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

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3 Experiments on Droplet Array Combustion C D E B A H G y C F A D B z x Figure 3.7: Isometric and Transparent View of the Combustion Chamber. A: thermally insulated combustion chamber, B: solenoid valve connecting vent line to outer vacuum, C: connection of sample probes with sample cylinders, D: solenoid valve for air supply, E: cooling units, F: window for backlit images, G: thermocouple setup, H: anticipated region of vaporizing droplet array [196, 197, 208, 293, 294, 296]. of the droplet array with z = 0mm. The combustion chamber serves as an experimental environment for droplet vaporization and combustion, allowing the formation of a gaseous vapor layer around the fuel droplets by exposing them to a “high temperature” situation. However, the preheating temperature is kept below the auto-ignition point of the fuel for all combustion runs. It is set to T Ψ = 500 K (= 226.85 ◦ C) by default. Ignition needs to be initiated by either one of the two hot-wire igniters (see Chap. 3.1.2). 68
3.1 Droplet Combustion Facility The combustion chamber is installed on the fourth platform of the DCU (Fig. 3.2, E) and has inner dimensions of (140×50×54) mm 3 (W×D×H). Its temperature is precisely controlled by a K-type thermocouple that is attached to the inner combustion chamber wall and by heating cartridges that are integrated into the combustion chamber housing. Two further thermocouples (S-type) measure the gas temperature inside the combustion chamber. Apart from these thermal aspects, the combustion chamber also houses four symmetrically aligned sample probes for exhaust gas sampling [208, 293, 294, 296]. The combustion chamber is designed in line with the following operational specification: • Facilitate fast heat-up periods starting from an ambient temperature level (within 45 to 60 min) • Maintain preheating temperature at set-point of e.g. 500±1K • Exchange air/exhaust from inside the combustion chamber within 15s • Restore set-point temperature within 40s after an air exchange • Facilitate execution of nominal experiment sequence including the insertion of the droplet array holder and the exhaust gas collection through the exhaust gas sampling system (see also Chap. 3.2.6) • Operate combustion chamber shutter (open/close position) in accordance with the experiment sequence • Minimize heat loss of combustion chamber induced by the insertion of the cold droplet array holder (steel frame) In particular the shutter design (Fig. 3.8) must not counteract the thermal insulation and airtightness of the combustion chamber. The latter requirement is essential for the flushing sequence at the end of a combustion run, which is subdivided into a complete evacuation and a succeeding refilling with fresh air. A leak at the shutter sealing might cause a major interference with the global pressure regulation of the DCU. By lifting the droplet array into the combustion chamber, a little air gap of 1mm on average remains between the combustion chamber opening (Fig. 3.8, D) and the steel frame of the droplet array holder inserted. This gap must 69
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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
Page 44 and 45: 2 Combustion Theory of partial pre-
Page 46 and 47: 2 Combustion Theory Formation of Fu
Page 48 and 49: 2 Combustion Theory Moreover, exper
Page 50 and 51: 2 Combustion Theory For the gas pha
Page 52 and 53: 2 Combustion Theory combustion, ext
Page 54 and 55: 2 Combustion Theory termed “natur
Page 56 and 57: 2 Combustion Theory thin layer of u
Page 58 and 59: 2 Combustion Theory nor generally c
Page 60 and 61: 2 Combustion Theory is assumed to o
Page 62 and 63: 2 Combustion Theory before it follo
Page 64 and 65: 2 Combustion Theory position, which
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: 3.1 Droplet Combustion Facility par
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 131 and 132: 3.3 Numerical Study of the Fluid Dy
Page 143 and 144: 4 Numerical Modeling and Simulation
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4.2 Basics for Numerical Modeling 4
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4.2 Basics for Numerical Modeling 4
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4.2 Basics for Numerical Modeling n
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4.2 Basics for Numerical Modeling P
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4.2 Basics for Numerical Modeling E
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4.3 Modeling of Ignition In the end
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4.3 Modeling of Ignition 10 W Time
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4.3 Modeling of Ignition Hence, the
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4.4 Modeling of Nitrogen Oxide Form
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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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On the Formation of Nitrogen Oxides During the Combustion of ...

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