On the Formation of Nitrogen Oxides During the Combustion of ...

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3 Experiments on Droplet Array Combustion efficient) ǫ λ , and distance l the light travels through. Hence, an infrared spectrum represents a fingerprint of a sample with numerous absorption peaks. These absorption peaks correspond to the vibrational frequencies between the bonds of the atoms making up the sample material. Generally, a molecule interacts with infrared light only when it is capable of absorbing specific spectral components by changing its dipole moment due to vibration. Symmetric stretch, asymmetric stretch, and deformation vibrations are most relevant here [97, 158, 420, 435]. The NEXUS ® 470 FT-IR spectrometer uses a Michelson interferometer to generate an interferogram in the first instance (cf. Fig. 3.13). Light from the infrared source is split into two beams by a beam splitter, one of them being reflected off a fixed mirror and the other one reflected off a moving mirror. Essentially, an electromagnetic wave is combined with a copy of itself that is delayed by time. This leads to interference between the two beams. By measuring the temporal coherence of the light beams at each time delay setting, the time domain is effectively converted into a spatial coordinate. Thus, the interferogram of Figure 3.13 shows the signal intensity in volts versus the displacement of the moving mirror measured in data points. Then, the raw data of the interferogram is Fourier transformed (FFT) into a single-beam spectrum, which is frequency dependent. It shows the energy distribution of the light source, and it includes the characteristics of the detector, beam splitter, and atmospheric conditions along with those of the sample that is contained in the optical measurement cell. Since a relative scale is required to determine the uncorrupted absorption intensity of the sample, a background spectrum must additionally be measured. It is typically obtained from either a cell with a constant flow of zero reference gas or a completely evacuated cell. To remove the information of the instrumental characteristics, the singlebeam sample spectrum is divided by the single-beam background spectrum (Fig. 3.13). The resulting spectrum is depicted in percent transmittance or percent absorbance. Finally, by collecting more than one scan within a measurement cycle, the system averages all of the data to improve the signal-to-noise ratio (SNR). Consequently, an increasing number of scans significantly improves the detection of individual gas components. Thus, 32, 40, or 64 scans were averaged for obtaining one spectrum within the present experiments, and a 0.5cm −1 resolution was chosen with one scan per second [97, 158, 420, 423, 434–436]. 88
3.2 Measurement Techniques and Data Acquisition Interferogram: sample signal 4 V 0 background signal 4 V 0 −4 2300 2100 1900 Data points 1700 −4 2300 2100 1900 Data points 1700 FFT FFT Intensity of single-beam: sample spectrum 40 20 0 4000 3000 2000 1000 cm −1 Wavenumber σ background spectrum 40 20 0 4000 3000 2000 1000 cm −1 Wavenumber σ (S)/(B) 80 % Wavenumber σ Transmittance 40 0 4000 3000 2000 1000 cm −1 Figure 3.13: Process of Obtaining a Transmission Spectrum. For optical spectroscopy in the infrared spectrum, it is customary to work with wavelength λ and wavenumber σ (= 1/λ). The expression (S)/(B) indicates the ratio of sample and background. Combined Measurement Setup Both analysis devices were coupled according to Figure 3.14 to become one unit with the chemiluminescent NO x analyzer downstream of the FT-IR spec- 89
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TECHNISCHE UNIVERSITÄT MÜNCHEN In
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Vorwort Die vorliegende Arbeit ents
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Kurzfassung Die vorliegende Arbeit
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Contents List of Figures List of Ta
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CONTENTS 5 Results 155 5.1 Droplets
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LIST OF FIGURES xiv 3.3 Droplet Arr
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LIST OF FIGURES 5.19 Progression of
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LIST OF TABLES C.2 Overview of Tele
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NOMENCLATURE g Gravitational force
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NOMENCLATURE σ S Surface tension N
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NOMENCLATURE () T Thermal, temperat
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NOMENCLATURE PAL PAN PDU PFA PFC PH
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1 Introduction In thermal engines t
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1 Introduction 1.3 Oxides of Nitrog
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1 Introduction residence time of th
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1 Introduction Chapter 3 describes
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2 Combustion Theory 2.1.1 Premixed
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2 Combustion Theory molecules by ea
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2 Combustion Theory four types. Out
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2 Combustion Theory ventional combu
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2 Combustion Theory of partial pre-
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2 Combustion Theory Formation of Fu
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2 Combustion Theory Moreover, exper
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2 Combustion Theory For the gas pha
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2 Combustion Theory combustion, ext
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2 Combustion Theory termed “natur
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2 Combustion Theory thin layer of u
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2 Combustion Theory nor generally c
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2 Combustion Theory is assumed to o
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2 Combustion Theory before it follo
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Page 66 and 67: 2 Combustion Theory 2.3 Kinetic Mod
Page 68 and 69: 2 Combustion Theory 1.2 m s −1 La
Page 70 and 71: 2 Combustion Theory Mole fraction o
Page 72 and 73: 2 Combustion Theory Reburn Miller a
Page 74 and 75: 2 Combustion Theory The results of
Page 76 and 77: 2 Combustion Theory Temperature T 3
Page 78 and 79: 2 Combustion Theory 0.0004 GRI 3.0
Page 80 and 81: 2 Combustion Theory In conclusion,
Page 83 and 84: 3 Experiments on Droplet Array Comb
Page 85 and 86: 3.1 Droplet Combustion Facility and
Page 87 and 88: 3.1 Droplet Combustion Facility C D
Page 89 and 90: 3.1 Droplet Combustion Facility ous
Page 91 and 92: 3.1 Droplet Combustion Facility for
Page 93 and 94: 3.1 Droplet Combustion Facility par
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Page 97 and 98: 3.1 Droplet Combustion Facility a c
Page 99 and 100: 3.1 Droplet Combustion Facility •
Page 101 and 102: 3.1 Droplet Combustion Facility Tab
Page 103 and 104: 3.1 Droplet Combustion Facility Fig
Page 105 and 106: 3.2 Measurement Techniques and Data
Page 113: 3.2 Measurement Techniques and Data
Page 131 and 132: 3.3 Numerical Study of the Fluid Dy
Page 143 and 144: 4 Numerical Modeling and Simulation
Page 145 and 146: 4.2 Basics for Numerical Modeling 4
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Page 149 and 150: 4.2 Basics for Numerical Modeling n
Page 151 and 152: 4.2 Basics for Numerical Modeling P
Page 153 and 154: 4.2 Basics for Numerical Modeling E
Page 155 and 156: 4.3 Modeling of Ignition In the end
Page 157 and 158: 4.3 Modeling of Ignition 10 W Time
Page 159 and 160: 4.3 Modeling of Ignition Hence, the
Page 161 and 162: 4.4 Modeling of Nitrogen Oxide Form
Page 163 and 164: 4.5 Simulation of Single Droplets t
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4.5 Simulation of Single Droplets e
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4.6 Model Validation with index i
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4.6 Model Validation utilized model
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4.6 Model Validation Figure 4.7 dep
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4.6 Model Validation 340 K Ambient
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4.6 Model Validation Table 4.1: Val
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4.7 Scope and Limitations of Single
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4.7 Scope and Limitations of Single
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5 Results In total, it includes 99
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5 Results atmosphere of Figure 5.1
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5 Results 32 g kg −1 2400 K Emiss
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5 Results 4.0 g kg −1 Emission in
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5 Results uses constant spatial pos
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5 Results 16 g kg −1 Emission ind
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5 Results Maximum temperature Tmax
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5 Results Even though the parameter
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5 Results Flame stand-off ratio ζ
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5 Results 5.2.3 Comparison with Mic
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5 Results 0.50 5000 ppm Emission in
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5 Results Ψ = 0.1695 (t Ψ = 5 s):
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5 Results 6.0 g kg −1 Emission in
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5 Results combustion in exhaust gas
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5 Results Flame stand-off ratio ζ
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5 Results D 0 being varied between
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5 Results 0.40 g kg −1 Initial dr
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5 Results A twofold trend was obser
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5 Results 5.6 Recommendations and F
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6 Summary and Conclusions In times
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APPENDIX
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A Chemical Mechanisms The earliest
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A Chemical Mechanisms only deduced
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A Chemical Mechanisms Another, very
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A Chemical Mechanisms the reactions
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B Investigated Conditions There are
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B Investigated Conditions Table B.1
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B Investigated Conditions high mech
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C Design Details of Experiment Equi
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D Raw Data of Microgravity Experime
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SUPERVISED THESES Student Sebastian
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References [1] J.A. Aardenne van, G
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REFERENCES [20] K. Annamalai and W.
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REFERENCES [39] C.H. Beck, R. Koch,
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REFERENCES [60] F. Buda, R. Bounace
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REFERENCES [80] Comsol AB (Stockhol
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