to 18,000, while keeping 55 % H 2 molar fraction in the fuel. Besides local temperatures and concentrations, the results revealed insights on the behaviour of localized extinction in the near-field. It was observed that the degree of extinction increased as the hydrogen content in fuel was decreased and as the jet Reynolds number was increased. Based on the distribution of the temperature, a fully burning probability index able to quantify the degree of extinction along the streamwise coordinate was defined and applied to the present flame measurements. A comparison of measured conditional mean of mass fractions and laminar flame calculations underlined the significant level of differential diffusion in the near-field that tended to decrease farther downstream. The results also showed high local CO levels induced by the high content of CO 2 in the oxidizer and flame products. A shift of maximum flame temperature was observed toward the rich side of the mixture fraction space, most likely as a consequence of reduced heat release in the presence of product dissociation. Main characteristics of laser Raman scattering measurements in CO 2 -diluted oxy-fuel conditions compared to air-diluted conditions are also highlighted. Most data, including scalar fluctuations and conditional statistics are available upon request.

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“…The phenomenon induces local temperature drops due to increasing heat removal rates from convection and diffusion along with decreasing chemical reaction rates [22].…”

Section: Localized Extinctionmentioning

confidence: 99%

“…the diffusivities are set equal for all species [22], giving the so-called equal diffusivities transport model. However, in the near field of simple jet flames at low to moderate Reynolds number, this assumption is known to be inaccurate as diffusion effects tend to strongly influence the mixing process.…”

Section: Influence Of Differential Diffusionmentioning

confidence: 99%

On the structure of the near field of oxy-fuel jet flames using Raman/Rayleigh laser diagnostics

Sevault

Dunn

Ditaranto

2012

Combustion and Flame

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“…It is well known that the oxidation of methane is mainly taking place in the flame front, very close to the burner surface, in a sequential process involving many intermediate reactive species [49]. As mentioned above small amounts of L2 is added to methane, which is oxidized rapidly near the burner surface [17].…”

Section: Modelmentioning

confidence: 99%

Size distribution of silica nanoparticles: its impact on green energy

Dutka¹,

Turkin

Vainchtein³

et al. 2016

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1The kinetics of formation of silica fractal-like aggregates during combustion of a stoichiometric methane/air mixture with the hexamethyldisiloxane admixture is studied. Oxidation of hexamethyldisiloxane proceeds very fast with formation of SiO 2 molecules and compact silica clusters at a height of a few millimeters above the burner. At a sufficiently high concentration of hexamethyldisiloxane random collisions of nanoparticles leads to agglomerates with fractal-like structure. The transmission electron microscopy is combined with the theoretical analysis to find conditions for formation of silica fractal-like aggregates. The onset of fractal aggregate formation is discussed by studying the characteristic time scales of collisions and coalescence. One dimensional model is formulated to describe the evolution of the size distribution of fractal-like silica particles undergoing generation, convection, sintering and Smoluchowski coagulation. The simulation results are compared to experimental data.

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“…In order to model the radiation intensity source term , a P-1 model (also known as the Gibb's model or Spherical Harmonics model) is chosen [26] which assumes that the radiation intensity is isotropic or direction-independent at a given location in space.…”

Section: Accepted Manuscriptmentioning

confidence: 99%