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

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Experimental study of engine-like turbulent combustion Updraft and downdraft syngas compositions have similar burning velocities in laminar conditions but the same is not found in turbulent conditions, where the difference on peak pressure is higher by about 25%. As the turbulent burning velocity is proportional to the laminar burning velocity, analysing the correlations for laminar burning velocity of the typical syngas compositions developed on this work show that the effect of pressure is very significant (coefficient β for updraft is 40% higher in relation to downdraft syngas). The higher pressure used on RCM also makes temperature to increase due to compression but the effect of temperature on burning velocity for typical syngas compositions is irrelevant since the coefficient α is of the same order. tel-00623090, version 1 - 13 Sep 2011 Another major finding is that syngas typical compositions are characterized by high ignition timings due to their low burning velocities. One should be aware of the low equivalent rotation speed used on the RCM. This could compromise the use of typical syngas compositions on high rotation speed engines. 166
Chapter 6 CHAPTER 6 NUMERICAL SIMULATION OF A SYNGAS- FUELLED ENGINE Over the past years, several simulation codes of varying degree of sophistication of the SI engine combustion process have been developed and applied to predict engine performance (Rakopoulus, 1993). However, sparse theoretical studies have been reported so far in the literature as regards modeling syngas combustion in SI engines (Sridhar et al. 2006; Rakopoulus et al., 2008). Therefore, computational models of syngas combustion in SI engines are strongly desirable; in order to supplement the relevant experimental studies that usually concern operation of pure syngas. tel-00623090, version 1 - 13 Sep 2011 Several model frameworks are used for the simulation of the ‘closed’ part of the sparkignition engine cycle; these can be classified as ‘zero-’, ‘multi-zone’ and ‘multidimensional’ models. The first two types are classified as thermodynamic models, where the equations constituting the basic structure of the model are based on conservation of mass and energy and are only dependent on time (resulting in ordinary differential equations). Multidimensional models are also termed fluid mechanic or fluid dynamic models, where the governing equations are the Navier–Stokes equations in addition to conservation of mass and energy. Multi-zone models are distinguished from zero-dimensional models by the inclusion of certain geometrical parameters in the basic thermodynamic approach. The choice of multi-zone or multi-dimensional model is largely determined by the application. If the objective is to evaluate a large range of conditions, perform parametric studies and/or predict optimum engine settings, a reasonable accuracy and fast computation on a PC system is desirable. These conditions are satisfied by multizone models. Recent examples are the investigations of causes for cycle-to-cycle variations in engines (Aghdam et al., 2007) and causes for the increased combustion variability leading to lean limits (Ayala and Heywood, 2007). Multi-dimensional models are inappropriate for such studies as they are computationally too demanding. Their best use is for more detailed studies for limited conditions or particular features (e.g. flow through valves, fuel injection, bulk in-cylinder flow and turbulence development), or to support theory and model development. The following reports in detail the development and validation of a multi-zone thermodynamic combustion model. The purpose is the prediction of the engine incylinder pressure. The validation of the code is made by comparison with experimental 167
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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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Chapter 4 CHAPTER 4 EXPERIMENTAL AN
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Chapter 4 4.1 Laminar burning veloc
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Chapter 4 4.1.1.1 Flame morphology
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Chapter 4 P i = 1.0 bar, Ti = 293 K
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Chapter 4 Figure 4.5 shows schliere
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Chapter 4 P i = 2.0 bar, T i = 293
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Chapter 4 Sn (m/s) 3.0 2.5 2.0 1.5
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Chapter 4 5 ms 10 ms 15 ms 20 ms 25
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Chapter 4 behaviour of the curves r
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Chapter 4 1.50 Sn (m/s) 1.25 1.00 0
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Chapter 4 0.5 0.4 φ =1.0 Su (m/s)
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Chapter 4 variation of the normaliz
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Chapter 4 4.1.1.6 Comparison with o
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Chapter 4 The values of laminar bur
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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 and 126: Chapter 4 Notice the similar behavi
Page 127 and 128: Chapter 4 A very good agreement bet
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
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: Chapter 5 observation emphasis the
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
Page 177 and 178: Chapter 6 For all the above express
Page 179 and 180: Chapter 6 motions within the cylind
Page 183 and 184: Chapter 6 Heat transfer Wei et al.,
Page 185 and 186: Chapter 6 The calibration coefficie
Page 187 and 188: Chapter 6 6.3.2.2 In-cylinder volum
Page 189 and 190: Chapter 6 40 Experimental 30 Numeri
Page 191 and 192: Chapter 6 80 70 60 Numerical Experi
Page 193 and 194: Chapter 6 downdraft syngas than for
Page 195 and 196: Chapter 6 80 23º BTDC 60 29.5º BT
Page 197 and 198: Chapter 6 with experimental results
Page 199 and 200: Conclusions CHAPTER 7 CONCLUSIONS 7
Page 201 and 202: Conclusions radius and time for syn
Page 203 and 204: Conclusions conditions, therefore s
Page 205 and 206: Conclusions tel-00623090, version 1
Page 207 and 208: References References tel-00623090,
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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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