The Experts below are selected from a list of 28986 Experts worldwide ranked by ideXlab platform
Jesus Benajes - One of the best experts on this subject based on the ideXlab platform.
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evaluating the reactivity controlled compression ignition operating range limits in a high compression ratio medium duty diesel engine fueled with biodiesel and ethanol
International Journal of Engine Research, 2017Co-Authors: Jesus Benajes, Antonio Garcia, Javier Monsalveserrano, Iyad Balloul, Gerard PradelAbstract:This work investigates the load limits of reactivity controlled compression ignition combustion, a dual-fuel concept which combines port fuel injection of low-reactivity fuels with direct injection of diesel fuel, in a medium-duty diesel engine. The experiments were conducted in a single-cylinder diesel engine derived from the multi-cylinder production engine. In this sense, the stock turbocharger and exhaust gas recirculation systems were replaced by an external compressor and dedicated low-pressure exhaust gas recirculation loop, respectively. Additionally, a port fuel injector was installed in the Intake manifold to allow gasoline injection. First, this article presents some results highlighting the effect of the exhaust gas recirculation rate, gasoline fraction, diesel start of injection, diesel injection strategy and Intake Temperature on the emissions, performance and combustion development in a representative operating condition: 1200 r/min and 6.5 bar indicated mean effective pressure (25% load). ...
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a rcci operational limits assessment in a medium duty compression ignition engine using an adapted compression ratio
Energy Conversion and Management, 2016Co-Authors: Jesus Benajes, Antonio Garcia, Jose V Pastor, Vicente BoronatAbstract:Abstract Reactivity Controlled Compression Ignition concept offers an ultra-low nitrogen oxide and soot emissions with a high thermal efficiency. This work investigates the capabilities of this low Temperature combustion concept to work on the whole map of a medium duty engine proposing strategies to solve its main challenges. In this sense, an extension to high loads of the concept without exceeding mechanical stress as well as a mitigation of carbon oxide and unburned hydrocarbons emissions at low load together with a fuel consumption penalty have been identified as main Reactivity Controlled Compression Ignition drawbacks. For this purpose, a single cylinder engine derived from commercial four cylinders medium-duty engine with an adapted compression ratio of 12.75 is used. Commercial 95 octane gasoline was used as a low reactivity fuel and commercial diesel as a high reactivity fuel. Thus, the study consists of two different parts. Firstly, the work is focused on the development and evaluation of an engine map trying to achieve the maximum possible load without exceeding a pressure rise rate of 15 bar/CAD. The second part holds on improving fuel consumption and carbon oxide and unburned hydrocarbons emissions at low load. Results suggest that it is possible to achieve up to 80% of nominal conventional diesel combustion engine load without overpassing the constraints of pressure rise rate (below 15 bar/CAD) and maximum pressure peak (below 190 bar) while obtaining ultra-low levels of nitrogen oxide and soot emissions. Regarding low load challenges, it has developed a particular methodology sweeping the gasoline-diesel blend together with Intake Temperature or exhaust gas recirculation maintaining constant the combustion phasing and ultra-low nitrogen oxide and soot emissions. As a result a drastic decrease carbon oxide and unburned hydrocarbons emissions is obtained with a slight fuel consumption improvement.
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the role of the in cylinder gas Temperature and oxygen concentration over low load reactivity controlled compression ignition combustion efficiency
Energy, 2014Co-Authors: José M. Desantes, Jesus Benajes, Antonio Garcia, Javier MonsalveserranoAbstract:Several studies carried out with the aim of improving the RCCI (reactivity controlled compression ignition) concept in terms of thermal efficiency conclude that the main cause of the reduced efficiency at light loads is the reduced combustion efficiency. The present study used both a 3D computational model and engine experiments to explore the effect of the oxygen concentration and Intake Temperature on RCCI combustion efficiency at light load. The experiments were conducted using a single-cylinder heavy-duty research diesel engine adapted for dual fuel operation.
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the role of the in cylinder gas Temperature and oxygen concentration over low load reactivity controlled compression ignition combustion efficiency
Energy, 2014Co-Authors: José M. Desantes, Jesus Benajes, Antonio Garcia, Javier MonsalveserranoAbstract:Abstract Several studies carried out with the aim of improving the RCCI (reactivity controlled compression ignition) concept in terms of thermal efficiency conclude that the main cause of the reduced efficiency at light loads is the reduced combustion efficiency. The present study used both a 3D computational model and engine experiments to explore the effect of the oxygen concentration and Intake Temperature on RCCI combustion efficiency at light load. The experiments were conducted using a single-cylinder heavy-duty research diesel engine adapted for dual fuel operation. Results suggest that it is possible to achieve an improvement of around 1.5% in the combustion efficiency with both strategies studied; the combined effect of Intake Temperature and in-cylinder fuel blending as well as the combined effect of oxygen concentration and in-cylinder fuel blending (ICFB). In addition, the direct comparison of both strategies suggests that the combustion losses trend is mainly associated to the in-cylinder equivalence ratio stratification, which is determined by the diesel to gasoline ratio in the blend since the injection timing is kept constant for all the tests. Moreover, the combined effect of the Intake Temperature and ICFB promotes a slight improvement in the combustion losses over the combined effect of the oxygen concentration and ICFB.
Yong Qian - One of the best experts on this subject based on the ideXlab platform.
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combustion and emission characteristics of gasoline hydrogenated catalytic biodiesel blends in gasoline compression ignition engines under different loads of double injection strategies
Applied Energy, 2019Co-Authors: Wenjun Zhong, Tamilselvan Pachiannan, Zilong Li, Yong Qian, Yanzhi Zhang, Qian Wang, Zhixia He, Xingcai LuAbstract:Gasoline compression ignition mode is one of the low-Temperature combustion strategies using gasoline instead of diesel fuel and it is better than the other low-Temperature combustion modes in terms of ignition controllability. Difficulty in the ignition at low loads and maximum pressure rise rate during high loads is the main problem in commercializing this engine. In order to solve this problem, hydrogenated catalytic biodiesel is blended with gasoline in different proportions and its combustion and emission characteristics under different working loads are investigated in a single injection mode. Stable combustion is achieved using this gasoline/hydrogenated catalytic biodiesel blends without any combustion assistance and increasing Intake Temperature. Results show that G70H30 blending fuel illustrates a comprehensively better combustion and emissions performance. However, the high maximum pressure rise rate at high loads and high particulate matter emission are the main problems. Hence, multiple injection strategies are applied for G70H30 to solve the above problem. It reveals that the particulate matter emission for 20% pilot injection ratio is lower than that of single injection mode. The maximum pressure rise rate of 20% or 30% pilot injection ratio can meet the engine limit. While the carbon monoxide and hydrocarbons emissions for double injection mode are higher than that of single injection mode and it increases with increasing pilot injection ratio.
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achieving high efficient gasoline compression ignition gci combustion through the cooperative control of fuel octane number and air Intake conditions
Fuel, 2019Co-Authors: Chenxu Jiang, Guibin Liu, Yong QianAbstract:Abstract Gasoline compression ignition (GCI) is a promising advanced combustion mode to improve the fuel economy and reduce emissions. The Intake conditions have significant effects on GCI combustion. To explore the proper Intake conditions and fuels to achieve high efficiency under all loads, several experimental tests were carried out to investigate the effects of Intake pressure and Intake Temperature on GCI combustion and emissions in this paper. Four primary reference fuels (PRF) with the research octane number (RON) of 90, 80, 70 and 60 were applied in this paper, which are recorded as PRF90, PRF80, PRF70 and PRF60. The results show that high efficiency under all loads could be achieved indeed by choosing proper Intake pressure, Intake Temperature and fuels. The increase in Intake pressure could significantly improve the fuel economy and decrease the CO, THC and NOx emissions. The increase in Intake Temperature increased the thermal efficiency under low loads and decreased the CO and THC emissions, but increased the NOx emissions simultaneously. However, with the increase in loads, the increased Intake Temperature reduced the volumetric efficiency, thus worsening the fuel economy. In addition, the influence of Intake Temperature on GCI combustion decreased with the decrease in RON. In general, high efficiency could be achieved by applying PRF70 and Intake heating under low loads, as well as PRF70 under medium loads and PRF90 under high loads without Intake heating, combined with supercharge under all loads. The highest indicated thermal efficiency (ITE) could reach 47% with PRF70 under medium loads.
Andre L Oehma - One of the best experts on this subject based on the ideXlab platform.
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influence of intermediate Temperature heat release on autoignition reactivity of single stage ignition fuels with varying octane sensitivity
Proceedings of the Combustion Institute, 2020Co-Authors: Kwang Hee Yoo, Alexander K. Voice, Andre L OehmaAbstract:Abstract This study investigates the effects of intermediate Temperature heat release (ITHR) on autoignition reactivity of full boiling range gasolines with different octane sensitivity through Intake Temperature and simulated exhaust gas recirculation (EGR) sweeps in a homogenous charge compression ignition (HCCI) engine. To isolate the ITHR effects, low Temperature reactivity was suppressed through the use of high Intake Temperature and low Intake oxygen mole fraction. For quantification of ITHR, a new method was applied to the engine data by examining the maximum value of the second derivative of heat release rate. Combustion phasing comparisons of fuels with octane sensitivity showed that fuel with less octane sensitivity became more reactive as Intake Temperature and simulated EGR ratio decreased, while fuel with higher octane sensitivity had a reverse trend. For all of the fuels that were tested, the amount of ITHR increased as the Intake Temperature and oxygen mole fraction increased. These ITHR trends, depending on octane sensitivity, were almost identical with the trends of combustion phasing, showing that ITHR significantly affects fuel autoignition reactivity and determines octane sensitivity.
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impact of fuel composition and Intake pressure on lean autoignition of surrogate gasoline fuels in a cfr engine
Energy & Fuels, 2017Co-Authors: Vickey Kalaska, Dongil Kang, Andre L OehmaAbstract:The critical compression ratio (CCR) criterion (defined as the minimum compression ratio at which the fuel shows initial signs of autoignition) was examined for various gasoline surrogate fuels in a motored engine. This investigation builds on the concept of CCR which is a good indicator of a fuel’s autoignition characteristics, to study the fuel compositional effects with increasing Intake manifold pressure. The blends consisted of binary and ternary mixtures of n-heptane and/or iso-octane, and a fuel of interest. These fuels of interest were higher octane components; toluene, ethanol, and iso-butanol. A lean condition (Φ = 0.25) with varying Intake pressure (atmospheric to 3 bar, abs) and at a constant Intake Temperature of 155 °C was used to investigate the ignition behavior of all the blends. Two sets of blends consisted of varying percentages of fuels of interest, formulated to approximately have research octane numbers (RON) at 80 and 100. For comparison, neat iso-octane was selected as the represen...
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autoignition studies of c5 isomers in a motored engine
Proceedings of the Combustion Institute, 2017Co-Authors: Dongil Kang, Song Cheng, Stanislav V Ohac, Andre L Oehma, Yi YangAbstract:Abstract This study explores the autoignition characteristics of three C5 isomers, namely n -pentane, 2-methylbutane ( iso -pentane) and 2,2-dimethylpropane ( neo -pentane). These measurements are intended to enhance understanding of C5 autoignition chemistry, and provide experimental data to guide improvements to a general hydrocarbon oxidation mechanism. To that end, the autoignition behavior of these three C5 isomers was investigated in a modified CFR engine at an Intake Temperature of 120 °C and a fixed engine speed of 600 rpm to determine the critical compression ratio (CCR) at which hot ignition occurs. To find the critical compression ratio, the engine compression ratio (CR) was gradually increased to the point where CO in the engine exhaust rapidly decreased and significant high Temperature heat release was observed, while holding equivalence ratio constant. Fundamental ignition behaviors such as the CCR and the calculated percentage of low Temperature heat release (%LTHR) demonstrate the impact of chain length and methyl substitutions on ignition reactivity. The %LTHR shows a stronger two stage heat release for n- pentane than for neo- pentane observed at critical ignition conditions. In contrast, single stage heat release is observed for iso- pentane, leading to the weakest overall oxidation reactivity of the three isomers. Key reaction paths forming conjugate alkenes and C 5 oxygenated species control the autoignition reactivity of n- pentane and iso- pentane within the low Temperature and NTC regimes. However, neo- pentane forms no conjugate alkene due to its unique molecular structure, and instead produces iso -butene to retard its oxidation.
Hua Zhao - One of the best experts on this subject based on the ideXlab platform.
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investigation on gasoline homogeneous charge compression ignition hcci combustion implemented by residual gas trapping combined with Intake preheating through waste heat recovery
Energy Conversion and Management, 2014Co-Authors: Hui Xie, Hua Zhao, Tao ChenAbstract:Abstract Homogeneous charge compression ignition (HCCI) combustion achieved by residual gas trapping suffers from the limitation of the low load extension and fuel economy penalties whilst achieved by Intake preheating alone is limited by the high Intake thermal requirement and waste heat recovery. In the presented research, systematic engine experiments were carried out on a single cylinder engine on the combined use of residual gas trapping and Intake preheating to achieve optimized combustion and better fuel conversion efficiency in the HCCI operational range. The effect of different combinations between residual gas trapping and Intake preheating on HCCI combustion was explored and analyzed. It was indicated that the implementation transition from residual gas trapping to Intake preheating significantly influenced the fuel economy and emissions. The decreased loss resulting from changed valve configuration contributed much more than half of the fuel economy improvement. The variation in emissions depended both on the combustion Temperature influenced by dilution charge and the in-cylinder distribution affected by implementation form. It was also demonstrated that the increased benefit became less when the Intake Temperature further went up. Thus a relatively reasonable compromise between Intake thermal demand and engine efficiency could be achieved to optimize the HCCI combustion by combining waste heat recovery and residual gas trapping. Compared to negative valve overlap method alone, the supplementary of Intake preheating by waste heat recovery provided 8–12% fuel economy improvement throughout the typical load range of HCCI combustion. Also the low load boundary was effectively extended to 0.8 bar, without suffering excessive increase in CO and HC emissions.
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understanding of controlled autoignition combustion in a four stroke gasoline engine
Proceedings of the Institution of Mechanical Engineers Part D: Journal of Automobile Engineering, 2001Co-Authors: Hua Zhao, Zhiju Peng, Nicos LadommatosAbstract:Controlled autoignition (CAI) combustion has recently emerged as a viable alternative combustion process to the conventional spark ignition or compression ignition process for internal combustion engines, owing to its potential for high efficiency and extremely low NOx and particulate emissions. Since CAI combustion is a process dominated by chemical kinetics of the fuel-air mixture, an engine simulation model with detailed chemical kinetics has been developed and applied to a four-stroke gasoline engine fuelled with isooctane. After calibration and validation, the engine simulation model was used to study the effects of the Intake Temperature, exhaust gas recirculation (EGR), the air-fuel ratio, the compression ratio and the engine speed on CAI combustion in a four-stroke gasoline engine. The characteristics of CAI combustion investigated include the autoignition timing, the partial burning and knocking combustion and NO emission. Results show that CAI combustion could be achieved within a limited speed and load range. The lower end of the CAI combustion range was affected by partial burning, and the higher end of its operation was limited by knocking combustion. Among the engine parameters investigated, the Intake charge Temperature and EGR had the greatest effect on the CAI combustion process. The effect of EGR was further analysed in terms of its thermal (increase in heat capacity), dilution, chemical and charge heating effects by means of a series of simulation studies. It was found that the charge heating effect caused advanced ignition timing, faster heat release rate and moderate reduction in the CAI combustion duration. The thermal effect (increased heat capacity) retarded ignition, extended combustion duration and slowed down heat release rate. The dilution effect also resulted in longer combustion duration and slower burning but it did not affect the ignition timing. The chemical effect was found to accelerate the combustion process when the percentage of EGR was large.
Antonio Garcia - One of the best experts on this subject based on the ideXlab platform.
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evaluating the reactivity controlled compression ignition operating range limits in a high compression ratio medium duty diesel engine fueled with biodiesel and ethanol
International Journal of Engine Research, 2017Co-Authors: Jesus Benajes, Antonio Garcia, Javier Monsalveserrano, Iyad Balloul, Gerard PradelAbstract:This work investigates the load limits of reactivity controlled compression ignition combustion, a dual-fuel concept which combines port fuel injection of low-reactivity fuels with direct injection of diesel fuel, in a medium-duty diesel engine. The experiments were conducted in a single-cylinder diesel engine derived from the multi-cylinder production engine. In this sense, the stock turbocharger and exhaust gas recirculation systems were replaced by an external compressor and dedicated low-pressure exhaust gas recirculation loop, respectively. Additionally, a port fuel injector was installed in the Intake manifold to allow gasoline injection. First, this article presents some results highlighting the effect of the exhaust gas recirculation rate, gasoline fraction, diesel start of injection, diesel injection strategy and Intake Temperature on the emissions, performance and combustion development in a representative operating condition: 1200 r/min and 6.5 bar indicated mean effective pressure (25% load). ...
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a rcci operational limits assessment in a medium duty compression ignition engine using an adapted compression ratio
Energy Conversion and Management, 2016Co-Authors: Jesus Benajes, Antonio Garcia, Jose V Pastor, Vicente BoronatAbstract:Abstract Reactivity Controlled Compression Ignition concept offers an ultra-low nitrogen oxide and soot emissions with a high thermal efficiency. This work investigates the capabilities of this low Temperature combustion concept to work on the whole map of a medium duty engine proposing strategies to solve its main challenges. In this sense, an extension to high loads of the concept without exceeding mechanical stress as well as a mitigation of carbon oxide and unburned hydrocarbons emissions at low load together with a fuel consumption penalty have been identified as main Reactivity Controlled Compression Ignition drawbacks. For this purpose, a single cylinder engine derived from commercial four cylinders medium-duty engine with an adapted compression ratio of 12.75 is used. Commercial 95 octane gasoline was used as a low reactivity fuel and commercial diesel as a high reactivity fuel. Thus, the study consists of two different parts. Firstly, the work is focused on the development and evaluation of an engine map trying to achieve the maximum possible load without exceeding a pressure rise rate of 15 bar/CAD. The second part holds on improving fuel consumption and carbon oxide and unburned hydrocarbons emissions at low load. Results suggest that it is possible to achieve up to 80% of nominal conventional diesel combustion engine load without overpassing the constraints of pressure rise rate (below 15 bar/CAD) and maximum pressure peak (below 190 bar) while obtaining ultra-low levels of nitrogen oxide and soot emissions. Regarding low load challenges, it has developed a particular methodology sweeping the gasoline-diesel blend together with Intake Temperature or exhaust gas recirculation maintaining constant the combustion phasing and ultra-low nitrogen oxide and soot emissions. As a result a drastic decrease carbon oxide and unburned hydrocarbons emissions is obtained with a slight fuel consumption improvement.
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the role of the in cylinder gas Temperature and oxygen concentration over low load reactivity controlled compression ignition combustion efficiency
Energy, 2014Co-Authors: José M. Desantes, Jesus Benajes, Antonio Garcia, Javier MonsalveserranoAbstract:Several studies carried out with the aim of improving the RCCI (reactivity controlled compression ignition) concept in terms of thermal efficiency conclude that the main cause of the reduced efficiency at light loads is the reduced combustion efficiency. The present study used both a 3D computational model and engine experiments to explore the effect of the oxygen concentration and Intake Temperature on RCCI combustion efficiency at light load. The experiments were conducted using a single-cylinder heavy-duty research diesel engine adapted for dual fuel operation.
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the role of the in cylinder gas Temperature and oxygen concentration over low load reactivity controlled compression ignition combustion efficiency
Energy, 2014Co-Authors: José M. Desantes, Jesus Benajes, Antonio Garcia, Javier MonsalveserranoAbstract:Abstract Several studies carried out with the aim of improving the RCCI (reactivity controlled compression ignition) concept in terms of thermal efficiency conclude that the main cause of the reduced efficiency at light loads is the reduced combustion efficiency. The present study used both a 3D computational model and engine experiments to explore the effect of the oxygen concentration and Intake Temperature on RCCI combustion efficiency at light load. The experiments were conducted using a single-cylinder heavy-duty research diesel engine adapted for dual fuel operation. Results suggest that it is possible to achieve an improvement of around 1.5% in the combustion efficiency with both strategies studied; the combined effect of Intake Temperature and in-cylinder fuel blending as well as the combined effect of oxygen concentration and in-cylinder fuel blending (ICFB). In addition, the direct comparison of both strategies suggests that the combustion losses trend is mainly associated to the in-cylinder equivalence ratio stratification, which is determined by the diesel to gasoline ratio in the blend since the injection timing is kept constant for all the tests. Moreover, the combined effect of the Intake Temperature and ICFB promotes a slight improvement in the combustion losses over the combined effect of the oxygen concentration and ICFB.