Browse Topic: Lean burn engines

Items (750)

Designing Next-Generation Piston Geometry for LPG Powered Spark Ignition Engines: An Integrated CFD and Experimental Approach

2025-28-0123To be published on 02/07/2025

The efficiency of combustion has a major impact on the performance and emission characteristics of a spark-ignited LPG (Liquified Petroleum Gas) engine. The shape of the combustion chamber determines the homogeneous charge intake velocity, which is crucial for the turbulent motion that encourages flame propagation and quickens combustion. It need the right amount of compression ratio, charge squish velocity and turbulent kinetic energy to sustain combustion and propel laminar flames. There are a number of names for the motion of the charge within the cylinder: swirl, squish, tumble and turbulence. All of these terms affect how air and fuel are mixed and burned. Piston shape affects in-cylinder motion, which in turn reduces fuel consumption and improves combustion characteristics. The shape of the piston quench zone has a substantial impact on the charge velocity inside the combustion chamber. The impact on charge motion was analyzed using computer modeling using STAR-CD on pentroof

Sagaya Raj, Gnana, R L, Krupakaran, Pasupuleti, Thejasree, Natarajan, Manikandan

Dual Injection Concept and Lean Burn Characteristics with Methanol on a SI-Engine

2024-24-0030

09/18/2024

The research for sustainable alternative fuels for combustion engines was driven by the urgency to meet future emission regulation norms and mitigate climate change and dependency on fossil fuels. In this context, methanol emerges as a promising candidate due to its potential for greenhouse gas-neutral production methods and its advantageous characteristics for employment in SI engines. Adverse effects, such as elevated emissions due to incomplete combustion along with liner impingement and oil dilution as a consequence of the high injected fuel mass and the large enthalpy of vaporization, can be improved by a dual injection concept. The tests were conducted on a single-cylinder research engine derived from a common passenger vehicle engine. The exhaust gas composition was measured with an FTIR-analyzer employing a methanol-specific evaluation method, standard exhaust gas analyzers, and a solid particle counter system with 10 and 23 μm cut-off sizes. The ratio of DI mass to total mass

Fitz, Patrick, Fellner, Felix, Rößlhuemer, Raphael, Härtl, Martin, Jaensch, Malte

Optimization of a Virtual H2 Engine Using a 1D Simulation Tool Targeting High Engine Performance along with Near-Zero Emission Levels

2024-24-0015

09/18/2024

Hydrogen engines are currently considered as a viable solution to preserve the internal combustion engine (ICE) as a power unit for vehicle propulsion. In particular, lean-burn gasoline Spark-Ignition (SI) engines have been a major subject of investigation, due to their reduced emission levels and high thermodynamic efficiency. Lean charge is suitable for passenger car applications, where the demand of mid/low power output does not require an excessive amount of air to be delivered by the turbocharging unit, but can difficulty be tailored in the field of high-performance engine, where the air mass delivered would require oversized turbocharging systems or more complex charging solutions. For this reason, the range of feeding conditions near the stochiometric is explored in the field of high-performance engines (20 BMEP), leading to the consequent issue of abatement of pollutant emissions. In this work, a 1D model is applied to the modeling of a four cylinder engine fueled with direct

Marinoni, Andrea, Montenegro, Gianluca, Cerri, Tarcisio, Della Torre, Augusto, Onorati, Angelo

TOC

99-06-03-0TOC

06/21/2024

TOC

Tobolski, Sue

1D Modeling of a High-Performance Engine Fueled with H ₂ and Equipped with a Low NO _x After-Treatment Device

2024-37-0009

06/12/2024

Hydrogen engines are currently considered as a viable solution to preserve the internal combustion engine (ICE) as a power unit for vehicle propulsion. In particular, lean-burn gasoline Spark-Ignition (SI) engines have been a major subject of investigations, due to their reduced emission levels and high thermodynamic efficiency. Lean charge is suitable for the purpose of passenger car applications, where the demand of mid/low power output does not require an excessive amount of air to be delivered by the turbocharging unit, but can difficulty be tailored in the field of high performance engine, where the air mass delivered would require oversized turbocharging systems or more complex charging solutions. For this reason, the range of feeding conditions near the stochiometric value is explored in the field of high performance engines, leading to the consequent issue of abatement of pollutant emissions. In this work a 1D model is applied to the modeling of a V8 engine fueled with direct

Montenegro, Gianluca, Marinoni, Andrea, Della Torre, Augusto, D'Errico, Gianluca, Onorati, Angelo, Cerri, Tarcisio

Numerical Investigation of Combustion Characteristics in a Binary Fuel Blend of C ₈ H ₁₈ and H ₂

04-17-03-0017

06/10/2024

The escalating energy demand in today’s world has amplified exhaust emissions, contributing significantly to climate change. One viable solution to mitigate carbon dioxide emissions is the utilization of hydrogen alongside gasoline in internal combustion engines. In pursuit of this objective, combustion characteristics of iso-octane/hydrogen/air mixtures are numerically investigated to determine the impact of hydrogen enrichment. Simulations are conducted at 400 K over a wide range of equivalence ratio 0.7 ≤ Ф ≤ 1.4 and pressure 1–10 atm. Adiabatic flame temperature, thermal diffusivity, laminar burning velocity, and chemical participation are assessed by varying hydrogen concentration from 0 to 90% of fuel molar fraction. As a result of changes in thermal properties and chemical participation, it is noticed that the laminar burning velocity (LBV) increases with higher hydrogen concentration and decreases as pressure increases. Chemical participation and mass diffusion were found to be

Almansour, Bader

Combustion Analysis of Active Pre-Chamber Design for Ultra-Lean Engine Operation

03-17-05-0040

04/27/2024

In this article, the effects of mixture dilution using EGR or excessive air on adiabatic flame temperature, laminar flame speed, and minimum ignition energy are studied to illustrate the fundamental benefits of lean combustion. An ignition system developing a new active pre-chamber (APC) design was assessed, aimed at improving the indicated thermal efficiency (ITE) of a 1.5 L four-cylinder gasoline direct injection (GDI) engine. The engine combustion process was simulated with the SAGE detailed chemistry model within the CONVERGE CFD tool, assuming the primary reference fuel (PRF) to be a volumetric mixture of 93% iso-octane and 7% n-heptane. The effects of design parameters, such as APC volume, nozzle diameter, and nozzle orientations, on ITE were studied. It was found that the ignition jet velocity from the pre-chamber to the main chamber had a significant impact on the boundary heat losses and combustion phasing. The simulation showed that, under 16.46 compression ratio (CR) and

Peethambaram, Mohan Raj, Zhou, Quanbao, Waters, Benjamin, Pendlebury, Ken, Fu, Huiyu, Haines, Andrew, Hale, David, Hu, Tiegang, Zhang, Jiaxiang, Wu, Xuesong, Zhang, Xiaoyu

Pre-Chamber Combustion System Development for an Ultra-Lean Gasoline Engine

2024-01-2110

04/09/2024

Amid rising demands for fuel efficiency and emissions reduction, enhancing the thermal efficiency of gasoline engines has become imperative, which requires higher efficiency combustion strategies and integrated optimized design to maximize the work output from fuel. In gasoline engine, both increasing the compression ratio and using lean burn mode improve the ratio of useful work output to the energy input effectively, which resulting in higher thermal efficiency. Although there is limited scope for increasing the compression ratio due to the higher sensitivity to knocking, especially under stoichiometric conditions, reduced sensitivity could be got with leaner mixture fill into cylinder, which can further increase the specific heat ratio and thermal efficiency. However, realizing the efficiency benefits of lean burn in gasoline engines necessitates overcoming critical challenges like ensuring robust ignition process and accelerating burning rates to achieve short, stable combustion

Du, Jiakun, Qi, Hongzhong, Chen, Hong, Li, Yuhuai, Zhan, Wenfeng, Jiang, Xiaoxiao, Wu, Weilong, Zhang, Zonglan

Performance of Spark Current Boost System on a Production Engine under Lean-Burn Conditions

2024-01-2106

04/09/2024

In order to improve the fuel economy for future high-efficiency spark ignition engines, the applications of advanced combustion strategies are considered to be beneficial with an overall lean and/or exhaust gas recirculation diluted cylinder charge. Stronger and more reliable ignition sources become more favorable under extreme lean/EGR conditions. Existing research indicates that the frequency of plasma restrikes increases with increased flow velocity and decreased discharge current level, and a higher discharge current can reduce the gap resistance and maintain the stretched plasma for a longer duration under flow conditions. An in-house developed current boost control system provides flexible control of the discharge current level and discharge duration. The current boost ignition system is based on a multi-coil system with a discharge current level of 180mA. In this study, a comparative study has been conducted to investigate the efficacy of multi-coil and multi-core ignition

Yu, Xiao, Leblanc, Simon, Wang, Linyan, Zheng, Ming, Tjong, Jimi

Analysis of Dual Fuel Hydrogen/Diesel Combustion Varying Diesel and Hydrogen Injection Parameters in a Single Cylinder Research Engine

2024-01-2363

04/09/2024

In the perspective of a reduction of emissions and a rapid decarbonisation, especially for compression ignition engines, hydrogen plays a decisive role. The dual fuel technology is perfectly suited to the use of hydrogen, a fuel characterized by great energy potential. In fact, replacing, at the same energy content, the fossil fuel with a totally carbon free one, a significant reduction of the greenhouse gases, like carbon dioxide and total hydrocarbon, as well as of the particulate matter can be obtained. The dual fuel with indirect injection of gaseous fuel in the intake manifold, involves the problem of hydrogen autoignition. In order to avoid this difficulty, the optimal conditions for the injection of the incoming mixture into the cylinder were experimentally investigated. All combustion processes are carried out on a research engine with optical access. The engine speed has is set at 1500 rpm, while the EGR valve is deactivated. The purpose of this work is to research the minimum

Mancaruso, Ezio, Rossetti, Salvatore, Vaglieco, Bianca Maria

Numerical Study on the Design of a Passive Pre-Chamber for a Heavy-Duty Hydrogen Combustion Engine

2024-01-2112

04/09/2024

Lean-burn hydrogen internal combustion engines are a good option for future transportation solutions since they do not emit carbon-dioxide and unburned hydro-carbons, and the emissions of nitric-oxides (NOx) can be kept low. However, under lean-burn conditions the combustion duration increases, and the combustion stability decreases, leading to a reduced thermal efficiency. Turbulent jet ignition (TJI) can be used to extend the lean-burn limit, while decreasing the combustion duration and improving combustion stability. The objective of this paper is to investigate the feasibility of a passive pre-chamber TJI system on a heavy-duty hydrogen engine under lean-burn conditions using CFD modelling. The studied concept is mono-fuel, port-fuel injected, and spark ignited in the pre-chamber. The overall design of the pre-chamber is discussed and the effect of design parameters on the engine performance are studied. From this analysis, it was found that the volume of the pre-chamber and the

Maas, Ralph, Bekdemir, Cemil, Somers, Bart

Optical Investigation of Lean Combustion Characteristics of Non-Uniform Distributed Orifice Passive Pre-Chamber on a High Compression Ratio GDI Engine

2024-01-2101

04/09/2024

The passive pre-chamber (PC) is valued for its jet ignition (JI) and is suitable for wide use in the field of gasoline direct injection (GDI) for small passenger cars, which can improve the performance of lean combustion. However, the intake, exhaust, and ignition combustion stability of the engine at low speed is a shortcoming that has not been overcome. Changing the structural design to increase the fluidity of the main chamber (MC) and pre-chamber (PC) may reduce jet ignition performance, affecting engine dynamics. This investigation is based on non-uniformly nozzles distributed passive pre-chamber, which is adjusted according to the working medium exchange between PC and MC. The advantages and disadvantages of the ignition mode of PC and SI in the target engine speed range are compared through optical experiments on a small single-cylinder GDI engine. The results show that with the increase of λ from 1.0 to 1.6, the promotion effect of PCJI on dynamic performance gradually

Tang, Yuanzhi, Lou, Diming, Fang, Liang, Fan, Benzheng, Wu, Xijiang, Wang, Zhiyu, Zhang, Yunhua, Tan, Piqiang, Hu, Zhiyuan

Simulation Study of Sparked-Spray Induced Combustion at Ultra-Lean Conditions in a GDI Engine

2024-01-2107

04/09/2024

Ultra-lean combustion of GDI engine could achieve higher thermal efficiency and lower NOx emissions, but it also faces challenges such as ignition difficulties and low-speed flame propagation. In this paper, the sparked-spray is proposed as a novel ignition method, which employs the spark to ignite the fuel spray by the cooperative timing control of in-cylinder fuel injection and spark ignition and form a jet flame. Then the jet flame fronts propagate in the ultra-lean premixed mixture in the cylinder. This combustion mode is named Sparked-Spray Induced Combustion (SSIC) in this paper. Based on a 3-cylinder 1.0L GDI engine, a 3D simulation model is established in the CONVERGE to study the effects of ignition strategy, compression ratio, and injection timing on SSIC with a global equivalence ratio of 0.50. The results show it is easier to form the jet flame when sparking at the spray front because the fuel has better atomization and lower turbulent kinetic energy at the spray front. The

Li, Minglong, Long, Quan, Yu, Wangchao, Hu, Zongjie, Yin, Yong, Qin, Xiongjie, Li, Liguang

Numerical Study of an EGR Dilution in a Pre-Chamber Spark Ignited Engine Fuelled by Natural Gas

2024-01-2081

04/09/2024

Exhaust gas recirculation (EGR) is a proven strategy for the reduction of NOX emissions in spark ignited (SI) engines and compression ignition engines, especially in lean burn conditions where the increase of thermal efficiency is obtained. The dilution level of the mixture with EGR is in a conventional SI engine limited by the increase of combustion instability (CoV IMEP). A possible method to extend the EGR dilution level and ensure stable combustion is the implementation of an active pre-chamber combustion system. The pre-chamber spark ignited (PCSI) engine enables fast and stable combustion of lean mixtures in the main chamber by utilizing high ignition energy of multiple flame jets penetrating from the pre-chamber to the main chamber. In this paper, as an initial research step, a numerical analysis is performed by employing the 0D/1D simulation model, validated with the initial experimental and 3D-CFD results. The simulation model is used for the prediction of possible benefits of

Dilber, Viktor, Krajnovic, Josip, Ugrinić, Sara, Sjeric, Momir, Tomic, Rudolf, Kozarac, Darko

Combustion and HC&PN Emission Characteristics at First Cycle Starting of Gasoline Engine under Lean Burn Based on Active Pre-Chamber

2024-01-2108

04/09/2024

As a novel ignition technology, pre-chamber ignition can enhance ignition energy, promote flame propagation, and augment turbulence. However, this technology undoubtedly faces challenges, particularly in the context of emission regulations. Of this study, the transient characteristics of combustion and emissions in a hybrid electric vehicle (HEV) gasoline engine with active pre-chamber ignition (PCI) under the first combustion cycle of quick start are focused. The results demonstrate that the PCI engine is available on the first cycle for lean combustion, such as lambda 1.6 to 2.0, and exhibit particle number (PN) below 7×107 N/mL at the first cycle. These particles are predominantly composed of nucleation mode (NM, <50 nm) particles, with minimal accumulation mode (AM, >50 nm) particles. It was observed that under a quick start engine speed of 800r/min, reducing the injection pulse width of pre-chamber and port fuel injection (PFI), advancing the injection timing of pre-chamber

Miao, Xinke, Liu, Renhe, Zhang, Zhiheng, Deng, Jun, Li, Liguang, Hong, Wei

Experimental Comparison of Different Cycle-Based Methodologies for the INDICATING in Hydrogen-Fueled Internal Combustion Engines

2024-01-2834

04/09/2024

High cycle-to-cycle variations (CTCV) in a Hydrogen-Fueled Internal Combustion Engine (H2-ICE), especially in the lean-burn condition, not only lower the engine’s efficiency but also increase emissions and torque variations. High CTCV are mainly due to the variations in: mixture motion within the cylinder at the time of spark, amount of air and fuel fed to the cylinder, and mixing of the fresh mixture and residual gases within the cylinder during each cycle. In this article, multiple cycle-based methodologies were compared and analyzed specifically for H2-ICEs based on systematic experimentation. The experimental test campaign was performed on a Port Fuel Injection (PFI) H2-ICE designed by PUNCH Torino and data is processed with MATLAB. A MATLAB code is also proposed as a tool for comparing multiple methodologies for the analysis of CTCV specifically for H2-ICE. In order to compare different methodologies, the operating conditions of the H2-ICE were kept constant for all the results

Azeem, Naqash, Beatrice, Carlo, Vassallo, Alberto, Gessaroli, Davide, Pesce, Francesco, Golisano, Roberto, Sacco, Nicola

Oxygenated Fuels as Reductants for Lean NOx Trap Regeneration

2024-01-2132

04/09/2024

The push for environmental protection and sustainability has led to strict emission regulations for automotive manufacturers as evident in EURO VII and 2026 EPA requirements. The challenge lies in maintaining fuel efficiency and simultaneously reducing the carbon footprint while meeting future emission regulations. Alcohol (primarily methanol, ethanol, and butanol) and ether (dimethyl ether) fuels, owing to their comparable energy density to existing fuels, the comparative ease of handling, renewable production, and suitable emission characteristics may present an attractive drop-in replacement, fully or in part as an additive, to the gasoline/diesel fuels, without extensive modifications to the engine geometry. Additionally, lean and diluted combustion are well-researched pathways for efficiency improvement and reduction of engine-out emissions of modern engines. Modern internal combustion engines typically employ various in-cylinder emission reduction techniques along with a multi

Sandhu, Navjot Singh, Yu, Xiao, Ting, David, Zheng, Ming

Development of a Turbulent Jet-Controlled Compression Ignition Engine Concept Using Spray-Guided Stratification for Fueling a Passive Prechamber

03-17-04-0031

01/24/2024

Improving thermal efficiency of an internal combustion engine is one of the most cost-effective ways to reduce life cycle-based CO2 emissions for transportation. Lean burn technology has the potential to reach high thermal efficiency if simultaneous low NOx, HC, and CO emissions can be achieved. Low NOx can be realized by ultra-lean (λ ≥ 2) spark-ignited combustion; however, the HC and CO emissions can increase due to slow flame propagation and high combustion variability. In this work, we introduce a new combustion concept called turbulent jet-controlled compression ignition, which utilizes multiple turbulent jets to ignite the mixture and subsequently triggers end gas autoignition. As a result, the ultra-lean combustion is further improved with reduced late-cycle combustion duration and enhanced HC and CO oxidation. A low-cost passive prechamber is innovatively fueled using a DI injector in the main combustion chamber through spray-guided stratification. This concept has been

Yu, Xin, Zhang, Anqi, Baur, Andrew, Engineer, Nayan, Cleary, David

Characterization of an Integrated Three-Way Catalyst/Lean NOx Trap System for Lean Burn SI Engines

2023-01-1658

10/31/2023

The push for environmental protection and sustainability has led to strict emission regulations for automotive manufacturers as evident in EURO VII and 2026 EPA requirements. The challenge lies in maintaining fuel efficiency and simultaneously reducing the carbon footprint while meeting future emission regulations. Alcohol (primarily methanol, ethanol, and butanol) and ether (dimethyl ether) fuels, owing to their comparable energy density to existing fuels, the comparative ease of handling, renewable production, and suitable emission characteristics may present an attractive drop-in replacement, fully or in part as an additive, to the gasoline/diesel fuels, without extensive modifications to the engine geometry. Additionally, lean and diluted combustion are well-researched pathways for efficiency improvement and reduction of engine-out emissions of modern engines. Modern spark ignition (SI) engines typically employ various in-cylinder emission reduction techniques along with a three

Sandhu, Navjot Singh, Leblanc, Simon, Yu, Xiao, Reader, Graham, Zheng, Ming

Improvement of the EGR Dilution Tolerance in Gasoline Engines by the Use of a HSASI Pre-Chamber Spark Plug

2023-01-1805

10/24/2023

Charge dilution in gasoline engines reduces NOx emissions and wall heat losses by the lower combustion temperature. Furthermore, under part load conditions de-throttling allows the reduction of pumping losses and thus higher engine efficiency. In contrast to lean burn, charge dilution by exhaust gas recirculation (EGR) under stoichiometric combustion conditions enables the use of an effective three-way catalyst. A pre-chamber spark plug with hot surface-assisted spark ignition (HSASI) was developed at the UAS Karlsruhe to overcome the drawbacks of charge dilution, especially under part load or cold start conditions, such as inhibited ignition and slow flame speed, and to even enable a further increase of the dilution rate. The influence of the HSASI pre-chamber spark plug on the heat release under EGR dilution and stoichiometric conditions was investigated on a single-cylinder gasoline engine. The performance of the HSASI spark plug was compared with a passive pre-chamber spark plug

Holzberger, Sascha, Kettner, Maurice, Kirchberger, Roland

Investigation of the Effect of Pre-Chamber Specifications on Pre-Chamber Jet Combustion Characteristics Using an Optically Accessible Engine

2023-01-1801

10/24/2023

This study focused on a lean-burn regime using a pre-chamber for improving the efficiency of internal combustion engines. Combustion images were visualized using a two-stroke, single-cylinder, optically accessible engine fitted with a cylindrical pre-chamber. The L/D ratio of the pre-chamber length (L) to its diameter (D) and the diameter of the pre-chamber orifice were varied as parameters. Combustion characteristics were analyzed based on the visualized jet flow configuration and combustion chamber pressure measurements. The results revealed that the combustion duration tended to be longer with a smaller L/D ratio and that the coefficient of variation (COV) of the indicated mean effective pressure (IMEP) was smaller and more stable. With a smaller orifice diameter, the jet velocity was faster, and the flame development duration was shorter, but the combustion duration was longer; IMEP tended to be lower, but the COV of IMEP was smaller

Chiba, Takaaki, UGAJIN, Taisei, Shinozaki, Kaito, Tahara, Ryota, Sugiyama, Ryo, Iijima, Akira

Experimental Study of High-Pressure Reacting and Non-reacting Sprays for Various Gasoline Blends

04-17-02-0009

10/06/2023

Research into efficient internal combustion (IC) engines need to continue as the majority of vehicles will still be powered by IC or hybrid powertrains in the foreseeable future. Recently, lean-burn gasoline compression ignition (GCI) with high-pressure direct injection has been receiving considerable attention among the research community due to its ability to improve thermal efficiency and reduce emissions. To maximize GCI benefits in engine efficiency and emissions tradeoff, co-optimization of the combustion system and fuel formation is required. Thus, it is essential to study the spray characteristics of different fuels under engine-like operating conditions. In this work, high-pressure spray characteristics are experimentally studied for three blends of gasoline, namely, Naphtha, E30, and research octane number (RON) 98. A single-hole custom-built injector was used to inject fuel into a constant volume chamber with injection pressure varying from 40 MPa to 100 MPa. The chamber

Ullal, Ankith, Lehnert, Bastian, Zhu, Shengrong, Révidat, Stephan, Shirley, Mark, Ha, Kyoung Pyo, Wensing, Michael, Ullrich, Johannes

Research of Fuel Components to Expand Lean-limit in Super Lean Burn Condition (Part III

2023-32-0002

09/29/2023

In this research, we investigated the improvement of combustion and anti-knocking properties as factors that affect the lean limit in order to reflect in fuel design. First, as a basic study, characteristics such as the Laminar burning velocity and Ignition energy of hydrocarbons, which are highly effective in improving combustion speed, were examined. In addition, using the knowledge obtained in the basic study, several concept fuels were created by blending the blend- stocks of the refinery aiming to meet or exceed the current standards in Japan. Their lean limits, thermal efficiencies, and effects on CO2 emission were investigated

Naiki, Taketora, Yasutake, Yuki, Watanabe, Manabu, Obata, Ken

Effects of Fuel Components on Thermal Efficiency and Emissions in Super Lean Burn S.I. Engine

2023-32-0003

09/29/2023

To reduce CO2 emission from the vehicles equipped with internal combustion engine, it is important to combine novel fuel characteristics with combustion technology for high thermal efficiency engine. Lean boosted technology has been studied for a long time because of its potential to increase engine thermal efficiency. Super lean-burn whose excess air ratio λ is higher than 2.0 is expected to achieve both high thermal efficiency and low NOx emissions. In such high λ condition, the chemical reaction effect of fuel components becomes more important. However, it is not evaluated enough due to the difficulty of achieving super lean condition. Therefore, in this paper the effects of fuel on combustion speed, knocking, emission and thermal efficiency are analyzed with super lean burn engine. As a result, it is clarified that the fuel effect on enhancing combustion, especially latter half of combustion is important to reduce HC emission and improves thermal efficiency in super lean burn

Matsubara, Naoyoshi, Kaneko, Kazuki, Kitano, Koji, Yokoo, Nozomi, Nakata, Koichi, Yasutake, Yuki, Naiki, Taketora, Obata, Ken, Watanabe, Manabu

Simulation of charged species flow and ion current detection for knock sensing in gasoline engines with active pre-chamber

2023-32-0005

09/29/2023

Recently, it has been wildly recognized that active pre- chamber has a significant effect on extending the lean burn limit of gasoline engines. Ion current signals in the combustion is also considered as a promising approach to the engine knock detection. In this study, the feasibility of employing ion current in an active pre- chamber for combustion diagnosis was analyzed by three-dimensional numerical simulation on a single- cylinder engine equipped with active pre-chamber. The flow characteristics of charged species (NO+, H3O+ and electrons) in the main chamber and pre-chamber under knock conditions are investigated at different engine speeds, intake pressures and ignition timings. The results show that the ion current can theoretically be used for the knock detection of the active pre- chamber. The peak value of the electron or H3O+ mass fraction caused by knocking backflow can be used as knock indication peak. Intake pressure is the most critical factor affecting the intensity of

MIAO, Xinke, FEI, Shengyi, DENG, Jun, LI, Liguang, HU, Yinuo, MA, Junjie

Effects of pre-chamber specifications on lean burn operation in a pre-chamber engine with fuel reformed gas

2023-32-0007

09/29/2023

Lean combustion has been well known to be an effective method to improve the thermal efficiency. However, leaner mixture is prone to cause the unstable combustion and poorer unburned hydrocarbon (UTHC) emissions. Pre-chamber turbulent jet combustion has been proved to enhance the combustion stability under ultra-lean conditions. However, more NOx is formed during the combustion, resulting in the fact that the tailpipe NOx emission is too high to be still not available for the real application. In this report, in order to achieve a higher air excess ratio while keeping lower UTHC emissions, and especially NOx emission, a new combustion technique which combined pre-chamber jet combustion with fuel reforming was proposed and experimentally demonstrated on a pre-chamber engine

SHEN, Fuchao, TOTSUKA, Masaya, KUBOYAMA, Tatsuya, MORIYOSHI, Yasuo, YAMADA, Toshio, SHIMIZU, Kenichi, YOSHIDA, Takashi

Effect of Olefin Content in Gasoline on Knock Characteristics and HCHO Emission in Lean Burn Spark Ignition Engine

2023-32-0083

09/29/2023

In transportation sector, higher engine thermal efficiency is currently required to solve the energy crisis and environmental problems. In spark ignition (SI) engine, lean-burn strategy is the promising approach to improve thermal efficiency and lower emissions. Olefins are the attractive component for gasoline additives, because they are more reactive and have advantage in lean limit extension. However, owing to lower research octane number (RON), it is expected to exhibit the drawback to reducing the anti-knock performance. The experiments were performed using a single-cylinder engine for 6 fuel types including gasoline blends which have difference in RON varying between 90.4 and 100.2. The results showed that adding olefin content to the premium gasoline provided unfavorable effect on auto-ignition as the auto-ignition happened at unburned gas temperature of 808 K which was 52 K lower at excess air of 2.0. Thus, it reduced anti-knock performance. Additional oxygenated fuels such as

Shinabuth, Dittapoom, Ohmori, Yuya, Kitajima, Katsuki, Ono, Tomoya, Sakaida,, Satoshi, Sakai, Yasuyuki, Konno, Mitsuru, Tanaka, Kotaro

Gas-Dynamic Interactions between Pre-Chamber and Main Chamber in Passive Pre-Chamber Ignition Gasoline Engines

03-17-01-0008

08/30/2023

Pre-chamber turbulent jet ignition (TJI) is a method of generating distributed ignition sites through multiple high-speed turbulent jets in order to achieve an enhanced burn rate in the engine cylinder when compared to conventional spark plug ignition. To study the gas-dynamic interactions between the two chambers in a gasoline engine, a three-dimensional numerical model was developed using the commercial CFD code CONVERGE. The geometry and parameters of the engine used were based on a modified turbocharged GM four-cylinder 2.0 L GDI gasoline engine. Pre-chambers with nozzle diameters of 0.75 mm and 1.5 mm were used to investigate the effect of pre-chamber geometry on pre-chamber charging, combustion, and jet formation. The local developments of gas temperature and velocity were captured by adaptive mesh refinement, while the turbulence was resolved with the k-epsilon model of the Reynolds averaged Navier–Stokes (RANS) equations. The combustion process was modeled with the extended

Yu, Tianxiao, Lee, Dong Eun, Gore, Jay P., Qiao, Li

Effects of Engine Speed on Prechamber-Assisted Combustion

2023-24-0020

08/28/2023

Lean combustion technologies show promise for improving engine efficiency and reducing emissions. Among these technologies, prechamber-assisted combustion (PCC) is established as a reliable option for achieving lean or ultra-lean combustion. In this study, the effect of engine speed on PCC was investigated in a naturally aspirated heavy-duty optical engine: a comparison has been made between analytical performances and optical flame behavior. Bottom view natural flame luminosity (NFL) imaging was used to observe the combustion process. The prechamber was fueled with methane, while the main chamber was fueled with methanol. The engine speed was varied at 1000, 1100, and 1200 revolutions per minute (rpm). The combustion in the prechamber is not affected by changes in engine speed. However, the heat release rate (HRR) in the main chamber changed from two distinct stages with a faster first stage to more gradual and merged stages as the engine speed increased. NFL imaging revealed that

Palombi, Lucia, Sharma, Priybrat, Cenker, Emre, Magnotti, Gaetano

Hydrogen ICE Combustion Challenges

2023-24-0077

08/28/2023

Hydrogen promises to provide some highly desired features for clean and efficient combustion, but harvesting efficiency and emission potentials as well as meeting engine durability requirements needs careful adaption of both, combustion system components and engine operation strategies. Key points for H2-ICE combustion are some specific and unique features of H2/air mixtures, among which – to name only a few – excellent dilutability, lean burn capability, low ignition energy and high molecular diffusivity and their consequences on ICE operation do play prominent roles. H2 admission via port or direct injection, compression ratio selection and injection timing provide a set of parameters to control combustion features. Cooling layout of cylinder head, liner and piston as well as heat rejection from components such as spark plugs, H2-DI injectors or valves must respect enhanced gas to component heat transfer in order to mitigate irregular combustion tendencies such as endgas knock and

Winklhofer, Ernst, Jocham, Bernhard, Philipp, Harald, Kapus, Paul, Leitner, Daniel, Heindl, Rene, Diniz-Netto, Nilton

Fuel Stratification to Improve the Lean Limit in a Methane-Fueled Heavy-Duty Spark-Ignition Optical Engine

2023-24-0045

08/28/2023

Natural gas is an attractive fuel for heavy-duty internal combustion engines as it has the potential to reduce CO2, particulate, and NOx emissions. This study reports optical investigations on the effect of methane stratification at lean combustion conditions in a heavy-duty optical diesel engine converted to spark-ignition operation. The combination of the direct injector (DI) and port-fuel injectors (PFI) fueling allows different levels of in-cylinder fuel stratification. The engine was operated in skip-firing mode, and high-speed natural combustion luminosity color images were recorded using a high-speed color camera from the bottom view, along with in-cylinder pressure measurements. The results from methane combustion based on port-fuel injections indicate the lean burn limit at λ = 1.4. To improve the lean limit of methane combustion, fuel stratification is introduced into the mixture using direct injections. Two different volume fractions of direct injections (20% and 40% by

Panthi, Niraj, Sharma, Priybrat, Magnotti, Gaetano

Hydrogen Admixture Strategies for Small-Scale Cogeneration Gas Engines: A Comparison between different Engine Combustion Processes

2023-01-1206

06/26/2023

Cogeneration represents a key element within the energy transition by enabling a balancing of the long-term fluctuations of regeneratives. Regarding the expected increase of hydrogen share in natural gas pipelines in Germany, this work deals with investigations of hydrogen-associated advantages for the lean and stoichiometric operations of natural gas cogeneration engines, in relation to numerous challenges, such as the efficiency-NOx trade-off. Charge dilution is commonly regarded as one of the most effective ways for improving thermal efficiency of spark-ignition gas engines. While excess air serves as a diluent in the lean combustion process, stoichiometric combustion dilution may be obtained by exhaust gas recirculation (EGR). Combining hydrogen addition with mixture dilution is an appealing approach for a better handling of the efficiency-emissions trade-off. The lean and the diluted stoichiometric combustion processes with hydrogen blending were investigated beforehand

Beltaifa, Youssef, Kettner, Maurice, Salim, Naqib, Berlet, Peter, Pöhlmann, Klaus, Züfle, Michael

Pre-investigations on Reactive Exhaust Gas Recirculation for a Naturally Aspirated Cogeneration Gas Engine

2023-01-1212

06/26/2023

Given its ability to be combined with the three-way catalyst, the stoichiometric operation is significantly more attractive than the lean-burn process, when considering the increasingly severe NOx limit for cogeneration gas engines in Germany. However, the high temperature of the stoichiometric combustion results in increased wall heat losses, restricted combustion phasings (owing to knock tendency) and thus efficiency penalties. To lower the temperature of the stoichiometric combustion and thus improve the engine efficiency, exhaust gas recirculation (EGR) is one of the most effective means. Nevertheless, the dilution with EGR has much lower tolerance level than with excess air, which leads to a consequent drop in the thermal efficiency. In this regard, reducing the water vapor concentration in the recirculated exhaust gas and increasing the EGR reactivity are two potential measures that may extend the mixture dilution limit and result in engine efficiency benefits. Here, the reactive

Beltaifa, Youssef, Kettner, Maurice, Eilts, Peter, Ruchel, Bosse, Fröstl, Sebastian

Optical Study on Spark Plug Gap in Extending Methane Lean Combustion Limits under High Ignition Energy Conditions

03-16-08-0059

06/22/2023

Lean combustion has the potential to achieve high thermal efficiency for internal combustion engines. However, natural gas (NG) engines often suffer from slow burning rates and large cyclic variations when adopting lean combustion. In this study, the effects of spark plug gaps (SPGs) on methane lean combustion are optically investigated under high ignition energy conditions. Synchronization measurements of in-cylinder pressure and high-speed photography are performed for combustion analysis. The results show that large SPGs with high ignition energy exhibit great improvement in engine combustion stability and power capability. Under ultra-lean conditions, a large SPG with a high ignition energy of 150–200 mJ can extend the lean limit to 1.55. Combustion images indicate that this is contributed by the enlarged initial flame kernel, which promotes early flame propagation. Besides, an empirical criterion is adopted to quantify the underlying mechanism, and the results confirm that a more

Zhang, Xiao, Zhang, Ren, Chen, Lin

Repetitive Multi-pulses Enabling Lean CH ₄ -Air Combustion Using Surface Discharges

03-16-08-0061

06/20/2023

The development of efficient and reliable ignition systems for lean fuel-air mixtures is of great interest for applications associated with the use of combustion in transportation, electricity production, and other heavy industries. In this study, we report the use of repetitive nanosecond pulsed surface discharges for the ignition of lean methane (CH4)-air mixtures at pressures above 1 bar. Powered by ten 10-ns voltage pulses at 10 kHz, a commercially available non-resistive spark plug was used to generate surface discharges, which were able to ignite CH4-air mixtures at 1.5 bar and with equivalence ratios (ϕ) ranging from 1.0 to 0.5. At the leanest conditions, e.g., ϕ ≤ 0.6, nitric oxide (NO) and nitrogen dioxide (NO2) emission were reduced to <10% of their values at ϕ = 1.0, demonstrating the advantage of lean burn in emission reduction. Consistent ignition was obtained under extremely lean conditions (e.g., ϕ = 0.5) with a minimum of five pulses and a minimum Coulomb transfer of 82

Umstattd, Ryan J., Jiang, Chunqi

Combustion, Performance, Emissions and Energy Analysis of Hydrogen Fuelled Spark-Ignition Engine under Lean Burn Condition

2023-28-1334

05/25/2023

The design and development of a hydrogen powered spark-ignition engine, aimed for installation on a vehicle for on-road application. The experiment was conducted at WOT (Wide Open Throttle) condition at a speed of 4000 rpm with an excess air-fuel ratio of 1.3, 1.5, 2.2, 2.5, 3, 3.75, and 4.0. The ignition timing was optimized for maximum torque at each value of the excess air ratio. The various parameters analyzed such as in-cylinder pressure, Pressure and Volume, Logarithm of Pressure and Volume, Mass fraction burned, Cummulative heat release, Net heat release, Rate of pressure rise, and Mean gas temperature. The results show that there is a profound effect of excess air-fuel ratio on the engine’s mean effective pressure, output power, Brake thermal efficiency, Volumetric efficiency, Brake specific fuel consumption, and NOx emissions. The peak cylinder pressure decreases with an increase in excess air-fuel ratio and NOx emissions are reduced due to reduced mean gas temperature. Also

Shinde, Apurwa, KARUNAMURTHY, K, SHINDE, BALU JALINDAR, Rairikar, Sandeep, Thipse, Sukrut S

Investigation Effects of Pre-chamber Volume Variations on the Performance of a Natural Gas Lean-Burn Engine

03-16-07-0054

04/20/2023

The pre-chamber ignition system accelerates combustion efficiently by supplying multiple ignition points, high ignition energy, and strong turbulent disturbance. This system expands the lean combustion limit and improves combustion stability on natural gas engines. This work studied the effects of pre-chamber volume variations on combustion, performance, and emission behaviors of a natural gas lean-burn engine under experimental and numerical methods. Results show an increase in the pre-chamber volume from 0.3% to 4.4% of compression volume can increase the in-cylinder pressure in single-stage combustion. The energy and exergy efficiency of the engine Model-1.3% increased up to 43.7% and 41.9%, respectively, which are the highest values among the prepared models. Simultaneously, the model heat loss with the maximum pre-chamber volume was two times higher than the minimum pre-chamber volume. The exhaust gas exergy of Model-1.3% and Model-2.1% are the lowest values, approximately 29% of

Talei, Mehdi, Jafarmadar, Samad, Amini Niaki, Seyed Reza

Experimental Research on Performance Development of Direct Injection Hydrogen Internal Combustion Engine with High Injection Pressure

03-16-07-0053

04/19/2023

As a carbon-free power with excellent performance, the direct injection (DI) hydrogen-fueled internal combustion engine (H2-ICE) has the potential to contribute to carbon dioxide (CO2)-neutral on-road transport solutions. Aiming at high thermal efficiency, the influences of key factors on thermal efficiency over wide operating conditions of a turbocharging DI H2-ICE were investigated under the lean-burn strategy. And the nitrogen oxides (NOx) emission characteristics region was clarified in the high efficiency. The results confirm the optimal ignition strategy with the CA50 of 8–9 crank angle degrees after top dead center (°CA ATDC). The late-injection strategy manifests a significant advantage in brake thermal efficiency (BTE) compared with the early-injection strategy, and this advantage can be amplified by the increased load or injection pressure. The effects of injection (EOIs) pressure on BTE exhibit different laws at different EOIs. Under the early-injection strategy, the lower

Hu, Zhen, Ma, Wenzhong, Ma, Junjie, Zhou, Lei, Wei, Haiqiao, Wei, Hong, Huang, Zeyuan, Hu, Yinuo, Hu, Ke, Yuan, Shuang

Model Based Development for Super Lean Burn Gasoline Engine Using Kolmogorov Microscales

2023-01-0201

04/11/2023

Combustion in a lean atmosphere diluted with a large amount of air can greatly improve fuel efficiency by reducing cooling loss [1, 2]. On the other hand, when air-fuel mixture in cylinder becomes lean, the turbulent combustion speed will decrease, resulting in problems such as the generation of unburned hydrocarbon (HC) and combustion instability [3, 4]. In order to solve these problems, it is important to increase the turbulence intensity and combustion speed [5, 6, 7, 8, 9, 10]. When designing combustion in cylinder by using Computational Fluid Dynamics (CFD), K-epsilon model is widely used for a turbulence model, and the calculated turbulence energy k or turbulence intensity u’ have been used as important indices of combustion velocity [11, 12]. However, it has been confirmed by measurements that the flow will conversely weaken near the top dead center and the combustion duration will become longer when the air flow in the cylinder is extremely strengthened by improved intake port

SAKAI, Hiroyuki, Kimura, Koshiro, Omura, Tetsuo, Takahashi, Daishi

A 3D-CFD Numerical Approach for Combustion Simulations of Spark Ignition Engines Fuelled with Hydrogen: A Preliminary Analysis

2023-01-0207

04/11/2023

With growing concern about global warming, alternatives to fossil fuels in internal combustion engines are searched. In this context, hydrogen is one of the most interesting fuels as it shows excellent combustion properties such as laminar flame speed and energy density. In this work a CFD methodology for 3D-CFD in-cylinder simulations of engine combustion is proposed and its predictive capabilities are validated against test-bench data from a direct injection spark-ignition (DISI) prototype. The original engine is a naturally aspirated, single cylinder compression ignition (Diesel fueled) unit. It is modified substituting the Diesel injector with a spark plug, adding two direct gas injectors, and lowering the compression ratio to run with hydrogen fuel. A 3D-CFD model is built, embedding in-house developed ignition and heat transfer models besides G-equation one for combustion. Three different lean-burn conditions are selected among the tested ones for the validation of the numerical

Sfriso, Stefano, Berni, Fabio, Fontanesi, Stefano, D'Adamo, Alessandro, Antonelli, Marco, Frigo, Stefano

Development of 50% Thermal Efficiency S.I. Engine to Contribute Realization of Carbon Neutrality

2023-01-0241

04/11/2023

To prevent global warming, many countries are making efforts to reduce CO2 emissions toward achieving 2050 carbon neutrality. In order to reduce CO2 concentration quickly, in addition to spread of renewable energy and expansion of BEV, it is also important to reduce CO2 emissions by improving thermal efficiency of ICE (internal combustion engine) and utilizing carbon neutral fuels such as synthetic fuels and biofuels. It is well known that lean burn is an effective technology to increase thermal efficiency of engine highly. However, since NOx emission from lean burn engine cannot be reduced with three-way catalyst, there have been issues such as complicated system configuration due to the addition of NOx reduction catalyst or limiting lean operation to narrow engine speed and load in order to meet emission regulation of each country. This paper introduces super lean burn engine with over lambda 2.5 that achieves both high thermal efficiency and significantly low NOx emission in order

Kimura, Koshiro, SAKAI, Hiroyuki, Omura, Tetsuo, Takahashi, Daishi

Characterization of High-Tumble Flow Effects on Early Injection for a Lean-Burn Gasoline Engine

2023-01-0238

04/11/2023

The influence of early induction stroke direct injection on late-cycle flows was investigated for a lean-burn, high-tumble, gasoline engine. The engine features side-mounted injection and was operated at a moderate load (8.5 bar brake mean effective pressure) and engine speed (2000 revolutions per minute) condition representative of a significant portion of the duty cycle for a hybridized powertrain system. Thermodynamic engine tests were used to evaluate cam phasing, injection schedule, and ignition timing such that an optimal balance of acceptable fuel economy, combustion stability, and engine-out nitrogen oxide (NOx) emissions was achieved. A single cylinder of the 4-cylinder thermodynamic engine was outfitted with an endoscope that enabled direct imaging of the spark discharge and early flame development. Tejhese measurements were complemented by optical-engine tests used to directly measure the impact of fuel injection dynamics on late-cycle flows via a combination of particle

MacDonald, James Richard, White, Logan, Ekoto, Isaac, Pickett, Lyle, Oh, Heechang, Han, Donghee

Combustion Characteristics of Iso-Octane/Hydrogen Flames under T and P Effects up to near Flammability Limits

2023-01-0333

04/11/2023

Lean combustion is an approach to achieving higher thermal efficiency for spark ignition engines. However, it faces low burning velocity and unstable combustion problems near the lean flammability limits region. The current work is attempting to investigate the combustion characteristics of iso-octane flame with 0% and 30% H2 up to near lean limits (λ = 1.7) at 100-300 kPa and 393-453 K. The flame appeared spherically by 37 mJ spark energy at λ = 0.8-1.2, whereas the ultra-lean mixtures, λ ≥ 1.3, ignited at 3000 mJ under wrinkles and buoyancy effects. The impact of initial pressure and temperature on the lean mixture was stronger than the stoichiometric mixture regarding flame radius and diffusional-thermal instability. The buoyancy appeared at the highest burning velocity of 27.41 cm/s. The buoyancy region extended from λ = 1.5 to λ = 1.3 at 393 K, λ = 1.6 to λ= 1.4 at 423 K and λ = 1.7 to λ = 1.5 at 453 K with an increase in initial pressure (higher pressure, more λ under buoyancy

Akram, M. Zuhaib, Aziz, Muhammad, Ma, Fanhua, Deng, Yangbo, Akram, M. Waqar, Akhtar, Ali

Effective Ignition of Lean Methane/Hydrogen Mixture in a Rapid Compression Machine

2023-01-0255

04/11/2023

The use of renewable natural gas and green hydrogen can significantly reduce the carbon footprint of engines. For future spark ignition engines, lean burn strategy and high compression ratio need to be adopted to further improve thermal efficiency, reducing energy consumption. The efficacy of the ignition system is essential to initiate self-sustainable flame under those extreme conditions. In this work, a rapid compression machine is employed to compress air-fuel mixture to engine-like boundary conditions before the spark event to experimentally investigate the ignition and combustion characteristics of the methane-air mixtures under extreme lean conditions. Hydrogen is also added to support the ignition process and enhance flame propagation speed. Lean methane-air mixtures with excess air ratio up to 2.8 are used, with 10 vol% hydrogen addition into the methane fuel. The ignition criteria under various ignition strategies are explored. Both in-cylinder pressure and high-speed direct

Yu, Xiao, Jin, Long, Reader, Graham, Wang, Meiping, Zheng, Ming

Combustion Experiments of Focusing Engine with Asymmetric Double-Piston System Leading to Relatively-Silent High Compression Ratios

2023-01-0401

04/11/2023

In our previous reports, we proposed a new focusing engine with high thermal efficiency based on relatively-silent high compression and nearly-complete air-insulation effect, which employs pulsed multi-jets of gas collided around chamber center. Local compression level due to the gas jets colliding around chamber center before reaction can be varied from zero to 100MPa and 3000K, by changing the number of jets and intake pressure. Relatively-silent high compression is possible, because region around chamber wall is at pressure level of traditional engines. This is suitable for various usages of automobiles, aerocrafts, and rockets, and also for various fuels including hydrogen, because high compression around chamber center leads to stable auto-ignition and potential of low NOx at very lean burning operation. We developed two types of focusing compression engines, without and with piston. For the new engine without piston, we obtained nearly-complete air-insulation and high thrust. In

Naitoh, Ken, Kobayashi, Tomotaka, Saba, Satoshi, Kase, Fumiya, Matsuno, Ryui, Tanishima, Riku, Kawano, Keidai

Analysis of Boosting Architectures for Hydrogen Internal Combustion Engines

2023-01-0411

04/11/2023

Restrictive future CO2 emissions regulations are incentivizing evaluation of carbon-free fuels. This is particularly true in the difficult to electrify heavy commercial vehicle segment. The reemergence of hydrogen internal combustion (H2 ICE) for large displacement engines can both expedite hydrogen adoption and reduce total cost of ownership. This paper covers how the application of various boosting architectures can address challenges unique to H2 ICE. The research presented is derived from simulations conducted by AVL List GmbH and SuperTurbo Technologies on a 13L H2 ICE. The GT Power model was calibrated from dyno testing at AVL of an operational engine and then modified with different boosting systems. The primary H2 ICE challenge that is addressed is the requirement for the engine to maintain a lean-burn combustion strategy through transient operation in order to control NOx formation and minimize aftertreatment requirements. This high lambda requirement can create challenges for

Brin, Jared, Waldron, Thomas

Investigation of Compressor Deposit in Turbocharger for Gasoline Engines (Part 2: Practical Application to Turbocharger

2023-01-0412

04/11/2023

Contribution to carbon neutrality is one of the most important challenges for the automotive industry. Though CO2 emission has been reduced through electrification, internal combustion engines equipped in vehicles such as Hybrid Electric Vehicle (HEV) and Plug-in Hybrid Electric Vehicle (PHEV) are still necessary for the foreseeable future, and continuous efforts to improve fuel economy are demanded. To improve powertrain thermal efficiency, direct-injection turbocharged gasoline engines have been widely utilized in recent years. Super lean-burn combustion engine has been being researched as the next generation of turbocharged gasoline engines. It is known that an increase of the boost pressure causes deposit formation, which decrease the turbocharger efficiency, in the turbocharger compressor housing. To avoid the efficiency loss due to deposit, air temperature at compressor outlet has to be limited low. In this paper, the methodology was constructed to predict compressor efficiency

Ura, Haruto, Kuma, Hiroshi, Hirano, Satoshi, Ishizaki, Noriya

Increasing Engine Efficiency with Hydrogen Assisted Lean Burn Operation on a Small Bore, Long Stroke DISI Engine

2023-01-0246

04/11/2023

Internal combustion engines fall under increased environmental and social pressure. However, they will still play an important role in future transport, especially in hybrid propulsion systems. As a consequence, efficiency of SI engines has to be further increased. Lean burn operation provides a promising way to reach this target. An extremely downsized SI single cylinder research engine is used for the investigations. The engine features a stroke-to-bore ratio of 1.5, leading to higher piston speeds and hence increased tumble motion. The resulting increase in turbulent flame speed supports sufficient combustion performance of diluted mixtures. Although the mentioned provisions increase combustion stability for lean burn operation the reachable relative air/fuel ratio is limited. In order to extend the lean burn capabilities of the engine (λ ≥ 2.0) and further exploit the efficiency advantages of this combustion process the engine is upgraded with a hydrogen port fuel injection. With

Wenz, Erich, Eilts, Peter

Active Plasma Probing for Lean Burn Flame Detection

2023-01-0293

04/11/2023

Combustion diagnostics of highly diluted mixtures are essential for the estimation of the combustion quality, and control of combustion timing in advanced combustion systems. In this paper, a novel fast response flame detection technique based on active plasma is introduced and investigated. Different from the conventional ion current sensing used in internal combustion engines, a separate electrode gap is used in the detecting probing. Further, the detecting voltage across the electrode gap is modulated actively using a multi-coil system to be slightly below the breakdown threshold before flame arrival. Once the flame front arrives at the probe, the ions on the flame front tend to decrease the breakdown voltage threshold and trigger a breakdown event. Simultaneous electrical and optical measurements are employed to investigate the flame detecting efficacy via active plasma probing under both quiescent and flow conditions. The RT-FPGA system provides flexible, prompt, and precise

Wang, Linyan, Yu, Xiao, Cong, Binghao, Li, Liguang, Chen, Guangyun, Zheng, Ming

A Review of Ultra-lean and Stratified Charged Combustion in Natural Gas Spark Ignition Engines

03-16-07-0050

03/15/2023

Natural gas (NG) can be compressed to a high pressure of around 200 bar for use in engines and other applications. Compressed natural gas (CNG) contains 87–92% methane (CH4) and has a low carbon-to-hydrogen ratio compared to other hydrocarbon (HC) fuels. Due to this, it can potentially reduce carbon dioxide (CO2) emissions by more than 20% compared to conventional fuels like diesel or gasoline. This makes CNG one of the most environmentally friendly fuels for internal combustion engines (ICEs). To improve the thermal efficiency of ICEs, higher compression ratios (CRs) and leaner combustion are essential. Since CNG is a gaseous fuel, it has several advantages over liquid fuels due to its favorable physical and chemical properties. A few of these advantages are minimal fuel evaporation issues, a low-carbon content in the fuel composition and a high-octane number. The CNG high-octane number allows for a high CR, resulting in higher thermal efficiency and lower emissions. It should be

Ziyaei, Siyamak, Mazlan, Siti Khalijah, Lappas, Petros

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