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LIST OF FIGURES
Figure 2.1. Start of combustion for SI, CI and HCCI engines……….8 Figure 4.1. Experimental and simulated normalized injection rate profile………..41 Figure 4.2. Comparison of experimental and simulated spray penetration
length……….42
Figure 4.3. Numerical and experimental comparison of overall SMD
distribution……….42
Figure 4.4. Schematic distribution of the measuring points………..43 Figure 4.5. Comparison of predicted and measured radial SMD distribution
of a hollow cone spray at a two different locations from the
injector tip. (a) 20 mm and (b) 40 mm from the injector tip…………...44
Figure 4.6. Spray shape comparison at several times after SOI.
(Left-experiment [16], right model)………45
Figure 4.7. Caterpillar 3401 SCOTE geometrical details………..46 Figure 4.8. Computational grid for HCCI/PCCI simulations………..48 Figure 4.9. Pressure profile and apparent heat release rate of CASE C…………49 Figure 4.10. Pressure profile and apparent heat release rate of CASE D…………49 Figure 4.11. Pressure profile and apparent heat release rate of CASE M………...50 Figure 4.12. Comparison of predicted and measured NOx emissions for
run set #3………..51
Figure 4.13. Comparison of predicted and measured CO2 emissions for
run set #3………..51
Figure 4.14. Comparison of predicted and measured HC emissions for
run set #3………..52
Figure 4.15. Comparison of predicted and measured CO emissions for
run set #3………..52
Figure 5.1. Computational grid for dual-fuel simulation……….59 Figure 5.2. Pressure and apparent heat release rate for sample
diesel case…...60
Figure 5.3. Pressure and apparent heat release rate for 25% of
gasoline case………61
Figure 5.4. Pressure and apparent heat release rate for 95% of
gasoline case………61
Figure 5.5. Shell-CTC model constants correlation………62 Figure 5.6. NOx and soot dual-fuel predictions using the CTC model………63 Figure 5.7. General scheme of the diesel combustion proposed by
Dec(1997) [91]……….64
Figure 5.8. 3-D computational mesh of the Sandia vessel………66 Figure 5.9. OH radical distribution during the transient period of flame
liftoff. The number in the upper corner of each image is time
after start of injection (SOI)………67
Figure 5.10. Predicted diesel triple flame structure………..68 Figure 5.11. Liftoff length transient variation for Case 3………..69
x
Figure 5.12. Steady liftoff length results……….69
Figure 5.13. Transient liftoff length for all the nine cases proposed………..70
Figure 5.14. Schematic of the Cummins dual fuel engine setup………71
Figure 5.15. 90° sector computational grid at TDC for the Cummins diesel/natural-gas, dual-fuel engine………..73
Figure 5.16. Experimental pressure profile and AHRR for all the proposed cases……….74
Figure 5.17. Numerical pressure profile and AHRR for all the proposed cases……….74
Figure 5.18. Pressure profile and apparent heat release rate for case 5……...…..75
Figure 5.19. NOx emissions comparison for all the proposed cases………75
Figure 5.20. Computational grid used with the eight-hole injector……….77
Figure 5.21. Pressure and HRR for different injectors in a G75D25 case…………78
Figure 5.22. Mean and Peak temperature for different injectors in a G75D25 case………79
Figure 5.23. NOx and Soot emissions for different injectors in a G75D25 case………79
Figure 5.24. CO2 and CO emissions for different injectors in a G75D25 case………80
Figure 5.25. Equivalence ratio distribution just before ignition with the six-hole injector………80
Figure 5.26. Equivalence ratio distribution just before ignition with the eight-hole injector……….80
Figure 5.27. Pressure, HRR profiles with injection timing = -50 deg ATDC……….81
Figure 5.28. Temperature profiles with injection timing = -50 deg ATDC………….81
Figure 5.29. Pressure, HRR profiles with injection timing = -15 deg ATDC……….82
Figure 5.30. Temperature profiles with injection timing = -15 deg ATDC………….82
Figure 5.31. Pressure and HRR profiles for G50D50………..83
Figure 5.32. Temperature profiles for G50D50……….84
Figure 5.33. Pressure and HRR profiles for G95D05………..84
Figure 5.34. Temperature profiles for G95D05……….85
Figure 5.35. NOx emissions for all the injection timings and mixture compositions………86
Figure 5.36. Soot emissions for all the injection timings and mixture compositions………86
Figure 5.37. CO2 emissions for all the injection timings and mixture compositions……….87
Figure 5.38. HC emissions for all the injection timings and mixture compositions………87
Figure 5.39. Pressure and HRR profiles for G50D50 and SOI = -50 ATDC………88
Figure 5.40. Temperature profiles for G50D50 and SOI = -50 ATDC……….……..88
Figure 5.41. Pressure and HRR profiles for G95D05 and SOI = -15 ATDC………89
Figure 5.42. Temperature profiles for G95D05 and SOI = -15 ATDC………...89
Figure 5.43. NOx and soot emissions for injection timing = -15 ATDC……….90
Figure 5.44. HC and CO2 emissions for injection timing = -15 ATDC………..90
Figure 5.45. G-surface and temperature distributions for G95D05 case with injection timing =-15 deg ATDC (obtained with Damkohler combustion strategy)………..91
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Figure 5.47. Temperature profiles for G95D05 case with SOI = 20ATDC………..92
Figure 5.48. Pressure and HRR profiles for G75D25 case with SOI = -20 ATDC………..93
Figure 5.49. NOx and Soot emissions for different injectors in a G75D25 case………...94
Figure 5.50. CO2 and CO emissions for different injectors in a G75D25 case………...94
Figure 5.51. Equivalence ratio distribution just before ignition with both the injectors………95
Figure 5.52. Pressure and HRR profile with SOI = -15 ATDC………..…96
Figure 5.53. NOx emissions for low load and speed conditions………97
Figure 5.54. Soot emissions for low load and speed conditions………...97
Figure 5.55. Temperature distributions for G95D05 with SOI = -15 ATDC……….98
Figure 6.1. Schematic of the proposed concept………..102
Figure 6.2. Computational grid with around 20000 cells at TDC………..103
Figure 6.3. Pressure profile for the different load conditions……….103
Figure 6.4. Mean temperature profile………104
Figure 6.5. NOx and soot results for concept validation simulation……….104
Figure 6.6. Temperature distribution in full load condition……….105
Figure 6.7. Temperature distribution in partial load condition………...106
Figure 6.8. Schematic of the two stroke solution……….107
Figure 6.9. Schematic of the four stroke solution………108
Figure 6.10. Computational grids of the two-stroke solution………109
Figure 6.11. Computational grids of the four-stroke solution………...110
Figure 6.12. Fuel Injection profile……….110
Figure 6.13. Pressure and HRR for the two stroke solution………112
Figure 6.14. Mean temperature profile for the two stroke solution……….112
Figure 6.15. Pressure and HRR for the four stroke solution………113
Figure 6.16. Mean temperature profile for the four stroke solution……….113
Figure 6.17. Temperature distribution for the two-stroke solution in partial load condition………...114
Figure 6.18. Temperature distribution for the four-stroke solution in partial load condition………...115
Figure 6.19. Computational grid of a HD Engine at TDC……….116
Figure 6.20. Pressure and HRR of the HD Diesel engine………117
Figure 6.21. Mean temperature profile for the HD Diesel engine………...118
Figure 6.22. Soot emissions in full load condition……….119
Figure 6.23. NOx emissions in full load condition……….119
Figure 6.24. Soot emissions in partial load condition………120
Figure 6.25. NOx emissions in partial load condition………120
Figure 6.26. Equivalence ratio distributions for Ideal, two and four stroke solutions in full load condition……….121
Figure 6.27. Included spray angle used in the optimization process……….122
Figure 6.28. Injector positioning and orientation for the two stroke solution………..123
Figure 6.29. Injector positioning and orientation for the four stroke solution………..123
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Figure 6.31. NOx production for the two stroke solution………..124
Figure 6.32. Soot production for the four stroke solution……….125
Figure 6.33. NOx production for the four stroke solution……….125
Figure 6.34. HRR profiles for the two stroke solution………...126
Figure 6.35. HRR profiles for the four stroke solution………..127
APPENDIXES FIGURES A3.1 1-D scheme for two stroke solution……….142
