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Konstantinos Boulouchos - One of the best experts on this subject based on the ideXlab platform.
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phenomenological micro pilot ignition model for medium speed Dual Fuel Engines
Fuel, 2021Co-Authors: Aleš Srna, Yuri M. Wright, Hyunchun Park, Omar Seddik, Panagiotis Kyrtatos, Konstantinos BoulouchosAbstract:Abstract The medium-speed Dual-Fuel engine has become popular in the marine industry for its advantages of fulfilling the stringent emission regulations and relative affordability of natural gas. In such Engines, the ignition process importantly influences the subsequent combustion processes and engine performance. This work developed a phenomenological micro-pilot ignition model with a minimal number of tuning parameters aiming to improve the understanding of the ignition event and enable better control of the Dual-Fuel engine. The model comprises of a spray and a chemistry submodel to accurately capture the interaction between the direct injection of a small amount of diesel Fuel (called micro-pilot) and a two-stage ignition of the diesel Fuel mixed with the surrounding reactive charge in relatively low temperature. A 1D transient spray model is adapted to reproduce the micro-pilot spray characteristics by assuming a realistic trapezoidal Fuel injection profile and the varying discharge coefficient during the transient spray period. The chemical reactions are modeled with a 0D transient flamelet approach based on an opposed flow reactor. The model is validated using three sets of experimental data, namely ECN Spray A (constant volume chamber), RCEM with optical accessibility, and finally, medium-speed Dual-Fuel engine. Quantitatively good predictions of the spray formation, ignition delay, and ignition location over broad conditions ranging from the conventional diesel ignition to the micro-pilot ignition in the Dual-Fuel engine are demonstrated. Finally, the developed model is used to explore the characteristics of micro-pilot ignition under conditions relevant to the medium-speed Dual-Fuel Engines.
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Experimental Investigation of Pilot-Fuel Combustion in Dual-Fuel Engines, Part 2: Understanding the Underlying Mechanisms by means of Optical Diagnostics Highlights
Fuel, 2019Co-Authors: Aleš Srna, Michele Bolla, Yuri Wright, Kai Herrmann, Konstantinos Boulouchos, Beat Von Rotz, Gilles BruneauxAbstract:The pilot-Fuel auto-ignition and combustion under engine-like conditions in compressed methane/air mixtures are investigated in a RCEM using a single-hole coaxial injector. In Part 1, the phenomenology of the pilot-Fuel combustion was studied based on the thermodynamic analysis. With the addition of methane, a prolonged pilot-Fuel combustion duration was observed, especially at increased EGR rates. The aim of Part 2 is to improve the understanding of the underlying processes governing the pilot-Fuel burning and premixed flame initiation in Dual-Fuel Engines. The thermodynamic analysis is supplemented by optical diagnostics including the high-speed CH2O-PLIF, Schlieren and OH*, and corroborated with homogeneous reactor and laminar flame speed calculations. The investigations focus on determining the role of (a) ignition location and number of ignition kernels, (b) stratification of the autoignition time due to the methane chemistry effects, and (c) the role of flame propagation during the pilot-Fuel burning. In the initial phase, combustion is found to propagate through an auto-igniting front. When combustion reaches the lean zones with a high spatial stratification of the autoignition time, premixed flame propagation becomes the dominant mechanism, owing to its higher spreading rate. Both processes influence the pilot-Fuel combustion duration. At higher methane concentration, the simulations predict an increasing stratification of the ignition delay in lean regions, while the laminar flame speed in the pilot-Fuel lean regions moderately increases. Overall, this explains the observed trend of longer pilot-Fuel combustion duration in the Dual-Fuel cases and indicates an increasing role of flame-propagation in the Dual-Fuel combustion pilot-Fuel burning.
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experimental investigation of pilot Fuel combustion in Dual Fuel Engines part 1 thermodynamic analysis of combustion phenomena
Fuel, 2019Co-Authors: Aleš Srna, Kai Herrmann, Konstantinos Boulouchos, Beat Von Rotz, Gilles BruneauxAbstract:Abstract The pilot-Fuel auto-ignition and combustion in compressed methane/air mixtures are investigated. Experiments were performed in an optically accessible rapid compression-expansion machine featuring quiescent charge conditions and a single-hole coaxial diesel injector mounted on the cylinder periphery. It enabled thermodynamic analysis of the pilot-Fuel combustion without these phenomena being masked by the rapid premixed-flame propagation like in the engine test rigs with turbulent charge. The aim of this study is to elucidate the first-order influences of charge and pilot-Fuel parameters on the ignition delay and transition into the premixed flame propagation. For this purpose, a comprehensive measurement matrix including variations of the premixed Fuel equivalence ratio, charge temperature, and oxygen content as well as the variation of pilot injection duration is tested. The heat release rate (HRR) metrics describing the pilot-Fuel combustion duration, peak HRR, and cumulative HRR during the pilot-Fuel combustion are derived. Correlations of the HRR metrics to the ignition delay, pilot-Fuel mixing state at ignition and the volume of the pilot-Fuel jet are investigated. Methane is found to increase the ignition delay and prolong the pilot-Fuel combustion duration. This effect is amplified for pilot-injection strategies with leaner pilot-Fuel mixtures at ignition or in the case of reduced charge oxygen content. Despite the reduced pilot-Fuel reactivity the co-combustion of entrained methane leads to higher peak-HRR, except in the reduced charge oxygen cases, where the excessively reduced mixture reactivity with the introduction of methane leads even to a reduced peak-HRR. The phenomenology of the Dual-Fuel combustion process is described in Part 1, whereas Part 2 of this work aims at improving the understanding of the underlying processes by application of advanced optical diagnostic methods.
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Experimental Investigation of Pilot-Fuel Combustion in Dual-Fuel Engines, Part 1: Thermodynamic Analysis of Combustion Phenomena Highlights
Fuel, 2019Co-Authors: Aleš Srna, Kai Herrmann, Konstantinos Boulouchos, Beat Von Rotz, Gilles BruneauxAbstract:The pilot-Fuel auto-ignition and combustion in compressed methane/air mixtures are investigated. Experiments were performed in an optically accessible rapid compression-expansion machine featuring quiescent charge conditions and a single-hole coaxial diesel injector mounted on the cylinder periphery. It enabled thermodynamic analysis of the pilot-Fuel combustion without these phenomena being masked by the rapid premixed-flame propagation like in the engine test rigs with turbulent charge. The aim of this study is to elucidate the first-order influences of charge and pilot-Fuel parameters on the ignition delay and transition into the premixed flame propagation. For this purpose, a comprehensive measurement matrix including variations of the premixed Fuel equivalence ratio, charge temperature, and oxygen content as well as the variation of pilot injection duration is tested. The heat release rate (HRR) metrics describing the pilot-Fuel combustion duration, peak HRR, and cumulative HRR during the pilot-Fuel combustion are derived. Correlations of the HRR metrics to the ignition delay, pilot-Fuel mixing state at ignition and the volume of the pilot-Fuel jet are investigated. Methane is found to increase the ignition delay and prolong the pilot-Fuel combustion duration. This effect is amplified for pilot-injection strategies with leaner pilot-Fuel mixtures at ignition or in the case of reduced charge oxygen content. Despite the reduced pilot-Fuel reactivity the co-combustion of entrained methane leads to higher peak-HRR, except in the reduced charge oxygen cases, where the excessively reduced mixture reactivity with the introduction of methane leads even to a reduced peak-HRR. The phenomenology of the Dual-Fuel combustion process is described in Part 1, whereas Part 2 of this work aims at improving the understanding of the underlying processes by application of advanced optical diagnostic methods.
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Effect of methane on pilot-Fuel auto-ignition in Dual-Fuel Engines
Proceedings of the Combustion Institute, 2019Co-Authors: Aleš Srna, Michele Bolla, Yuri Wright, Kai Herrmann, Sushant Pandurangi, Rolf Bombach, Konstantinos Boulouchos, Gilles BruneauxAbstract:The ignition behavior of n-dodecane micro-pilot spray in a lean-premixed methane/air charge was investigated in an optically accessible Rapid Compression-Expansion Machine at Dual-Fuel engine-like pressure/temperature conditions. The pilot Fuel was admitted using a coaxial single-hole 100 µm injector mounted on the cylinder periphery. Optical diagnostics include combined high-speed CH2O-PLIF (10 kHz) and Schlieren (80 kHz) imaging for detection of the first-stage ignition, and simultaneous high-speed OH* chemiluminescence (40 kHz) imaging for high-temperature ignition. The aim of this study is to enhance the fundamental understanding of the interaction of methane with the auto-ignition process of short pilot-Fuel injections. Addition of methane into the air charge considerably prolongs ignition delay of the pilot spray with an increasing effect at lower temperatures and with higher methane/air equivalence ratios. The temporal separation of the first CH2O detection and high-temperature ignition was found almost constant regardless of methane content. This was interpreted as methane mostly deferring the cool-flame reactivity. In order to understand the underlying mechanisms of this interaction, experimental investigations were complemented with 1D-flamelet simulations using detailed chemistry, confirming the chemical influence of methane deferring the reactivity in the pilot-Fuel lean mixtures. This shifts the onset of first-stage reactivity towards the Fuel-richer conditions. Consequently, the onset of the turbulent cool-flame is delayed, leading to an overall increased high-temperature ignition delay. Overall, the study reveals a complex interplay between entrainment, low T and high T chemistry and micro-mixing for Dual-Fuel auto-ignition processes for which the governing processes were identified
Aleš Srna - One of the best experts on this subject based on the ideXlab platform.
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phenomenological micro pilot ignition model for medium speed Dual Fuel Engines
Fuel, 2021Co-Authors: Aleš Srna, Yuri M. Wright, Hyunchun Park, Omar Seddik, Panagiotis Kyrtatos, Konstantinos BoulouchosAbstract:Abstract The medium-speed Dual-Fuel engine has become popular in the marine industry for its advantages of fulfilling the stringent emission regulations and relative affordability of natural gas. In such Engines, the ignition process importantly influences the subsequent combustion processes and engine performance. This work developed a phenomenological micro-pilot ignition model with a minimal number of tuning parameters aiming to improve the understanding of the ignition event and enable better control of the Dual-Fuel engine. The model comprises of a spray and a chemistry submodel to accurately capture the interaction between the direct injection of a small amount of diesel Fuel (called micro-pilot) and a two-stage ignition of the diesel Fuel mixed with the surrounding reactive charge in relatively low temperature. A 1D transient spray model is adapted to reproduce the micro-pilot spray characteristics by assuming a realistic trapezoidal Fuel injection profile and the varying discharge coefficient during the transient spray period. The chemical reactions are modeled with a 0D transient flamelet approach based on an opposed flow reactor. The model is validated using three sets of experimental data, namely ECN Spray A (constant volume chamber), RCEM with optical accessibility, and finally, medium-speed Dual-Fuel engine. Quantitatively good predictions of the spray formation, ignition delay, and ignition location over broad conditions ranging from the conventional diesel ignition to the micro-pilot ignition in the Dual-Fuel engine are demonstrated. Finally, the developed model is used to explore the characteristics of micro-pilot ignition under conditions relevant to the medium-speed Dual-Fuel Engines.
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Experimental Investigation of Pilot-Fuel Combustion in Dual-Fuel Engines, Part 2: Understanding the Underlying Mechanisms by means of Optical Diagnostics Highlights
Fuel, 2019Co-Authors: Aleš Srna, Michele Bolla, Yuri Wright, Kai Herrmann, Konstantinos Boulouchos, Beat Von Rotz, Gilles BruneauxAbstract:The pilot-Fuel auto-ignition and combustion under engine-like conditions in compressed methane/air mixtures are investigated in a RCEM using a single-hole coaxial injector. In Part 1, the phenomenology of the pilot-Fuel combustion was studied based on the thermodynamic analysis. With the addition of methane, a prolonged pilot-Fuel combustion duration was observed, especially at increased EGR rates. The aim of Part 2 is to improve the understanding of the underlying processes governing the pilot-Fuel burning and premixed flame initiation in Dual-Fuel Engines. The thermodynamic analysis is supplemented by optical diagnostics including the high-speed CH2O-PLIF, Schlieren and OH*, and corroborated with homogeneous reactor and laminar flame speed calculations. The investigations focus on determining the role of (a) ignition location and number of ignition kernels, (b) stratification of the autoignition time due to the methane chemistry effects, and (c) the role of flame propagation during the pilot-Fuel burning. In the initial phase, combustion is found to propagate through an auto-igniting front. When combustion reaches the lean zones with a high spatial stratification of the autoignition time, premixed flame propagation becomes the dominant mechanism, owing to its higher spreading rate. Both processes influence the pilot-Fuel combustion duration. At higher methane concentration, the simulations predict an increasing stratification of the ignition delay in lean regions, while the laminar flame speed in the pilot-Fuel lean regions moderately increases. Overall, this explains the observed trend of longer pilot-Fuel combustion duration in the Dual-Fuel cases and indicates an increasing role of flame-propagation in the Dual-Fuel combustion pilot-Fuel burning.
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experimental investigation of pilot Fuel combustion in Dual Fuel Engines part 1 thermodynamic analysis of combustion phenomena
Fuel, 2019Co-Authors: Aleš Srna, Kai Herrmann, Konstantinos Boulouchos, Beat Von Rotz, Gilles BruneauxAbstract:Abstract The pilot-Fuel auto-ignition and combustion in compressed methane/air mixtures are investigated. Experiments were performed in an optically accessible rapid compression-expansion machine featuring quiescent charge conditions and a single-hole coaxial diesel injector mounted on the cylinder periphery. It enabled thermodynamic analysis of the pilot-Fuel combustion without these phenomena being masked by the rapid premixed-flame propagation like in the engine test rigs with turbulent charge. The aim of this study is to elucidate the first-order influences of charge and pilot-Fuel parameters on the ignition delay and transition into the premixed flame propagation. For this purpose, a comprehensive measurement matrix including variations of the premixed Fuel equivalence ratio, charge temperature, and oxygen content as well as the variation of pilot injection duration is tested. The heat release rate (HRR) metrics describing the pilot-Fuel combustion duration, peak HRR, and cumulative HRR during the pilot-Fuel combustion are derived. Correlations of the HRR metrics to the ignition delay, pilot-Fuel mixing state at ignition and the volume of the pilot-Fuel jet are investigated. Methane is found to increase the ignition delay and prolong the pilot-Fuel combustion duration. This effect is amplified for pilot-injection strategies with leaner pilot-Fuel mixtures at ignition or in the case of reduced charge oxygen content. Despite the reduced pilot-Fuel reactivity the co-combustion of entrained methane leads to higher peak-HRR, except in the reduced charge oxygen cases, where the excessively reduced mixture reactivity with the introduction of methane leads even to a reduced peak-HRR. The phenomenology of the Dual-Fuel combustion process is described in Part 1, whereas Part 2 of this work aims at improving the understanding of the underlying processes by application of advanced optical diagnostic methods.
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Experimental Investigation of Pilot-Fuel Combustion in Dual-Fuel Engines, Part 1: Thermodynamic Analysis of Combustion Phenomena Highlights
Fuel, 2019Co-Authors: Aleš Srna, Kai Herrmann, Konstantinos Boulouchos, Beat Von Rotz, Gilles BruneauxAbstract:The pilot-Fuel auto-ignition and combustion in compressed methane/air mixtures are investigated. Experiments were performed in an optically accessible rapid compression-expansion machine featuring quiescent charge conditions and a single-hole coaxial diesel injector mounted on the cylinder periphery. It enabled thermodynamic analysis of the pilot-Fuel combustion without these phenomena being masked by the rapid premixed-flame propagation like in the engine test rigs with turbulent charge. The aim of this study is to elucidate the first-order influences of charge and pilot-Fuel parameters on the ignition delay and transition into the premixed flame propagation. For this purpose, a comprehensive measurement matrix including variations of the premixed Fuel equivalence ratio, charge temperature, and oxygen content as well as the variation of pilot injection duration is tested. The heat release rate (HRR) metrics describing the pilot-Fuel combustion duration, peak HRR, and cumulative HRR during the pilot-Fuel combustion are derived. Correlations of the HRR metrics to the ignition delay, pilot-Fuel mixing state at ignition and the volume of the pilot-Fuel jet are investigated. Methane is found to increase the ignition delay and prolong the pilot-Fuel combustion duration. This effect is amplified for pilot-injection strategies with leaner pilot-Fuel mixtures at ignition or in the case of reduced charge oxygen content. Despite the reduced pilot-Fuel reactivity the co-combustion of entrained methane leads to higher peak-HRR, except in the reduced charge oxygen cases, where the excessively reduced mixture reactivity with the introduction of methane leads even to a reduced peak-HRR. The phenomenology of the Dual-Fuel combustion process is described in Part 1, whereas Part 2 of this work aims at improving the understanding of the underlying processes by application of advanced optical diagnostic methods.
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Effect of methane on pilot-Fuel auto-ignition in Dual-Fuel Engines
Proceedings of the Combustion Institute, 2019Co-Authors: Aleš Srna, Michele Bolla, Yuri Wright, Kai Herrmann, Sushant Pandurangi, Rolf Bombach, Konstantinos Boulouchos, Gilles BruneauxAbstract:The ignition behavior of n-dodecane micro-pilot spray in a lean-premixed methane/air charge was investigated in an optically accessible Rapid Compression-Expansion Machine at Dual-Fuel engine-like pressure/temperature conditions. The pilot Fuel was admitted using a coaxial single-hole 100 µm injector mounted on the cylinder periphery. Optical diagnostics include combined high-speed CH2O-PLIF (10 kHz) and Schlieren (80 kHz) imaging for detection of the first-stage ignition, and simultaneous high-speed OH* chemiluminescence (40 kHz) imaging for high-temperature ignition. The aim of this study is to enhance the fundamental understanding of the interaction of methane with the auto-ignition process of short pilot-Fuel injections. Addition of methane into the air charge considerably prolongs ignition delay of the pilot spray with an increasing effect at lower temperatures and with higher methane/air equivalence ratios. The temporal separation of the first CH2O detection and high-temperature ignition was found almost constant regardless of methane content. This was interpreted as methane mostly deferring the cool-flame reactivity. In order to understand the underlying mechanisms of this interaction, experimental investigations were complemented with 1D-flamelet simulations using detailed chemistry, confirming the chemical influence of methane deferring the reactivity in the pilot-Fuel lean mixtures. This shifts the onset of first-stage reactivity towards the Fuel-richer conditions. Consequently, the onset of the turbulent cool-flame is delayed, leading to an overall increased high-temperature ignition delay. Overall, the study reveals a complex interplay between entrainment, low T and high T chemistry and micro-mixing for Dual-Fuel auto-ignition processes for which the governing processes were identified
Gilles Bruneaux - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation of pilot Fuel combustion in Dual Fuel Engines part 1 thermodynamic analysis of combustion phenomena
Fuel, 2019Co-Authors: Aleš Srna, Kai Herrmann, Konstantinos Boulouchos, Beat Von Rotz, Gilles BruneauxAbstract:Abstract The pilot-Fuel auto-ignition and combustion in compressed methane/air mixtures are investigated. Experiments were performed in an optically accessible rapid compression-expansion machine featuring quiescent charge conditions and a single-hole coaxial diesel injector mounted on the cylinder periphery. It enabled thermodynamic analysis of the pilot-Fuel combustion without these phenomena being masked by the rapid premixed-flame propagation like in the engine test rigs with turbulent charge. The aim of this study is to elucidate the first-order influences of charge and pilot-Fuel parameters on the ignition delay and transition into the premixed flame propagation. For this purpose, a comprehensive measurement matrix including variations of the premixed Fuel equivalence ratio, charge temperature, and oxygen content as well as the variation of pilot injection duration is tested. The heat release rate (HRR) metrics describing the pilot-Fuel combustion duration, peak HRR, and cumulative HRR during the pilot-Fuel combustion are derived. Correlations of the HRR metrics to the ignition delay, pilot-Fuel mixing state at ignition and the volume of the pilot-Fuel jet are investigated. Methane is found to increase the ignition delay and prolong the pilot-Fuel combustion duration. This effect is amplified for pilot-injection strategies with leaner pilot-Fuel mixtures at ignition or in the case of reduced charge oxygen content. Despite the reduced pilot-Fuel reactivity the co-combustion of entrained methane leads to higher peak-HRR, except in the reduced charge oxygen cases, where the excessively reduced mixture reactivity with the introduction of methane leads even to a reduced peak-HRR. The phenomenology of the Dual-Fuel combustion process is described in Part 1, whereas Part 2 of this work aims at improving the understanding of the underlying processes by application of advanced optical diagnostic methods.
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Experimental Investigation of Pilot-Fuel Combustion in Dual-Fuel Engines, Part 2: Understanding the Underlying Mechanisms by means of Optical Diagnostics Highlights
Fuel, 2019Co-Authors: Aleš Srna, Michele Bolla, Yuri Wright, Kai Herrmann, Konstantinos Boulouchos, Beat Von Rotz, Gilles BruneauxAbstract:The pilot-Fuel auto-ignition and combustion under engine-like conditions in compressed methane/air mixtures are investigated in a RCEM using a single-hole coaxial injector. In Part 1, the phenomenology of the pilot-Fuel combustion was studied based on the thermodynamic analysis. With the addition of methane, a prolonged pilot-Fuel combustion duration was observed, especially at increased EGR rates. The aim of Part 2 is to improve the understanding of the underlying processes governing the pilot-Fuel burning and premixed flame initiation in Dual-Fuel Engines. The thermodynamic analysis is supplemented by optical diagnostics including the high-speed CH2O-PLIF, Schlieren and OH*, and corroborated with homogeneous reactor and laminar flame speed calculations. The investigations focus on determining the role of (a) ignition location and number of ignition kernels, (b) stratification of the autoignition time due to the methane chemistry effects, and (c) the role of flame propagation during the pilot-Fuel burning. In the initial phase, combustion is found to propagate through an auto-igniting front. When combustion reaches the lean zones with a high spatial stratification of the autoignition time, premixed flame propagation becomes the dominant mechanism, owing to its higher spreading rate. Both processes influence the pilot-Fuel combustion duration. At higher methane concentration, the simulations predict an increasing stratification of the ignition delay in lean regions, while the laminar flame speed in the pilot-Fuel lean regions moderately increases. Overall, this explains the observed trend of longer pilot-Fuel combustion duration in the Dual-Fuel cases and indicates an increasing role of flame-propagation in the Dual-Fuel combustion pilot-Fuel burning.
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Experimental Investigation of Pilot-Fuel Combustion in Dual-Fuel Engines, Part 1: Thermodynamic Analysis of Combustion Phenomena Highlights
Fuel, 2019Co-Authors: Aleš Srna, Kai Herrmann, Konstantinos Boulouchos, Beat Von Rotz, Gilles BruneauxAbstract:The pilot-Fuel auto-ignition and combustion in compressed methane/air mixtures are investigated. Experiments were performed in an optically accessible rapid compression-expansion machine featuring quiescent charge conditions and a single-hole coaxial diesel injector mounted on the cylinder periphery. It enabled thermodynamic analysis of the pilot-Fuel combustion without these phenomena being masked by the rapid premixed-flame propagation like in the engine test rigs with turbulent charge. The aim of this study is to elucidate the first-order influences of charge and pilot-Fuel parameters on the ignition delay and transition into the premixed flame propagation. For this purpose, a comprehensive measurement matrix including variations of the premixed Fuel equivalence ratio, charge temperature, and oxygen content as well as the variation of pilot injection duration is tested. The heat release rate (HRR) metrics describing the pilot-Fuel combustion duration, peak HRR, and cumulative HRR during the pilot-Fuel combustion are derived. Correlations of the HRR metrics to the ignition delay, pilot-Fuel mixing state at ignition and the volume of the pilot-Fuel jet are investigated. Methane is found to increase the ignition delay and prolong the pilot-Fuel combustion duration. This effect is amplified for pilot-injection strategies with leaner pilot-Fuel mixtures at ignition or in the case of reduced charge oxygen content. Despite the reduced pilot-Fuel reactivity the co-combustion of entrained methane leads to higher peak-HRR, except in the reduced charge oxygen cases, where the excessively reduced mixture reactivity with the introduction of methane leads even to a reduced peak-HRR. The phenomenology of the Dual-Fuel combustion process is described in Part 1, whereas Part 2 of this work aims at improving the understanding of the underlying processes by application of advanced optical diagnostic methods.
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Effect of methane on pilot-Fuel auto-ignition in Dual-Fuel Engines
Proceedings of the Combustion Institute, 2019Co-Authors: Aleš Srna, Michele Bolla, Yuri Wright, Kai Herrmann, Sushant Pandurangi, Rolf Bombach, Konstantinos Boulouchos, Gilles BruneauxAbstract:The ignition behavior of n-dodecane micro-pilot spray in a lean-premixed methane/air charge was investigated in an optically accessible Rapid Compression-Expansion Machine at Dual-Fuel engine-like pressure/temperature conditions. The pilot Fuel was admitted using a coaxial single-hole 100 µm injector mounted on the cylinder periphery. Optical diagnostics include combined high-speed CH2O-PLIF (10 kHz) and Schlieren (80 kHz) imaging for detection of the first-stage ignition, and simultaneous high-speed OH* chemiluminescence (40 kHz) imaging for high-temperature ignition. The aim of this study is to enhance the fundamental understanding of the interaction of methane with the auto-ignition process of short pilot-Fuel injections. Addition of methane into the air charge considerably prolongs ignition delay of the pilot spray with an increasing effect at lower temperatures and with higher methane/air equivalence ratios. The temporal separation of the first CH2O detection and high-temperature ignition was found almost constant regardless of methane content. This was interpreted as methane mostly deferring the cool-flame reactivity. In order to understand the underlying mechanisms of this interaction, experimental investigations were complemented with 1D-flamelet simulations using detailed chemistry, confirming the chemical influence of methane deferring the reactivity in the pilot-Fuel lean mixtures. This shifts the onset of first-stage reactivity towards the Fuel-richer conditions. Consequently, the onset of the turbulent cool-flame is delayed, leading to an overall increased high-temperature ignition delay. Overall, the study reveals a complex interplay between entrainment, low T and high T chemistry and micro-mixing for Dual-Fuel auto-ignition processes for which the governing processes were identified
Hyunchun Park - One of the best experts on this subject based on the ideXlab platform.
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phenomenological micro pilot ignition model for medium speed Dual Fuel Engines
Fuel, 2021Co-Authors: Aleš Srna, Yuri M. Wright, Hyunchun Park, Omar Seddik, Panagiotis Kyrtatos, Konstantinos BoulouchosAbstract:Abstract The medium-speed Dual-Fuel engine has become popular in the marine industry for its advantages of fulfilling the stringent emission regulations and relative affordability of natural gas. In such Engines, the ignition process importantly influences the subsequent combustion processes and engine performance. This work developed a phenomenological micro-pilot ignition model with a minimal number of tuning parameters aiming to improve the understanding of the ignition event and enable better control of the Dual-Fuel engine. The model comprises of a spray and a chemistry submodel to accurately capture the interaction between the direct injection of a small amount of diesel Fuel (called micro-pilot) and a two-stage ignition of the diesel Fuel mixed with the surrounding reactive charge in relatively low temperature. A 1D transient spray model is adapted to reproduce the micro-pilot spray characteristics by assuming a realistic trapezoidal Fuel injection profile and the varying discharge coefficient during the transient spray period. The chemical reactions are modeled with a 0D transient flamelet approach based on an opposed flow reactor. The model is validated using three sets of experimental data, namely ECN Spray A (constant volume chamber), RCEM with optical accessibility, and finally, medium-speed Dual-Fuel engine. Quantitatively good predictions of the spray formation, ignition delay, and ignition location over broad conditions ranging from the conventional diesel ignition to the micro-pilot ignition in the Dual-Fuel engine are demonstrated. Finally, the developed model is used to explore the characteristics of micro-pilot ignition under conditions relevant to the medium-speed Dual-Fuel Engines.
Mohamed Y. E. Selim - One of the best experts on this subject based on the ideXlab platform.
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improving the performance of Dual Fuel Engines running on natural gas lpg by using pilot Fuel derived from jojoba seeds
Renewable Energy, 2008Co-Authors: Mohamed Y. E. Selim, M S Radwan, H E SalehAbstract:The use of jojoba methyl ester as a pilot Fuel was investigated for almost the first time as a way to improve the performance of Dual Fuel engine running on natural gas or liquefied petroleum gas (LPG) at part load. The Dual Fuel engine used was Ricardo E6 variable compression diesel engine and it used either compressed natural gas (CNG) or LPG as the main Fuel and jojoba methyl ester as a pilot Fuel. Diesel Fuel was used as a reference Fuel for the Dual Fuel engine results. During the experimental tests, the following have been measured: engine efficiency in terms of specific Fuel consumption, brake power output, combustion noise in terms of maximum pressure rise rate and maximum pressure, exhaust emissions in terms of carbon monoxide and hydrocarbons, knocking limits in terms of maximum torque at onset of knocking, and cyclic variability data of 100 engine cycles in terms of maximum pressure and its pressure rise rate average and standard deviation. The tests examined the following engine parameters: gaseous Fuel type, engine speed and load, pilot Fuel injection timing, pilot Fuel mass and compression ratio. Results showed that using the jojoba Fuel with its improved properties has improved the Dual Fuel engine performance, reduced the combustion noise, extended knocking limits and reduced the cyclic variability of the combustion.
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effect of engine parameters and gaseous Fuel type on the cyclic variability of Dual Fuel Engines
Fuel, 2005Co-Authors: Mohamed Y. E. SelimAbstract:Abstract This paper presents an analysis of the cycle-to-cycle combustion variation as reflected in the combustion pressure data of a single cylinder, naturally aspirated, four stroke, Ricardo E6 engine converted to run as Dual Fuel engine on diesel and gaseous Fuel of LPG or methane. A measuring set-up consisting of a piezo-electric pressure transducer with charge amplifier and fast data acquisition card installed on an IBM microcomputer was used to gather the data of up to 1200 consecutive combustion cycles of the cylinder under various combination of engine operating and design parameters. These parameters included type of gaseous Fuel, engine load, compression ratio, pilot Fuel injection timing, pilot Fuel mass, and engine speed. The data for each operating conditions were analyzed for the maximum pressure, the maximum rate of pressure rise—representing the combustion noise, and indicated mean effective pressure. The cycle-to-cycle variation is expressed as the mean value, standard deviation, and coefficient of variation of these three parameters. It was found that the type of gaseous Fuel and engine operating and design parameters affected the combustion noise and its cyclic variation and these effects have been presented.
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Pressure-time characteristics in diesel engine Fueled with natural gas
Renewable Energy, 2001Co-Authors: Mohamed Y. E. SelimAbstract:Combustion pressure data are measured and presented for a Dual Fuel engine running on Dual Fuel of diesel and compressed natural gas, and compared to the diesel engine case. The maximum pressure rise rate during combustion is presented as a measure of combustion noise. Experimental investigation on diesel and Dual Fuel Engines revealed the noise generated from combustion in both cases. A Ricardo E6 diesel version engine is converted to run on Dual Fuel of diesel and compressed natural gas and is used throughout the work. The engine is fully computerized and the cylinder pressure data, crank angle data are stored in a PC for off-line analysis. The effect of engine speeds, loads, pilot injection angle, and pilot Fuel quantity on combustion noise is examined for both diesel and Dual engine. Maximum pressure rise rate and some samples of ensemble averaged pressure–crank angle data are presented in the present work. The combustion noise, generally, is found to increase for the Dual Fuel engine case as compared to the diesel engine case.
