On the Formation of Nitrogen Oxides During the Combustion of Partially Pre-Vaporized Droplets

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On the Formation of Nitrogen Oxides During the Combustion of Partially Pre-Vaporized Droplets

On the Formation of Nitrogen Oxides During the Combustion of Partially Pre-Vaporized Droplets

01 Jan 2012-

TL;DR: In this paper, the trade-off between ambient temperature and available oxygen determines the NOx formation of droplets burning in hot exhaust gas, and the degree of droplet vaporization has an effect on flame stabilization around the droplet and on nitrogen oxide formation.

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Abstract: This study contributes to the topic of nitrogen oxide (NOx) formation at the level of single droplet and droplet array combustion The results show that the trade-off between ambient temperature and available oxygen determines the NOx formation of droplets burning in hot exhaust gas The degree of droplet vaporization has an effect on flame stabilization around the droplet and on NOx formation In the ignition model, the NOx production rate turns out to be very sensitive against the ignition position

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Book•

Atomization and Sprays

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Arthur Henry Lefebvre

01 Dec 1988

TL;DR: In this paper, the basic processes in Atomization are discussed, and the drop size distributions of sprays are discussed.Preface 1.General Considerations 2.Basic Processes of Atomization 3.Drop Size Distributions of Sprays 4.Atomizers 5.Flow in Atomizers 6.AtOMizer Performance 7.External Spray Charcteristics 8.Drop Evaporation 9.Drop Sizing Methods Index

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Abstract: Preface 1.General Considerations 2.Basic Processes in Atomization 3.Drop Size Distributions of Sprays 4.Atomizers 5.Flow in Atomizers 6.Atomizer Performance 7.External Spray Charcteristics 8.Drop Evaporation 9.Drop Sizing Methods Index

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1,214 citations

Journal Article•DOI•

Combustion, Flames and Explosions of Gases

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H. F. Coward

01 Sep 1938-Nature

TL;DR: Bone, Newitt and Townend as mentioned in this paper published a comprehensive monograph "Flame and Combustion in Gases" by Prof. W. de C. Ellis and W. A. Townend.

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Abstract: ELEVEN years ago appeared the comprehensive monograph entitled “Flame and Combustion in Gases” by Prof. W. A. Bone and D. T. A. Townend, followed a year or two later by “Gaseous Combustion at High Pressures” by Bone, Newitt and Townend. Except for a small volume on "Flame"by 0. C. de C. Ellis and W. A. Kirkby (1936), the subject has not since been treated as a whole in English, until the recent appearance of the work by Bernard Lewis and G. von Elbe now under review. Combustion, Flames and Explosions of Gases By Dr. Bernard Lewis Dr. Guenther von Elbe. (The Cambridge Series of Physical Chemistry.) Pp. xiv + 415. (Cambridge: At the University Press, 1938.) 21s. net.

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290 citations

Rate of the Reaction, O+N_2O->2NO

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C. P. Fenimore

01 Jan 1962

9 citations

Proceedings Article•DOI•

Reduction of NOx Formation by Water Sprays in Strained Two-Stage Flames

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S. C. Li¹, N. Ilincic¹, F. A. Williams¹•Institutions (1)

University of California, San Diego¹

10 Jun 1996

TL;DR: In this article, a two-phase laminar counterflow configuration exhibits a green premixed flame, a blue diffusion flame and a vaporization plane, all three are flat and parallel.

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Abstract: Staged combustion can be employed to reduce the formation of CO and NOx, stabilize the flame, decrease the flame temperature and create better working conditions in gas turbine combustors. To help understand influences of partial premixing and addition of water on NOx formation, we study two-stage flames in a counterflow spray burner. This paper reports experimental and theoretical results concerning two-stage combustion in which one feed stream is composed of a fuel-rich mixture of methane and air and the other is air. Water sprays are added to the air stream. This two-phase laminar counterflow configuration exhibits a green premixed flame, a blue diffusion flame and a vaporization plane. All three are flat and parallel. The separation distances between them decrease with increasing equivalence ratio and strain rate. Flow visualization is provided through illumination by an argon ion laser sheet, velocity fields and spray structure are measured by a phase-doppler particle analyzer, concentration fields of major stable species are measured by gas chromatography of samples withdrawn from the flame, and temperature fields are measured by a thermocouple. Numerical integrations which employ a recent chemical-kinetic data base are performed to model the flame structure and NOx formation. Comparisons of experimental results with numerical predictions are made to test agreement. This work provides information on hydrocarbon combustion in both premixed flames and diffusion flames, indicates how NOx is formed in fuel-rich flames and suggests how the pollutants can be reduced.Copyright © 1996 by ASME

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8 citations

Lean, premixed, prevaporized fuel combustor conceptual design study

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A. J. Fiorentino¹•Institutions (1)

Pratt & Whitney¹

01 Aug 1979

TL;DR: In this article, four combustor concepts, designed for the energy efficient engine, utilize variable geometry or other flow modulation techniques to control the equivalence ratio of the initial burning zone.

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Abstract: Four combustor concepts, designed for the energy efficient engine, utilize variable geometry or other flow modulation techniques to control the equivalence ratio of the initial burning zone. Lean conditions are maintained at high power to control oxides of nitrogen while near stoichometric conditions are maintained at low power for low CO and THC emissions. Each concept was analyzed and ranked for its potential in meeting the goals of the program. Although the primary goal of the program is a low level of nitric oxide emissions at stratospheric cruise conditions, both the ground level EPA emission standards and combustor performance and operational requirements typical of advanced subsonic aircraft engines are retained as goals as well. Based on the analytical projections made, two of the concepts offer the potential of achieving the emission goals; however, the projected operational characteristics and reliability of any concept to perform satisfactorily over an entire aircraft flight envelope would require extensive experimental substantiation before engine adaptation can be considered.

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7 citations

References

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Molecular theory of gases and liquids

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Joseph O. Hirschfelder, Charles F. Curtiss, R. Byron Bird

01 Jan 1954

11,894 citations

"On the Formation of Nitrogen Oxides..." refers background or methods in this paper

...After some rearranging [180], the diffusion velocity ∆um,i can be calculated from Equation (4....
[...]
...the diffusion velocity) and the radial heat flux q̇r can be derived from molecular gas kinetics [169, 180, 213], which is based on population dynamics....
[...]
...where ui is the bulk velocity, which corresponds to the velocity in a single component flow, and ∆um,i is the diffusion velocity, from which additional terms for multi-component flows originate [45, 180, 277]....
[...]
...is obtained by a similar derivation, studying the transfer of kinetic energy by collisions [180]....
[...]
...This is the best first-order approximation to the exact formulation(5) [147, 180, 341] and avoids evaluating a linear system of equations [325]....
[...]

Journal Article•

Nitrous oxide (N_2O) : the dominanat ozone-depleting substance emitted in the 21st century

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A. R. Ravishankara

01 Jan 2009-Nature

TL;DR: Nitrous oxide emission currently is the single most important ozone-depleting emission and is expected to remain the largest throughout the 21st century, and N2O is unregulated by the Montreal Protocol, which would enhance the recovery of the ozone layer from its depleted state and reduce the anthropogenic forcing of the climate system.

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3,069 citations

"On the Formation of Nitrogen Oxides..." refers background in this paper

...Thus, the contribution of combustion processes to the overall N2O formation is meaningful, despite the fact that combustion is only a minor direct source of N2O formation and NOx formation is predominant with regard to the sum of all oxides of nitrogen [19, 51, 135, 347]....
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Book•

The scientist and engineer's guide to digital signal processing

[...]

Steven W. Smith

01 Jan 1997

TL;DR: Getting Started with DSPs 30: Complex Numbers 31: The Complex Fourier Transform 32: The Laplace Transform 33: The z-Transform Chapter 27 Data Compression / JPEG (Transform Compression)

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Abstract: In early 1980s, DSP was taught as a graduate level course in electrical engineering. A decade later, DSP had become a standart part of the ungraduate curriculum.

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3,046 citations

Journal Article•DOI•

Mechanism and modeling of nitrogen chemistry in combustion

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James A. Miller¹, Craig T. Bowman²•Institutions (2)

Sandia National Laboratories¹, Stanford University²

01 Jan 1989-Progress in Energy and Combustion Science

TL;DR: In this article, the mechanisms and rate parameters for the gas-phase reactions of nitrogen compounds that are applicable to combustion-generated air pollution are discussed and illustrated by comparison of results from detailed kinetics calculations with experimental data.

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2,843 citations

"On the Formation of Nitrogen Oxides..." refers background or methods in this paper

...Bowman [50, 51] and Miller and Bowman [289] classify the following major categories of NO formation with respect to the oxidation of nitrogen in combustion....
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...[289, 291] also demonstrated the importance of HCCO for the temperature range of 1200 to 1500 K....
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...According to Bowman [51] and Miller and Bowman [289], the principal gas phase reactions forming N2O in the combustion of fossil fuel are: NCO+NO⇋N2O+CO, (2....
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...Both combustion modification and post-combustion methods need to be considered to meet the most stringent regulations enacted for NOx reduction [50, 51, 289, 443]....
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...According to Sano [373, 374] and Miller and Bowman [289], the essential step of NO2 formation in flames is represented by Equation (2....
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Book•

Theoretical and numerical combustion

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Thierry Poinsot, Denis Veynante

01 Jan 2001

2,834 citations

"On the Formation of Nitrogen Oxides..." refers background or methods in this paper

...The governing equations for the conservation of momentum and energy make use of the shear stress tensor τi j [341]....
[...]
...However, the system of differential equations is commonly very stiff due to discrepancies in the timescales of the reactions involved [341, 443]....
[...]
...According to Poinsot and Veynante [341] and Annamalai and Puri [19] the diffusion coefficient of a single species m in a multi-component gas can be approximated by Equation (4....
[...]
...This is the best first-order approximation to the exact formulation(5) [147, 180, 341] and avoids evaluating a linear system of equations [325]....
[...]
...This assumption eliminates the need to deal with partial differential equations and still provides a reasonable level of accuracy [244, 341, 443]....
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