Browse Topic: Lean burn engines

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Studying the Lean Burn Operation in Two-Wheelers to Increase Fuel Efficiency and Investigate the Use of Lean NOx Trap Catalyst (LNT) for Lean Burn System2024-32-005804/18/2025
This study offers an overview of the impact of lean burn technology in two-wheeler vehicles, specifically concentrating on enhancing the fuel economy and addressing the challenges associated with its adoption. Lean burn systems, characterized by a fuel-air mixture with a higher air content than stoichiometric ratio. The study focuses on technology which meets stringent emission standards while enabling the optimization of fuel efficiency. The lean burn system employs strategies to optimize air-fuel ratio using electronic fuel injection, ignition timing control, and advanced engine control algorithms like - updated torque modulation control algorithm for drivability, lambda control algorithm for rich and lean switch and NOx modelling algorithm for LNT catalyst efficiency tracking. The challenges related to lean burn systems, includes issues related to combustion stability, nitrogen oxide (NOx) emissions, and their impact on drivability, is summarized in the study. Mitigation strategies
Somasundaram, Karthikeyan, Sivaji, Purushothaman, John Derin, C, Vishal, Karwa, Manoj Kumar, S, Maynal, Rajesh
Investigation on the Applicability of Passive Type Pre-Chamber with One Port Fuel Injection System to Small Gasoline Engines2024-32-003304/18/2025
Pre-chamber combustion has been applied as a method of low fuel consumption in spark ignition engines, and in recent years the application of pre-chambers to gasoline engines has also been actively studied. In many gasoline engines, stoichiometric combustion is common. We decided that a passive type pre-chamber with only one port fuel injection is sufficient for stoichiometric combustion. The pre-chamber system relatively has two merits of lower cost and ease of installing than other prechamber systems. Therefore, we focused on investigating the effects of improving combustion speed and knock resistance in use of the passive type pre-chamber and the applicability of the pre-chamber system in various operating points. As the concrete approach, we evaluated the heat balance and the knock resistance with and without a pre-chamber in engine bench test. As a result, the knock resistance and the fuel consumption were improved. In addition, as a result of considering lean burn in the passive
Nakao, Yoshinori, Sakurai, Yota, Hisano, Atsushi, Saitou, Masahito, Suzuki, Tomoharu
Effect of Ignition Position on Lean Limit of Main Chamber Combustion in Pre-Chamber Ignition2024-32-002204/18/2025
An engine was built in this study that enabled the conditions in a pre-chamber and in the main combustion chamber to be visualized simultaneously for the purpose of elucidating the mechanism of pre-chamber combustion. An investigation was made of how the state of pre-chamber combustion, including the location of initial flame generation and its subsequent propagation, influenced pre-chamber jet combustion. The state of pre-chamber combustion was intentionally varied by changing the position of pre-chamber ignition. As a result, it was found that changing the position of pre-chamber ignition varied the location where the pre-chamber flame occurred, how the flame propagated and the timing and strength of the flame jet that was ejected into the main chamber. The results revealed that these differences in the state of pre-chamber combustion markedly changed the rate of combustion fluctuation, combustion period, lean-burn limit and other combustion characteristics depending on the ignition
Onuma, Takeru, Yamada, Hiroto, Ugajin, Taisei, Shinozaki, Kaito, Tahara, Ryota, Iijima, Akira
Effects of octane number and sensitivity on combustion of jet ignition engine2022-01-052503/29/2022
Octane number (ON) and octane sensitivity (OS), the fuel anti-konck indexes, are critical for the design of advanced jet ignition engines. In this study, twelve fuels with different research octane number (RON) and varying OS were formulated based on ethanol reference fuels (ERFs) to investigate effects of OS on combustion of jet ignition engine. The results indicated that jet ignition decreased ON demand of the fuel when compared with spark ignition. For jet ignition, the knocking intensity increased with the increase of OS under the same ON. For fuels with high and medium RON fuels (RON=100 and RON=92), a medium OS ranging from 3 to 5 was more favorable to achieve higher thermal efficiency. Though ignition delay and combustion duration decreased with the increase of OS, the combustion efficiency and the knocking intensity limited thermal efficiency of the fuel. The behavior of OS made little difference under stoichiometric and lean burn. For fuels with high OS (OS>7), coefficient of
zhao, ziqing, cai, kaiyuan, wang, wei, Li, Yanfei
An innovative Argon/Miller Power Cycle for combustion engine: Thermodynamic Analysis of its Efficiency and its Power Density2022-01-051003/29/2022
Increasing engine efficiency and reducing emissions are fundamental ways to achieve carbon emissions peak and carbon neutrality for transportation and power industry. The Argon Power Cycle (APC) is a novel concept for high efficiency and zero emissions, which is defined as a power cycle with a mixture of argon and oxygen as the working fluid. For an APC, ultra-lean combustion and high dilution combustion are used to increase thermal efficiency, while leading to low power density. To elevate both efficiency and power density, the Miller cycle combined with an APC was considered. The thermal conversion efficiency and the power density of an innovative Argon/Miller Power Cycle were explored through modification of a previous thermodynamic method. Meanwhile, the mixture of H2 and O2 is controlled at a stoichiometric ratio. The results show that with a compression ratio of 7, when the argon dilution ratio rises from 79% to 95%, the thermal conversion efficiency increases from 46.0% to 66.1
Wang, Chenxu, JIN, Shaoye, Deng, Jun, Li, Liguang
A Study of Combustion Inefficiencies in SI Engines Powered by Alcohol and Ether Fuels Using Detailed Emission Speciation2022-01-061703/29/2022
Advanced combustion engines, as power sources, dominate all aspects of the transportation sector. Stringent emission and fuel efficiency standards have promoted the research interest in advanced combustion strategies and alternative fuels. Owing to the comparable energy density to the existing fossil fuels and renewable production, alcohol and ether fuels may be a suitable replacement, or an additive to the gasoline/diesel fuels to meet the future emission standards with minimal modification to current engine geometry. Furthermore, lean and diluted combustion are well-researched pathways for efficiency improvement and reduction of engine-out emissions of modern engines. However, lean-burn or EGR dilution can introduce combustion inefficiencies in the form of excessive hydrocarbon, carbon monoxide, and hydrogen emissions. In this study, the total energy loss to the exhaust in the form of emission species due to incomplete/inefficient combustion of alcohol (butanol and ethanol) and ether
Sandhu, Navjot Singh, Yu, Xiao, Leblanc, Simon
A Novel Pre-chamber Combustion System Combined with Fuel Reformation for Stable Lean-burn Operation2022-01-051303/29/2022
In order to improve thermal efficiency of gasoline engines, lean-burn operation with the pre-chamber was examined. To achieve stable operation with an air excess ratio of λ = 2.0 or higher, a new combustion technique that combines Pre-chamber combustion and fuel reforming was proposed. In the proposed system, a small amount of reforming gas containing hydrogen is supplied to the Pre-chamber to promote the combustion with an extremely lean mixture in the Pre-chamber. The combustion in the main chamber can be accelerated. NOx emissions are reduced due to the lean combustion in the Pre-chamber. In this study, the proposed system was demonstrated. Before the experiment, 1D engine cycle simulation was conduced to find the specifications and conditions of the engine to realized the proposed combustion concept. The amount of hydrogen injected was evaluated using the hydrogen volume fraction, VFH2. As a result, it was found that combustion concept can be realized with the hydrogen volume
Kuboyama, Tatsuya
Turbocharger Turbine for Charging a Lean-Burn Gasoline Engine2022-01-045203/29/2022
Lean-burn combustion is a promising technology for reducing fuel consumption and CO2-emissions of gasoline engines. Due to the air dilution, the indicated engine efficiency increases, resulting in lower fuel consumption and less CO2-emissions. However, the air dilution decreases the combustion temperature, which leads to increased demands on the charging system. In order to map the same engine operating point, higher boost pressures are required at lower available exhaust enthalpy. This places high efficiency requirements on the turbocharger. Hence, state of the art single-stage turbochargers are unable to provide enough boost pressure to enable lean-burn over a sufficiently wide engine operating range. In this paper, a single-stage turbocharger turbine is developed with the objective of enabling a lean-burn engine operation with an air-fuel ratio of λ=2 in the range of the Worldwide Harmonized Light-Duty Vehicles Test Cycle (WLTC). For this purpose, extensive 1D-engine simulations are
Sagan, Lukas, Kuestner, Christoph, Eilts, Peter, Seume, Joerg
Simulation Research on Ultra-lean Constant-volume Combustion Initiated by Spark-ignited Micro-fuel-jet2022-01-051903/29/2022
In the ultra-lean combustion mode, the combustion temperature is relatively low, which is expected to avoid the high-temperature NOx generation. And it also can use excess air to fully oxidize CO, HC and Soot, to achieve cleaner combustion. But at the same time, ultra-lean combustion also has difficulties in ignition and flame propagation. This paper used CONVERGE to simulate the combustion process and products of a new ultra-lean combustion mode, which ignited the ultra-lean premixed fuel/air mixture with the spark-ignited micro-fuel-jet, in a constant-volume vessel with a 6-hole GDI injector. The differences of combustion processes and products were simulated for two spark-ignition positions including ‘on’ the micro-jet spray and ‘between’ two micro-jet sprays. It was found that the combustion duration (the time for burned-fuel-ratio from 10% to 90%) if igniting ‘on’ the micro-jet spray could be shortened by about 14.3%, and the amount of NOx generated would increase about 21.0%. At
Long, Quan, Li, Minglong, Zhou, Yang, Hu, Zongjie, Li, Liguang
Impact of Plasma Stretch on Spark Energy Release Rate and Ignition Capability under Lean Burn Conditions2022-01-052603/29/2022
Performance of the ignition system becomes more important than ever, because of the extensively used EGR in modern spark ignition engines. Future lean burn SI and SACI combustion modes demands even stronger ignition capability for robust ignition control. For spark based ignition systems, extensive research has been carried out to investigate the discharge characteristics on ignition process, including discharge current amplitude, discharge duration, spark energy and plasma stretching. The individual contribution of the parameters on flame kernel formation process is hard to distinguish from each other, especially under flow conditions, but is of importance to the development of future ignition systems. For example, it is a known fact that ignition capability can be improved by increase discharge current amplitude. However, it is not clear whether this enhancement is contributed by a longer plasma stretch or by increase in total ignition energy. A longer plasma stretch can be enhanced
Yu, Xiao, Wang, Linyan, Yang, Zhenyi, Zheng, Ming
High Efficiency HD Hydrogen Combustion Engines: Improvement Potentials for Future Regulations2022-01-057003/29/2022
Hydrogen engines offer the possibility of a carbon neutral transportation – a focal point of current propulsion development activities especially for EU and US future concepts. From today's point of view, hydrogen can play an important role in this regard as it is a carbon-free fuel, no CO2 emissions are produced during its combustion process. Besides, it can be well used for lean burn combustion leading to very low NOx emissions, a key benefit in combination with an optimized after-treatment system for future ultra-low NOx legislations of heavy-duty (HD) engines. Comprehensive investigations using single-cylinder tests and model-based development approach are performed aiming the definition of a high efficiency hydrogen engine concept. An optimization regarding compression ratio and engine calibration (regarding AFR, EGR rates and optimal combustion phase) is carried out while considering knocking. In a next step, efficiency improvements potentials resulting from the turbocharger
Rezaei, Reza, Kovacs, David, Hayduk, Christopher, Delebinski, Thaddaeus
Study of Pre-chamber Jet Combustion Behavior using a Small Two-stroke Optically Accessible Engine2022-32-007601/09/2022
A small 2-stroke engine can be an effective power source for an electric generator mounted on a series hybrid electric vehicle. In recent years, a technology referred to as pre-chamber jet combustion has attracted attention as a means of enhancing thermal efficiency by improving mixture ignitability. In this study, experiments were conducted to investigate differences in combustion behavior between the application of spark-ignited (SI) combustion and pre-chamber jet combustion to a small, two-stroke engine. The experimental equipment used was a two-stroke, single-cylinder, optically accessible engine with a displacement of 63.3 cm3. Differences between conventional SI combustion and pre-chamber jet combustion were examined by means of in-cylinder pressure analysis, in-cylinder combustion visualization and image processing software. The diameter of the connecting orifice of the pre-chamber was varied between two types. The results revealed that the combustion time and indicated mean
DEUSHI, Takato, NAKA, Takuma, TSUJIGUCHI, Tatsuya, IIJIMA, Akira, YAMAGUCHI, Shiro, KUROIWA, Minoru, ETO, Kuniyoshi
Effect of Different Fuel Supply System on Combustion Characteristics in Hydrogen SI Engine2022-32-009201/09/2022
In recent years, internal combustion engine using hydrogen gas, has attracted attention as one solution to the problem of global warming. Hydrogen gas has excellent combustion characteristics such as wide limits of inflammability and fast burning velocity because of high diffusion rate. Therefore, it has been made to obtain stable ignition and combustion by adding hydrogen with lean mixture in spark ignition engines using hydrocarbon fuels and to be attempted efficient operation by engine researchers. The purpose of this study is to reduce cooling loss in a gas engine using hydrogen gas and hydrogen Mixer system (Mixer) engine was remodeled to hydrogen Port Injection (PI) system engine. In this report, the heterogeneity of hydrogen mixture is clarified by comparing the combustion characteristics of the Mixer and the PI, and the effect of the difference in hydrogen supply systems on cooling loss is system. Ignition delay of the PI system is shorter than that of the Mixer. This is to
Koshikawa, Shoi, Matsuya, Yuki, Sekine, Tsukasa, Matsumura, Eriko, Senda, Jiro, Morita, Gin, Nakazono, Toru
Analysis of Cylinder to Cylinder Variations in a Turbocharged Spark Ignition Engine at lean burn operations2022-32-004401/09/2022
In recent years, the improvement in the fuel efficiency and reduction in CO2 emission from internal combustion engines has been an urgent issue. The lean burn technology is one of the key technologies to improve thermal efficiency of SI engines. However, combustion stability deteriorates at lean burn operations. The reduction in cycle-to-cycle and cylinder-to-cylinder variations is one of the major issues to adapt the lean burn technique for production engines. However, the details of the causes and mechanisms for the combustion variations under the lean burn operations have not been cleared yet. The purpose of this study is to control cylinder to cylinder combustion variation. A conventional turbocharged direct injection SI engine was used as the test engine to investigate the effect of engine control parameters on the cylinder to cylinder variations. The engine speed is set at 2200 rpm and the intake pressure is set at 58, 78, 98 kPa respectively. In-cylinder pressure, intake
Yamaizumi, Ryo, Shi, Haoyun, Kuboyama, Tatsuya, Moriyoshi, Yasuo
Extension of the Lean Limit of Gasoline Engines Under Part Load by Using Hot Surface Assisted Spark Ignition (HSASI)2022-32-005101/09/2022
Charge dilution by lean-burn is one way to increase the efficiency of spark ignition engines while reducing NOx emissions. This work focuses on increasing the flammability of lean mixtures inside a passive pre-chamber spark plug by elevating its temperature with the help of a controllable hot surface integrated into the pre-chamber. Thus, an extension of the lean limit under part load is aimed for. A pre-chamber spark plug prototype with an integrated, controllable glow plug was developed, called Hot Surface Assisted Spark Ignition (HSASI). Experimental investigations were conducted on a single-cylinder engine at the Karlsruhe University of Applied Sciences. Operating modes with an active glow plug (HSASI) and a non-active glow plug were compared. The lean limit for both operation modes were determined under part load. NOx, CO and THC emissions were measured for different air-fuel equivalence ratios λ. The lean limit is extended by more than 0.1 in λ at low loads with HSASI operation
Holzberger, Sascha, Kettner, Maurice, Kirchberger, Roland
Effect of Spark Plug Location on Combustion, Performance and Emission of High-Speed Digital Three Spark Ignition (DTSI) Engine Fueled with dedicated Gasoline and Hydrogen.2021-26-022709/22/2021
The United Nations sustainable development goals can be met by reduced use of fossil fuels in the power & transportation sector and by protecting the environment. Various efforts to utilize alternative fuels (with low or without carbon contents) in the transportation sector are in the anvil. In this research, an experimental study is performed on a single cylinder gasoline engine of 200 cc with port fuel injection and digital three spark ignition (DTSI). The effect of spark plug location is analyzed using gasoline and hydrogen fuels separately. The combustion, performance, and emissions characteristics are analyzed at 4000 rpm, WOT (Wide Open Throttle) condition with a compression ratio of 11:1 for three different spark plug locations, i.e., at Center, Left-hand side and Right-hand side of combustion bowl. The following are the best results for a centrally located spark plug in comparison with the spark plug located at the sides. The volumetric efficiency is increased by 3.6% and 10
SHINDE, BALU JALINDAR, KARUNAMURTHY, K
Euro VII and Beyond with Hydrogen Combustion for Commercial Vehicle Applications: From Concept to Series Development2021-01-119609/21/2021
One challenge for the development of commercial vehicles is the reduction of CO2 greenhouse, where hydrogen can help to reduce the fleet CO2. For instance, in Europe a drop in fleet consumption of 15% and 30% is set as target by the regulation until 2025 and 2030. Another challenge is EURO VII in EU or even already approved CARB HD Low NOx Regulation in USA, not only for Diesel but also for hydrogen combustion engines. In this study, first the requirements for the combustion and after-treatment system of a hydrogen engine are defined based on future emission regulations. The major advantages regarded to hydrogen combustion are due to the wide range of flammability and very high flame speed numbers compared to other fossil based fuels. Thus, it can be well used for lean burn combustion with much better fuel efficiency and very low NOx emissions with an ultra lean combustion. A comprehensive experimental investigation is performed on a HD 2 L single-cylinder engine. The hydrogen
Rezaei, Reza, Kovacs, David, Hayduk, Christopher, Mennig, Marian, Delebinski, Thaddaeus
Experimental and numerical investigation of a lean SI engine to be operated as range extender for hybrid powertrains2021-24-000509/05/2021
In the last few years, concern about the environmental impact of vehicles has increased, considering the growth of the dangerous effects on health of noxious exhaust emissions. For this reason, car manufacturers are moving towards more efficient combustion systems for Spark Ignition (SI) engines, aiming to comply with the increasingly stringent regulation imposed by EU and other legislators. Engine operation with very lean air/fuel ratios has demonstrated to be a viable solution to this problem. Stable ultra-lean combustion can be obtained with a Pre-Chamber (PC) ignition system, installed in place of the conventional spark plug. The efficiency of this configuration in terms of performance and emissions is due to its combustion process, that starts in the PC and propagates in the main chamber in the form of multiple hot turbulent jets. In this work, the benefits of the PC were assessed in a production small SI engine, fueled with gasoline and equipped with a proper designed pre-chamber
Frasci, Emmanuele, Sementa, Paolo, Arsie, Ivan, Jannelli, Elio, Vaglieco, Bianca Maria
Parametric Study to Optimize Gasoline Compression Ignition Operation under Medium Load-Conditions2021-01-046004/06/2021
Gasoline compression ignition (GCI) pertains to high efficiency lean burn compression ignition with gasoline fuels, where ignition is controlled by mixture’s auto-ignition chemistry as well as local mixture strength. The presented GCI combustion strategy is based on a multi-mode combustion strategy at various operating conditions. This study presents a part of work on the development of an optimum combustion strategy at medium loading condition for commercial gasoline fuel with research octane number (RON) = 91. The single cylinder engine with a compression ratio (CR) = 16 features a centrally mounted multi-hole injector with a spark plug at a distance from the injector under shallow pent-roof combustion chamber design. The design of combustion chamber and piston was previously optimized based on CFD numerical analysis. The experimental study at medium load condition (IMEP = 6 bar) investigated the effect of fuel injection strategy, exhaust gas recirculation (EGR) and re-breathing on
Raman, Vallinayagam, Viollet, Yoann, Sim, Jaeheon, Badra, Jihad, Chang, Junseok
Thermodynamic and Chemical Analysis of the Effect of Working Substances on the Argon Power Cycle2021-01-044704/06/2021
The Argon Power Cycle engine is a novel concept for high efficiency and zero emission through the replacement of N2 by Ar. However, the higher in-cylinder temperature and pressure as by-products cause heavier knock. The anti-knock strategies, such as reducing compression ratio and retarding ignition time, offset the efficiency increased by the Argon Power Cycle. Therefore, knock control becomes the most urgent task for the Argon Power Cycle engine development. The anti-knock methods, including fuel replacement, ultra-lean combustion, high dilution combustion, and water injection, were considered. The simulated ignition delay times were used to evaluate the probability of knock. The Otto cycle, combined with chemical equilibrium, was utilized to confirm the effect on the thermal conversion efficiency and each in-cylinder thermodynamic state parameter. The results show that the ignition delay times increase by a factor of two when the Ar dilution ratio increases from 79% to 95%. With a
Jin, Shaoye, Deng, Jun, Li, Liguang
Analysis on Emission Characteristics of Urban Buses Based on Remote Online Monitoring2021-01-060104/06/2021
In this study, a new system of assessment method was developed to evaluate the characteristics of urban buses based on remote online monitoring. Four types of buses, including China V emission standards diesel bus, lean-burn CNG bus, air-fuel equivalence ratio combustion CNG bus and gas-electric hybrid bus, were chosen as samples to analyze the emission characteristics of urban buses with different engine types in urban scenario. Based on the traffic conditions in Beijing, the actual emission characteristics of buses under newly-built driving conditions were analyzed. Moreover, the emission factor database of urban buses in Beijing was established to analyze the characteristics of excess emission. The research results are shown as follows. 1) Compared with other types of buses, NOX emission factor and emission rate of lean-burn CNG bus are much higher. The equivalent air-fuel ratio CNG engine combined with TWC catalytic converter and hybrid power technology can better reduce NOX
Feng, Qian, Zhen, Kai, Lu, Yang, Yang, Xingzi, Yang, Yanyan, Liu, Baoxian, Li, Mengliang, Li, Zhijun
Investigate Chemical Effects of Pre-Chamber Combustion Products on Main Chamber Ignition Performance under an Ultra-Lean Condition2020-01-200109/15/2020
Pre-chamber ignition systems are considered as an effective technique to achieve an ultra-lean burn combustion. Hot combustion products and flames generated from pre-chamber combustion create high-speed turbulent jets, which ignite an ultra-lean mixture in the main chamber. This turbulent ignition can be classified as a jet and flame ignition process with thermal and chemical kinetic effects imposed on the main chamber by the pre-chamber. The purpose of this paper is to investigate the chemical effects of pre-chamber combustion products on main chamber ignition performance over a range of operating conditions in pre-chamber. A zero-dimensional pre-chamber combustion model was developed using CHEMKIN-PRO software. By varying the equivalence ratio of reactants, simulation results indicated that the pre-chamber generated more active radicals when burning around stoichiometric conditions but more low-carbon species when burning in rich conditions. Therefore, rapid ignition performance was
Tang, Wenxian, Sarathy, Mani
In-Cylinder Optical Measurement for Analyzing Control Factor of Ignition Phenomena under Diluted Condition2020-01-204809/15/2020
To increase thermal efficiency of internal combustion engines, dilution combustion systems, such as lean burn and exhaust gas recirculation systems, have been developed. These systems require spark-ignition coils generating large discharge current and discharge energy to achieve stable ignition under diluted mixture conditions. Several studies have clarified that larger discharge current increases spark-channel stretch and decreases the possibility of spark channel blow-off and misfire. However, these investigations do not mention the effect of larger discharge current and energy on the initial combustion period. The purpose of this study was to investigate the relation among dilution ratio, initial-combustion period, and coil specifications to clarify the control factor of the dilution limit. Four coils having different current profiles were evaluated under 2000 rpm and 6-bar net-indicated mean effective pressure under a diluted mixture condition through combustion-performance and in
Oryoji, Kazuhiro, Uchise, Yoshifumi, Akagi, Yoshihiko, Qingchu, Chen, Kuboyama, Tatsuya, Moriyoshi, Yasuo
Hydrogen Selective Catalytic Reduction of Nitrogen Oxide on Pt- and Pd-Based Catalysts for Lean-Burn Automobile Applications2020-01-217309/15/2020
The utilization of H2 to catalytically treat NO emissions under lean-burn engine exhaust conditions was studied on Pt- and Pd-containing catalysts supported on CeO2 and MgO. The catalytic performance was examined using a fixed-bed reactor whose dry effluent gas stream was analyzed by an online FTIR analyzer. The catalysts NO conversion and N2 selectivity were measured in the range of 125-3000C with a feed gas composition of 0.05%NO/1%H2/10%O2/N2. The CeO2-based catalysts exhibited higher NO conversion, and the most effective catalyst was Pd/CeO2, with a conversion of 67% and selectivity of 70% near 2300C. The prepared solids were characterized using different techniques (BET, ICP-OES, CO pulse chemisorption, STEM, EELS and EDS) to correlate the structural and morphological properties of the metallic phase and the support with the catalytic activity. CeO2 is a more effective support as it yields higher metal dispersion and better facilitates the reduction of the Pt and Pd catalysts.
Alghamdi, Nawaf M., Restrepo Cano, Juan, Anjum, Dalaver H., Im, Hong G., Kalamaras, Christos, Gascon, Jorge, Sarathy, S. Mani
Lean-Burn Stratified Alcohol Fuels Engines of Power Density up to 475 kW/Liter Featuring Super-Turbocharging, Rotary Valves, Direct Injection, and Jet Ignition2020-01-203609/15/2020
Direct injection (DI) and jet ignition (JI), plus assisted turbocharging, have been demonstrated to deliver high efficiency, high power density positive ignition (PI) internal combustion engines (ICEs) with gasoline. Peak efficiency above 50% and power density of 340 kW/liter at the 15,000 rpm revolution limiter working overall λ=1.45 have been report-ed. Here we explore the further improvement in power density that may be obtained by replacing gasoline with ethanol or methanol, thanks to the higher octane number and the larger latent heat of vaporization, which translates in an increased resistance to knock, and permits to have larger compression ratios. Results of simulations are proposed for a numerical engine that uses rotary valves rather than poppet valves, while also using mechanical, rather than electric, assisted turbocharging. While with gasoline, the power density is 410-420 kW/liter, the use of oxygenates permits to achieve up to 475 kW/liter working with methanol.
Boretti, Alberto
Combustion Visualization and Experimental Study on Multi-Point Micro-Flame Ignited (MFI) Hybrid Lean-Burn Combustion in 4-Stroke Gasoline Engines2020-01-207009/15/2020
Lean-burn combustion is an effective method for increasing the thermal efficiency of gasoline engines fueled with stoichiometric fuel-air mixture, but leads to an unacceptable level of high cyclic variability before reaching ultra-low nitrogen oxide (NOx) emissions emitted from conventional gasoline engines. Multi-point micro-flame ignited (MFI) hybrid combustion was proposed to overcome this problem, and can be can be grouped into double-peak type, ramp type and trapezoid type with very low frequency of appearance. This research investigates the micro-flame ignition stages of double-peak type and ramp type MFI combustion captured by high speed photography. The results show that large flame is formed by the fast propagation of multi-point flame occurring in the central zone of the cylinder in the double-peak type. However, the multiple flame sites occur around the cylinder, and then gradually propagate and form a large flame accelerated by the independent small flame in the ramp type
Fu, Xue-Qing, He, Bang-Quan, Xu, Sipeng, Chen, Tao, Zhao, Hua, Yang, Jian-Jun, Gao, Haiyang, Liu, Shuang-Xi, Fu, Xuesong
Stereoscopic Micro-PIV Measurement of Near-Wall Velocity Distribution in Strong Tumble Flow under Motored SI Engine Condition2020-01-201909/15/2020
In a state-of-the-art lean-burn spark ignition engine, a strong in-cylinder flow field with enhanced turbulence intensity is formed, and understanding the wall heat transfer mechanism of such a complex flow is required. The flow velocity and temperature profiles inside the wall boundary layer are strongly related to the heat transfer mechanism. In this study, two-dimensional three-component (2D3C) velocity distribution near the piston top surface was measured during the compression stroke in a strong tumble flow using a rapid compression and expansion machine (RCEM) and a stereoscopic micro-PIV system. The bore, stroke, compression ratio, and compression time were 75 mm, 128 mm, 15, and 30 ms (equivalent to 1000 rpm), respectively. A double-pulse Nd:YAG laser sheet was introduced from the intake side, and PIV images were captured near the piston surface around the TDC under motored conditions with a measurement region of 5.2 mm × 6.9 mm (1200 × 1600 pixel, 4.3 μm/pixel) using two CCD
Yamakita, Yoko, Bae, Jaeok, Nagasawa, Tsuyoshi, Kosaka, Hidenori
The Variation of Functional Characteristics of a Euro VI Selective Catalytic Reduction Reactor after Ageing2020-01-220509/15/2020
The selective catalytic reduction (SCR) of nitrogen oxides by ammonia is commonly applied as a method of exhaust aftertreatment for lean burn compression ignition (CI) engines. The catalytic reactor of an SCR system, like all catalytic emission control devices, is susceptible to partial deactivation as its operating time progresses. Long-term exposure of an SCR reactor to exhaust gas of fluctuating temperature and composition results in variations of the characteristics of its catalytically active layer. The aim of this study was to observe and investigate the variation of parameters characterizing the SCR reactor as a result of its ageing. Attention was paid to changes in ammonia storage capacity, selectivity of chemical reactions and maximum achievable NOx conversion efficiency. The experimental setup was a heavy duty (HD) Euro VI-compliant engine and its aftertreatment system (ATS). The setup was installed on a transient engine dyno instrumented with emission measurement devices
Dzida, Jakub, Bielaczyc, Piotr, Brzeżański, Marek
Analysis of the Combustion Process of SI Engines Equipped with Non-Conventional Ignition System Architecture2020-37-003506/30/2020
The use of lean or ultra-lean ratios is an efficient and proven strategy to reduce fuel consumption and pollutant emissions. However, the lower fuel concentration in the cylinder hinders the mixture ignition, requiring greater energy to start the combustion. The prechamber is an efficient method to provide high energy favoring the ignition process. It presents the potential to reduce the emission levels and the fuel consumption, operating with lean burn mixtures and expressive combustion stability. In this paper the analysis of the combustion process of SI engines equipped with an innovative architecture and operating in different injection modes was described. In particular, the effect of the prechamber ignition on the engine stability and the efficiency was investigated in stoichiometric and lean-burn operation conditions. The activity was carried out in two parts. In the first part the investigation was performed in a research small direct injection spark ignition (DISI) engine
Sementa, Paolo, Catapano, Francesco, Di Iorio, SILVANA, Todino, Michele, Vaglieco, Bianca Maria
Improving Heavy Duty Natural Gas Engine Efficiency: A Systematic Approach to Application of Dedicated EGR2020-01-081804/14/2020
The worldwide trend of tightening CO2 emissions standards and desire for near zero emissions is driving development of high efficiency natural gas engines for a low CO2 replacement of traditional diesel engines. A Cummins Westport ISX12 G was previously converted to a Dedicated EGR® (D-EGR®) configuration with two out of the six cylinders acting as the EGR producing cylinders. Using a systems approach, the combustion and turbocharging systems were optimized for improved efficiency while maintaining the potential for achieving 0.02 g/bhp-hr NOX standards. A prototype variable nozzle turbocharger was selected to maintain the stock torque curve. The EGR delivery method enabled a reduction in pre-turbine pressure as the turbine was not required to be undersized to drive EGR. A high energy Dual Coil Offset (DCO®) ignition system was utilized to maintain stable combustion with increased EGR rates. High compression ratio, reduced squish pistons were designed to maintain MBT combustion phasing
Kocsis, Michael C., Mitchell, Robert, Moiz, Ahmed Abdul, Kalaskar, Vickey, Williams, D. Ryan, Sjovall, Scott
Experimental and 1D Numerical Investigations on the Exhaust Emissions of a Small Spark Ignition Engine Considering the Cylinder-by-Cylinder Variability2020-01-057804/14/2020
This paper reports a numerical and experimental analysis on a twin-cylinder turbocharged Spark Ignition engine carried out to investigate the cylinder-to-cylinder variability in terms of performance, combustion evolution and exhaust emissions. The engine was tested at 3000 rpm in 20 different steady-state operating conditions, selected with the purpose of observing the influence of cylinder-by-cylinder A/F ratio variations and the EGR effects on the combustion process and exhaust emissions for low to medium/high loads. The experimental outcomes showed relevant differences in the combustion evolution (characteristic combustion angles) between cylinders and not negligible variations in the emissions of the single cylinder exhaust and the overall engine one. This misalignment resulted to be due to differences in the injected fuel amount by the port injectors in the two cylinders, mainly deriving from the specific fuel rail geometry. The experimental data were then used to validate a 1D
Marchitto, Luca, Teodosio, Luigi, Tornatore, Cinzia, Valentino, Gerardo, Bozza, Fabio
Experimental Study on the Characteristics of Short Circuits and Restrikes of Spark Channels2020-01-112304/14/2020
Ignition performance is critical for the implementation of diluted combustion for spark-ignition engines. The short circuit and restrike phenomena can influence the initial ignition volume and discharge duration which are important for the stable ignition processes. In this study, the short circuits and restrikes of spark channels are studied with various flow velocities, spark plug gaps and discharge energies. The development of the spark channels is captured by using the direct imaging technique with a CMOS camera equipped with an image intensifier. A multi-coil ignition system is designed to enable flexible control of discharge energies. The results show that the spark plug gap size is a critical parameter to suppress the phenomena of short circuits and restrikes. With the enlargement of spark plug gap, the maximum and average lengths of the spark channel effectively increase. Meanwhile, increasing discharge power is another effective method to improve the short circuit and restrike
Huang, Shuai, Li, Tie, Wang, Ning, Wang, Xinran, Yang, Zhenyi, Yu, Xiao, Zheng, Ming
Experimental Investigation of the Influence of Ignition System Parameters on Combustion in a Rapid Compression-Expansion Machine2020-01-112204/14/2020
Lean burn combustion concepts with high mean effective pressures are being pursued for large gas engines in order to meet future stringent emission limits while maintaining high engine efficiencies. Since severe boundary conditions for the ignition process are encountered with these combustion concepts, the processes of spark ignition and flame initiation are important topics of applied research, which aims to avoid misfiring and to keep cycle-to-cycle combustion variability within reasonable limits. This paper focuses on the fundamental investigation of early flame kernel development using different ignition system settings. The investigations are carried out on a rapid compression-expansion machine in which the spark ignition process can be observed under engine-like pressure and excess air ratio conditions while low flow velocities are maintained. The schlieren setup for high-speed optical investigations of the area of the spark plug electrodes is described and a suitable post
Kiesling, Constantin, Pirker, Gerhard, Tilz, Anton, Oppl, Thomas, Nickl, Andreas, Wimmer, Andreas, Meyer, Georg
Assessment of the Ignition System Requirement on Diluted Mixture Spark Engines2020-01-111604/14/2020
In order to face the new challenges, spark ignition engines are evolving by following some strategies and technologies. Among them, alternative combustion processes based on the dilution of the homogeneous mixture, either with fresh air or with Exhaust Gas Recirculation (EGR), are being explored. In a higher or lower extent, these changes modify in-cylinder thermodynamic conditions during the engine operation (pressure, temperature and gas composition) thus conditioning the spark ignition system requirements that will have to evolve to become more reliable and powerful. In this framework, an experimental study on the effect of the key in-cylinder conditions on the ignition system performance has been carried out in a single-cylinder spark-ignition (SI) research engine. The study includes EGR, lambda and energizing time sweeps to assess the behavior of the engine in different operating conditions. Furthermore, various Insulated-Gate Bipolar Transistors (IGBT) and spark plugs have been
Molina, Santiago, Martin, Jaime, Novella, Ricardo, Gomez-Soriano, Josep, Padilla, Jose
Discharge Current Management for Diluted Combustion under Forced Flow Conditions2020-01-111804/14/2020
Lean burn or EGR diluted combustion with enhanced charge motion is effective in improving the efficiency of spark ignition engines. However, the ignition process under these conditions is getting more challenging due to higher ignition energy required by the lean or diluted mixture, as well as the interactions of the gas flow on the flame kernel. Enhanced spark discharge energy is essential to initiate the combustion under these conditions. Moreover, the discharge process should be more carefully controlled to improve the effectiveness of the spark. In this study, spark ignition systems with boosted discharge energy are used to ignite diluted air-fuel mixture under forced flow conditions. The impacts of the discharge current level, the discharge duration and the discharge current profile on the ignition are investigated in detail using optical diagnosis. It is evident from the results that extended discharge duration helps promote the flame propagation, though the effectiveness is
Yang, Zhenyi, Wang, Linyan, Sandhu, Navjot S., Yu, Xiao, Zheng, Ming
Combustion Stability Improvement via Multiple Ignition Sites on a Production Engine2020-01-111504/14/2020
For spark ignition (SI) engines, further improvement of engine efficiency has become the major development trend, and lean burn/EGR technologies, as well as intensified in-cylinder flow, need to be adapted to reach that target. Stronger ignition sources become more favorable under extreme lean/EGR conditions. Among the ignition technologies developed, multiple ignition sites technology has been proved to be an effective way to help with the initial flame kernel development. In this paper, a spark ignited 4-cylinder turbo-charged production engine is employed to investigate the impact of multiple ignition sites technology on engine performance under lean burn conditions. Four in-house designed 3-core sparkplugs are installed on the cylinders to replace traditional stock sparkplugs, in order to generate multiple ignition sites in the cylinders. Under partial load, the pumping loss can be reduced when engine is running under lean conditions, so the brake engine efficiency can be improved
Yu, Xiao, Zhang, Xiaoxi, Zhang, Tangliang, Chen, Guangyun, Tjong, Jimi, Zheng, Ming
Simulation Analysis of Early and Late Miller Cycle Strategies Influence on Diesel Engine Combustion and Emissions2020-01-066204/14/2020
Based on the working model of a diesel engine, the influence of 2 Miller cycle strategies-Early Intake Valve Closure (EIVC) and Late Intake Valve Closure (LIVC) on the combustion and emissions of diesel engine was analyzed. Then the working condition of each Miller cycle strategies on the engine under the rated speed was optimized through the adjust of the valve timing, boost pressure and the injection timing. The research found that both delaying and advancing the closure timing of the intake valve can decrease the pressure and temperature during compression stroke, prolonging the ignition delay. However, due to the decrease of the working media inside the cylinder, the average in-cylinder temperature and soot emissions will increase, which can be alleviated by raising the boost pressure and the resulting compensation of the intake loss. The study found that together with increasing boost pressure and delaying injection timing, both EIVC and LIVC can reduce the NOx and soot emissions
Yang, Shuai, Yang, Xiaolin, Liu, Haifeng, Feng, Zhiwei, Li, Xiuyuan
Measurement of Fuel Distribution in a Small PFI Spark-Ignition Engine Using Tracer PLIF2020-01-078604/14/2020
The distribution of fuel-air mixture inside the engine cylinder strongly influences the combustion process. Planar laser-induced fluorescence (PLIF) is commonly used for fuel distribution measurement, however, it is mostly reported on moderate- to large-sized engines. In the present work, PLIF is applied to measure the fuel distribution inside the cylinder of a small, four-stroke, port-fuel-injection (PFI), spark-ignition engine with displacement volume of 110 cm3. Iso-octane was used as the base fuel, and 3-pentanone (15% by volume) was added as a fluorescent tracer in the base fuel. The effect of equivalence ratio, considering ϕ = 1.2, 1.0, and 0.8, on in-cylinder fuel distribution was studied with low throttle opening of 25% at 1200 rpm. PLIF images were recorded at different crank angle degrees during both intake and compression strokes over a swirl measurement plane located at the TDC position. It was found that the fuel stratification was present from intake to even late
Garg, Shubham, Mittal, Mayank, Sahu, Srikrishna, Lakshminarasimhan, V
Impact of Spark Plasma Length on Flame Kernel Development under Flow Condition2020-01-111404/14/2020
Advanced ignition systems with enhanced discharge current have been extensively investigated in research, since they are highly regarded as having the potential to overcome challenges that arise when spark-ignition engines are running under lean or EGR diluted conditions. Local flow field is also of particular importance to improve the ignitability of the air-fuel mixture in SI engines as the spark plasma channel can be stretched by the flow across the spark gap, leading to longer plasma length, thus more thermal spark energy distributed to the air-fuel mixture in the vicinity of the spark plug. Research results have shown that a constantly high discharge current is effective to maintain a stable spark plasma channel with less restrikes and longer plasma holding period. However, with the further increase in discharge current, plasma channel becomes thicker, and the stretched plasma length becomes shorter under a constant flow speed, which may suppress the advantages of the enhanced
Zhu, Hua, Tan, Qingyuan, Yu, Xiao, Yang, Zhenyi, Liang, Li, Zheng, Ming, Reader, Graham, Qian, Jin
Analysis of a Prechamber Ignited HPDI Gas Combustion Concept2020-01-082404/14/2020
High-pressure direct injection (HPDI) of natural gas into the combustion chamber enables a non-premixed combustion regime known from diesel engines. Since knocking combustion cannot occur with this combustion process, an increase in the compression ratio and thus efficiency is possible. Due to the high injection pressures required, this concept is ideally suited to applications where liquefied natural gas (LNG) is available. In marine applications, the bunkering of and operation with LNG is state-of-the-art. Existing HPDI gas combustion concepts typically use a small amount of diesel fuel for ignition, which is injected late in the compression stroke. The diesel fuel ignites due to the high temperature of the cylinder charge. The subsequently injected gas ignites at the diesel flame. The HPDI gas combustion concept presented in this paper is of a monovalent type, meaning that no fuel other than natural gas is used. The high-pressure gas jet is ignited with the aid of flame torches from
Zelenka, Jan, Kammel, Gernot, Wimmer, Andreas, Bärow, Enrico, Huschenbett, Matthias
Two prototype engines with colliding and compression of pulsed supermulti-jets through a focusing process, leading to nearly complete air insulation and relatively silent high compression for automobiles, motorcycles, aircrafts, and rockets2020-01-083704/14/2020
We have proposed a new compressive combustion principle based on pulsed supermulti-jets colliding through focusing process, by injection from chamber wall to chamber center. This principle has potential of relatively-silent high compression around chamber center because of auto-ignition far from chamber wall and nearly-complete air insulation due to encasing of burned high temperature gas. The present principle leading to higher thermal efficiency and higher power will be applicable for automobiles, aircrafts, rockets, and also flying cars to be realized in the future. Then, water cooling system made smaller or even eliminated will result in lower price, while auto-ignition in an area larger than that created by traditional spark-ignition will lead to less NOx emission at very lean burning. Thus, we here show four new evidences based on experimental data and computational and theoretical considerations. (1) Quantitative clarification of compression level at condition without combustion
Konagaya, Remi, Naitoh, Ken, Kobayashi, Tomotaka, Isshiki, Yuuki, Ito, Hajime, Makimoto, Hiroki, Kobayashi, Yoshiki, Tada, Yusuke, Kikuchi, Nozomu, Hosoi, Aya, Fujii, Yuto
Energy Enhanced Adaptive Spark Ignition for Lean Combustion Initiation2020-01-084104/14/2020
For internal combustion engine systems, lean and diluted combustion is an important technology applied for fuel efficiency improvement. Because of the thermodynamic boundary conditions and the presence of in-cylinder flow, the development of a well-sustained flame kernel for lean combustion is a challenging task. Reliable spark discharge with the addition of enhanced delivered energy is thus needed at certain time durations to achieve successful combustion initiation of the lean air-fuel mixture. For a conventional transistor coil ignition system, only limited amount of energy is stored in the ignition coil. Therefore, both the energy of the spark discharge and the duration of the spark discharge are bounded. To break through the energy limit of the conventional transistor coil ignition system, in this work, an adaptive spark ignition system is introduced. The system has the ability to reconstruct the conductive ion channels whenever it is interrupted during the spark discharge
Tan, Qingyuan, Zheng, Ming, Wang, Linyan, Li, Liguang, Yu, Xiao, Zhu, Hua
Design and Simulation of a Multi Fuel Gas Mixture System of a Wankel Rotary Engine2020-01-054804/14/2020
The paper first includes the main objective and boundary conditions for design and simulation of a multi fuel gas mixture system of a Wankel rotary engine. New regenerative fuels are more and more important for use in automotive propulsion and stationary applications of combustion engines. Due to the special design and operation of rotary engines there are opportunities for running these engines in future electric and hybrid applications with new designed liquids and gaseous fuels based on regenerative energy sources. Nevertheless, rotary engines have advantages in avoidance of preignition and detonation especially when using gaseous fuels with a higher percentage of hydrogen. The focus is on basic research and analyses of main physical and thermodynamic properties of separate lean burn gases (lower calorific value, mixed calorific value, AFR) and their effects on fuel mixing and engine performance. Furthermore, the scope of the investigation is on the development of simulation models
Dost, Tobias, Getzlaff, Joern
Combustion Enhancement in a Gas Engine Using Low Temperature Plasma2020-01-082304/14/2020
Low temperature plasma ignition has been proposed as a new ignition technique as it has features of good wear resistance, low energy release and combustion enhancement. In the authors’ previous study, lean burn limit could be extended by low temperature plasma ignition while a voltage drop during discharge, leading to the transition to arc discharge, was found. In this study, the structure of plug and power supply’s performance with steep voltage rising with time, dV/dt, are examined to investigate the effects on combustion performance. As a result, the following conclusions were deduced. (1) The lean combustion limit was extended when a four-pole plug with IES power source was used due to volumetric ignition. (2) A modified one-pole plug to improve the electric insulation, leading to prevent the voltage drop, could not extend the lean limit due to less volumetric ignitability. The specifications of plug must be improved to expand the ignition volume. (3) Using a variable dV/dt power
Moriyoshi, Yasuo, Kuboyama, Tatsuya, Tanoue, Kimitoshi
A Numerical Study on the Ignition of Lean CH 4 /Air Mixture by a Pre-Chamber-Initiated Turbulent Jet2020-01-082004/14/2020
To provide insights into the fundamental characteristics of pre-chamber combustion engines, the ignition of lean premixed CH4/air due to hot gas jets initiated by a passive narrow throated pre-chamber in a heavy-duty engine was studied computationally. A twelve-hole pre-chamber geometry was investigated using CONVERGETM software. The numerical model was validated against the experimental results. To elucidate the main-chamber ignition mechanism, the spark plug location and spark timing were varied, resulting in different pressure gradient during turbulent jet formation. Different ignition mechanisms were observed for turbulent jet ignition of lean premixed CH4/air, based on the geometry effect. Ignition behavior was classified into the flame and jet ignition depending on the significant presence of hot active radicals. The jet ignition, mainly due to hot product gases was found to be advanced by the addition of a small concentration of radicals. In turbulent conditions, the ignition
Sanal, Sangeeth, Silva, Mickael, Hlaing, Ponnya, Cenker, Emre, Johansson, Bengt, Im, Hong G.
Ultra-Lean and High EGR Operation of Dual Mode, Turbulent Jet Ignition (DM-TJI) Engine with Active Pre-chamber Scavenging2020-01-111704/14/2020
Continuous efforts to improve thermal efficiency and reduce exhaust emissions of internal combustion engines have resulted in development of various solutions towards improved lean burn ignition systems in spark ignition engines. The Dual Mode, Turbulent Jet Ignition (DM-TJI) system is one of the leading technologies in that regard which offers higher thermal efficiency and reduced NOx emissions due to its ability to operate with very lean or highly dilute mixtures. Compared to other pre-chamber ignition technologies, the DM-TJI system has the distinct capability to work with a very high level of EGR dilution (up to ~40%). Thus, this system enables the use of a three-way catalyst (TWC). Auxiliary air supply for pre-chamber purge allows this system to work with such high EGR dilution rate. This work presents the results of experimental investigation carried out with a Dual Mode, Turbulent Jet Ignition (DM-TJI) optical engine equipped with a cooled EGR system. The results show that the
Atis, Cyrus, Chowdhury, Sadiyah Sabah, Ayele, Yidnekachew, Stuecken, Thomas, Schock, Harold, Voice, Alexander K.
A New Efficient Combustion Method for ICEs2020-01-131404/14/2020
The best known methods for combustion in Internal Combustion Engines (ICEs) are: Spark Ignition (SI), Compression Ignition (CI) and Homogeneous Charge Compression Ignition (HCCI). Each of these combustion methods has well known limitations for efficiency and clean exhaust. This paper presents a new method of combustion, called Entry Ignition (EI) that overcomes some of these limitations. EI burns a homogeneous fuel air mixture at constant pressure with combustion occurring at the inlet where the unburned mixture flows into the combustion chamber. Combustion results from the unburned mixture mixing with the much hotter burned gases already in the combustion chamber. EI can operate in a conventional piston-type engine, with the only major change being in the valving. EI’s efficiency gain results from the following. Firstly, EI is not subject to “knocking” and so can operate at CI-level compression ratios or higher. Secondly, EI allows lean burn, which improves efficiency for basic
Cheeseman, Peter C.
Investigation of Homogeneous Lean SI Combustion in High Load Operating Conditions2020-01-095904/14/2020
Homogeneous lean combustion (HLC) can be utilized to substantially improve spark ignited (SI) internal combustion engine efficiency. Higher efficiency is vital to enable clean, efficient and affordable propulsion for the next generation light duty vehicles. More research is needed to ensure robustness, fuel efficiency/NOx trade-off and utilization of HLC. Utilization can be improved by expanding the HLC operating window to higher engine torque domains which increases impact on real driving. The authors have earlier assessed boosted HLC operation in a downsized two-litre engine, but it was found that HLC operation could not be achieved above 15 bar NMEP due to instability and knocking combustion. The observation led to the conclusion that there exists a lean load limit. Therefore, further experiments have been conducted in a single cylinder research DISI engine to increase understanding of high load lean operation. HLC is known to suppress end-gas autoignition (knock) by decreasing
Clasen, Kristoffer H., Koopmans, Lucien
Quasi-Dimensional Multi-Zone Combustion Diagnostic Tool for SI Engines with Novel NOx and CO Emissions Models2020-01-028904/14/2020
In this work an innovative quasi-dimensional multi-zone combustion diagnostic tool for homogeneous charge spark ignition (SI) engines is developed for the evaluation of heat release, flame propagation parameters, combustion velocities as well as engine-out NOx emissions based on in-cylinder pressure data analysis. The tool can be used to assess the effects of fuel, design and operating parameters on the SI engine combustion and NOx emissions formation processes. Certain novel features are included in the presently developed combustion diagnostic tool. Firstly, combustion chambers of any shape and spark plug position can be considered due to an advanced model for the calculation of the geometric interaction between a spherically expanding flame and a general combustion chamber geometry. Then, the temperature stratification in the burned gas developed during the combustion phase, which has to be captured for realistic calculations of emissions formation, is taken into account by a multi
Michos, Konstantinos N., Bikas, Georgios
Spectroscopy Based Tool for Temperature Evaluation during the Spark Discharge2019-32-050201/24/2020
In this work, a new tool is proposed and tested to investigate the early phase of spark ignition (SI) processes. The diagnostic tool is based on Spark-Induced Breakdown Spectroscopy (SIBS), a consolidated technique in which the plasma formed by spark generation between two electrodes is used as the excitation source for optical emission spectroscopy (OES). The spark discharge of a commercial ignition system was analyzed through OES to correlate the characteristic evolution of the discharge with the formation of reactive species inside the activated volume. Specifically, an open-source spectrum simulation program (Lifbase) together with the NIST database was used for defining relations between the ultraviolet emission bands of nitrogen first negative system (FNS_N2) in the glow phase for different plasma temperature and pressure values. Besides plasma density and ion energy, electron and gas temperatures are important parameters that govern the reaction rate of active species generation
Merola, S., Irimescu, A., Vaglieco, B.M., Di Iorio, S., Sementa, P.
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