The Experts below are selected from a list of 17850 Experts worldwide ranked by ideXlab platform
Evatt R Hawkes - One of the best experts on this subject based on the ideXlab platform.
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Effect of intake air temperature and common-rail pressure on ethanol combustion in a single-cylinder light-duty diesel Engine
Fuel, 2016Co-Authors: Changhwan Woo, Sanghoon Kook, Evatt R HawkesAbstract:Gasoline compression ignition (GCI) Engines have a great potential to achieve the simultaneous reduction of smoke and nitrogen oxides (NOx) emissions via partially premixed combustion (PPC) using Low cetane number fuel for the extended pre-combustion mixing time. The premixed combustion realised in high compression ratio Engines also improves the Engine efficiency with previous studies often reporting 50% brake efficiency or higher. The ability to control the combustion phasing by the fuel injection timing differentiates this new regime from widely investigated homogenous charge compression ignition (HCCI) or its variants making it a practical alternative to conventional gasoline or diesel combustion. In this study, ethanol produced from biomass has been selected as a GCI fuel, considering its higher octane number (i.e. Lower cetane number), evaporative cooling and oxygen contents than gasoline, all of which could further improve the GCI combustion. The ethanol-fuelled GCI, or in short ECI, was investigated in a single-cylinder automotive-size diesel Engine connected to an Eddy Current (EC) dynamometer. The focus is the Engine start-up conditions and the influence of intake air temperature and common-rail pressure on ECI combustion. From the experiments, it is found that the Engine can be successfully started by ECI combustion using a conventional start motor at Low Engine Speed of 1000 rpm when the intake air temperature is higher than 60 °C. For higher Engine Speed of 2000 rpm and stable operations, however, a double injection strategy and increased intake air temperature of 80 °C are required suggesting the important role of wall wetting on ECI combustion. From the intake air temperature variations up to 100 °C, it is observed that both the peak in-cylinder pressure and heat release rate increase, leading to the improved Engine efficiency. The measured Engine-out emissions of unburnt hydrocarbon and carbon monoxide also show a decreasing trend with increasing intake air temperature, likely due to the reduced wall wetting. The smoke and NOxemissions of ECI combustion are much Lower than those of a conventional diesel, regardless of the intake air temperature. The common-rail pressure variations at fixed brake power conditions show that the friction loss increases with increasing common-rail pressure, leading to the increased brake specific fuel consumption. This suggests that the common-rail pressure for ECI applications should remain Low for the efficiency gain. The Engine-out emissions also exhibit an increasing trend with increasing common-rail pressure although the smoke and NOxlevels are always Lower than that of a conventional diesel. Compared to the diesel reference case, the optimised Engine operating conditions of this study achieves 50% higher fuel conversion efficiency, 5% Lower brake specific fuel consumption and 27% Lower NOxemissions while smoke emissions are kept at a negligible level.
Zuohua Huang - One of the best experts on this subject based on the ideXlab platform.
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experimental study on the performance of and emissions from a Low Speed light duty diesel Engine fueled with n butanol diesel and isobutanol diesel blends
Proceedings of the Institution of Mechanical Engineers Part D: Journal of Automobile Engineering, 2013Co-Authors: Guo Li, Xiaolei Gu, Xue Jiang, Zuohua HuangAbstract:The effects of isobutanol- and n-butanol-enriched diesel fuel on the diesel Engine performance and emissions are investigated. Neat diesel, 15% isobutanol–85% diesel, 30% isobutanol–70% diesel, 15% n-butanol–85% diesel, and 30% n-butanol–70% diesel blends are investigated in this study. The tests were carried out at light and medium loads and a fixed Low Engine Speed, and by using various combinations of the exhaust gas recirculation rate and the injection timing to investigate the effect of the molecular structure difference on soot formation. The results show that n-butanol–diesel blends give a longer ignition delay than isobutanol–diesel blends do. Hence isobutanol has a higher peak cylinder pressure and a higher premixed heat release rate than n-butanol does. Adding butanol (isobutanol and/or n-butanol) to diesel fuel is able to decrease the soot emissions substantially, while the change in the nitrogen oxide emissions varies slightly. Soot emissions from n-butanol–diesel blends are Lower than those f...
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Combustion behaviors of a direct-injection Engine operating on various fractions of natural gas-hydrogen blends
International Journal of Hydrogen Energy, 2007Co-Authors: Jinhua Wang, Haiyan Miao, Ke Zeng, Zuohua Huang, Bing Liu, Yu Fang, Deming JiangAbstract:Abstract Combustion behaviors of a direct injection Engine operating on various fractions of natural gas–hydrogen blends were investigated. The results showed that the brake effective thermal efficiency increased with the increase of hydrogen fraction at Low and medium Engine loads and high thermal efficiency was maintained at the high Engine load. The phase of the heat release curve advanced with the increase of hydrogen fraction in the blends. The rapid combustion duration decreased and the heat release rate increased with the increase of hydrogen fraction in the blends. This phenomenon was more obviously at the Low Engine Speed, suggesting that the effect of hydrogen addition on the enhancement of burning velocity plays more important role at relatively Low cylinder air motion. The maximum mean gas temperature and the maximum rate of pressure rise increased remarkably when the hydrogen volumetric fraction exceeds 20% as the burning velocity increases exponentially with the increase of hydrogen fraction in fuel blends. Exhaust HC and CO 2 concentrations decreased with the increase of the hydrogen fraction in fuel blends. Exhaust NO x concentration increased with the increase of hydrogen fraction at high Engine load. The study suggested that the optimum hydrogen volumetric fraction in natural gas–hydrogen blends is around 20% to get the compromise in both Engine performance and emissions.
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Combustion characteristics of a direct-injection Engine fueled with natural gas-hydrogen mixtures
Energy & Fuels, 2006Co-Authors: Zuohua Huang, Jinrong Yu, Ke Zeng, Jinhua Wang, Bing Liu, Deming JiangAbstract:In this article, we experimentally studied combustion characteristics of a direct-injection spark-ignited Engine fueled with natural gas-hydrogen blends. For a specific operation mode, the results show that the heat release rate decreases with the increase of hydrogen fraction in the blends when hydrogen fraction is less than a certain volumetric fraction while the heat release rate increases with the increase of hydrogen fraction in the blends when hydrogen fraction is over a certain value. This phenomenon indicates that only when the hydrogen fraction in natural gas reaches a certain fraction can a large improvement in combustion be realized. Flame development duration, rapid combustion duration, and total combustion duration increase with the increase of hydrogen fraction in the blends when hydrogen fraction is less than a certain volumetric fraction, while they decrease with the increase of hydrogen fraction when hydrogen fraction is over the value. The crank angle of the center of heat release curve moves away from the top-dead-center with the increase of hydrogen fraction in the blends when the hydrogen fraction is less than a certain volumetric fraction, and it moves close to the top-dead-center when hydrogen fraction is over the certain value. Maximum cylinder gas pressure, maximum mean gas temperature, maximum rate of pressure rise, and maximum heat release rate decrease with the increase of hydrogen fraction when the hydrogen fraction is less than a certain volumetric fraction, and they increase with the increase of hydrogen fraction when hydrogen fraction is over the certain value. For fixed injection duration, the influence of hydrogen addition on natural gas-hydrogen mixture combustion is larger at Low Engine Speed operation condition than that at high Engine Speed operation condition.
Deming Jiang - One of the best experts on this subject based on the ideXlab platform.
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Combustion behaviors of a direct-injection Engine operating on various fractions of natural gas-hydrogen blends
International Journal of Hydrogen Energy, 2007Co-Authors: Jinhua Wang, Haiyan Miao, Ke Zeng, Zuohua Huang, Bing Liu, Yu Fang, Deming JiangAbstract:Abstract Combustion behaviors of a direct injection Engine operating on various fractions of natural gas–hydrogen blends were investigated. The results showed that the brake effective thermal efficiency increased with the increase of hydrogen fraction at Low and medium Engine loads and high thermal efficiency was maintained at the high Engine load. The phase of the heat release curve advanced with the increase of hydrogen fraction in the blends. The rapid combustion duration decreased and the heat release rate increased with the increase of hydrogen fraction in the blends. This phenomenon was more obviously at the Low Engine Speed, suggesting that the effect of hydrogen addition on the enhancement of burning velocity plays more important role at relatively Low cylinder air motion. The maximum mean gas temperature and the maximum rate of pressure rise increased remarkably when the hydrogen volumetric fraction exceeds 20% as the burning velocity increases exponentially with the increase of hydrogen fraction in fuel blends. Exhaust HC and CO 2 concentrations decreased with the increase of the hydrogen fraction in fuel blends. Exhaust NO x concentration increased with the increase of hydrogen fraction at high Engine load. The study suggested that the optimum hydrogen volumetric fraction in natural gas–hydrogen blends is around 20% to get the compromise in both Engine performance and emissions.
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Combustion characteristics of a direct-injection Engine fueled with natural gas-hydrogen mixtures
Energy & Fuels, 2006Co-Authors: Zuohua Huang, Jinrong Yu, Ke Zeng, Jinhua Wang, Bing Liu, Deming JiangAbstract:In this article, we experimentally studied combustion characteristics of a direct-injection spark-ignited Engine fueled with natural gas-hydrogen blends. For a specific operation mode, the results show that the heat release rate decreases with the increase of hydrogen fraction in the blends when hydrogen fraction is less than a certain volumetric fraction while the heat release rate increases with the increase of hydrogen fraction in the blends when hydrogen fraction is over a certain value. This phenomenon indicates that only when the hydrogen fraction in natural gas reaches a certain fraction can a large improvement in combustion be realized. Flame development duration, rapid combustion duration, and total combustion duration increase with the increase of hydrogen fraction in the blends when hydrogen fraction is less than a certain volumetric fraction, while they decrease with the increase of hydrogen fraction when hydrogen fraction is over the value. The crank angle of the center of heat release curve moves away from the top-dead-center with the increase of hydrogen fraction in the blends when the hydrogen fraction is less than a certain volumetric fraction, and it moves close to the top-dead-center when hydrogen fraction is over the certain value. Maximum cylinder gas pressure, maximum mean gas temperature, maximum rate of pressure rise, and maximum heat release rate decrease with the increase of hydrogen fraction when the hydrogen fraction is less than a certain volumetric fraction, and they increase with the increase of hydrogen fraction when hydrogen fraction is over the certain value. For fixed injection duration, the influence of hydrogen addition on natural gas-hydrogen mixture combustion is larger at Low Engine Speed operation condition than that at high Engine Speed operation condition.
Changhwan Woo - One of the best experts on this subject based on the ideXlab platform.
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Effect of intake air temperature and common-rail pressure on ethanol combustion in a single-cylinder light-duty diesel Engine
Fuel, 2016Co-Authors: Changhwan Woo, Sanghoon Kook, Evatt R HawkesAbstract:Gasoline compression ignition (GCI) Engines have a great potential to achieve the simultaneous reduction of smoke and nitrogen oxides (NOx) emissions via partially premixed combustion (PPC) using Low cetane number fuel for the extended pre-combustion mixing time. The premixed combustion realised in high compression ratio Engines also improves the Engine efficiency with previous studies often reporting 50% brake efficiency or higher. The ability to control the combustion phasing by the fuel injection timing differentiates this new regime from widely investigated homogenous charge compression ignition (HCCI) or its variants making it a practical alternative to conventional gasoline or diesel combustion. In this study, ethanol produced from biomass has been selected as a GCI fuel, considering its higher octane number (i.e. Lower cetane number), evaporative cooling and oxygen contents than gasoline, all of which could further improve the GCI combustion. The ethanol-fuelled GCI, or in short ECI, was investigated in a single-cylinder automotive-size diesel Engine connected to an Eddy Current (EC) dynamometer. The focus is the Engine start-up conditions and the influence of intake air temperature and common-rail pressure on ECI combustion. From the experiments, it is found that the Engine can be successfully started by ECI combustion using a conventional start motor at Low Engine Speed of 1000 rpm when the intake air temperature is higher than 60 °C. For higher Engine Speed of 2000 rpm and stable operations, however, a double injection strategy and increased intake air temperature of 80 °C are required suggesting the important role of wall wetting on ECI combustion. From the intake air temperature variations up to 100 °C, it is observed that both the peak in-cylinder pressure and heat release rate increase, leading to the improved Engine efficiency. The measured Engine-out emissions of unburnt hydrocarbon and carbon monoxide also show a decreasing trend with increasing intake air temperature, likely due to the reduced wall wetting. The smoke and NOxemissions of ECI combustion are much Lower than those of a conventional diesel, regardless of the intake air temperature. The common-rail pressure variations at fixed brake power conditions show that the friction loss increases with increasing common-rail pressure, leading to the increased brake specific fuel consumption. This suggests that the common-rail pressure for ECI applications should remain Low for the efficiency gain. The Engine-out emissions also exhibit an increasing trend with increasing common-rail pressure although the smoke and NOxlevels are always Lower than that of a conventional diesel. Compared to the diesel reference case, the optimised Engine operating conditions of this study achieves 50% higher fuel conversion efficiency, 5% Lower brake specific fuel consumption and 27% Lower NOxemissions while smoke emissions are kept at a negligible level.
Phil Jenner - One of the best experts on this subject based on the ideXlab platform.
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Lean-burn characteristics of a turbocharged opposed rotary piston Engine fuelled with hydrogen at Low Engine Speed conditions
International Journal of Hydrogen Energy, 2021Co-Authors: Jianbing Gao, Guohong Tian, Yuanjian Zhang, Shikai Xing, Phil JennerAbstract:Abstract Opposed rotary piston (ORP) Engines have high power density and compact designs which meet the requirements of power sources of hybrid vehicles. Hydrogen applications to ORP Engines can effectively decrease greenhouse gas emissions; however, hydrogen combustion in ORP Engines around stoichiometric ratio generated large quantities of nitrogen oxides (NOx), especially for Low Engine Speed conditions. Lean-burn as an effective method to decrease NOx emissions was adopted in this research. A 3D numerical simulation method was used to explore the effect of equivalence ratio (≤1) on combustion and NOx emission characteristics of this ORP Engine fuelled with hydrogen. The results indicated that peak in-cylinder pressure increased with equivalence ratio for 1000 revolutions per minute (RPM); however, the value over the equivalence ratio of 0.9 was the maximum among 2000 RPM scenarios. The effect of equivalence ratio on heat release rates was greatly dependent on the Engine Speeds. Start of combustion over 1000 RPM Engine Speed was advanced with the increase of equivalence ratio; and it was the earliest over the equivalence ratio of 0.9 at 2000 RPM conditions. During the exhaust stroke, in-cylinder pressure of free discharge was much higher than atmosphere pressure, which significantly increased the pumping losses of exhaust stroke. Accumulated NOx emissions over the equivalence ratio of 0.9 reached the maximum value for given Engine Speeds; and the NOx emissions were almost zero for severe lean-burn (
