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

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Chapter 1 choose three typical compositions of syngas considered as mixture of five gases (H 2 - CO-CH 4 -CO 2 -N 2 ) and make its combustion characterization under laminar and turbulent conditions with the objective to its application in stationary energy production systems based on internal combustion engines. 1.2 Thesis layout This work was divided into seven chapters with the following contains: Chapter 1– Introduction tel-00623090, version 1 - 13 Sep 2011 In this introductory chapter a brief overview about the environmental problems caused by the extensively use of fossil fuels is given in order to provide reasons for the increasing use of renewable energy sources with focus on biomass. The technologies for converting biomass into fuels are summarized. The use of gasification as the right technology to apply when a gas fuel is the final product is justified, which was the spark that motivates this work. The objectives are defined. Chapter 2 – Bibliographic revision This chapter touches upon two topics of interest for the present work - gasification and combustion. A global perspective of the gasification process is given, namely: its definition, the main chemical reactions, the main types of reactors, the typical composition of the syngas, the end use for the syngas as well as the technical problems that still remains in this technology, pointing out the necessary research lines. The influence of various process parameters in the final composition of the syngas is evaluated based on bibliographical data. It is evaluated the influence in the final composition of the syngas of biomass kind, reactor type, oxidizer and the reactor operational conditions. The syngas coming from a gasification process is under study for energy proposes. This is accomplished by combustion. Therefore, premixed flames combustion theory is revised. Stretch rate and the corresponding Karlovitz and Markstein numbers are defined. Following, the experimental methods for burning velocity determination are described with emphasis for the constant volume and constant pressure methods. 15
Introduction Chapter 3 – Experimental set up and diagnostics In this chapter the experimental devices used in this work are illustrated. The experimental procedures are described. The flammability limits of typical syngas syngas compositions are determined and several other combustion parameters like the combustion efficiency and pressure gain. Chapter 4 – Experimental and numerical laminar syngas combustion tel-00623090, version 1 - 13 Sep 2011 In this chapter, the experimental study of three typical syngas compositions is presented in terms of burning velocity, Markstein lengths and Karlovitz number. Constant volume spherically expanding flames are used to determine a burning velocity correlation valid for engine conditions. This information about laminar burning velocity of syngas-air flames is then applied on a multi-zone numerical heat transfer simulation code of the wall-flame interaction. The adapted code allows simulating the combustion of homogeneous premixed gas mixtures within constant volume spherical chamber in order to predict the quenching distance of typical syngas-air flames. Chapter 5 – Experimental study of engine-like turbulent syngas combustion An experimental approach to syngas engine-like conditions on a rapid compression machine is made. Engine-like conditions can be reproduced in a RCM when working on two strokes mode simulating a single cycle of an internal combustion engine working with typical syngas compositions. Together with pressure measurements, direct visualizations are also carried out to follow the early stage of the ignition process. The study of the compression process in a RCM operating without combustion is useful to identify different parameters related with its operation, namely the heat transfer to the walls. Once determined, these parameters can also be used during the usual firing cycle. In fact, a common practice in engine testing for combustion diagnostic is, prior to the usual firing tests. Stationary power applications usually use natural gas as fuel, thus a methane-air mixture, the main constituent of the natural gas, is also included in our work as a reference for comparison with syngas compositions. Chapter 6 – Numerical simulation of a syngas engine In this chapter a multi-zone thermodynamic combustion model is presented. The purpose is the prediction of the engine in-cylinder pressure. The validation of the code is made by comparison with experimental literature data and in addition with the rapid 16
Page 1 and 2: THÈSE Pour l’obtention du Grade
Page 3 and 4: Acknowledgements Acknowledgements T
Page 5 and 6: Résumé __________________________
Page 7 and 8: Nomenclature Nomenclature Roman tel
Page 9 and 10: Nomenclature Subscripts tel-0062309
Page 11 and 12: Contents tel-00623090, version 1 -
Page 13 and 14: Contents 6.4. SYNGAS FUELLED-ENGINE
Page 15 and 16: Introduction CHAPTER 1 INTRODUCTION
Page 17: Introduction proves to have higher
Page 21 and 22: Bibliographic revision CHAPTER 2 BI
Page 23 and 24: Bibliographic revision point today
Page 25 and 26: Bibliographic revision - Boudouard
Page 27 and 28: Bibliographic revision Table 2.1 -
Page 29 and 30: Bibliographic revision Biomass Dryi
Page 31 and 32: Bibliographic revision Circulating
Page 33 and 34: Bibliographic revision or eliminate
Page 35 and 36: Bibliographic revision established
Page 37 and 38: Bibliographic revision Hydrogen Hyd
Page 39 and 40: Bibliographic revision of low moist
Page 41 and 42: Bibliographic revision scrubbing an
Page 43 and 44: Bibliographic revision suggests tha
Page 45 and 46: Bibliographic revision 1 d( δ A) 1
Page 47 and 48: Bibliographic revision Since n is
Page 49 and 50: Bibliographic revision 2 ( rsr ) 2
Page 51 and 52: Bibliographic revision This evoluti
Page 53 and 54: Bibliographic revision The burning
Page 55 and 56: Bibliographic revision δVG = − a
Page 57 and 58: Bibliographic revision 2 1 − −
Page 59 and 60: Bibliographic revision where the su
Page 61 and 62: Bibliographic revision the stretche
Page 63 and 64: Bibliographic revision burning velo
Page 65 and 66: Experimental set ups and diagnostic
Page 67 and 68: Experimental set ups and diagnostic
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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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Chapter 4 are tested and discussed.
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Chapter 4 7 500 Pressure (bar) 6 5
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Chapter 4 Pressure (bar) 7 6 5 4 3
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Chapter 4 4.2.3.4 Quenching distanc
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Chapter 4 10000 Quenching distance
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Chapter 5 CHAPTER 5 EXPERIMENTAL ST
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Chapter 5 30 10 25 8 Pressure (bar)
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Chapter 5 30 Piston position (mm) 2
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Chapter 5 5.1.1.4 In-cylinder press
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Chapter 5 estimation of various par
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Chapter 5 TDC 1.25 ms 2.5 ms 3.75 m
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Chapter 5 Piston position (mm) 500
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Chapter 5 From figure 5.15 is possi
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Chapter 5 From figure 5.16 is obser
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Chapter 5 80 Pressure (bar) 70 60 5
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Chapter 5 80 10 Pmax (bar) 70 60 50
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Chapter 5 -5.0 ms -3.75 ms -2.5 ms
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Chapter 5 observation emphasis the
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Chapter 6 CHAPTER 6 NUMERICAL SIMUL
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Chapter 6 centered at the spark plu
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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 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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