Browse Topic: Combustion and combustion processes

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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
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
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
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
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
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
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
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
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, Chapelot, Pierre, Günthner, Michael, Jung, Philipp Emanuel
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
Experimental Evaluation of Direct and Port Fuel Injection Strategies on a Heavy-Duty Liquefied Petroleum Gas Engine03-18-03-002205/09/2025
Liquefied petroleum gas (LPG) is a popular alternative fuel in the transportation sector as a result of its favorable physical and chemical properties, availability, and relatively lower emissions compared to conventional fuels. However, much of its use is currently in light-duty applications, usually in manifold or port-injected configurations primarily due to their simplicity and ease of conversion. However, there are shortfalls in heavy-duty applications where decarbonization efforts are direly needed. The key reasons for this shortfall in alternative fuel adoption in the heavy-duty sector are the deficit in engine performance when compared to conventional heavy-duty diesel engines and the lack of specialized hardware to bridge this performance gap, for example, direct injectors optimized for LPG fuel operation on large-bore engines. To address this, this study evaluated the performance, emissions, and combustion characteristics of a heavy-duty single-cylinder research engine, the
Fosudo, Toluwalase, Windom, Bret, Olsen, Daniel
Journal Article
Optimization of HEV Vehicle’s Engine Modulated Noise2025-01-008405/05/2025
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 200-2000Hz, 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
Development of Offline Simulation Software for Active Sound Design in Electric Vehicles2025-01-001705/05/2025
With the increasing adoption of electric vehicles (EVs), Active Sound Design (ASD) has become a crucial method for enhancing both sound quality and the overall driving experience, addressing the absence of the distinctive engine sounds found in internal combustion vehicles. This paper presents an ASD offline simulation software developed on the MATLAB platform. The software integrates a vehicle dynamics model with three key sound synthesis algorithms—order synthesis, pitch shifting, and granular synthesis—enabling comprehensive control strategy development, real-time sound playback, and rapid adjustments. It comprises multiple functional modules, including configuration, order generation, pitch shifting, and granular synthesis interfaces, offering a user-friendly environment for flexible sound parameter tuning under various simulated driving conditions. Users can easily configure vehicle dynamics, adjust gain values, and visually manipulate sound parameters to create a customized ASD
Qian, Yushu, Xie, Liping, Xiong, Chenggang, Liu, Zhien
Technical Paper
The Accelerated Roughness Noise Optimization of One PHEV Vehicle2025-01-008705/05/2025
To optimize the noise that heard like ‘kalakala’ produced by the plug hybrid electric vehicle when accelerating with a small accelerated pedal opening while in the charging state of series modal. The LMS test 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 250-400Hz and450-700Hz. The 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 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, selected a reasonable moment of inertia and frequency of the Crank torsional damper, to decrease the torsional excitation of the engine. Secondly, investigated the structural
Shouhui, Huang, Zhongxun, Hu, Zhao, Yun, Shanyin, Ren, Ruifeng, Dong, Teng, Charlie, Changshui, Zhou, Xu, Ling
Technical Paper
Electric Bus NVH Challenges and Refinement Using Innovative Approach2025-01-008005/05/2025
The trend towards electrification propulsion in the automotive industry is highly in demand due to zero-emission and becoming more significant across the world. Battery electric vehicles have lower overall noise as compared to conventional I.C Engine counterparts due to the absence of engine combustion and mechanical noise. However, other narrowband and tonal noises are becoming dominant and are strongly perceived inside the cabin. With the ongoing push towards electrification, there is likely to be increased focus on the noise impact of gearing required for the transmission of power from the electric motor to the road. Direct coupling of E-motors with Axle has resulted in severe tonal noises from the driveline due to instant e-motor torque ramp up from 0 rpm and reverse torque on driving axle during regenerative braking. The tonal noises from the rear axle during vehicle running become very critical for customer perception. For automotive NVH engineers, it has become a challenge to
Doshi, Sohin, Kalsule, Dhanaji, Sawangikar, Pradeep, Suresh, Vineeth, Sharma, Manish
Technical Paper
Sound Design for Electric Vehicles: Enhancing Safety and User Experience Through Acoustic Vehicle Alerting System (AVAS)2025-01-006805/05/2025
Silent motors 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 motors 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 virtual
Rodrigues Ferraz Esteves, Ana Raquel, Campos Magalhães, Eduardo Miguel, Bernardes de Almeida, Gilberto
Technical Paper
Plug-In Hybrid and Range Extender NVH – Challenges and Solutions2025-01-010105/05/2025
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 OEMs meet fleet CO2 reduction targets, hybridized propulsion solutions will continue to play a vital role in the electrification strategy of vehicle manufacturers. Plug-in hybrid electric vehicles (PHEV) and range extender vehicles (REx) come with unique NVH challenges due to their different possible operation modes. First, the paper outlines different driveline and vehicle architectures for PHEV and REx. Given the multiple general architectures, as well as operation modes which typically accompany these vehicles, NVH characterizations and noise source-path analysis can be more complicated than conventional vehicles. In the following steps, typical NVH related challenges are highlighted and potential solutions for NVH optimization are
Wellmann, Thomas, Ford, Alex, Pruetz, Jeffrey
Technical Paper
Research on Basic Characteristics of a Two-Stroke Opposed Piston Engine2024-32-011204/18/2025
This study investigated the performance characteristics of a two-stroke opposed piston engine that is capable of constantly operating with high power output and high efficiency. An investigation was also made of the performance obtained by applying a pseudo uniflow condition as a measure against large hydrocarbon (HC) emissions owing to blow-by of unburned mixture, which is an issue of two-stroke engines. The test engine had a displacement of 127 cm3 and a bore and stroke of 48 x 70 mm. One-point and dual-point ignition systems were used, and regular gasoline was supplied as the test fuel using a carburetor-based fueling system. Experiments were conducted at engine speeds of 1500 and 3000 rpm at ignition timings of 45 deg. and 35 deg. before top dead center. The results showed that large quantities of HC emissions were emitted because stable combustion was not achieved. This revealed that a stronger uniflow condition must be applied as a countermeasure rather than a simple pseudo
Fukushima, Shumpei, Uehara, Ryota, Hayashi, Yoshiaki, Igarashi, Ryo, Tokita, Kazuho, Iijima, Akira
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
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
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
Numerical Studies on the Relation between the Multiple Auto-Ignition and Pressure Wave in the Premixed Charge2024-32-007904/18/2025
The relation between the multiple auto-ignition in the premixed charge with fuel concentration distribution and associated pressure wave are numerically investigated. This study assumes that the auto-ignition phenomenon in the end-gas of PCCI combustion, a next-generation combustion method which is expected to achieve both low fuel consumption and low emissions at a high level. Detailed numerical analysis considering the elementary chemical reactions of the compressible reacting fluid flow described in the one-dimensional coordinate system with high spatial and time resolution was performed to clarify the detailed phenomena of the onset of the multiple auto-ignition and the pressure wave propagation in the gas.
Iizumi, Kota, Yoshida, Kenji
Technical Paper
Effects of CO 2 Concentration on Combustion Characteristics of Compressed Biomethane Gas2024-32-011104/18/2025
One way to decarbonize spark-ignition (SI) engines is to use alternative fuels to improve thermal efficiency. Compressed biomethane gas (CBG), mainly composed of methane and carbon dioxide produced from food waste, has attracted attention as an alternative fuel, but its carbon dioxide content is indeterminate. This study investigates the effects of carbon dioxide content on engine performance (thermal efficiency, etc.), emission characteristics, and turbulent burning velocity using a CBG surrogate fuel mixed with methane and carbon dioxide. A single-cylinder SI engine is used as the test engine, and experiments are conducted under different load conditions with a constant crank angle of 50% mass fraction burned (CA50). Engine performance is analyzed based on heat balance from in-cylinder pressure analysis. Emission characteristics are measured using an emission gas analyzer. Using the boundary conditions obtained from the experiments, parameters such as unstretched laminar burning
Kobayashi, Takuma, Shimizu, Taketoshi, Yoshimura, Kei, Sok, Ratnak, Kusaka, Jin
Technical Paper
Study on the Optimal Pre-Chamber Geometry for Active Pre-Chamber Gas Engines2024-32-002304/18/2025
In a pre-chamber engine, fuel in the main-chamber is ignited and combusted by the combustion gas injected from the pre-chamber. Therefore, further fuel dilution is possible and thermal efficiency can be also improved. However, adding a pre-chamber to an engine increases the number of design parameters which have a significant impact on the main combustion and the exhaust gas. Then, in this study, the optimum geometry of the pre-chamber in an active pre-chamber gas engine was investigated. The considered parameters were the volume of pre-chamber, the diameter of a nozzle hole, and the number of nozzle holes. 18 types of pre-chambers with different geometries were prepared. Using these pre-chambers, engine experiments under steady conditions were conducted while changing the conditions such as engine speeds, mean indicated pressure and air excess ratio. Based on the experimental data, neural network models were constructed that predict thermal efficiency, NOx and CO emissions from the
Yasuda, Kotaro, Yamasaki, Yudai, Sako, Takahiro, Takashima, Yoshitane, Suzuki, Kenta
Technical Paper
Experimental Study on Thermo-Catalytic Ammonia Decomposition into Hydrogen2024-32-011804/18/2025
In order to rapidly achieve the goal of global net-zero carbon emissions, ammonia (NH3) has been deemed as a potential alternative fuel, and reforming partial ammonia to hydrogen using engine exhaust waste heat is a promising technology which can improve the combustion performance and reduce the emission of ammonia-fueled engines. However, so far, comprehensive research on the correlation between the reforming characteristic for accessible engineering applications of ammonia catalytic decomposition is not abundant. Moreover, relevant experimental studies are far from sufficient. In this paper, we conducted the experiments of catalytic decomposition of ammonia into hydrogen based on a fixed-bed reactor with Ru-Al2O3 catalysts to study the effects of reaction temperature, gas hour space velocity (GHSV) and reaction pressure on the decomposition characteristics. At the same time, energy flow analysis was carried out to explore the effects of various reaction conditions on system
Li, Ze, Li, Tie, Chen, Run, Li, Shiyan, Zhou, Xinyi, Wang, Ning
Technical Paper
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