In recent years, to satisfy the more and more stringent energy efficiency and pollutants emission regulations of ship, which had been issued by the International Marine Organization (IMO), the combustion improvement of the two-stroke low-speed diesel engines has been paid much attention. The phenomenological combustion model, as an effective and economic approach, is widely used for parametric study on diesel engine combustion process. However, the fuel of two-stroke low-speed diesel engine is heavy oil, and there are few researches focused on the modeling of heavy oil spray. Therefore, a spray model that can describe the heavy oil spray evolution is needed. In this study, a one-dimensional discrete diesel spray model based on the conservation of the momentum flux and mass flow rate along the spray axis is modified for heavy oil. By in-depth analysis of physical properties of diesel and heavy oil, viscosity is found to be the main factor that results in the difference of the fuel concentration and velocity distribution over the spray cross-sectional area. According to the turbulent jet theory, the Schmidt number, which represents the capability of mass and momentum diffusion, proves to be inversely related to fuel viscosity. In order to involve the viscosity effects into the one-dimensional diesel spray model, the relation between viscosity and Schmidt number is derived as a simple formulation to account for the fuel concentration and velocity distribution. The calculation of heavy oil spray penetration is validated by the experiment data, and the results shows that the improved spray model has the capability to predict the propagation of heavy oil spray.
{"title":"Study on the Phenomenological Spray Modelling of Heavy Oil for Marine Diesel Engines","authors":"Changfu Han, Long Liu, Dai Liu, Yan Peng","doi":"10.1115/ICEF2018-9505","DOIUrl":"https://doi.org/10.1115/ICEF2018-9505","url":null,"abstract":"In recent years, to satisfy the more and more stringent energy efficiency and pollutants emission regulations of ship, which had been issued by the International Marine Organization (IMO), the combustion improvement of the two-stroke low-speed diesel engines has been paid much attention. The phenomenological combustion model, as an effective and economic approach, is widely used for parametric study on diesel engine combustion process. However, the fuel of two-stroke low-speed diesel engine is heavy oil, and there are few researches focused on the modeling of heavy oil spray. Therefore, a spray model that can describe the heavy oil spray evolution is needed. In this study, a one-dimensional discrete diesel spray model based on the conservation of the momentum flux and mass flow rate along the spray axis is modified for heavy oil. By in-depth analysis of physical properties of diesel and heavy oil, viscosity is found to be the main factor that results in the difference of the fuel concentration and velocity distribution over the spray cross-sectional area. According to the turbulent jet theory, the Schmidt number, which represents the capability of mass and momentum diffusion, proves to be inversely related to fuel viscosity. In order to involve the viscosity effects into the one-dimensional diesel spray model, the relation between viscosity and Schmidt number is derived as a simple formulation to account for the fuel concentration and velocity distribution. The calculation of heavy oil spray penetration is validated by the experiment data, and the results shows that the improved spray model has the capability to predict the propagation of heavy oil spray.","PeriodicalId":441369,"journal":{"name":"Volume 1: Large Bore Engines; Fuels; Advanced Combustion","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127129667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Microemulsions are sustainable alternatives to fos sil fuels, which could possibly be used without any modifications in current engines and storage-transportation-supply infrastructure. Our current work attempts to examine the usability of butanol-diesel-water microemulsion fuels in a diesel engine. A small percentage of water is desirable, as it reduces the NOx and smoke emissions. The microemulsion regions were mapped out in ternary phase diagrams, and the fuel was characterized as per ASTM D975, and further examined for its performance in a diesel engine. The formulated microemulsions satisfied the ASTM standards, and had properties (density, viscosity, flash points, cloud points, copper strip corrosion rating, sulfur content, and ash percent) close to those of neat diesel. The percentage change in property ε was calculated as [|(εdiesel − εmicroemulsion)|/εdiesel] × 100. The calorific values for the microemulsion fuels showed a maximum reduction of 8.31% as compared to that of neat diesel. The brake thermal efficiency, however, increased by 15.38% for the same, with respect to the value for neat diesel (2% higher overall efficiency of the engine). The brake specific fuel consumption was also lowered by 5.04%, and the maximum reduction in emissions of CO, unburnt HC, CO2, and NOx were observed to be 53.48%, 67.40%, 30.82%, and 41.72%, respectively, relative to those of neat diesel. The present experimental investigations thus suggest that the microemulsions could be used as a sustainable cleaner alternative to diesel.
{"title":"Performance of Microemulsion Fuels As an Alternative for Diesel Engine","authors":"Iyman Abrar, A. Bhaskarwar","doi":"10.1115/ICEF2018-9566","DOIUrl":"https://doi.org/10.1115/ICEF2018-9566","url":null,"abstract":"Microemulsions are sustainable alternatives to fos sil fuels, which could possibly be used without any modifications in current engines and storage-transportation-supply infrastructure. Our current work attempts to examine the usability of butanol-diesel-water microemulsion fuels in a diesel engine. A small percentage of water is desirable, as it reduces the NOx and smoke emissions. The microemulsion regions were mapped out in ternary phase diagrams, and the fuel was characterized as per ASTM D975, and further examined for its performance in a diesel engine. The formulated microemulsions satisfied the ASTM standards, and had properties (density, viscosity, flash points, cloud points, copper strip corrosion rating, sulfur content, and ash percent) close to those of neat diesel. The percentage change in property ε was calculated as [|(εdiesel − εmicroemulsion)|/εdiesel] × 100. The calorific values for the microemulsion fuels showed a maximum reduction of 8.31% as compared to that of neat diesel. The brake thermal efficiency, however, increased by 15.38% for the same, with respect to the value for neat diesel (2% higher overall efficiency of the engine). The brake specific fuel consumption was also lowered by 5.04%, and the maximum reduction in emissions of CO, unburnt HC, CO2, and NOx were observed to be 53.48%, 67.40%, 30.82%, and 41.72%, respectively, relative to those of neat diesel. The present experimental investigations thus suggest that the microemulsions could be used as a sustainable cleaner alternative to diesel.","PeriodicalId":441369,"journal":{"name":"Volume 1: Large Bore Engines; Fuels; Advanced Combustion","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126678749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. S. Aznar, Farouk Chorou, J.-Y. Chen, A. Dreizler, R. Dibble
Carbon capture has been deemed crucial by the Intergovernmental Panel on Climate Change if the world is to achieve the ambitious goals stated in the Paris agreement. A deeper integration of renewable energy sources is also needed if we are to mitigate the large amount of greenhouse gas emitted as a result of increasing world fossil fuel energy consumption. These new power technologies bring an increased need for distributed fast dispatch power and energy storage that counteract their intermittent nature. A novel technological approach to provide fast dispatch emission free power is the use of the Argon Power Cycle, a technology that makes carbon capture an integral part of its functioning principle. The core concept behind this technology is a closed loop internal combustion engine cycle working with a monoatomic gas in concert with a membrane gas separation unit. By replacing the working fluid of internal combustion engines with a synthetic mixture of monoatomic gases and oxygen, the theoretical thermal efficiency can be increased up to 80%, more than 20% over conventional air cycles. Furthermore, the absence of nitrogen in the system prevents formation of nitrogen oxides, eliminating the need for expensive exhaust gas after-treatment and allowing for efficient use of renewable generated hydrogen fuel. In the case of hydrocarbon fuels, the closed loop nature of the cycle affords to boost the pressure and concentration of gases in the exhaust stream at no penalty to the cycle, providing the driving force to cost effective gas membrane separation of carbon dioxide. In this work we investigated the potential benefits of the Argon Power Cycle to improve upon current stationary power generation systems regarding efficiency, air pollutants and greenhouse gas emissions. A cooperative fuel research engine was used to carry out experiments and evaluate engine performance in relation to its air breathing counterpart. A 30% efficiency improvement was achieved and results showed a reduction on engine heat losses and an overall increase on the indicated mean effective pressure, despite the lesser oxygen content present in the working fluid. Greenhouse gas emissions were reduced as expected due to a substantial increase in efficiency and nitric oxides were eliminated as it was expected. Numerical simulation were carried out to predict the performance and energy penalty of a membrane separation unit. Energy penalties as low as 2% were obtained capturing 100% of the carbon dioxide generated.
{"title":"Experimental and Numerical Investigation of the Argon Power Cycle","authors":"M. S. Aznar, Farouk Chorou, J.-Y. Chen, A. Dreizler, R. Dibble","doi":"10.1115/ICEF2018-9670","DOIUrl":"https://doi.org/10.1115/ICEF2018-9670","url":null,"abstract":"Carbon capture has been deemed crucial by the Intergovernmental Panel on Climate Change if the world is to achieve the ambitious goals stated in the Paris agreement. A deeper integration of renewable energy sources is also needed if we are to mitigate the large amount of greenhouse gas emitted as a result of increasing world fossil fuel energy consumption. These new power technologies bring an increased need for distributed fast dispatch power and energy storage that counteract their intermittent nature. A novel technological approach to provide fast dispatch emission free power is the use of the Argon Power Cycle, a technology that makes carbon capture an integral part of its functioning principle. The core concept behind this technology is a closed loop internal combustion engine cycle working with a monoatomic gas in concert with a membrane gas separation unit. By replacing the working fluid of internal combustion engines with a synthetic mixture of monoatomic gases and oxygen, the theoretical thermal efficiency can be increased up to 80%, more than 20% over conventional air cycles. Furthermore, the absence of nitrogen in the system prevents formation of nitrogen oxides, eliminating the need for expensive exhaust gas after-treatment and allowing for efficient use of renewable generated hydrogen fuel. In the case of hydrocarbon fuels, the closed loop nature of the cycle affords to boost the pressure and concentration of gases in the exhaust stream at no penalty to the cycle, providing the driving force to cost effective gas membrane separation of carbon dioxide. In this work we investigated the potential benefits of the Argon Power Cycle to improve upon current stationary power generation systems regarding efficiency, air pollutants and greenhouse gas emissions. A cooperative fuel research engine was used to carry out experiments and evaluate engine performance in relation to its air breathing counterpart. A 30% efficiency improvement was achieved and results showed a reduction on engine heat losses and an overall increase on the indicated mean effective pressure, despite the lesser oxygen content present in the working fluid. Greenhouse gas emissions were reduced as expected due to a substantial increase in efficiency and nitric oxides were eliminated as it was expected. Numerical simulation were carried out to predict the performance and energy penalty of a membrane separation unit. Energy penalties as low as 2% were obtained capturing 100% of the carbon dioxide generated.","PeriodicalId":441369,"journal":{"name":"Volume 1: Large Bore Engines; Fuels; Advanced Combustion","volume":"175 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131538920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Non-intrusive measurements are always desirable in flame research, particularly in the study of internal combustion engines where intrusive measurements are usually not applicable. With the use of digital image processing and color analysis, the imaging system can be turned into an abstract multi-spectral system to determine the characteristics of flame emission. First this study conducts a precise calibration to make up a spectral correlation between the camera spectrum responses and the radical emissions of an ethanol diffusion flame. The color model of HSV is used to represent the camera spectrum responses. The actual wavelength of each radical of the diffusion flame has also been examined using a spectrograph. Subsequent experiment is the application of the spectral correlation into a direct injection spark ignition optical engine to research the combustion behavior. Two fuel injectors, different in nozzle configuration, were utilized and tested individually. The high-speed imaging system films hundreds of engine combustion cycles, and each cycle covers the propagation from the flame ignition stage towards the end of combustion. In those cycles, the presence of radicals of interest was captured and represented by Hue degree.
{"title":"Flame Emission Characteristics in a Direct Injection Spark Ignition Optical Engine Using Image Processing Based Diagnostics","authors":"Zhe Sun, Zhen-Wei Ma, Xuesong Li, Min Xu","doi":"10.1115/ICEF2018-9746","DOIUrl":"https://doi.org/10.1115/ICEF2018-9746","url":null,"abstract":"Non-intrusive measurements are always desirable in flame research, particularly in the study of internal combustion engines where intrusive measurements are usually not applicable. With the use of digital image processing and color analysis, the imaging system can be turned into an abstract multi-spectral system to determine the characteristics of flame emission. First this study conducts a precise calibration to make up a spectral correlation between the camera spectrum responses and the radical emissions of an ethanol diffusion flame. The color model of HSV is used to represent the camera spectrum responses. The actual wavelength of each radical of the diffusion flame has also been examined using a spectrograph. Subsequent experiment is the application of the spectral correlation into a direct injection spark ignition optical engine to research the combustion behavior. Two fuel injectors, different in nozzle configuration, were utilized and tested individually. The high-speed imaging system films hundreds of engine combustion cycles, and each cycle covers the propagation from the flame ignition stage towards the end of combustion. In those cycles, the presence of radicals of interest was captured and represented by Hue degree.","PeriodicalId":441369,"journal":{"name":"Volume 1: Large Bore Engines; Fuels; Advanced Combustion","volume":"135 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134037811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Soloiu, J. Moncada, R. Gaubert, Spencer Harp, M. Ilie, J. Wiley
High reactivity gas-to-liquid kerosene (GTL) was investigated with port fuel injection (PFI) of low reactivity n-butanol to conduct reactivity controlled compression ignition (RCCI). In the preliminary stage, the GTL was investigated in a constant volume combustion chamber, and the results indicated a narrower negative temperature coefficient (NTC) region than ultra-low sulfur diesel (ULSD#2). The engine research was conducted at 1500 RPM and various loads with early n-butanol PFI and dual DI pulses of GTL at 60 crank angle degrees (CAD) before top dead center (TDC) and at a timing close to TDC. Boost and PFI fractions (60% by mass n-butanol) were kept constant in order to analyze the fuel reactivity effect on combustion. Conventional diesel combustion (CDC) mode with a single injection and the same combustion phasing (CA50) was used as an emissions baseline for RCCI. RCCI increased ignition delay and combustion duration decreased compared to CDC. Results showed that in order to maintain CA50 for RCCI within 1 CAD, GTL mass required for the first DI pulse to be 15% lower than that of ULSD#2 at higher loads. Peak heat release rate decreased for GTL by 25% given the high volatility and low viscosity of GTL. In general, using GTL, NOx and soot levels were reduced across load points by up to 15% to 30%, respectively, compared to ULSD RCCI, while maintaining RCCI combustion efficiency at 93–97%. Meanwhile, reductions of 85% in soot and 90% in NOx were determined when using RCCI compared to CDC. The more favorable heat release placement of GTL led to increased thermal efficiency by 3% at higher load compared to ULSD#2. The higher volatility and increased reactivity for GTL achieved lower UHC and CO than ULSD#2 at lower load. The study concluded that GTL offered advantages when used with n-butanol for this RCCI fueling configuration.
{"title":"GTL Kerosene and N-Butanol in RCCI Mode: Combustion and Emissions Investigation","authors":"V. Soloiu, J. Moncada, R. Gaubert, Spencer Harp, M. Ilie, J. Wiley","doi":"10.1115/ICEF2018-9585","DOIUrl":"https://doi.org/10.1115/ICEF2018-9585","url":null,"abstract":"High reactivity gas-to-liquid kerosene (GTL) was investigated with port fuel injection (PFI) of low reactivity n-butanol to conduct reactivity controlled compression ignition (RCCI). In the preliminary stage, the GTL was investigated in a constant volume combustion chamber, and the results indicated a narrower negative temperature coefficient (NTC) region than ultra-low sulfur diesel (ULSD#2). The engine research was conducted at 1500 RPM and various loads with early n-butanol PFI and dual DI pulses of GTL at 60 crank angle degrees (CAD) before top dead center (TDC) and at a timing close to TDC. Boost and PFI fractions (60% by mass n-butanol) were kept constant in order to analyze the fuel reactivity effect on combustion. Conventional diesel combustion (CDC) mode with a single injection and the same combustion phasing (CA50) was used as an emissions baseline for RCCI. RCCI increased ignition delay and combustion duration decreased compared to CDC. Results showed that in order to maintain CA50 for RCCI within 1 CAD, GTL mass required for the first DI pulse to be 15% lower than that of ULSD#2 at higher loads. Peak heat release rate decreased for GTL by 25% given the high volatility and low viscosity of GTL. In general, using GTL, NOx and soot levels were reduced across load points by up to 15% to 30%, respectively, compared to ULSD RCCI, while maintaining RCCI combustion efficiency at 93–97%. Meanwhile, reductions of 85% in soot and 90% in NOx were determined when using RCCI compared to CDC. The more favorable heat release placement of GTL led to increased thermal efficiency by 3% at higher load compared to ULSD#2. The higher volatility and increased reactivity for GTL achieved lower UHC and CO than ULSD#2 at lower load. The study concluded that GTL offered advantages when used with n-butanol for this RCCI fueling configuration.","PeriodicalId":441369,"journal":{"name":"Volume 1: Large Bore Engines; Fuels; Advanced Combustion","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114225754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Large natural gas engines that introduce premixed fuel and air into the engine cylinders allow a small fraction of fuel to evade combustion, which is undesirable. The premixed fuel and air combust via flame propagation. Ahead of the flame front, the unburned fuel and air are driven into crevices, where conditions are not favorable for oxidation. The unburned fuel is a form of waste and a source of potent greenhouse gas emissions. A concept to vent unburned fuel into the crankcase through built-in slots in the liner during the expansion stroke has been tested. This venting process occurs before the exhaust valve opens and the unburned fuel sent into the crankcase can be recycled to the intake side through a closed crankcase ventilation system. The increased communication between the cylinder and the crankcase changes the ring pack dynamics, which results in higher oil consumption. Oil consumption was measured using a sulfur tracer technique. Careful design is required to achieve the best tradeoff between reductions in unburned hydrocarbon emissions and oil control.
{"title":"Liner Design to Reduce Unburned Hydrocarbon Exhaust Emissions","authors":"Paul S. Wang, Allen Y. Chen","doi":"10.1115/ICEF2018-9682","DOIUrl":"https://doi.org/10.1115/ICEF2018-9682","url":null,"abstract":"Large natural gas engines that introduce premixed fuel and air into the engine cylinders allow a small fraction of fuel to evade combustion, which is undesirable. The premixed fuel and air combust via flame propagation. Ahead of the flame front, the unburned fuel and air are driven into crevices, where conditions are not favorable for oxidation. The unburned fuel is a form of waste and a source of potent greenhouse gas emissions. A concept to vent unburned fuel into the crankcase through built-in slots in the liner during the expansion stroke has been tested. This venting process occurs before the exhaust valve opens and the unburned fuel sent into the crankcase can be recycled to the intake side through a closed crankcase ventilation system. The increased communication between the cylinder and the crankcase changes the ring pack dynamics, which results in higher oil consumption. Oil consumption was measured using a sulfur tracer technique. Careful design is required to achieve the best tradeoff between reductions in unburned hydrocarbon emissions and oil control.","PeriodicalId":441369,"journal":{"name":"Volume 1: Large Bore Engines; Fuels; Advanced Combustion","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124870234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An optimal combustion phasing leads to a high combustion efficiency and low carbon emissions in diesel engines. With the increasing complexity of diesel engines, model-based control of combustion phasing is becoming indispensable, but precise prediction of combustion phasing is required for such strategies. Since cylinder-to-cylinder variations in combustion can be more significant with advanced combustion techniques, this work focuses on developing a control-oriented combustion phasing model that can be leveraged to provide cylinder-specific estimates. The pressure and temperature of the intake gas reaching each cylinder are predicted by a semi-empirical model and the coefficients of this intake pressure and temperature model are varied from cylinder-to-cylinder. A knock integral model is leveraged to estimate the SOC (start of combustion) and the burn duration is predicted as a function of EGR fraction, equivalence ratio of fuel and residual gas fraction in a burn duration model. After that, a Wiebe function is utilized to estimate CA50 (crank angle at 50% mass of fuel has burned). This cylinder-specific combustion phasing prediction model is calibrated and validated across a variety of operating conditions. A large range of EGR fraction and fuel equivalence ratio were tested in these simulations including EGR levels from 0 to 50%, and equivalence ratios from 0.5 to 0.9. The results show that the combustion phasing prediction model can estimate CA50 with an uncertainty of ±0.5 crank angle degree in all six cylinders. The impact of measurement errors on the accuracy of the prediction model is also discussed in this paper.
{"title":"Cylinder-Specific Combustion Phasing Modeling for a Multiple-Cylinder Diesel Engine","authors":"Wenbo Sui, Carrie M. Hall","doi":"10.1115/ICEF2018-9560","DOIUrl":"https://doi.org/10.1115/ICEF2018-9560","url":null,"abstract":"An optimal combustion phasing leads to a high combustion efficiency and low carbon emissions in diesel engines. With the increasing complexity of diesel engines, model-based control of combustion phasing is becoming indispensable, but precise prediction of combustion phasing is required for such strategies. Since cylinder-to-cylinder variations in combustion can be more significant with advanced combustion techniques, this work focuses on developing a control-oriented combustion phasing model that can be leveraged to provide cylinder-specific estimates. The pressure and temperature of the intake gas reaching each cylinder are predicted by a semi-empirical model and the coefficients of this intake pressure and temperature model are varied from cylinder-to-cylinder. A knock integral model is leveraged to estimate the SOC (start of combustion) and the burn duration is predicted as a function of EGR fraction, equivalence ratio of fuel and residual gas fraction in a burn duration model. After that, a Wiebe function is utilized to estimate CA50 (crank angle at 50% mass of fuel has burned). This cylinder-specific combustion phasing prediction model is calibrated and validated across a variety of operating conditions. A large range of EGR fraction and fuel equivalence ratio were tested in these simulations including EGR levels from 0 to 50%, and equivalence ratios from 0.5 to 0.9. The results show that the combustion phasing prediction model can estimate CA50 with an uncertainty of ±0.5 crank angle degree in all six cylinders. The impact of measurement errors on the accuracy of the prediction model is also discussed in this paper.","PeriodicalId":441369,"journal":{"name":"Volume 1: Large Bore Engines; Fuels; Advanced Combustion","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125692027","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhenyi Yang, Xiao Yu, Shui Yu, Jianming Chen, Guangyun Chen, M. Zheng, G. Reader, D. Ting
Lean or diluted combustion has been considered as an effective strategy to improve the thermal efficiency of spark ignition engines. Under lean or diluted conditions, the combustion speed is reduced by the diluting gas. In order to speed up the combustion, in-cylinder flow is intentionally enhanced to promote the flame propagation. However, it is observed that the flow may make the spark ignition process more challenging due to the shortened discharge duration, the frequent re-strikes of spark plasma and the more complicated interactions between the flow and the flame. In this research, the effects of spark discharge current level and discharge duration on flame kernel development and flame propagation of lean methane air mixture are investigated under flow velocity of about 25 m/s and background pressure of 4 bar abs in an optical combustion chamber. A dual coil ignition system and an in-house developed current management module are used to create different discharge current levels. The average discharge current levels range from 55 mA, 190 mA, up to 250 mA. Detached flame kernel is observed under some test conditions. The flame propagation speed with the detached flame is generally slower than the flame developed from a flame kernel attached to the spark plug. The flame detachment is related to both the discharge current level and the discharge duration. When the discharge current level is high at 250 mA, the detached flame is observed at shorter discharge duration of 0.8 ms, while when the discharge current is low at 190 mA, detached flame can happen at longer discharge duration of 1.3 ms. Various discharge current and discharge durations are adopted to initiate the combustion in a single-cylinder engine operating with lean gasoline air mixture. It is shown from the results that a higher discharge current level and longer discharge duration are beneficial for controlling the combustion phasing and improving the operation stability of the engine.
稀薄或稀释燃烧被认为是提高火花点火发动机热效率的有效方法。在稀薄或稀释条件下，燃烧速度因稀释气体而降低。为了加速燃烧，有意加强缸内流动以促进火焰的传播。然而，由于放电时间的缩短、火花等离子体的频繁重击以及流动与火焰之间更复杂的相互作用，流动可能使火花点火过程更具挑战性。在光学燃烧室中，在流速约为25 m/s、背景压力为4 bar abs的条件下，研究了火花放电电流水平和放电持续时间对稀薄甲烷空气混合物火焰核发展和火焰传播的影响。双线圈点火系统和内部开发的电流管理模块用于创建不同的放电电流水平。平均放电电流水平范围从55毫安，190毫安，高达250毫安。在一些试验条件下观察到分离的火焰核。火焰的传播速度与分离的火焰一般较慢的火焰发展，从一个火焰核附加到火花塞。火焰脱离与放电电流水平和放电持续时间有关。当放电电流为250 mA时，放电持续时间较短，为0.8 ms，而当放电电流为190 mA时，放电持续时间较长，为1.3 ms。在稀薄汽油空气混合气单缸发动机中，采用不同的放电电流和放电时间来启动燃烧。结果表明，较高的放电电流和较长的放电时间有利于控制燃烧的分相，提高发动机的运行稳定性。
{"title":"Impacts of Spark Discharge Current and Duration on Flame Development of Lean Mixtures Under Flow Conditions","authors":"Zhenyi Yang, Xiao Yu, Shui Yu, Jianming Chen, Guangyun Chen, M. Zheng, G. Reader, D. Ting","doi":"10.1115/ICEF2018-9771","DOIUrl":"https://doi.org/10.1115/ICEF2018-9771","url":null,"abstract":"Lean or diluted combustion has been considered as an effective strategy to improve the thermal efficiency of spark ignition engines. Under lean or diluted conditions, the combustion speed is reduced by the diluting gas. In order to speed up the combustion, in-cylinder flow is intentionally enhanced to promote the flame propagation. However, it is observed that the flow may make the spark ignition process more challenging due to the shortened discharge duration, the frequent re-strikes of spark plasma and the more complicated interactions between the flow and the flame.\u0000 In this research, the effects of spark discharge current level and discharge duration on flame kernel development and flame propagation of lean methane air mixture are investigated under flow velocity of about 25 m/s and background pressure of 4 bar abs in an optical combustion chamber. A dual coil ignition system and an in-house developed current management module are used to create different discharge current levels. The average discharge current levels range from 55 mA, 190 mA, up to 250 mA. Detached flame kernel is observed under some test conditions. The flame propagation speed with the detached flame is generally slower than the flame developed from a flame kernel attached to the spark plug. The flame detachment is related to both the discharge current level and the discharge duration. When the discharge current level is high at 250 mA, the detached flame is observed at shorter discharge duration of 0.8 ms, while when the discharge current is low at 190 mA, detached flame can happen at longer discharge duration of 1.3 ms.\u0000 Various discharge current and discharge durations are adopted to initiate the combustion in a single-cylinder engine operating with lean gasoline air mixture. It is shown from the results that a higher discharge current level and longer discharge duration are beneficial for controlling the combustion phasing and improving the operation stability of the engine.","PeriodicalId":441369,"journal":{"name":"Volume 1: Large Bore Engines; Fuels; Advanced Combustion","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122205192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yasuhisa Ichikawa, H. Sekiguchi, O. Bondarenko, K. Hirata
This study aims to develop an exhaust gas temperature increase technique of a lean burn gas engine, to improve the performance of the waste heat recovery devices that potentially can be installed in the future. This paper shows the exhaust gas temperature increase technique using an EGR device. In our experiments, the lean burn gas engine has the rated power output of 400 kW with spark-ignition and pre-chamber systems. The EGR device was developed and installed to the gas engine. The experimental results showed that the exhaust gas temperature was increased to +30 °C at the EGR rate of 15 % with maintained NOx emission and CA MFB 50% by decreasing the relative air/fuel ratio (Λ) and advancing the ignition timing (θig). In addition, the gross generation efficiency was slightly increased with increasing the EGR rate. This result was explained using three factors; the internal engine efficiency, the combustion efficiency, and the recirculated energy rate.
{"title":"An Exhaust Gas Temperature Increase Technique Using EGR Device for the Application of Waste Heat Recovery Technology on a Lean Burn Gas Engine","authors":"Yasuhisa Ichikawa, H. Sekiguchi, O. Bondarenko, K. Hirata","doi":"10.1115/ICEF2018-9635","DOIUrl":"https://doi.org/10.1115/ICEF2018-9635","url":null,"abstract":"This study aims to develop an exhaust gas temperature increase technique of a lean burn gas engine, to improve the performance of the waste heat recovery devices that potentially can be installed in the future. This paper shows the exhaust gas temperature increase technique using an EGR device.\u0000 In our experiments, the lean burn gas engine has the rated power output of 400 kW with spark-ignition and pre-chamber systems. The EGR device was developed and installed to the gas engine. The experimental results showed that the exhaust gas temperature was increased to +30 °C at the EGR rate of 15 % with maintained NOx emission and CA MFB 50% by decreasing the relative air/fuel ratio (Λ) and advancing the ignition timing (θig). In addition, the gross generation efficiency was slightly increased with increasing the EGR rate. This result was explained using three factors; the internal engine efficiency, the combustion efficiency, and the recirculated energy rate.","PeriodicalId":441369,"journal":{"name":"Volume 1: Large Bore Engines; Fuels; Advanced Combustion","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126657135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ashwin Salvi, R. Hanson, Rodrigo Zermeno, G. Regner, M. Sellnau, F. Redon
Gasoline compression ignition (GCI) is a cost-effective approach to achieving diesel-like efficiencies with low emissions. Traditional challenges with GCI arise at low-load conditions due to low charge temperatures causing combustion instability and at high-load conditions due to peak cylinder pressure and noise limitations. The fundamental architecture of the two-stroke Achates Power Opposed-Piston Engine (OP Engine) enables GCI by decoupling piston motion from cylinder scavenging, allowing for flexible and independent control of cylinder residual fraction and temperature leading to improved low load combustion. In addition, the high peak cylinder pressure and noise challenges at high-load operation are mitigated by the lower BMEP operation and faster heat release for the same pressure rise rate of the OP Engine. These advantages further solidify the performance benefits of the OP Engine and demonstrate the near-term feasibility of advanced combustion technologies, enabled by the opposed-piston architecture. This paper presents initial results from a steady state testing on a brand new 2.7L OP GCI multi-cylinder engine. A part of the recipe for successful GCI operation calls for high compression ratio, leading to higher combustion stability at low-loads, higher efficiencies, and lower cycle HC+NOx emissions. In addition, initial results on catalyst light-off mode with GCI are also presented. The OP Engine’s architectural advantages enable faster and earlier catalyst light-off while producing low emissions, which further improves cycle emissions and fuel consumption over conventional engines.
汽油压缩点火(GCI)是一种经济有效的方法，以实现类似柴油的效率和低排放。传统的GCI挑战出现在低负荷条件下，因为低装药温度会导致燃烧不稳定，而在高负荷条件下，由于峰值气缸压力和噪音限制。二冲程Achates Power对置活塞发动机(OP Engine)的基本结构通过将活塞运动与气缸扫气分离，从而实现GCI，从而灵活独立地控制气缸残余馏分和温度，从而改善低负荷燃烧。此外，在相同的压力上升速率下，较低的BMEP运行和更快的热量释放减轻了高负荷运行时的峰值气缸压力和噪音挑战。这些优势进一步巩固了OP发动机的性能优势，并证明了在对置活塞架构下先进燃烧技术的近期可行性。本文介绍了一种全新的2.7L OP GCI多缸发动机稳态测试的初步结果。GCI成功运行的秘诀之一是需要高压缩比，从而在低负荷下实现更高的燃烧稳定性、更高的效率和更低的循环HC+NOx排放。此外，还给出了GCI对催化剂点火模式的初步研究结果。与传统发动机相比，OP发动机的结构优势能够更快、更早地催化点火，同时产生低排放，进一步改善循环排放和燃油消耗。
{"title":"Initial Results on a New Light-Duty 2.7L Opposed-Piston Gasoline Compression Ignition Multi-Cylinder Engine","authors":"Ashwin Salvi, R. Hanson, Rodrigo Zermeno, G. Regner, M. Sellnau, F. Redon","doi":"10.1115/ICEF2018-9610","DOIUrl":"https://doi.org/10.1115/ICEF2018-9610","url":null,"abstract":"Gasoline compression ignition (GCI) is a cost-effective approach to achieving diesel-like efficiencies with low emissions. Traditional challenges with GCI arise at low-load conditions due to low charge temperatures causing combustion instability and at high-load conditions due to peak cylinder pressure and noise limitations. The fundamental architecture of the two-stroke Achates Power Opposed-Piston Engine (OP Engine) enables GCI by decoupling piston motion from cylinder scavenging, allowing for flexible and independent control of cylinder residual fraction and temperature leading to improved low load combustion. In addition, the high peak cylinder pressure and noise challenges at high-load operation are mitigated by the lower BMEP operation and faster heat release for the same pressure rise rate of the OP Engine. These advantages further solidify the performance benefits of the OP Engine and demonstrate the near-term feasibility of advanced combustion technologies, enabled by the opposed-piston architecture.\u0000 This paper presents initial results from a steady state testing on a brand new 2.7L OP GCI multi-cylinder engine. A part of the recipe for successful GCI operation calls for high compression ratio, leading to higher combustion stability at low-loads, higher efficiencies, and lower cycle HC+NOx emissions. In addition, initial results on catalyst light-off mode with GCI are also presented. The OP Engine’s architectural advantages enable faster and earlier catalyst light-off while producing low emissions, which further improves cycle emissions and fuel consumption over conventional engines.","PeriodicalId":441369,"journal":{"name":"Volume 1: Large Bore Engines; Fuels; Advanced Combustion","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126684669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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