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

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Numerical simulation of a syngas-fuelled engine Concerning hydrogen-air flames, the extensive experimental work done by Verhelst, (2005) has been chosen for including the dependence on the air-fuel ratio, temperature, pressure and residual burned gas content: α ⎛T ⎞ ⎛ P ⎞ Su = Su ⎜ ⎟ ⎜ ⎟ − f 0 T P ⎝ 0 ⎠ ⎝ 0 ⎠ β ( 1 γ ) (6.28) Here, the reference conditions T 0 and P 0 are 365K and 5 bar, respectively. The influence of the equivalence ratio at these conditions is embodied in S u0 and is estimated at: S φ φ φ u0 3 2 =− 4.77 + 8.65 −0.394 − 0.296 (6.29) tel-00623090, version 1 - 13 Sep 2011 The values for α, β and γ are the following: α = 1.232 β = φ − φ + φ − φ < 3 2 2.9 6.69 5.06 1.16, 0.6 β = 0.0246φ + 0.0781, φ ≥ 0.6 γ = 2.715 −0.5φ (6.30) Where γ expresses the effect of residual gases. Verhelst and Sierens, (2007) selected a residual mass fraction of 27% given the best correspondence for the pressure trace during compression and maximum combustion pressure. Concerning methane–air flames, the correlation expressing the laminar burning velocity of Muller et al., (1997) has been adopted, since it is reliable for a wide range of pressures and preheats temperatures: 0 0 m T ⎛ u Tb −T ⎞ Su = A( T ) yF, u 0 ⎜ ⎟ T ⎝Tb −Tu ⎠ 0 ⎛ G ⎞ AT ( ) = Fexp ⎜ − 0 ⎟ ⎝ T ⎠ n (6.31) Where, y F,u = (1+AFR s /φ) represents the mass fuel fraction in the unburned mixture, AFR s is the stoichiometric air–fuel ratio;T 0 =-E/ln(p/B) is a representative temperature of the inner layer, defined by Peters and Williams, (1987) as the thin layer within which the first oxidation of methane into CO, hydrogen and water occurs; p is pressure, and the fuel-dependent constants are equal to: B=3.1557×10 8 (bar), E=23873 (K), F=2.21760×10 1 (cm/s) ,G=-6444.27 (K), m =0.565175 and n=2.5158. 180
Chapter 6 The calibration coefficient C 2 in the DamkÖhler model was set equal 1.7 as reported by Verhelst and Sierens, (2007). 6.3.1.2 Results and discussion The simulations results, compared to the respective references, have been presented in figures 6.3 and 6.4. 50 40 Numerical Experimental (Bade and Karim, 2001) Pressure (bar) 30 20 tel-00623090, version 1 - 13 Sep 2011 10 0 240 270 300 330 360 390 420 450 480 Crank Angle (degrees) Figure 6.3 – In cylinder pressure validation for CFR engine fueled by methane: ε=8.5, 900 rpm, IT=20º BTDC, φ=0.99. Pressure (bar) 60 50 40 30 20 Numerical Experimental (Verhelst, 2005) 10 0 240 270 300 330 360 390 420 450 480 Crank Angle (degrees) Figure 6.4 – In cylinder pressure validation for CFR engine fueled by hydrogen: ε=9.0, 600 rpm, IT=20º BTDC, φ=0.59. As clearly visible from these figures, a very good agreement is found. This allows validate the developed model and applied it to typical syngas compositions. 181
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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
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Chapter 4 0.5 0.4 φ=1.2 Su (m/s) 0
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Chapter 4 0.3 φ=0.8 Su (m/s) 0.2 0
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Chapter 4 a minimum pressure to exp
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Chapter 4 Notice the similar behavi
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Chapter 4 A very good agreement bet
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Chapter 4 ( ) Q = h T − T (4.21)
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Chapter 4 tel-00623090, version 1 -
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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
Page 177 and 178: Chapter 6 For all the above express
Page 179 and 180: Chapter 6 motions within the cylind
Page 181 and 182: Chapter 6 tel-00623090, version 1 -
Page 183: Chapter 6 Heat transfer Wei et al.,
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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Page 221 and 222: Appendix A - Overdetermined linear
Page 223 and 224: Appendix A - Overdetermined linear
Page 225 and 226: Appendix B- Syngas-air mixtures pro
Page 227 and 228: Appendix C -Rivère model Heat flux
Page 229 and 230: Appendix C -Rivère model The work
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