Browse Topic: Combustion and combustion processes

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Application of Sustainable Aviation Fuels in Compression-Ignition Aviation Engines: In-Flight Investigations2025-01-0317To be published on 07/02/2025
To achieve a significant reduction in net CO₂ emissions in the aviation sector, sustainable aviation fuels (SAFs) are considered a key factor. Current research efforts are therefore focused on SAFs, which exhibit properties that differ from conventional kerosene, particularly in aspects critical to compression-ignition (CI) engines, such as cetane number, evaporation behavior or lubricity. These differences necessitate dedicated investigations to assess their suitability and performance in such engines. However, real operating conditions — such as intake air- and exhaust- pressure levels during flight — cannot be fully replicated on standard engine test benches. For this reason, real flight experiments were conducted to address these limitations. Notably, this work marks the first instance of in-flight testing of SAFs in CI aviation engines, constituting a significant milestone in this research area. In the course of these investigations, ASTM D7566 Annex A2-compliant HEFA
Kleissner, Florian, Reitmayr, Christian, Hofmann, Peter
Technical Paper
Variable Valve Actuation and Split Injection to Enhance the Gas Exchange of a Passive Pre-chamber Igniter2025-01-0315To be published on 07/02/2025
Pre-chambers, in general, represent an established technology for combustion acceleration by increasing the available ignition energy. Realizing rapid fuel conversion facilitates mixture dilution extension with satisfying combustion stability. More importantly, knock-induced spark retarding can be circumvented, thus reducing emissions and increasing efficiency at high engine loads. Adapted valve actuation and split injections were investigated for this study to enhance the gas exchange of a passive pre-chamber igniter in a single-cylinder engine. The findings support the development of passive pre-chamber ignition systems operable over the whole engine map for passenger vehicles. There are two configurations of pre-chamber igniters: passive pre-chambers and scavenged pre-chambers. This study focuses on the passive design, incorporating an additional small volume around the spark plug into the cylinder head. Hot jets exit this volume after the ignition onset through several orifices
Fellner, Felix, Härtl, Martin, Jaensch, Malte
Technical Paper
Numerical analysis of direct-injection and combustion inside a H2 engine2025-01-0301To be published on 07/02/2025
The direct injection of hydrogen (H2) inside internal combustion engines (ICEs) is gaining large research interest over the port-fuel injection strategy, because of several advantages as higher volumetric efficiencies, increased power output and reduced risks of abnormal combustion. However, the required high pressure ratios across the injector nozzle produce moderate-to-high under-expanded jets, characterized by complex flow structures. This poses a challenge for the numerical modelling of the mixture preparation by means of 3D computational fluid dynamic (CFD) approaches. In this work, a validated 3D-CFD methodology has been employed to simulate the closed-valve cycle of a direct injection H2 engine equipped with a centrally mounted hollow-cone injector and a non-axisymmetric piston bowl. First, injection and mixture preparation have been studied considering an early injection at the beginning of the compression stroke, and a delayed injection in the second half of the compression
Capecci, Marcolucio, Sforza, Lorenzo, Lucchini, Tommaso, D'Errico, Gianluca, Pezza, Vincenzo, Tosi, Sergio
Technical Paper
Experimental and Numerical Analysis of Direct Injection Process for Hydrogen-Fuelled Internal Combustion Engines2025-01-0307To be published on 07/02/2025
In the context of the clean transport sector, there has been growing interest in the use of hydrogen in internal combustion engines due to its potential to nearly eliminate all engine-out criteria pollutants, while maintaining high thermal efficiency through the use of a lean combustion process. Direct Injection (DI) is widely recognized as a method for enhancing thermal efficiency and minimizing the risk of abnormal combustion. However, a major challenge is the reduced time available for mixture homogenization, making injection timing a critical parameter to optimize. To address this, a comprehensive experimental campaign was conducted in a constant volume vessel to assess the performance of a hydrogen injector using the Schlieren technique. The jet behavior was analyzed by varying injector recess, injection pressure, and back pressure. Subsequently, the case study was replicated in a 3D Computational Fluid Dynamics (CFD) environment, addressing the complexities associated with
Pucillo, Francesco, Piano, Andrea, Millo, Federico, Giordana, Sergio, Rapetto, Nicola, Vargiu, Luca
Technical Paper
Effect of Gasoline Component on Fuel Economy of WLTC Drive with EGR and Lean Combustion2025-01-0305To be published on 07/02/2025
It is becoming increasingly clear that research into alternative fuels, including drop-in fuels, is essential for the continued survival of the internal combustion engine. In this study, the authors have evaluated olefinic and oxygenated fuels as drop-in fuels using a single-cylinder engine and considering fuel characteristic parameters. The authors have assessed thermal efficiency by adding the EGR or air from 0 to the maximum value that allows stable combustion. Next, we attempted to predict fuel efficiency for four types of passenger cars (Japanese small K-car N/A, K-car T/C, Series-HV, and Power-split-HV) by changing the fuels. We created a model in OpenModelica to estimate fuel efficiency during WLTC driving. The results indicated that fuel economy could potentially be improved by adding an olefin fuel that burns stably even with a large amount of EGR or air and an oxygen fuel whose octane number increases. It was observed that the fuel economy improvement rate was particularly
Moriyoshi, Yasuo, Xu, Fuguo, Wang, Zhiyuan, Tanaka, Kotaro, Kuboyama, Tatsuya
Technical Paper
In-Depth Experimental Investigation into Performance and Emission Characteristics of a Diesel Light-Duty Engine Fuelled with Pure Hydrogen2025-01-0314To be published on 07/02/2025
Transitioning to zero-carbon fuels is pivotal for expediting the reduction of carbon emissions. Hydrogen demonstrates significant adaptability and emerges as a principal zero-carbon alternative fuel for carbon-based internal combustion engine (ICE) platforms. Implementing hydrogen in both spark ignition (SI) and compression ignition (CI) engines has proven to be both economically viable and timely; nevertheless, it presents several technical challenges that must be addressed. The study analyses the performance and emissions of a single-cylinder boat engine converted from diesel to 100% hydrogen. A port fuel injection (PFI) system was adopted to operate the engine with hydrogen by replacing the diesel injector with a spark plug engine without any modification to the cylinder head. The engine features an automated shutdown system to mitigate intake backfire risks associated with hydrogen PFI systems. A comprehensive engine characterization was conducted at a wide range of relative air-to
Mohamed, Mohamed, Zaman, Zayne, Lu, Enshen, Feng, Yizhuo, Wang, Xinyan, Zhao, Hua
Technical Paper
Method for externally controlled availability of lubricating oil in internal combustion engines.2025-01-0302To be published on 07/02/2025
Reduced emissions in internal combustion engines (ICE) are a key component in reaching green-house-gas and pollutive emissions regulations. With increased effort, clean and efficient burning combustion cycles are being developed. With the need of even more efficient engines the friction of ICE engines plays an increasing role in engine efficiency. Also, ingress of lubricating oil into the combustion chamber is a source of particle emissions. Increased optimization to reduce parasitic drag in the piston assembly such as reduced ring pre-tension ore thinner grade oils further increase oil ingress into the combustion chamber with the result of increased particle emissions. The transport mechanisms of oil ingress into the combustion chamber therefore the topic of current research. Specially developed research engines with a vertical optical window have big potentials to visualize phenomena of the oil behavior inside the piston assembly in internal combustion engines. Therefore, these
Stark, Michael, Fellner, Felix, Härtl, Martin, Jaensch, Malte
Technical Paper
Effect of Ignition Condition and Fuel Octane Number on Knock Intensity in a Small 2-Stroke Engine2025-01-0211To be published on 06/16/2025
The internal combustion engines are widely used on automotive transportation for its high energy storage system efficiency and economic benefits. The 4-stroke engine has dominated all other forms to date, because the Otto cycle is simpler to comprehend. However, the significant benefits such as, less pumping work and friction, lighter construction of 2-stroke engine, helped with applications which appreciate the simplicity and power density as well as meet the emission regulations. The disadvantages of the 2-stroke engine mainly caused by the lack of sufficient scavenging process, which limited its trapping efficiency. Also, the overlap of the intake and exhaust phases results in charge short-circuiting, more fuel consumption and high unburned hydrocarbon emissions. For the reason above, it is difficult for 2-stroke engines to realize stoichiometric combustion and unable to use three-way catalyst to control emissions. The residual exhaust gas in the cylinder makes the spark ignition
Liu, Jinru, Yamazaki, Yoshiaki, Otaki, Yusuke, Kato, Hayato, Yokota, Takumi, Iijima, Akira
Technical Paper
Decarbonisation of GDI Engines Utilising On-board Hydrogen Production in an Improved Design Thermochemical Exhaust Assisted Fuel Reformer2025-01-0186To be published on 06/16/2025
Engine intake charge enrichment with hydrogen (H2) is one way to enhance engine thermal efficiency and reduce pollutant emissions while replacing carbon-based fuel. Waste energy from hot exhaust gas can be thermochemically recovered as hydrogen in catalytic exhaust gas fuel reforming, which can then be used in combustion. This study focuses on tailoring the design of the fuel reformer, including the catalyst chemistry and coating on ceramic and metallic structures, to benefit the whole system’s fuel economy and reduce engine out emissions. The main reformer improvements focused on exhaust flow management and interaction with the engine's after-treatment system, while the final stage focused on the reformer's internal design structure. The new design iteration enabled hydrogen production improvements in the range of 78% to 86% in the critical exhaust gas temperature range of 410 oC to 520 oC with gas hourly space velocities (h-1) in highly demanding engine operating conditions ranging
Lee, Seung Woo, Wahbi, Ammar, Herreros, Jose, Zeraati Rezaei, Soheil, Tsolakis, Athanasios, Millington, Paul
Technical Paper
Effects of Injection and Intake Timing on Atomization and Combustion in a Hybrid Gasoline Direct Injection Optical Engine under the Low-Speed Low-Load Condition2025-01-0203To be published on 06/16/2025
With the growing trend of hybridization in modern engines, hybrid gasoline direct injection (GDI) engines are typically designed for high-load, mid-to-high-speed operation to achieve optimal fuel economy. However, these engines inevitably operate under low-speed, low-load conditions where insufficient intake air often leads to poor air-fuel mixing and weak turbulence, resulting in suboptimal combustion. Adjusting intake and injection timing presents a simple and effective approach to optimizing the combustion process in hybrid GDI engines. In this study, an optical engine with a combustion system geometry identical to that of an advanced hybrid GDI engine is used. The engine features a compression ratio of 15.0:1 and is equipped with a variable timing camshaft for intake timing control and an electronically controlled system for injection timing. High-speed color imaging, using transparent pistons and cylinder liners, captures the in-cylinder spray development and combustion processes
Cui, Mingli, Fu, Jinhong, Man, Xingjia, Nour, Mohamed, Zhang, Weixuan, Li, Xuesong, Xu, Min
Technical Paper
Flame developments of pilot diesel ignited hydrogen jet in an optical dual direct injection engine2025-01-0237To be published on 06/16/2025
This study aims to characterise the flame development for hydrogen-diesel dual direct injection (H2DDI) in an optically accessible heavy-duty engine through high-speed imaging of the natural combustion luminosity. A single hole, side mounted injector was used to inject H2 at 350 bar in addition to a centrally mounted eight-hole diesel injector providing the ignition source for the H2. The diesel pilot flame was examined without H2 to establish the combustion characteristics of the pilot flame. The pilot fuel energy was reduced from 1200J to 120J while examining the distribution of the pilot flame as the H2 energy fraction was increased. The flame distribution transitioned from an initial quasi-steady diesel flame at peak load (1200 J), to a piston bowl wall-centric flame distribution (840 J) and then to an injector centric flame (120 J). The pilot fuel quantity of 120 J was selected to investigate the ignition process of hydrogen main fuel mixtures supplying 90% energy (only 10% energy
Heaton, Alastar, Chan, Qing Nian, Kook, Sanghoon
Technical Paper
Higher Content n-Butanol Blending Ratios in Diesel Fuel Spray and Combustion Characteristics: Addressing Oxygenated Fuel Challenges with Spark-Assisted Combustion Strategies2025-01-0210To be published on 06/16/2025
This study investigates the effects of oxygenated fuels, specifically long-chain alcohols, impact fuel atomization and combustion behavior in CI engines. The objective is to examine how higher n-butanol blending ratios in diesel fuel influence spray dynamics and combustion performance under varying engine conditions using an advanced combustion strategy. Experiments were conducted using a constant volume chamber (CVC) and a rapid compression-expansion machine (RCEM), both designed to replicate CI engine conditions. N-butanol was blended with diesel at ratios ranging from 70% to 90% with 10% increments, and key parameters such as spray formation, cone angle, penetration length, in-cylinder pressure, combustion performance, and efficiency were analyzed. The study also evaluated the effects of varying injection pressures on spray behavior. The results demonstrate that increasing n-butanol content significantly alters spray and combustion characteristics. Higher n-butanol proportions lead
Warsita, I Wayan, Lim, Ocktaeck
Technical Paper
numerical investigation into the combustion and emission characteristics of ammonia direct injection mechanism2025-01-0241To be published on 06/16/2025
Ammonia is an attractive option because of its relatively low greenhouse gas (GHG) emissions, high energy density, competitive cost, and ubiquitous infrastructure for manufacturing, storage, and distribution. In this work, the optimum combustion characteristics are investigated to propose an efficient ammonia engine for future investigation. The effects of ammonia addition on diesel combustion characteristics were numerically investigated in a CI engine. The investigation was conducted by structured 3D CFD modeling to analyze the combustion characteristics. The validation of the boundary condition was compared to the designed experimental ammonia engine. The direct injection timing of 10o-50oBTDC and injection pressure 300-800 bar was proposed to identify the optimum autoignition characteristics. The equivalence ratios 1, 0.75, 0.5, and 0.25 were used in order to analyze the high cetane number characteristics and the air-fuel ratio.
Setiawan, Ardhika, Lim, Ocktaeck
Technical Paper
Comparison of HRD and Petro Diesel in Industrial Engine Applications2025-01-0243To be published on 06/16/2025
Renewable fuels are seen as a key enabler on the path to a lower carbon future. A low greenhouse gas fuel of particular interest is hydrotreated renewable diesel (HRD), also known as hydrotreated vegetable oil (HVO). HRD is of interest because it is a drop-in replacement to existing petroleum fuels used in diesel engines. An experimental investigation was undertaken to evaluate combustion characteristics of HRD versus a standard petroleum diesel. The work was carried out using a 2.5-liter fully instrumented single-cylinder research engine. This engine was chosen because it provides a very precise view of the difference in combustion and emissions of the fuels. Results represent the difference in combustion characteristics of the fuels, rather than potential differences in engine performance seen in a production engine, as each particular engine model will react a bit differently to the changes in combustion. The engine was operated according to three ISO 8178-4 test cycles: C1, D2, and
Bardell, Michael, Abi-Akar, Hind, Seiler, Patrick, Nash, Brady, McMahon, Donna, Ioannou, Marios
Technical Paper
Research on Combustion Characteristics of Flash-Boiling Spray in Cylinders Based on Machine Learning Methods2025-01-0205To be published on 06/16/2025
With the increasing number of vehicles in operation, exhaust emissions from engines have exerted negative impacts on ecological environments, prompting researchers to actively pursue cleaner and more efficient in-cylinder combustion strategies. Flash-boiling spray technology, capable of generating superior fuel atomization under relatively low injection pressures, has emerged as a promising approach for achieving performance breakthroughs in gasoline direct injection (GDI) engines. While current research primarily focuses on morphological characterization and mechanistic analysis of flashboiling spray, there remains insufficient understanding of flame development characteristics under flash boiling spray conditions within engine cylinders. This study systematically investigates the combustion characteristics of TPRF and PRF fuels under both subcooled and flash-boiling spray conditions through the integration of image processing and machine learning methodologies. Experimental
Zhang, Weixuan, Shahbaz, Muhammad, Cui, Mingli, Li, Xuesong, Xu, Min
Technical Paper
Optimization of the lubricating oil composition to reduce emissions from hydrogen engines2025-01-0212To be published on 06/16/2025
The decarbonization of the transport sector has become a priority for governmental authorities and industrial stakeholders alike, driving regulatory measures and innovation in powertrain technologies. Among the innovative solutions, hydrogen combustion engines have gained significant attention due to their customization to diverse applications, including heavy-duty vehicles, passenger cars, generators, and even two- and three-wheelers. Hydrogen combustion, characterized by high ignitability, rapid flame speed, soot-free operation, and water as a combustion by-product, introduces distinct challenges for engine lubrication. These unique characteristics require the development and adaptation of lubricant formulations to ensure optimal engine performance and durability. Specifically, tailored lubricants play a vital role in addressing four key challenges: pre-ignition, particulate emissions, water contamination, and wear protection. This study investigates the impact of crucial formulation
Gohl, Marcus, Wulff, Robert, Scholl, Peter, Günthner, Michael, Jung, Philipp Emanuel, Chapelot, Pierre
Technical Paper
Evaluating the Impact of Displacing Injected Gasoline with Aspirated Ammonia in a Direct Injection Spark Ignition Engine2025-01-0226To be published on 06/16/2025
Replacing fossil fuels with renewable ammonia could provide a crucial step towards the decarbonisation of transport sectors. However, many challenges remain in utilising ammonia within combustion systems: the volumetric energy density of ammonia is significantly lower than that of gasoline, exposure to ammonia (including ammonia slip) can be detrimental to human health, and the production of emissions, including unregulated emissions (such as N2O), from ammonia combustion can be catastrophic for the environment if not treated appropriately. Therefore, there is a need to determine the efficacy of ammonia as a fuel for internal combustion engines and the impact on the efficiency of energy release and the resulting exhaust emissions. A modern spark ignition engine was modified such that ammonia was aspirated through the engine intake air to incrementally displace engine gasoline and maintain a constant work output. It was found that displacing the fuel energy supplied by direct injected
Sivaranjitham, Annaniya Mitchell, Hellier, Paul, Ladommatos, Nicos, Millington, Paul, Alcove Clave, Silvia
Technical Paper
A Comparative Assessment of Port Fuel Injection and Direct Injection of Hydrogen in Internal Combustion Engines: Performance, Efficiency, and Emissions2025-01-0239To be published on 06/16/2025
With the transition toward low-carbon fuels-based transportation systems, hydrogen is becoming increasingly promising as a sustainable internal combustion engine (ICE) fuel. There are two pathways for introducing hydrogen: Port Fuel Injection (PFI) and Direct Injection (DI) in an engine, which greatly affects performance, efficiency, and emissions. In the Port Fuel Injection (PFI); hydrogen is introduced into the intake manifold and mixed with air before reaching the combustion chamber. This approach is preferred due to its affordability, ease of use, and compatibility with current engine configurations. Because of PFI's more uniform air-fuel mixture, combustion is smoother, and NOx emissions are reduced. On the other hand, it raises the possibility of pre-ignition, particularly when engine loads are high, and a decrease in volumetric efficiency due to a reduction in the volume of intake air as hydrogen replaces it. Direct injection gives exact control over the timing and volume of
Ahirwar, Sachin, Kumar, Naveen
Technical Paper
Investigating lubricants base oils reactivity in ammonia/hydrogen engines via accelerated aging2025-01-0240To be published on 06/16/2025
As a carbon-free molecule, ammonia is more and more considered as a relevant fuel for long distance and off-road applications. However, this gas has different combustion characteristics compared to conventional fuels, challenging the suitability of lubricants to such engines. In this work, the evolution of lubricants under conditions mimicking ammonia combustion was assessed. Mineral and polyester lubricant base oils were exposed to oxygen, nitrogen oxides, and ammonia in a pressurized reactor under stirring. Oil aliquots were sampled at regular intervals, and characterized using Fourier Transform Infrared Spectroscopy (FTIR), viscosity and total oxygen and nitrogen contents measurements. Exposure to air containing nitrogen oxides resulted in quicker accumulation of oxidation products compared to neat air, for both the mineral and complex polyester base oil. Besides, exposure to gaseous ammonia in air resulted in a slower oxidation rate for both oils, compared to neat air. A global
Doncoeur, Carole, Giarracca, Lucia, Cologon, Perrine, Rousselle, Christine
Technical Paper
Combustion and emission characteristics of marine Ammonia-Diesel dual fuel single-cylinder engine with MP injector change2025-01-0235To be published on 06/16/2025
Recently, as regulations on greenhouse gas emissions due to global warming have tightened, there has been growing interest in engines that use environmentally friendly fuels. In this context, ammonia is gaining attention as a potential alternative to fossil fuels in the future. However, due to the unique fuel characteristics of ammonia compared to traditional fuels, research is being conducted on using diesel as an ammonia ignition source. In this study, combustion and exhaust characteristics were compared according to the characteristics of micro-pilot diesel injectors in the marine ammonia-diesel dual fuel single-cylinder engine. Various injectors with different hole numbers and sizes were examined (Injector A: more holes and larger size, Injector B: fewer holes and smaller size). To maintain a constant energy ratio between ammonia and diesel at a steady load, the injection duration was adjusted, and the MP injection timing varied in 5 CAD intervals to evaluate performance and
Jang, Ilpum, Park, Cheolwoong, Kim, Minki, Park, Chansoo, Kim, Yongrae, Park, Gyeongtae, Lee, Jeongwoo
Technical Paper
Understanding how blending different ratios of renewable fuels with diesel impacts the toxicity of exhaust particulates to human health.2025-01-0207To be published on 06/16/2025
The urgent need to decarbonise transport has increased the utilisation of renewable fuels with current hydrocarbons. Heavy duty vehicle electrification solutions are yet to be realised and therefore the reliance on diesel engines may still be present for decades to come. Currently, the diesel supplied to fuel stations across the UK is a 7% blended biodiesel, whilst in South Korea a 5% blend is utilised. Biodiesel is produced from renewable sources for example; crops, waste residue and oils or biomass. Particulates from diesel combustion are known to be toxic, due to the presence of polyaromatic hydrocarbons (PAHs) however there is very limited understanding of blending oxygenated fuels on the toxicity of the particulates produced. PAHs are aromatic structures that can be metabolised into chemicals which can disrupt DNA replication and potentially influence cancer mechanisms if inhaled in high quantities. Soyabean methyl-ester (SME) was blended at lower ratios, e.g., 5%, 10%, 15% and
Hailwood, Emma, Hellier, Paul, Ladommatos, Nicos, Leonard, Martin
Technical Paper
Development of Combustion System for a Hybrid-dedicated Homogeneous Lean Burn Engine2025-01-0216To be published on 06/16/2025
This study explores methods to extend the lean combustion limit, improve efficiency, and reduce engine-out emissions in a hybrid-dedicated homogeneous lean combustion engine. Under lean combustion conditions, slow laminar flame speed restricts flame kernel growth, leading to instability and limiting the lean combustion threshold. To address this challenge, a combustion system was developed that leverages the engine’s internal flow to enlarge the spark channel at the spark gap and promote the formation of a larger-scale flame kernel. The combustion chamber was optimized by redesigning the intake port geometry and piston bowl to generate a high tumble flow. This new design significantly increased airflow around the spark plug gap, accelerating the initial combustion process and effectively expanding the lean combustion limit. Additionally, multiple ignition was implemented to prevent spark channel shortening caused by increased electrical resistance, further enhancing combustion
Oh, Heechang, Lee, Jonghyeok, Sim, Kiseon, Park, Jongil, Kim, Taekyun, Kang, Hyunjin, Hong, Seungwoo, Han, Donghee, Kim, Dokyun
Technical Paper
Effects of Double Injection Strategy in a Diesel-Ammonia Dual-Fuel Engine2025-01-0206To be published on 06/16/2025
This study investigates the application of a double injection strategy in a single-cylinder marine diesel-ammonia dual-fuel engine retrofitted for experimental analysis. Diesel micro-pilot (MP) injection was used to ignite ammonia combustion, with diesel and ammonia injected separately into the cylinder through dedicated injectors. The first MP injection timing was fixed at -20 CAD before ammonia injection timing, and both early and late double MP injection strategies were implemented to evaluate their effects on ammonia combustion, engine performance, and exhaust emissions. Under all conditions, the ammonia injection timing remained constant. Early double injection strategies, with the second MP injection occurring before the first, enhanced premixed diesel combustion by raising in-cylinder temperature and pressure. However, this early heat release was ineffective for ammonia evaporation and combustion due to poor timing alignment. In contrast, late double injection strategies, with
Park, Chansoo, Jang, Ilpum, Park, Cheolwoong, Kim, Minki, Park, Gyeongtae
Technical Paper
Development of After-treatment Systems and Control Strategy for a Hybrid-dedicated Homogeneous Lean Burn Engine2025-01-0217To be published on 06/16/2025
Lean-burn gasoline engines can improve fuel economy thanks to the higher specific heat ratio of the mixture and the reduced cooling loss during the combustion process. In addition, when combined with hybrid technology, the technology can achieve more synergies by overcoming obstacles such as limited operating conditions. However, the challenge of this technology is to reduce exhaust emissions to a level suggested by future stringent regulations. In lean-burn gasoline engines, nitric oxide (NOx) emissions are difficult to convert using conventional three-way catalysts (TWCs). Therefore, developing an effective NOx after-treatment system has been a key technology in the development of lean-burn engines. In addition, hydrocarbon (HC) emissions are also challenging because they increase under lean combustion conditions, while the lower exhaust temperature under lean conditions makes them hard to oxidize. Therefore, a catalyst technology capable of effectively converting HC, even at a low
Oh, Heechang, Lee, Jonghyeok, Sim, Kiseon, Lim, SeungSoo, Park, Jongil, Park, Minkyu, Kang, Hyunjin, Han, Donghee, Lee, Kwiyeon, Song, Jinwoo
Technical Paper
Residual Gas and Emission Characteristics in a Propane-Fueled Spark-Ignition Engine with Varying Combustion Durations2025-01-0202To be published on 06/16/2025
This research investigates the impact of combustion duration on combustion characteristics, emissions, and residual gas in a propane-fueled spark ignition engine under varying engine speeds. Using a two-cylinder V-twin engine and AVL-Boost simulation, experiments were conducted at speeds ranging from 3000 to 8000 rpm with combustion durations between 40° and 80° crank angle. The study integrates simulation and experimental methods to address challenges in measuring residual gas and effective release energy (ERE) under different conditions. Results show that longer combustion durations generally lead to increased residual gas and BSFC, while also influencing peak fire temperature, effective release energy, and emission characteristics. At 3000 rpm, optimal conditions were observed with a peak BMEP of 11.11 bar, torque of 25.01 Nm, power output of 14.87 kW, and a minimum BSFC of 311.43 g/kWh. Longer combustion durations elevated the residual gas, reaching up to 0.946 at 8000 rpm, and
Quach, Nhu Y, Lim, Ocktaeck
Technical Paper
Thermal efficiency improvement and emission reduction of methanol spark ignition engine using lean-burn strategy2025-01-0224To be published on 06/16/2025
Methanol is a promising fuel for achieving carbon neutrality in the transportation sector, particularly for internal combustion engine vehicles. With its high-Octane number, methanol enables higher thermal efficiency compared to gasoline engines. Additionally, its wide flammability range allows stable engine operation under lean burn conditions at low to mid-load levels. In this study, experiments were conducted on a single-cylinder engine to examine the combustion and emission characteristics under varying excess air ratios and injection timings. The results showed that the highest thermal efficiency was achieved at the highest excess air ratio, despite the lowest combustion efficiency and the longest burn duration. This outcome highlights that a larger air mass reduces heat loss and pumping loss. Furthermore, NOx emissions decreased due to the reduction in in-cylinder temperatures. However, HC emissions increased as a result of the decline in combustion efficiency
Lee, Seungwon, Kim, Hyunsoo, Hwang, Joonsik, Bae, Choongsik
Technical Paper
Comparison of Methanol and Gasoline Fuel Spray Vaporization Using Direct-Injection Technology2025-01-0225To be published on 06/16/2025
Considering the large opportunity to reduce net lifecycle carbon emissions through the use of renewable methanol, we address spray technologies needed to overcome the challenge of wall wetting and poor vaporization for methanol and the need for improved computational modeling of these processes. High-speed extinction imaging followed by computed tomography reconstruction is utilized to provide three-dimensional liquid volume fraction for reference fuel injectors, to be used for model validation activities. The first injector is the symmetric 8-hole Spray M injector for the Engine Combustion Network, and the second injector is an asymmetric 6-hole injector designed for lateral-cylinder mounting. The degree of plume interaction and vaporization are characterized at representative injection conditions, showing substantially higher concentrations of liquid for methanol than gasoline even with preheated fuel temperatures (90 degrees C). In light of higher injected mass requirements for
Wan, Kevin, Clemente Mallada, Rafael, Buen, Zachary, White, Logan, Oh, Heechang, Dhanji, Meghnaa, Pickett, Lyle
Technical Paper
Evaluation of Several Jet Fuels under Compression-ignition Operation on Thermal Efficiency, NOx, Particulate Matter, and Particle Size Distribution2025-01-0244To be published on 06/16/2025
Alternative fuels such as Fischer-Tropsch Synthesized Paraffinic Kerosene (FT-SPK) and Catalytic Hydrothermal Conversion Jet (CHCJ) are among those important sustainable aviation fuels (SAFs) for future transportation. However, these alternative fuels often vary in their fuel characteristics, which depend on feedstock and fuel production processes. Therefore, a detailed analysis of combustion, emissions, and efficiency of these alternative fuels must be performed under controlled experiments to understand the impact of fuel properties and operating conditions. Using a single-cylinder research engine (SCRE), extensive operating conditions were performed to realize any difference in performance that can be fundamentally understood by fuel properties (e.g., cetane number, heat of combustion, and density) of these fuels in comparison with Jet-A. The experimental setup includes high-speed data acquisition for combustion analysis and gaseous and solid emissions benches for nitrogen oxides
Cung, Khanh, Miganakallu Narasimhamurthy, Niranjan, Khalek, Imad, Hansen, Greg
Technical Paper
An experimental and numerical study of ultra-lean combustion characteristics of methanol direct injection using various coil spark ignition strategies2025-01-0200To be published on 06/16/2025
Methanol is significantly emerging as a promising alternative fuel in the pursuit of carbon neutrality. This study aims to analyze the combustion characteristics of methanol in a spark-ignition (SI) engine operating under high compression ratios and ultra-lean conditions through both experimental and simulation approaches. The objective is to derive optimized combustion efficiency by employing various ignition strategies based on discharge energy. To this end, experiments were conducted using a Rapid Compression Expansion Machine (RCEM) to replicate realistic engine environments. The effects of discharge energy and spark duration across different spark coil configurations were investigated through both experimental methods and computational fluid dynamics (CFD) simulations. The experimental results showed that the use of multiple spark coils achieved an energy release rate of approximately 239 mJ/s, more than twice that of the single-coil configuration. Simulation results were in good
Choi, Jeongyeon, Lim, Ocktaeck
Technical Paper
Design and optimisation of pre-chamber ignition system for a heavy-duty hydrogen engine at lean conditions2025-01-0229To be published on 06/16/2025
Strict regulations and legislation for carbon emissions and pollution from heavy-duty engines are pushing towards carbon-free fuels such as Hydrogen as a fuel for internal combustion engines. Moving towards this goal, the engine design needs to fully comply with Hydrogen’s unique characteristics to achieve optimum performance and efficiency. One of the aspects that has the potential to improve combustion efficiency and emissions is adopting the pre-chamber ignition strategy in large bore engines at lean conditions. The pre-chamber is a small cavity, usually 3-6% of the total engine volume, installed on the cylinder head, housing the initial combustion event, which would then be injected into the main chamber via nozzles placed at the bottom of the pre-chamber. This ignition strategy would provide multiple flame fronts into the main chamber, accelerating combustion speed and enhancing engine performance. However, the pre-chamber must be designed dedicatedly for Hydrogen combustion to
Keshtkar, Hossein, Feng, Yizhuo, Zhao, Hua, Wang, Xinyan
Technical Paper
Ammonia-diesel Engines Segmented Modeling approach and Simplified Combustion model Research2025-01-0232To be published on 06/16/2025
Ammonia-diesel dual-fuel engines can effectively reduce greenhouse gas (GHG) emissions. Aiming at the real-time control requirements of ammonia/diesel dual-fuel engines, this study proposes a segmented real-time modeling method and a heat release rate model simplification strategy by linearized heat release rate curves. First, the engine working cycle is divided into three parts: intake and exhaust stage, compression and expansion stage, and combustion process. Different simulation steps and modeling strategies are designed to optimize computational efficiency while maintaining the necessary level of accuracy at each stage. Secondly, based on the calibrated heat release rate (HRR) curves, feature points are extracted to construct a simplified linear heat release model. In the absence of calibration data, the characteristic points of the HRR curves are obtained through interpolation. Compared with the commonly used combustion model, the Wiebe model, the proposed simplified model can
Li, Guangyuan, Chen, Run, Wang, Xinran, Li, Tie, Zheng, Kexiong, Liu, Shaoling, Liu, Yanchao, Lyu, Xiaodong
Technical Paper
Comparison of spark and turbulent jet ignition in a fully ammonia-fueled engine2025-01-0201To be published on 06/16/2025
Ammonia (NH₃) is an emerging carbon-free fuel with the potential to decarbonize the energy sector. However, its widespread adoption is hindered by challenges like low flame speed, high ignition energy, and elevated emissions of nitrogen oxides (NOx) and unburnt NH₃. These limitations necessitate innovative combustion strategies for efficient and stable engine operation. This study investigates the potential of turbulent jet ignition (TJI) to overcome these challenges through the implementation of a pre-chamber, a small auxiliary chamber equipped with a spark plug to create hot, reactive jets that propagate into the main chamber, promoting rapid combustion from distributed ignition sites. In this work, TJI operation is compared to conventional spark ignition (SI) in a Cummins ISB6.7 engine retrofitted for 100% ammonia operation. Experiments were conducted at 1200 and 1800 RPM across varying loads (25%, 50%, 75%, and 100%) with equivalence ratio and spark timing sweeps. Combustion
Dhotre, Akash, Voris, Alex, Okey, Nathan, Kane, Seamus, Northrop, William
Technical Paper
Analysis of Combustion Characteristics of a Small 2-Stroke Opposed Piston Engine Using an Optically Accessible Engine and Numerical Analysis2025-01-0223To be published on 06/16/2025
As global warming becomes more serious, decarbonization of internal combustion engines, which emit a large amount of carbon dioxide, is being promoted. It is predicted that many vehicles will still be equipped with engines in 2035, and a variety of powertrains will be required in the future. Therefore, we focused on the opposed-piston engine as an internal combustion engine specialized for power generation applications. The opposed-piston engine is characterized by its light weight due to the absence of a cylinder head, low S/V ratio due to the ultra-long stroke, reduced cooling loss due to the long stroke, and reduced vibration due to the offsetting of the reciprocating inertial forces of the left and right pistons. We believe that the engine for power generation can achieve the required high efficiency operation and vibration reduction. Therefore, in this study, combustion analysis of a two-stroke opposed-piston engine with features of low vibration, high efficiency, and high output
Yamazaki, Yoshiaki, Watanabe, Sou, Okawara, Ikumi, Otaki, Yusuke, Liu, Jinru, Iijima, Akira
Technical Paper
An Experimental Study on Aqueous Ammonia and Diesel Dual-Fuel Combustion with Ignition Improving Additives in a Compression Ignition Engine2025-01-0231To be published on 06/16/2025
Ammonia is a potential vector of renewably produced hydrogen for combustion systems and decarbonisation of transport. However, anhydrous ammonia remains dangerous and difficult to handle due to its volatility and toxicity. Therefore, a water-based solution of ammonium hydroxide (NH4OH) was proposed to investigate the potential use as a fuel in a compression-ignition engine. Ammonium hydroxide, also referred to as aqueous ammonia, is liquid phase under atmospheric conditions; therefore, the storage of such a fuel does not require high pressure. Previous work has established that ammonium hydroxide solution could contribute to energy release during co-combustion with fossil diesel. However, the presence of water reduced combustion stability and limited the extent to which aqueous ammonia could displace diesel. In addition, the characteristics of pollutant emissions of burning such a fuel remained less understood. This study therefore explores the potential of ignition improving additives
Han, Yanlin, Hellier, Paul, Schonborn, Alessandro, Ladommatos, Nicos
Technical Paper
A Comprehensive Experimental Analysis of Ethanol 27% Fuel Blend in a Turbocharged Gasoline Direct Injection Engine2025-01-0245To be published on 06/16/2025
India is committed to achieving a 20% ethanol blend in petrol (E20) by 2025, as part of its national biofuels policy to reduce carbon emissions, enhance energy security, and support the agricultural economy. Building on E20's achievement in reducing GHG emissions, E27 fuel—which contains 27% ethanol in gasoline—is one of the means of advancing India's ethanol strategy and reducing dependency on fossil fuels. In line with the literature and the preliminary study, an experimental analysis utilizing fuel blends ranging from E10 to E40 was conducted. It was found that E27 provides the optimal balance of emissions reduction and performance without requiring engine modifications, complying with the government's aim to boost ethanol blending and cut carbon emissions by 2030. This study examines a turbocharged gasoline direct injection (TGDI) engine powered passenger car that was tested using E27 fuel for a mileage accumulation of 20,000 km under real-world driving conditions. This evaluation
D R, Vigneshwar, Bhakthavachalu, Vijayabaskar, Muralidharan, M.
Technical Paper
Optimization of HEV Vehicle’s Engine Modulated Noise2025-01-0084To be published on 05/05/2025
One 1.5L Miller-cycle turbocharged four cylinder gasoline hybrid engine is installed on a certain hybrid vehicle. When accelerating at low to medium speeds with a small throttle, there is a "da da" knocking noise inside the car, which seriously affects the overall sound quality of the vehicle. By analyzing the vibration and noise data of the engine, it was found that the frequency of the abnormal knocking sound is 200-1000Hz, which presents a half order characteristic in the time domain, that is, one knocking occurs when the engine crankshaft rotates twice. Through Hilbert demodulation analysis of the vibration data in the problem frequency range, it was found that the knocking noise was modulated in the frequency domain, with a modulation frequency of half of the crankshaft rotation frequency. By building a fully flexible multi-body dynamic model of a hybrid powertrain and inputting the engine's cylinder pressure excitation, the combustion excitation is coupled with mechanical
Dan, Kong
Technical Paper
Plug-in hybrid and range extender NVH – Challenges and Solutions2025-01-0101To be published on 05/05/2025
The automotive industry continues to develop new powertrain and vehicle technologies aimed at reducing overall vehicle-level fuel consumption. While the use of electrified propulsion systems is expected to play an increasingly important role in helping OEM’s meet fleet CO2 reduction targets, hybridized propulsion solutions can play a vital role in the electrification strategy of vehicle manufacturers. Plug-in hybrid and range extender vehicles show unique NVH challenges due to their different possible operation modes. First, the paper outlines different driveline architectures for PHEV and range extenders. Given the multiple general architectures, as well as operation modes which typically occur for these vehicles, characterizations and source-path analysis of these vehicles can be more complicated than conventional vehicles. In the following steps, typical NVH related challenges are highlighted and potential solutions for NVH optimization are discussed. While the overall noise levels
Wellmann, Thomas, Ford, Alex, Pruetz, Jeffrey
Technical Paper
The accelerated roughness noise optimization of one PHEV vehicle2025-01-0087To be published on 05/05/2025
To optimize the ’kalakala’ noise that produced by the plug hybrid electric vehicle when accelerating with a small throttle while in the charging state. A LMS device was used to acquire the noise of the driver's outer ear . Through filtering and playback analysis, it was confirmed that the noise is mainly contains the frequency bands of 250-350Hz, 350-500Hz, and 500-700Hz. The three frequency bands of the noise were used as carriers for Hilbert transform, and their envelopes were obtained for Fourier transform analysis. It was found that the modulation order of the noise is 0.5 times that of the engine ignition order, and the modulation frequency is 20-30Hz, which let the customer hears like roughness. Regarding the spectral characteristics of this noise, firstly, at the excitation source, the impact of reducing engine combustion excitation on this noise is explored. At the same time, selected a reasonable moment of inertia and frequency of the pulley torsional damper, to decrease the
Shouhui, Huang, Zhongxun, Hu, Zhao, Yun, Shanyin, Ren, Ruifeng, Dong, Teng, Charlie, Changshui, Zhou, Xu, Ling
Technical Paper
Development of Offline Simulation Software for Active Sound Design in Electric Vehicles2025-01-0017To be published on 05/05/2025
With the increasing adoption of electric vehicles (EVs), Active Sound Design (ASD) has emerged as a crucial method to enhance both the sound quality and driving experience, addressing the lack of distinctive engine sounds present in internal combustion vehicles. This paper presents an ASD offline simulation software developed on the MATLAB platform to address these challenges. The software integrates a vehicle dynamics model with three key sound synthesis algorithms: order synthesis, pitch shifting, and granular synthesis, allowing for comprehensive control strategy development, real-time sound playback, and rapid adjustment. The software consists of several functional modules, including configuration, order generator, pitch shifting, and granular synthesis interfaces, which support user-friendly operation and flexible sound parameter adjustments. Users can simulate different driving conditions and evaluate the acoustic performance of the ASD system in real time. The system also allows
Qian, Yushu, Xie, Liping, Xiong, Chenggang, Liu, Zhien
Technical Paper
Sound Design for Electric Vehicles: Enhancing Safety and User Experience Through Acoustic Vehicle Alerting System (AVAS)2025-01-0068To be published on 05/05/2025
Silent engines are an excellent strategy to combat noise pollution. Still, they can pose risks for pedestrians who rely on auditory cues for safety and reduce driver awareness due to the absence of the familiar sounds of combustion engines. Sound design for silent engines not only tackles the above issues but goes beyond safety standards towards a user-centered approach by considering how users perceive and interpret sounds. This paper examines the evolving field of sound design for electric vehicles (EVs), focusing on Acoustic Vehicle Alerting Systems (AVAS). The study analyzes existing AVAS, classifying them into different groups according to their design characteristics, from technical concerns and approaches to aesthetic properties. Based on the proposed classification, an (adaptive) sound design methodology, and concept for AVAS are proposed based on state-of-the-art technologies and tools (APIs), like Wwise Automotive, and integration through a functional prototype within a
Rodrigues Ferraz Esteves, Ana Raquel, Campos Magalhães, Eduardo Miguel, Bernardes de Almeida, Gilberto
Technical Paper
Virtual Encoder for Achieving Crank Angle Resolution Measurements of In-Cylinder Pressure in Small Engines by using Time Based Data Acquisition2024-32-010504/18/2025
Small size engines feature several peculiarities that render them a challenge with respect to implementing measurements required for characterizing specific phenomena such as combustion evolution. Measuring in-cylinder pressure is well established as standard procedure for determining combustion characteristics, but in the case of small size units actually applying it can require alternative approaches. Fitting a crank angle encoder may be extremely difficult, as a consequence of the actual size of the power unit. Cost is another essential driver for small engine development that also influences how measurements are implemented. Within this context, the present work describes the development and implementation of a method that employs an algorithm that practically generates a ‘virtual’ encoder. Only a basic phasing signal is required, such as an inductive crankshaft position sensor output or that of an ignition pulser. The software was developed on an experimental engine with a crank
Irimescu, Adrian, Cecere, Giovanni, Merola, Simona Silvia, Vaglieco, Bianca Maria
Technical Paper
Prediction of Pre-Ignition Borderline on Supercharged SI Engine by Livengood-Wu Integral2024-32-000804/18/2025
The LSPI (Low Speed Pre-Ignition) is one of the consecutive abnormal combustion cycles of supercharged SI engine with direct injection fuel supply system [1]. The LSPI occurs when the engine is running at low speed and high load condition. It is important for the SI engine to control essentially with alternative fuel, e-fuel and hydrogen in the future. It is considered that the LSPI would be caused by the autoignition of the deposit, the lubricating oil from ring crevice, the lubricating oil from piston crown and so on [2, 3, 4, 5]. Among of these causes, this research focuses on the scattering lubricating oil from piston crown. The previous our research has reported on the two points. One is about the frequency and quantity of the lubricating oil scattering from piston crown [6]. Another is about the frequency of abnormal combustion by the engine test [7]. As the result, it has been cleared that the frequency of abnormal combustion is 1/10 of scattering frequency of the lubricating
Omori, Takaya, Tanaka, Junya
Technical Paper
Experimental Investigations of a Hydrogen Fueled Natural Gas Engine and Ion Current Measurement for Combustion Diagnostics in Pure Hydrogen Operationwith Water Injection2024-32-006504/18/2025
In the ongoing effort to decarbonize energy supply, a notable shift involves the conversion or retrofitting of combined heat and power plants to operate on hydrogen as an alternative to natural gas. In this transformative landscape, extensive research is underway to develop and explore innovative combustion processes for hydrogen-fueled engines, aiming to comprehend and optimize combustion processes concerning both engine performance and emissions. Among the various methods available for monitoring the combustion process and engine control, ion current sensing presents itself as a viable option. A unique feature of this research lies in utilizing the engine's spark plug itself as an electrical sensor, measuring the ion current generated during the flame development and combustion processes. Given the limited research on ion current sensing for hydrogen combustion processes, a series of experiments were conducted and presented in this work. These experiments involved sweeps of water-to
Salim, Naqib, Beltaifa, Youssef, Kettner, Maurice, Loose, Oliver, Weißgerber, Tycho
Technical Paper
Simultaneous Direct-Photography of Flame Propagation Inside Pre-Chamber and Main-Chamber in Gasoline Engine with Passive Pre-Chamber2024-32-009504/18/2025
Pre-chamber combustion is well known for the effective way to improve thermal efficiency in internal combustion engine. An active pre-chamber can accomplish super lean burn while a passive pre-chamber can easily improve combustion with low-cost. Therefore, various studies have been carried out. However, since its combustion characteristics are very complicated, the sequence of events for torch ignition and flame propagation in main-chamber from ignition and flame propagation inside pre-chamber have not been well clarified. Especially, investigation on the process from torch ejection to ignition of mixture in main-chamber has been carried out using combustion vessels and rapid compression machines, but this phenomenon has not been clarified. In this study, three types of optically accessible passive pre-chamber with different orifice patterns (normal six orifices, asymmetric five orifices and tangential five orifices) were designed and installed to a single-cylinder gasoline spark
Hokimoto, Satoshi, Moriyoshi, Yasuo, Kuboyama, Tatsuya, Egashira, Shuichi, Nagai, Yoshitaka
Technical Paper
The Similarity Study of the Transient Heat Transfer of Impinging Flames under CI Engine-Like Conditions2024-32-011904/18/2025
The optimization of engine combustion systems based on scaled model experiments can reduce the cost of the development of large-bore marine diesel engines. Illustrating the transient heat transfer similarity of impinging flames would be beneficial to scaled engine model experiments in the development and optimization of large-bore compression ignition engines. In this work, the investigation of the similarity of the transient heat transfer of wall-impinging flames was performed in a high-pressure high-temperature constant-volume vessel. Two different injectors featuring different hole sizes and different flame impingement distances were applied to simulate the diesel spray impinging flames under the large-bore and the small-bore compression ignition engine-like conditions with a geometry similarity ratio equal to 0.7. By varying the injection parameters such as injection pressure and injection duration, the scaling laws based on constant injection pressure, constant engine speed, and
Cao, Jiale, Li, Tie, Zhou, Xinyi, Xu, Xingyu, Chen, Run, Li, Shiyan, Ogawa, Hideyuki
Technical Paper
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
Technical Paper
Research on the Combustion Characteristics of Port Injection Hydrogen Engines for Motorcycles2024-32-009404/18/2025
To prevent global warming, reducing CO2 emissions is the most important issue, and for this reason, efforts are needed to realize a carbon neutral society. Since hydrogen can be stored and transported, and does not emit carbon dioxide when burned, it has attracted particular attention as a fuel for internal combustion engines in recent years and has been studied in various industrial fields[1]. However, many of these studies have been conducted on commercial and passenger vehicle engines, and there has not yet been sufficient validation on small motorcycle engines. Therefore, in this study, a single cylinder gasoline engine for two-wheeled vehicles was converted into a hydrogen engine with port injection, and the abnormal combustion, which is a problem of hydrogen combustion, was verified. In this report, the parameters affecting the abnormal combustion are summarized based on the experimental results, and the reason why the parameters are a factor of the abnormal combustion generation
Suzuki, Haruaki, Inui, Taichi, Okado, Takanori, Tamura, Shohei, Kagawa, Yuta, Ninomiya, Yoshinari
Technical Paper
Heat Transfer Characteristics of Lean Methane Flame in the Region near the Wall Boundary Layer2024-32-012004/18/2025
Since proportion of wall heat loss takes as high as 20-30% of the total engine heat loss, the reduction of wall heat loss is considered as an effective way to improve the engine thermal efficiency. The heat transfer near the wall boundary layer plays a significant role on the exploration about the mechanism of wall heat transfer which contributes to figuring out the approach to the reduction of wall heat loss. However, the near wall characteristics of heat transfer are still unclear. In this study, the premixed lean methane flame propagation was captured by the high-speed schlieren and the flame behavior in the near-wall region was investigated by the micro CH* chemiluminescence. The temporal histories of the wall temperature and the heat flux are measured by the co-axial thermocouple. The factors including the convective heat transfer coefficient and non-dimensionless numbers, Nusselt number and Reynolds number, were used to characterize the near wall characteristics. Also, the
Xuefeng, Xue, Run, Chen, Tie, Li
Technical Paper
Real-Time Control of Hydrogen Injection in a PFI Internal Combustion Engine based on an Online Physics-Based Model for Estimating Trapped Air and EGR2024-32-010304/18/2025
The use of hydrogen in port fuel injection (PFI) engines faces challenges related to abnormal combustions that must be addressed, especially in transient operation. The in-cylinder air-to-fuel ratio and the amount of trapped exhaust gas have a significant impact on the probability of abnormal combustion as well as NOx emissions, and should be real-time monitored in hydrogen engines. Thus, the real-time estimation of the composition and thermodynamic state of the trapped gas mixture is crucial during transient operations, although highly challenging. This study proposes an on-line real-time physics-based MIMO (Multi-Input-Multi-Output) model to accurately estimate the amount of trapped air and exhaust gas in the cylinder at the intake valve closing (IVC) event, based on the instantaneous in-cylinder pressure measurement. With proper estimation accuracy, the injector can be controlled to correctly provide the amount of fuel necessary to achieve the target air-to-fuel ratio (AFR) and
Galli, Claudio, Ciampolini, Marco, Drovandi, Lorenzo, Romani, Luca, Balduzzi, Francesco, Ferrara, Giovanni, Vichi, Giovanni, Minamino, Ryota
Technical Paper
Detailed Approach for Pre-Chamber Heat Release Analysis for the HSASI Pre-Chamber Spark Plug Using a Pressure Sensor Glow Plug2024-32-006304/18/2025
The hot surface-assisted spark ignition (HSASI) pre-chamber spark plug, which was developed at the Karlsruhe University of Applied Sciences, increases the dilution limit with excess air and the tolerance to residual gas in the pre-chamber compared to a conventional passive pre-chamber spark plug. In this study, the conventional glow plug which is integrated in the pre-chamber of the HSASI pre-chamber spark plug was replaced by a pressure sensor glow plug (PSG) from BERU. This allows for a detailed combustion analysis in the pre-chamber. The signal of the PSG was validated with a piezoelectric cylinder pressure sensor and a method to analyse the pre-chamber heat release was introduced. Experimental investigations were carried out on a single-cylinder gasoline engine. A series of operating points diluted with excess air and a variation in load were conducted. The gas flow rate through the orifices of the pre-chamber was calculated from the pressure difference between the pre-chamber and
Holzberger, Sascha, Kettner, Maurice, Kirchberger, Roland
Technical Paper
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