Etude de la combustion de gaz de synthèse issus d'un processus de ...

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Experimental and numerical laminar syngas combustion 0.6 Su (m/s) 0.5 0.4 0.3 0.2 0.5 bar 1.0 bar 2.0 bar Experimental Correlation 5.0 bar 0.1 0 0 5 10 15 20 25 Pressure (bar) (a) 0.7 tel-00623090, version 1 - 13 Sep 2011 Su (m/s) 0.6 0.5 0.4 0.3 0.2 0.1 0 0.2 0.15 0.5 bar 1.0 bar 2.0 bar 5.0 bar Experimental Correlation 0 5 10 15 20 25 Pressure (bar) 0.8 bar 1.0 bar (b) Experimental Correlation Su (m/s) 0.1 2.0 bar 0.05 5.0 bar 0 0 2 4 6 8 10 12 Pressure (bar) (c) Figure 4.36 – Comparison between experimental and correlated burning velocities of syngas-air stoichiometric mixtures at different initial pressures within the chamber. (a) updraft; (b) downdraft; (c) fluidized bed. 122
Chapter 4 A very good agreement between the correlation and the experimental burning velocity is found for every initial pressure test runs performed. Notice that for fluidized bed syngas the lower initial pressure with successful ignition was 0.8 bar. The maximum error of the burning velocity correlation is 8% for updraft syngas, 9% for downdraft syngas and 5% for fluidized bed syngas. These errors are perfectly reasonable and the discrepancy between syngas compositions errors has to do with experimental burning velocity scattering. 4.2. Multi-zone spherical combustion tel-00623090, version 1 - 13 Sep 2011 In an engine cycle, the heat losses could be endorsed 25% to wall-flame interaction and 75% to the wall-burned gases interaction (Boust, 2006). Therefore, robust heat transfer models of wall-flame interaction should be employed. A multi-zone numerical heat transfer simulation code developed at the Laboratoire de Combustion et Détonique for methane-air mixtures by Boust, (2006) is adapted herein to syngas-air mixtures. The code allows simulating the combustion of homogeneous premixed gas mixtures within constant volume spherical chamber centrally ignited. In spherical combustion conditions, the model could also be used for predicting the quenching distance. 4.2.1 Mathematical model 4.2.1.1 Flame propagation The flame is considered a perfect sphere without thickness. The propagation of the flame is imposed by its burning velocity that determines the thickness of the zone to burn during a predefined time Δt. The combustion is supposed isobaric, being the burning velocity S u given by the empirical correlation of Metghalchi and Keck, (1980) expressed by the Eqs. 4.16 - 4.18. The criterion that defines the end of combustion is the flame quenching distance. The quenching distance defines how close the flame approaches the wall and plays a definitive role on the wall-flame interaction as shown by Boust, (2006). The quenching implementation in the computational code consists of stopping the propagation of the flame when it approaches the wall in an equal distance to the frontal quenching distance δ q . In order to estimate the quenching distance, the correlation of Westbrook et al., (1981) is used: 123
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THÈSE Pour l’obtention du Grade
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Acknowledgements Acknowledgements T
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Résumé __________________________
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Nomenclature Nomenclature Roman tel
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Nomenclature Subscripts tel-0062309
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Contents tel-00623090, version 1 -
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Contents 6.4. SYNGAS FUELLED-ENGINE
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Introduction CHAPTER 1 INTRODUCTION
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Introduction proves to have higher
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Introduction Chapter 3 - Experiment
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Bibliographic revision CHAPTER 2 BI
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Bibliographic revision point today
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Bibliographic revision - Boudouard
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Bibliographic revision Table 2.1 -
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Bibliographic revision Biomass Dryi
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Bibliographic revision Circulating
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Bibliographic revision or eliminate
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Bibliographic revision established
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Bibliographic revision Hydrogen Hyd
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Bibliographic revision of low moist
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Bibliographic revision scrubbing an
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Bibliographic revision suggests tha
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Bibliographic revision 1 d( δ A) 1
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Bibliographic revision Since n is
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Bibliographic revision 2 ( rsr ) 2
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Bibliographic revision This evoluti
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Bibliographic revision The burning
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Bibliographic revision δVG = − a
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Bibliographic revision 2 1 − −
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Bibliographic revision where the su
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Bibliographic revision the stretche
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Bibliographic revision burning velo
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Experimental set ups and diagnostic
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Page 75 and 76: Experimental set ups and diagnostic
Page 89 and 90: Chapter 4 CHAPTER 4 EXPERIMENTAL AN
Page 91 and 92: Chapter 4 4.1 Laminar burning veloc
Page 93 and 94: Chapter 4 4.1.1.1 Flame morphology
Page 95 and 96: Chapter 4 P i = 1.0 bar, Ti = 293 K
Page 97 and 98: Chapter 4 Figure 4.5 shows schliere
Page 99 and 100: Chapter 4 P i = 2.0 bar, T i = 293
Page 101 and 102: Chapter 4 Sn (m/s) 3.0 2.5 2.0 1.5
Page 103 and 104: Chapter 4 5 ms 10 ms 15 ms 20 ms 25
Page 105 and 106: Chapter 4 behaviour of the curves r
Page 107 and 108: Chapter 4 1.50 Sn (m/s) 1.25 1.00 0
Page 109 and 110: Chapter 4 0.5 0.4 φ =1.0 Su (m/s)
Page 111 and 112: Chapter 4 variation of the normaliz
Page 113 and 114: Chapter 4 4.1.1.6 Comparison with o
Page 115 and 116: Chapter 4 The values of laminar bur
Page 117 and 118: Chapter 4 Pressure (bar) 7 6 5 4 3
Page 119 and 120: Chapter 4 0.5 0.4 φ=1.2 Su (m/s) 0
Page 121 and 122: Chapter 4 0.3 φ=0.8 Su (m/s) 0.2 0
Page 123 and 124: Chapter 4 a minimum pressure to exp
Page 125: Chapter 4 Notice the similar behavi
Page 129 and 130: Chapter 4 ( ) Q = h T − T (4.21)
Page 131 and 132: Chapter 4 tel-00623090, version 1 -
Page 133 and 134: Chapter 4 are tested and discussed.
Page 135 and 136: Chapter 4 7 500 Pressure (bar) 6 5
Page 137 and 138: Chapter 4 Pressure (bar) 7 6 5 4 3
Page 139 and 140: Chapter 4 4.2.3.4 Quenching distanc
Page 141 and 142: Chapter 4 10000 Quenching distance
Page 143 and 144: Chapter 5 CHAPTER 5 EXPERIMENTAL ST
Page 145 and 146: Chapter 5 30 10 25 8 Pressure (bar)
Page 147 and 148: Chapter 5 30 Piston position (mm) 2
Page 149 and 150: Chapter 5 5.1.1.4 In-cylinder press
Page 151 and 152: Chapter 5 estimation of various par
Page 153 and 154: Chapter 5 TDC 1.25 ms 2.5 ms 3.75 m
Page 155 and 156: Chapter 5 Piston position (mm) 500
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Page 159 and 160: Chapter 5 From figure 5.15 is possi
Page 161 and 162: Chapter 5 From figure 5.16 is obser
Page 163 and 164: Chapter 5 80 Pressure (bar) 70 60 5
Page 165 and 166: Chapter 5 80 10 Pmax (bar) 70 60 50
Page 167 and 168: Chapter 5 -5.0 ms -3.75 ms -2.5 ms
Page 169 and 170: Chapter 5 observation emphasis the
Page 171 and 172: Chapter 6 CHAPTER 6 NUMERICAL SIMUL
Page 173 and 174: Chapter 6 centered at the spark plu
Page 175 and 176: Chapter 6 H 2 O, (3) N 2 , (4) O 2
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Chapter 6 For all the above express
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Chapter 6 motions within the cylind
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Chapter 6 tel-00623090, version 1 -
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Chapter 6 Heat transfer Wei et al.,
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Chapter 6 The calibration coefficie
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Chapter 6 6.3.2.2 In-cylinder volum
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Chapter 6 40 Experimental 30 Numeri
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Chapter 6 80 70 60 Numerical Experi
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Chapter 6 downdraft syngas than for
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Chapter 6 80 23º BTDC 60 29.5º BT
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Chapter 6 with experimental results
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Conclusions CHAPTER 7 CONCLUSIONS 7
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Conclusions radius and time for syn
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Conclusions conditions, therefore s
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Conclusions tel-00623090, version 1
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References References tel-00623090,
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References tel-00623090, version 1
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Appendix A - Overdetermined linear
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Appendix A - Overdetermined linear
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Appendix B- Syngas-air mixtures pro
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Appendix C -Rivère model Heat flux
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Appendix C -Rivère model The work
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tel-00623090, version 1 - 13 Sep 20
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