Browse Topic: Combustion and combustion processes

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Experimental Study on Macroscopic Characteristics of Ammonia Spray under Flash Boiling and Non-Flash Boiling Conditions with Large-Diameter single-hole Nozzles2026-01-0339To be published on 04/07/2026
Ammonia is regarded as a potential alternative fuel, and its spray characteristics are crucial for efficient combustion in engines. For large-bore engines suitable for heavy-duty vehicles or ships, the adoption of large-diameter nozzles is expected to ensure an appropriate fuel flow rate while improving fuel-air mixing efficiency, thereby enhancing in-cylinder combustion performance. This paper conducted an experimental study on the characteristics of liquid ammonia sprays under wide thermodynamic conditions, a wide range of injection pressures, and a wide range of nozzle diameters. The study found that at room temperature, as the ambient pressure increases from 0.1 MPa to 4 MPa, the development of spray penetration slows down. However, at 0.05 MPa, the radial expansion of the near-field spray is greater, and the penetration is slightly behind that at 0.1 MPa. The liquid penetration increases with the increase in ambient temperature. This was because the increase in temperature reduced
Liu, Yi, Zhong, Jie, Hu, Yuchen, Zhu, Wuzhe, yunliang, Qi, QINGCHU, CHEN, Wang, Zhi
A Comparative Study of Evaluation Indicators in Spark Plug Electrode Erosion Resistance Using High Energy Ignition2026-01-0291To be published on 04/07/2026
Lean combustion is one of the effective methods to improve the efficiency of engine. High energy ignition can significantly enhance the stability of lean combustion, attracting widespread attention in engine applications, particularly in GDI engines. However, higher ignition energy accelerates the erosion rate of spark plug electrodes, thereby shortening their lifespan. Currently, there is no established quantitative evaluation method for assessing the erosion resistance of spark plug electrodes with a high energy ignition system. Thus, developing a reliable and rapid testing method to evaluate the erosion resistance of spark plug electrode materials is crucial and urgent. Such a method would facilitate the selection of superior electrode materials, ultimately improving the erosion resistance of spark plugs and extending their lifespan. This study developed an innovative erosion testing system for spark plug center electrode materials based on a self-made high energy ignition device
Zhang, Jianqi, Sun, Nan, Miao, Xinke, Li, Yang, Zhou, Chuan, Deng, Jun, Li, Liguang
Investigation of In-Cylinder Cycle-to-Cycle Variation Using PIV, LIF and RANS Simulation2026-01-0299To be published on 04/07/2026
To elucidate the cycle-to-cycle variations (CCV) in gas flow and combustion within gasoline engine cylinders, simultaneous two-section PIV and LIF measurements were performed using an optical engine, coupled with RANS simulations. The results revealed the following: The variation in the equivalence ratio per cycle has little effect on initial combustion but does influence IMEP. Evaluating the laminar combustion velocity (SL) and turbulent combustion velocity (ST) as factors determining initial combustion revealed almost no correlation with SL, while moderate correlations were observed between ST and CA10. The position of the tumble vortex center at ignition timing was found to be critical; the vortex center position most favorable for advancing combustion timing was located to the right and below the spark plug. Under nitrogen-enriched conditions with a dilution ratio of approximately 40%, cycle fluctuations increased. Concentration characteristics of THC and CO, obtained from high
Hokimoto, Satoshi, Moriyoshi, Yasuo, Kuboyama, Tatsuya
Effect of renewable fuel blends on particulate emissions in warm-up conditions in a GDI engine2026-01-0304To be published on 04/07/2026
Renewable gasoline offers significant benefits in reducing greenhouse gas (GHG) emissions. In this study, five gasolines with different renewable hydrocarbon classes and varying distillation curves were taken to investigate their effect on particle number (PN) emissions in a spark-ignition GDI engine at 10 bar indicated mean effective pressure (IMEP) and 2000 rpm. The engine coolant temperature was varied from 90°C to 35°C to investigate the effect of fuel evaporation on soot formation. Injectors with various spray plume targets and start of injection (SOI) timing (300° and 260° bTDC) were used to assess how different gasolines affect engine performance and to determine engine calibration requirements. A simplified transient cycle examines how engine motoring influences PN emissions for test gasolines. A high-speed camera and endoscope were used to identify the sources of soot during fuel combustion. Simulations were done to assess the quality of fuel-air mixing in support of the
Muniappan, Krishnamoorthi, Dahlander, Petter, Helmantel, Ayolt, Alemahdi, Nika, Lehto, Kalle
CFD-Guided DoE-ML Optimization Methods in a Heavy-Duty Hydrogen Engine2026-01-0326To be published on 04/07/2026
This study introduces a CFD-guided Design of Experiments (DoE) and Machine Learning (ML) framework for the co-optimization of piston and pre-chamber geometries in a passive pre-chamber heavy-duty hydrogen engine operating at medium and low loads. Starting from a reference configuration—an omega-type piston and a methane-optimized pre-chamber—the design space was parameterized using seven geometric variables. A Sobol sequence was employed to generate 96 randomized design variants in the DoE, each evaluated through high-fidelity 3D-CFD simulations to capture key combustion and performance metrics. The resulting dataset served as the foundation for developing and evaluating several ML regression models. A rigorous ML workflow was adopted, featuring 5-fold cross-validation and hyperparameter tuning via Bayesian optimization to ensure generalization and robustness. Model selection was based on multi-metric performance criteria including prediction accuracy, error stability, and sensitivity
Menaca, Rafael, Shakeel, Mohammad Raghib, Liu, Xinlei, Mohan, Balaji, AlRamadan, Abdullah, Cenker, Emre, Silva, Mickael, Zhang, Anqi, Pei, Yuanjiang, Im, Hong
Reactivity Controlled Compression Ignition (RCCI) Combustion Engine Characteristics Fuelled with Diesel/Compressed Natural Gas (CNG) and Diesel/Methanol Fuel Pairs2026-01-0319To be published on 04/07/2026
Ultra-low oxides of nitrogen (NOx) and particulate matter (PM) characteristics of reactivity controlled compression ignition (RCCI) combustion has motivated the researchers to explore more so that this can be implemented using a long range of alternative fuels. In this study, a comparative analysis of combustion, performance, and emission characteristics of RCCI combustion fuelled with diesel/compressed natural gas (CNG) and diesel/methanol fuel pairs have been carried out with respect to baseline compression ignition (CI) combustion. All experiments were performed in a constant speed engine at four different engine loads. The RCCI combustion experiments were performed at a constant premixed ratio (rp) of 0.50 and 15% exhaust gas recirculation (EGR). The results exhibited a significant reduction in oxides of nitrogen (NOx) emissions and relatively smoother RCCI combustion compared to baseline CI combustion. RCCI mode combustion resulted in relatively superior engine performance
Saikia, Bhargav, Kant, Akshay, Gupta, Abhishek, Singh, Akhilendra Pratap
Improving Winter Driving Range of EVs with a Novel Desiccant Device: Ceramic Humidity Regulator (CHR)2026-01-0117To be published on 04/07/2026
With Rapid growth of Electric Vehicles (EVs) in the market, challenges such as driving range, charging infrastructure, and reducing charging time needs to be addressed. Unlike traditional Internal combustion vehicles, EVs have limited heating sources and primarily uses electricity from the running battery, which reduces driving range. Additionally, during winter operation, it is necessary to prevent window fogging to ensure better visibility, which requires introducing cold outside air into the cabin. This significantly increases the energy consumption for heating and the driving range can be reduced to half of the normal range. This study introduces the Ceramic Humidity Regulator (CHR), a compact and energy-efficient device developed to address driving range improvement. The CHR uses a desiccant system to dehumidify the cabin, which can prevent window fogging without introducing cold outside air, thereby reducing heating energy consumption. CHR is based on desiccant dehumidification
Sakai, Naoki, Takahiko, Nakatani, Shinoda, Narimasa, Ihara, Yukio, Wakida, Norihiro, Kato, Kyohei, Anoop, Reghunathan-Nair
Design and Evaluation of a Deep Neural Network Model for Prediction of Diesel Equilibrium Combustion Products and Characteristics2026-01-0293To be published on 04/07/2026
Accurate prediction of equilibrium combustion products and thermodynamic properties is essential for optimizing engine performance, enhancing combustion efficiency, and reducing emissions in diesel-powered systems. Traditional methods for combustion modeling often involve solving complex chemical equilibrium equations or thermodynamic relations, which could be computationally expensive and time-consuming. In this study, we present a data-driven approach using a deep neural network (DNN) model to predict the equilibrium combustion products and key thermodynamic characteristics of diesel under varying thermodynamic conditions. The proposed DNN model is trained on a comprehensive dataset generated from equilibrium calculations. The inputs include pressure, temperature, and equivalence ratio, covering a relatively wide range to encompass diesel equilibrium combustion under various conditions. Outputs are equilibrium combustion products and thermodynamic properties, including enthalpy
Ji, Huangchang, Wang, Kai, Guo, Zhefeng, Han, Yang, Lee, Timothy
1D System Evaluations for Efficiency Trade-offs for a Heavy-Duty H2ICE Concept2026-01-0274To be published on 04/07/2026
Lean H2 combustion strategies have shown promising gross thermal efficiency and ultra-low engine-out NOx emissions for H2-fuel based internal combustion engine (H2ICE) systems in heavy-duty (HD) transport. Implementing lean combustion strategies require excessive air flow demand that further increases with the engine load increase. To meet such air flow demands efficiently across a wide engine operating region, a detailed system optimization is warranted including next-generation turbocharging systems. In this 1D system analysis campaign, a detailed study of various air-system configurations was conducted for a modified HD, direct-injection (DI), H2ICE concept based-off a Cummins heavy-duty 15L engine. The concept engine configuration had a geometric compression ratio of 10.4 and possessed no external exhaust gas recirculation (EGR). First, a calibrated 1D engine model representing the H2ICE concept was developed. Using the 1D model, a detailed system-level analysis was conducted at
Kumar, Praveen, Sari, Rafael, Merritt, Brock, Popuri, Sriram
Study of Deposit Control Additive Efficacy in Gasoline Direct Injection Engines2026-01-0349To be published on 04/07/2026
There is an increasing adoption of Direct-injection spark-ignition (DISI) engines in the market, which per 2024 EPA Automotive Trends Report represents 73% of new vehicles sold in the US. And while it is well accepted that DISI offers advantages over Port fuel injection (PFI) technology in meeting stringent CO2 emissions and fuel economy requirements set by the EPA, DISI engines are also associated with increased formation of injector deposits. These deposits may foul injectors and accumulate on the injector tip causing distorted spray patterns and diffusive combustion. Ultimately, this leads to engine performance deterioration and increased harmful emissions. To control deposit formation, detergent-type chemistries are added to the fuel in small amounts. Deposit control additives (DCAs) function by preventing the formation of deleterious injector deposits as well as removing existing ones. Standardized protocols describing the assessment of DCA in controlling injector deposits have
Soriano, Nestor, Chahal, Jasprit, Lang, Wendy, Cracknell, Roger, Williams, Rod
Persistent Elevated Soot Emissions Induced by Clustered Stochastic Preignition Events2026-01-0314To be published on 04/07/2026
Stochastic Preignition (SPI) is an abnormal combustion phenomenon that can occur in spark-ignition engines particularly under high-load operation. SPI is characterized by uncontrolled initiation of combustion prior to spark discharge, an abnormal combustion process that can lead to severe knock events and significant engine damage. SPI has been associated with fuel properties, lubricant composition, and engine design and operation. In this work, a single-cylinder test engine with a dry-sump oil system was utilized to study the SPI response of E10 and E25 fuels with a range of Reid Vapor Pressure (RVP). An automated test procedure was employed, consisting of ten square-waved load profile segments, with each segment composed of 5 min of low-load operation followed by 25 min of sustained high-load operation. These tests were replicated across multiple days of testing with a triple flush of lubricant between each test, and an online Fuel in Oil diagnostic measurement. Exhaust particulate
Splitter, Derek, Jatana, Gurneesh, DelVescovo, Dan, Douvry-Rabjeau, Julien, Fioroni, Gina, Chapman, Elana, Salyers, John
Accelerated Computed Tomography for Spray Characterization2026-01-0341To be published on 04/07/2026
Computed tomography (CT) is a valuable diagnostic technique for visualizing plume direction and assessing mixture quality within combustion chambers under engine-relevant conditions. High-speed extinction imaging followed by tomographic reconstruction enables temporally and spatially resolved measurements of liquid volume fraction and plume evolution in multi-jet sprays. Traditionally, tomographic reconstruction requires capturing multiple angular views by rotating the injector and averaging over numerous injections to ensure statistical convergence. This process is time-intensive, particularly due to the large volume of data acquisition and the corresponding delays in data saving, often requiring dozens of injections per view angle. In this study, we investigate the minimum number of injections required to achieve sufficient CT image quality, thereby significantly reducing experimental time. Two injectors are evaluated: a symmetric 8-hole Spray M injector from the Engine Combustion
Yi, Junghwa, Wan, Kevin, Pickett, Lyle
Model-based Development of a Heavy-Duty H2-ICE and Integrated, Turbogeneration, Electrification, and Supercharging (ITES) System2026-01-0426To be published on 04/07/2026
Changing global economic conditions and efforts to reduce greenhouse gas emissions to reduce their impact on climate and public health is driving the need to develop alternative technologies to meet the demands of heavy-duty vehicles and increase propulsion system efficiency. This study combines a Hydrogen internal combustion engine (H2-ICE) for its near zero CO2 emissions capability, with electrically assisted turbocharging, exhaust energy recovery, and mild hybridization to maximize propulsion system efficiency in real-world driving. The focus is on model-based integration and optimization of a technology package termed as the Integrated, Turbogeneration, Electrification, and Supercharging (ITES) system to demonstrate its potential for low emissions, high efficiency, and reduced cost will be demonstrated. In a previous study, a H2-ICE and aftertreatment concept for a MY2027 7.7L medium heavy-duty on-road engine was developed and evaluated through 1D simulation. The concept was to
Bustamante, Oscar, Correia Garcia, Bruno, Joshi, Satyum, Franke, Michael
Combustion Characterization of Hydroprocessed Esters and Fatty Acids (HEFA) as an Alternative Fuel for Use in IC Engines2026-01-0317To be published on 04/07/2026
In the endeavors to reduce reliance on fossil fuels and reduce greenhouse gas emissions, synthetic fuels from less carbon intensive feedstocks can provide an alternative. These synthetic fuels have gained traction in the aviation industry as sustainable aerospace fuels (SAFs). One such fuel is a synthetic paraffinic kerosene derived from hydroprocessed esters and fatty acids (HEFA). Preliminary research has also suggested that this fuel may also be favorable for use in IC engines. This investigation will explore the combustion characteristics of HEFA in an IC engine in more detail. The thermophysical properties of HEFA were investigated, and found comparable to or improving upon those of ULSD. Spray atomization analysis revealed more than 25% smaller SMD compared to ULSD, and lower span factor indicating a more uniform spray which can promote faster formation of a homogenous mixture. A tribological analysis using a pin-on-disk tribometer revealed comparable lubricity compared to ULSD
Soloiu, Valentin, Willis, James, Norton, Coleman, Davis, Zachary, Peralta Lopez, Guillermo, Rahman, Mosfequr
Experimental Characterisation of Combustion, Performance, and Emissions in a Hydrogen Opposed Piston Engine2026-01-0335To be published on 04/07/2026
Hydrogen has demonstrated significant potential in the adoption of zero-carbon fuels for conventional internal combustion engine platforms. However, with multiple H₂ICE technologies being adopted across wider platforms, several limitations have been observed, including abnormal combustion phenomena such as pre-ignition and backfire, as well as modifications in engine operating regimes. These complications arise from the distinct combustion characteristics of hydrogen compared to carbon-based fuels, necessitating careful optimisation to ensure reliable and efficient engine performance. The study aims to assess the adoption of pure hydrogen direct injection technology on a radical two-stroke opposed-piston engine with a 15 crank degree phase shift to optimise the engine's capability for hydrogen adoption through Atkinson-like cycles, while improving scavenging and reducing the pre-ignition risk associated with hydrogen DI adoption. The engine provides a flexible platform that can operate
Mohamed, Mohamed, Roeinfard, Nima, Wang, Xinyan, Zhao, Hua, Watts-Farmer, Archie, Rahman, Nadiur, Lempp, Francis
Optical investigation of Argon Power Cycle (APC)2026-01-0328To be published on 04/07/2026
The growing global demand for energy, combined with the urgent need to reduce greenhouse gas (GHG) emissions, is driving the development of alternative combustion technologies across transport sectors. Low- and zero-carbon fuels such as methanol, ammonia, and hydrogen are being explored as viable replacements for fossil fuels in internal combustion engine (ICE) applications. Among these, hydrogen stands out due to its wide flammability range and fast, carbon-free combustion. Research is ongoing to understand how hydrogen and other alternative fuels can be used most efficiently in ICEs. One promising concept is the Argon Power Cycle (APC), which could enable high-efficiency, zero-emission combustion in ICEs. In this approach, argon replaces air as the working fluid. Argon’s higher specific heat ratio (1.66 vs. 1.4 for air) and lower thermal conductivity both help increase efficiency. The absence of nitrogen also means NOx emissions are eliminated. The APC system is relatively simple
Kapp, Joakim, Cheng, Qiang, Vuorinen, Ville, Kaario, Ossi
A Comparative Study of Combustion Stability Improvement via Prolonged Discharge Duration under Engine Idling Conditions2026-01-0308To be published on 04/07/2026
Proper control over combustion and emission characteristics under engine idling conditions remains to be challenging, especially when engine block temperature is low. In previous publication from the author’s laboratory, a specially designed common-coil pack was demonstrated to improve engine idling performance by supplying prolonged ignition duration and elevated discharge current amplitude. In this paper, the progress on further development of the ignition system was reported with improved system stability and enhanced ignition performances. The impact of discharge current amplitude and discharge duration on the combustion stability was investigated in detail under a wide range of spark timings, aiming to eliminate misfire events and reduce engine-out emissions under engine block temperature of 30°C. Such improvement can help to reduce the HC and CO emissions during engine cold start process before the light up of the three-way catalyst, therefore, reduce the total emissions of a
Yu, Xiao, Zheng, Ming, Jin, Long, Leblanc, Simon
Investigation of Flame Speed Effects Towards Knock Suppression in a Boosted Spark-Ignited Engine Using 1-D Modeling2026-01-0311To be published on 04/07/2026
To combine high efficiencies and low pollutant emissions, engine manufacturers have developed downsized spark-ignited (SI) engines in light- and medium-duty applications utilizing charge boosting and high compression ratio. While these techniques have proven effective, abnormal combustion such as auto-ignition and knock present a challenge and an important limitation towards high efficiencies. In this work, simulations have been utilized for knock onset predictions as well to provide relevant insights and trends of engine and fuel parameters including flame speed on auto-ignition. A one-dimensional (1-D) GT-Power model was utilized in this study with a semi-predictive flame propagation model and kinetic mechanism solver to isolate the flame propagation rate on auto-ignition and knock. This work presents a comprehensive study of the laminar flame speed (LFS) effect on combustion at knocking conditions in a high compression ratio long stroke engine (LSE) fueled by propane. Knock onset
Douvry-Rabjeau, Julien, DelVescovo, Dan
Effects of methane addition to diesel in dual-fuel mode combustion in AFIDA2026-01-0344To be published on 04/07/2026
With the rising pressure of a global energy transition to cleaner energy systems, the transportation sector faces a challenge in maintaining its current structure and adapting to all the required changes. Dual-fuel technology emerges as a promising alternative to keep the viability of the sector while utilizing environmentally friendly fuels alongside traditional hydrocarbons, without deep structural changes in the current framework. This work investigates the impact of the use of methane gas coupled with diesel fuel, specially focusing its influence on the ignition delay time (IDT) in a dual-fuel combustion setting. The investigation employed the Advanced Fuel Ignition Delay Analyzer (AFIDA), a constant-volume combustion chamber capable of automated measuring of multiple samples in a single run. Methane gas was introduced into the chamber at molar concentrations of 1%, 2% and 3% and at initial pressures of 5 and 10 bar, with temperature values ranging from 653 to 723 K. With the same
Virginio, Thiago, Eraqi, Basem, Sakleshpur Nagaraja, Shashank, Sarathy, Mani
Challenges to Ranking Diesel Fuels for NOx Emissions Using a Constant-Volume Combustion Chamber2026-01-0348To be published on 04/07/2026
This study examined the use of a constant volume combustion chamber for the measurement of fuel effects on NOx emissions, with the goal of developing a method to rapidly screen or rank fuels in a small - volume experiment. A small amount of fuel was injected into the air at 650°C and 20 bars, where it ignited and burned. The chamber was sampled post-combustion using a chemiluminescence NOx analyzer. Extensive sampling method development was required to obtain repeatable results. Seven hydrocarbon fuels and two biodiesel fuels were tested, all of which have shown difference in NOx emissions in past engine studies. When using a single injection event to deliver the same amount of fuel energy, the test method could not clearly demonstrate the difference in NOx emissions between the hydrocarbon fuels as reported in engine combustion studies. To improve this, a dual-injection strategy was used. It included a small “pilot” injection followed by a main injection, timed based on each fuel’s
Luecke, Jon, Rahimi, Mohammad, Mohamed, Samah, Naser, Nimal, Chausalkar, Abhijeet, McCormick, Robert
Pathways to Exceed 50% Thermal Efficiency in Direct-Injection Gasoline Engines2026-01-0300To be published on 04/07/2026
Researches on high efficiency and low emission control strategies are crucial for addressing energy security and pollution challenges for combustion engines of vehicles. This paper investigates the effects of increasing compression ratio and air-fuel ratio (λ) under naturally aspirated conditions, as well as enhancing intake flow and λ under boosted intake combined with the Miller cycle, on combustion efficiency and pollutant emissions. Experiments were conducted on a high-compression-ratio (up to 16.6) single-cylinder thermodynamic gasoline engine. Under natural aspiration, the effective compression ratio was raised via valve timings adjustments, while λ was increased using integrated passive and active pre-chamber systems. Under boosted conditions, intake flow was controlled via a flow meter, and λ was controlled via an active pre-chamber to analyze the λ distribution and thermal efficiency at high-efficiency operating points. Results indicate that under natural aspiration
Deng, Jun, Li, Xiaoliang, Miao, Xinke, Xu, Bingxin, Zhang, JianQi, Li, Liguang
Development and Preliminary Combustion Experiments of a Prototype Engine with Sleeve Valves Based on the Focusing Compression Principle2026-01-0295To be published on 04/07/2026
Our laboratory has proposed the focusing compression principle which employs pulsed super-multi jets of gas colliding around the chamber center. This principle aims to achieve high thermal efficiency by reducing both exhaust and cooling losses. Exhaust loss is minimized due to relatively-silent high compression. Cooling loss is reduced due to thermal insulation caused by fuel-air mixture being confined to the chamber center and the compressible flow effect. In previous studies, we conducted fundamental gasoline combustion experiments on a proof-of-concept opposed-piston engine which incorporated this principle. This engine featured eight intake nozzles in an octagonal configuration and utilized non-sinusoidal and strongly asymmetric piston movements. The results indicated the possibility of high thermal efficiency based on less knocking under high compression, and the potential for stable combustion under lean-burn conditions. As a next step towards practical application with
NISHIZAWA, Tomohiko, Naitoh, Ken, baba, Shotaro, Ukegawa, Hiraku, Yamada, Sota, Ozono, Yuka, Abiko, Mirei, Suzuki, Yosuke, Hara, Namito, Ito, Yoshikuni, Matsubara, Kosaku, Uenoyama, Kazuyuki
Emission and Combustion Characteristics of a Hydrogen Direct-Injection Spark Ignition Engine using EGR2026-01-0325To be published on 04/07/2026
Hydrogen is recognized as a promising alternative fuel for internal combustion engines as it contains no carbon, but in addition to NOx emissions during hydrogen combustion, unburned hydrogen emissions have recently emerged as an important environmental issue. In this study, a 400 cc single-cylinder direct-injection hydrogen engine based on a 1.6 L Hyundai Kappa engine was used to analyze the effects of injection and ignition timing on combustion characteristics and engine emissions. Experimental results showed that the formation state of the air-fuel mixture varied with injection and ignition timing. Under conditions where locally fuel-rich mixtures were formed, NOx emissions increased while unburned hydrogen decreased. In contrast, when the mixture was relatively homogeneous, NOx decreased but unburned hydrogen increased. These findings clearly confirmed the trade-off relationship between NOx and unburned hydrogen emissions. To address this issue, exhaust gas recirculation (EGR) was
Yang, Heetae, Ki, Youngmin, Kim, Jungho Justin, Kim, Jinsu
A new approach for SI combustion modeling to address the upcoming fuel diversity scenario2026-01-0276To be published on 04/07/2026
Climate change concerns demand a drastic reduction in CO2 emissions, tending to what is called carbon neutrality. Even if political guidelines promote electrification, considering the transportation sector, not all applications have the same requirements and boundary conditions, and hence, their optimal solution is not necessarily the same. In this context, in parallel with pure electric powertrains, the internal combustion engine (ICE) still has a relevant role to play, mainly in hybrid powertrains, working together with an electrical motor. In this hybridization context, the spark-ignition (SI) engine used to be the most adopted solution because of its lower cost and complexity. Consequently, it can be concluded that the SI engine still has a significant role to play in the near future. However, when ICEs are considered, the search for carbon neutrality requires the use of fuels other than fossil fuels. At this point, many alternatives arise, from biofuels to synthetic e-fuels, or
Robayo-Rueda, Daniel, Lopez, J. Javier, Martin, Jaime, Novella, Ricardo
Combustion and Emission Characteristics of Biodiesel and Renewable Diesel in a 4-Stroke Locomotive Engine2026-01-0315To be published on 04/07/2026
Rail transportation in North America consumes substantial amounts of fossil fuel, raising energy security and supply chain resilience concerns. Adopting renewable or alternative fuels is a practical approach to reduce petroleum dependence and improve supply security. The objective of this paper is to investigate the combustion and emission characteristics of biodiesel and renewable diesel as a drop-in fuel without engine modification. In this study, a single-cylinder, four-stroke locomotive engine was employed to investigate the combustion and emissions characteristics of four fuels: conventional Diesel No. 2, plant-based biodiesel, animal-based biodiesel, and renewable diesel. The experimental campaign was carried out under both part-load and full-load operating conditions at the constant load, with injection duration adjusted to achieve the targeted engine’s load and speed. Results indicate that biodiesel and renewable diesel deliver comparable peak in-cylinder pressure, indicated
Ewphun, Pop-Paul, Biruduganti, Munidhar, El-Hannouny, Essam, Longman, Douglas, Fu, Xiao, Subramanya, Raghavendra
Effect of Ignition Timing on Combustion Performance in Ammonia-Hydrogen Blended Fuel Engine2026-01-0323To be published on 04/07/2026
Against the backdrop of energy structure transformation and upgraded environmental protection requirements, ammonia has been significantly attracted for its potential application as a zero-carbon fuel. However, it faces challenges such as difficult ignition, slow combustion rate, and low heating value. Thus, researching efficient combustion strategies suitable for ammonia as a fuel holds great significance. In this study, a two-cylinder diesel engine was modified into an ammonia-hydrogen blended fuel engine, experimental and simulation studies were carried out to investigate the effects of varying ignition timing on the combustion performance employed a passive pre-chamber ammonia-hydrogen fuel engine. The results show that the peak in-cylinder pressure exhibits a "first increase then decrease" trend as the ignition timing is retarded, reaching a maximum value of 7.42 MPa at the ignition timing of -27.5°CA ATDC. When the ignition timing is retarded beyond -15°CA ATDC, a double-peak
Deng, Jun, Luo, Mingyu, Shang, Quanbo, Tang, Yongjian, Qin, Jie, Li, Liguang
Optimization Strategies of Gliding Arc Plasma-Based Ammonia Cracker towards On-Board Applications2026-01-0292To be published on 04/07/2026
Ammonia has emerged as a viable hydrogen energy carrier owing to its superior hydrogen density, mature industrial utilization. However, ammonia faces critical challenges including inadequate ignition characteristics and sluggish combustion kinetics, necessitating supplementary high-reactivity fuels for optimizing combustion. Onboard ammonia cracking technology resolves this problem through on-demand hydrogen in-time production. Among existing decomposition methods, gliding arc plasma (GAP) demonstrates exceptional promise for on-board crackers given its decent hydrogen conversion rate and transient response capability. Prevailing research predominantly employs experimental methodologies wherein macroscopic parameters inadequately proxy microscopic electric field characteristics, thereby impeding mechanistic insight. This study establishes a quasi-1D numerical model to interrogate how electric field parameters modulate ammonia-to-hydrogen conversion yield and system energy efficiency in
Dong, Guangyu, LI, Xian, ZHOU, Yanxiong, XU, Jie, Li, Liguang
Optimizing an H2 combustion system and investigating abnormal combustions through advanced visualization techniques2026-01-0324To be published on 04/07/2026
The rapidly evolving mobility sector is facing the dual challenge of market expansion and the need for significant emissions reduction. Most of the transition tends to go in favor of electrification, yet it’s widely assumed that no single solution is perfect. Thus, hydrogen as an energy-vector presents a compelling alternative. H2 internal combustion engine use a well-known architecture and utilizes existing production facilities making it a viable short-term and cost-effective option. This context prompted us to investigate the hydrogen spark-ignited internal combustion engine, focusing specifically on critical combustion issues. Various studies have identified recurring challenges such as managing abnormal combustion and achieving high specific power. During our in-house developments, we also faced abnormal combustions and sought to determine the root cause of these issues. Initially, using a modular single-cylinder engine, a combustion system has been optimized regarding injection
LONDOS, Benoit, Bardi, Michele, Serrano, David, Laget, Olivier, Gautrot, Xavier, Bramoullé, Clément, Cordier, Matthieu
Flame Velocity and Combustion Behaviour of Ammonia–Hydrogen Blends: A Combined Experimental and Numerical Study2026-01-0320To be published on 04/07/2026
Ammonia is gaining importance as a viable energy vector for decarbonising the maritime sector. However, ammonia flame speed is much slower than that of traditional fuels, and this can result in incomplete burning, decreased engine efficiency, and increased undesirable emissions such as unburned ammonia (NH₃). While blending hydrogen with ammonia has been shown to mitigate some of ammonia's combustion drawbacks, the underlying mechanisms driving these improvements are still not fully understood. This study explores these processes to inform better optimisation. A 1.2 L optically accessible constant volume combustion chamber equipped with a wall-mounted surface spark plug was used to investigate the combustion characteristics and apparent flame velocity of ammonia-hydrogen blends. Chamber pressure and temperature were measured using high-frequency piezoresistive pressure transducers and K-type thermocouples. Flame propagation was captured at 9,000 frames per second using a Photron
Bodur, Tuna Murat, Bowling, William, La Rocca, Antonino, Cairns, Alasdair
Physics-Based Simulation for Sustainable Fuels Part 1: Simulation-Driven Hydrogen Engine Power Cylinder Unit Optimization and Experimental Confirmation2026-01-0278To be published on 04/07/2026
The demand for sustainable mobility and transportation is accelerating the adoption of alternative fuels, particularly hydrogen, in internal combustion engines. However, these engines present specific risks, such as explosive crankcase gas accumulation from blow-by and irregular combustion resulting from oil transport into the combustion chamber. Addressing these challenges requires advanced simulation tools to optimize power-cylinder-unit performance, specifically piston ring and gas dynamics. This study demonstrates simulation capabilities validated through detailed comparisons of measured and simulated inter-ring pressures across light vehicle, heavy-duty, large-bore, and motorsport applications, spanning a broad range of engine sizes covering displacements from 2 to 96 liters. Inter-ring pressure obtained via inhouse telemetry measurements within the power cylinder unit provided crank-angle resolved data throughout the ring pack, serving to validate 2D and 3D ring and gas dynamics
Köser, Philipp, Moreira, Rui, Deuß, Thomas, Morgado, Leonardo
Effect of Pre-Chamber Geometry on Methanol Cold-Start Combustion in an SI Engine2026-01-0307To be published on 04/07/2026
Vehicle pollutant emissions represent a key issue in the development of internal combustion engines. In recent decades, the automotive industry has been driven to explore innovative solutions, such as the use of alternative fuels and lean-burn combustion strategies, in order to meet increasingly stringent emission regulations. In this context, pre-chamber ignition systems show strong potential for reducing both fuel consumption and emissions, due to their ability to operate under lean mixtures and with non-conventional fuels. The aim of this work is to investigate the evolution of plasma jets under different in-cylinder combustion conditions, using methanol as fuel and integrating a pre-chamber heating system to improve cold-start operation. The experimental activity was carried out on a small optical spark-ignition (SI) engine, alternatively equipped with a conventional ignition system and a pre-chamber. The engine was operated at 2000 rpm under wide open throttle (WOT) in standard
Sementa, Paolo, Altieri, Nunzio, Tornatore, Cinzia
A Study on the Engine Vibration Control of Parallel Hybrid Vehicle based on the On-line Estimation of Engine Torque Fluctuations2026-01-0002To be published on 04/07/2026
For a hybrid electric vehicle (HEV) with a crankshaft-integrated e-motor, the e-motor can be utilized to compensate for typical combustion engine vibrations. This paper presents a feedforward engine vibration control methodology based on efficient real-time estimation of engine torque fluctuation, primarily derived from in-cylinder pressure profiles obtained through steady-state dynamometer tests at various operating points. The measured pressure profiles are decomposed into motoring pressure and combustion pressure components, where the motoring pressure component is further decomposed into idle speed pressure and throttle-associated motoring pressure components. These pressure components are converted into corresponding fluctuating torque elements. The resulting torque profiles are tabulated, then scaled and shifted according to the torque demand and ignition angle under real driving conditions, thereby enabling estimation of the pressure torque and subsequently total torque
Park, Keychun
The influence of split injection ratio on efficiency and NOx emissions in a pilot diesel-ignited hydrogen direct injection engine2026-01-0329To be published on 04/07/2026
This study investigates the impact of hydrogen split injection ratio on the combustion of pilot diesel-ignited hydrogen direct injection engines, which is expected to affect hydrogen-air mixture conditions and thus flame propagation and diffusion burning. Experiments were conducted on a 1-litre single-cylinder diesel engine equipped with an additional hydrogen injector operating at 35 MPa. Hydrogen of 95% total energy was injected at 150 and 60 °CA bTDC for the first and second pulses, which were selected as high efficiency injection timings from the previous equal split injection tests. The 5% diesel energy was injected near TDC to fix CA50 at 10 °CA aTDC for all tested split injection ratios. While varying the split ratio between the two hydrogen injections, in-cylinder pressure/aHRR profiles, engine efficiency/power output and engine-out emissions of NOx and CO2 were evaluated. Results showed that the hydrogen split ratio does not make a significant impact on IMEP/efficiency, which
Zhao, Yifan, Chan, Qing Nian, Kook, Sanghoon
Experimental Study on the effect of Ignition Strategy on Combustion and Emissions in a Direct Injection Hydrogen Engine2026-01-0330To be published on 04/07/2026
Hydrogen-fueled internal combustion engines (H₂ICEs) are a promising pathway toward carbon-neutral transportation, but their efficiency and emissions performance are highly sensitive to ignition control strategies. This study systematically investigates the combined effects of spark timing (−10 to −26 °CA bTDC) and spark energy (25–40 mJ) on combustion characteristics in a port fuel-injected H₂ICE operating at a constant speed of 1400 r/min under low, medium, and high load conditions. Results show that spark timing advance produces load-dependent effects: at low load, it increases the peak heat release rate while delaying peak pressure and shortening combustion duration; at medium and high loads, it advances both peaks toward TDC with an optimal spark timing shifting closer to −14 °CA. Ignition delay was only slightly reduced at low load but significantly shortened—by about 3 °CA—at high load. NOₓ emissions increased nearly linearly with spark advance, while slight retardation
ZHAO, KEQIN, Lou, Diming, zhang, yunhua, Fang, Liang, Tan, Piqiang, Hu, Zhiyuan
Effects of Gasoline Composition and Operating Parameters on the Response of Knock Limit to Nitric Oxide in a Lean-Burn DI-SI Engine2026-01-0313To be published on 04/07/2026
Lean operation of spark-ignition engines can lead to efficiency gains and lower NOx emissions due to reduced combustion temperatures. However, lean operation may still encounter difficulties with end-gas autoignition and knock, which worsen by the presence of trapped NO in the cylinder. This study assesses the impact of intake-seeded NO on end-gas autoignition and knock for two gasolines with similar octane rating but different composition: high cycloalkane fuel (HCA) and high olefin fuel (HO). Experiments were performed at stoichiometric and lean (lambda = 2) conditions and at two engine speeds of 1400 rpm and 2000 rpm to investigate the influence of equivalence ratio and residence time on end-gas autoignition trends. Chemical kinetics simulations revealed that the mechanisms that control the effect of NO on knock are similar at lambda = 2 and lambda = 1, with NO + HO2 = NO2 + OH being the main pathway for enhancing reactivity by promoting low-temperature heat release (LTHR
Kim, Namho, Abboud, Rami, Sjöberg, Magnus, Lopez Pintor, Dario, Saggese, Chiara, Matsubara, Naoyoshi, Kitano, Koji, Yamada, Ryota, Sugata, Kenji
Effect of Renewable Fuel Blends on Particulate Emissions Under Medium Engine Load and Injector Coking Conditions in a GDI Engine2026-01-0301To be published on 04/07/2026
Renewable gasoline is blended with fossil gasoline as part of the effort to achieve zero net carbon emissions. This study examined how five gasoline fuels with different hydrocarbon compositions affect engine-out gaseous and particle number (PN) emissions. Gasolines F3 and F4 reduce GHG emissions by 54% and 35%, compared with fossil gasoline. The other three gasolines reduce GHG emissions by 4-9%. Tests were conducted on a single-cylinder GDI engine at 10-14 bar indicated mean effective pressure (IMEP) and 2000 rpm. The injector-tip coking behavior of the test fuels and the resulting PN emissions were also investigated at 10 bar IMEP. Spray plume targets and start-of-injection (SOI) timing were adjusted to examine how the test fuels affected PN emissions. An endoscope was used to identify the sources of soot during fuel combustion. The experimental results show that PN varies with gasoline composition and engine operating conditions. Aromatics and olefins contribute more to injector
Muniappan, Krishnamoorthi, Dahlander, Petter, Helmantel, Ayolt, Alemahdi, Nika, Lehto, Kalle
Improving Transient Diesel Performance with E-Supercharging and Multiple-Input Multiple-Output Controls2026-01-0444To be published on 04/07/2026
Engine torque response for turbocharged diesel engines is limited by lag in air supply to the engine restricting the rate at which fuel can be delivered. This delay can lead to rich air-fuel mixtures and elevated soot emissions during transient events. Electric forced induction systems (EFIS) offer a potential solution to address both of these challenges. For this study, an electric supercharger (E-Booster) is integrated with the original forced induction system of a 4.5-L 4-cylinder turbocharged diesel engine to create a two-stage boosting system that assists induction during transients. Electric supercharger operation is managed by two control schemes, a model-based single-input single-output (SISO) and a model-based robust multiple-input multiple-output (MIMO) controller. Constant speed load acceptance (CSLA) experiments and emulated drive-cycles were performed in a dyno cell evaluating both control methods. The E-supercharged two-stage boosted engine has demonstrated significant
Vang, Nicholas, Rothamer, David, Ghandhi, Jaal, Ashta, Shubham, Qiu, Weijin, Rayasam, Sree Harsha, Shaver, Greg, Frushour, Bryan, Dou, Danan
A Holistic Approach to Pre-Chamber Design, Integration, and Operational Optimization2026-01-0310To be published on 04/07/2026
As internal combustion engines continue to play a critical role in hybrid on-road and numerous non-road applications, there is a continued push to increase efficiency and minimize tailpipe emissions. However, reduced investment in new engine architectures means retrofittable technologies are favored to continue incremental performance improvements to existing engine platforms. To maintain the relatively low capital cost of engine-based powertrains, these technologies must be low-cost and compatible with the diverse mix of fuels that may be encountered across various market segments in the future. Pre-chambers have shown significant potential for improving spark-ignited engine performance across a wide range of engine sizes, from motorsport applications to stationary power, and operating conditions, from stoichiometric operation to ultra-lean. Understanding the degree to which this central combustion technology must be tailored to optimize its performance with a variety of fuels and
Peters, Nathan, Pothuraju Subramanyam, Sai, Hoth, Alexander, Bunce, Mike
Real-Time Observations of the Effect of Fuel Dilution in an Engine Transient Friction Rig. Along with Real-Time Observations of Fuel Entering and Leaving Internal Combustion Engine Oil, over both Standard Engine, ICE and Hybrid, HEV Dynamic Drive Cycles.2026-01-0351To be published on 04/07/2026
Hybrid electric vehicles with an increasing level of electrification, are becoming a major part of the global energy transition. To achieve lower engine tailpipe exhaust emissions and improve total fuel consumption, typically the hybrid electric vehicle (HEV) control system efficiently and frequently switches between the internal combustion engine and electric motor drive, with multiple stops and restarts of the internal combustion engine. A consequential result of this switching is typically slower, or even incomplete engine warm up times, depending on the engine speed, load pattern and run time of the vehicle drive cycle. Along with the speed and load transient control, the engine stop and start processes are also challenging to control, with respect to cold start fuel and combustion by-products entering the oil. Consequently, contamination enters the engine oil but may not completely leave. These effects are highly transient over the drive cycle with contaminants, in particular fuel
Butcher, Richard, Bradley, Nathan, Thedering, Dennis
Effect of passive pre-chamber geometry on performance and emissions of a single-cylinder natural gas large bore engine.2026-01-0333To be published on 04/07/2026
The maritime industry is one of the most energy-intensive sectors, characterized by high fuel consumption and significant environmental impact. As global trade mainly relies on shipping, the challenge of reducing pollutant and greenhouse gas emissions becomes ever more pressing. Natural gas (NG) is regarded as a transitional fuel, capable of lowering CO₂ emissions by 20–30% compared to conventional marine fuels. However, to fully harness this potential, significant advances in combustion technology are necessary, particularly when ultra-lean combustion strategy is adopted. One of the most promising pathways is pre-chamber combustion, a solution that can simultaneously improve the efficiency and sustainability of NG marine engines. In this scenario, the passive pre-chamber geometry plays an important role, as it directly influences ignition behavior, combustion stability and exhaust emissions. This work presents an experimental study carried out on a single-cylinder marine engine
Marchitto, Luca, Tornatore, Cinzia, Pennino, Vincenzo, Mariani PhD, Antonio, Beatrice, Carlo, Accurso, Francesco, Gorietti, Valentina, Pesce, Francesco, Giardino, Angelo, Vitti, Luciano
Effect of Ignition Energy on Combustion Duration under Flow Conditions2026-01-0336To be published on 04/07/2026
Utilizing low carbon fuel in lean burn combustion presents a compelling strategy for improving thermal efficiency and reducing NOx emissions. Methane, the main content of natural gas, still receives challenge of a rapid and complete combustion process because of its low chemical reactivity. Further increase of excess air ratio would decrease the flame propagation speed significantly, leading to prolonged combustion durations. The long combustion duration deteriorates the performance of a spark ignition engine, in terms of poor combustion instability and misfire. Although ignition timing can be utilized to adjust the combustion phasing, the ignition process faces challenges due to reduced background pressure and temperature at advanced spark timings. In this paper, a rapid compression machine equipped with a specially designed combustion flow chamber is utilized to enhance the mean flow speed across the spark gap under the background pressure 6 bar abs. and temperature 600 K. A
Jin, Long, Yu, Xiao, Reader, Graham, Zheng, Ming
Impact of Hydrogen on Methane and Pollutant Emissions over Three-Way Catalysts with Natural Gas–Hydrogen Blends2026-01-0357To be published on 04/07/2026
Natural gas (NG) is a domestically abundant, low-cost fuel with the potential to displace gasoline and diesel fuel in commercial and off-road vehicles. NG engines typically produce lower engine-out pollutant emissions, such as NOx, CO and particulate matter, which could simplify emission control systems. Blending NG with hydrogen (H₂) can improve engine performance and increase combustion efficiency to further reduce engine-out emissions. Additionally, the presence of H2 in the exhaust stream may also facilitate the catalytic conversion of methane and other pollutants, resulting in cleaner tailpipe emissions. This study evaluates the impact of H2 on the conversion of methane, CO, and NOx emissions on a commercial three-way catalyst (TWC) in a flow reactor using synthetic gas mixtures that simulate stoichiometric engine exhausts with NG or NG+H₂ combustion. The work examines whether, and how, the additional amount of H₂ in the exhaust stream affects the conversion efficiency of methane
Prikhodko, Vitaly, Wang, Min, Park, Yeonshil, Chen, Hai-Ying, Pihl, Josh
Analysis of In-Cylinder Flow for Hybrid Gasoline Engine using High-Speed Particle Image Velocimetry2026-01-0298To be published on 04/07/2026
To curb global warming, reduction of CO2 emissions in automotive powertrains is required. Hybridization and further improvement of thermal efficiency has been promoted in internal combustion engines. Therefore, the 2.0-liter inline 4-cylinder direct-injection engine for 2 motor-hybrid powertrain have been developed to realize rapid combustion by in-cylinder flow enhancement. In this paper, in-cylinder flow analysis using high-speed PIV on the optical single-cylinder engine was performed, and evaluated the combustion promotion concept by analyzing the bulk flow and the turbulence. To achieve rapid combustion, the intake port shape for tumble flow enhancement and bowl-in type piston which was smoothly converted the tumble flow to upward flow were examined. As a method for turbulent component decomposition, the time filter method proposed by the authors were applied. The characteristics of the time filter method is that turbulent component does not include the cycle-by-cycle fluctuations
Okura, Yasuhiro, Urata, Yasuhiro
Characterisation of Particle Number and Size from a DI SI Engine Operating on Hydrogen: Operating Sensitivities and Filtration Effects2026-01-0378To be published on 04/07/2026
Hydrogen Internal Combustion Engines (H₂ICEs) offer the potential for near-zero carbon emissions. However, while nitrogen oxide (NOₓ) emissions have been extensively studied, particle number (PN) emissions, primarily resulting from lubricant oil pyrolysis due to hydrogen’s short quench distance, remain less well understood. This study investigates exhaust particle characteristics from a spark-ignition, single-cylinder research engine, based on MAHLE Powertrain’s downsizing engine combustion system, at Brunel University, London. It compares gasoline and hydrogen direct-injection strategies (central vs. side injection) across a wide range of operating conditions, including variations in engine speed, load, air-fuel ratio (λ), rail pressure, and spark timing. PN and particle size distribution were measured using Cambustion’s DMS500, paired with a catalytic stripper to isolate solid particles. To assess the impact of engine wear, tests were conducted on both a worn engine configuration
Harrington, Anthony, Zaman, Zayne, Nickolaus, Chris, Zhao, Hua, Wang, Xinyan, Hall, Jonathan
Potential for Total Cost of Ownership Reduction using Passive Pre-Chamber Ignition in Natural Gas Engines2026-01-0309To be published on 04/07/2026
Spark plug durability is a factor affecting the total cost of ownership (TCO) of spark-ignited natural gas engines, with some heavy-duty platforms requiring plug replacement after only 750 hours of operation. The high ignition energy demand under lean or diluted conditions accelerates electrode wear, shortening plug life and increasing maintenance frequency. This work evaluates passive pre-chamber (PC) ignition operating at lowered spark energies as a strategy to reduce spark energy requirements and extend plug durability, thereby lowering TCO. Experiments were conducted on a medium-duty Cummins 6.7L ISB engine at 1600 RPM and 50% load under varying exhaust gas recirculation (EGR) dilution levels (0–40%). Two passive pre-chambers, with 1.1 mm and 1.6 mm nozzle diameters, were compared against conventional spark ignition (SI). SI was operated with a fixed coil dwell of 4 ms (~90 mJ), while the PC configuration was tested across 2–4 ms dwell times (~30–90 mJ). Cylinder pressure analysis
Dhotre, Akash, Voris, Alex, Okey, Nathan, Kane, Seamus, Rajasegar, Rajavasanth, Northrop, William
Sensor Location Study for Non-Intrusive Start of Combustion (SOC) Detection Using Engine Block Vibration2026-01-0288To be published on 04/07/2026
This study investigates the impact of sensor location on accelerometer-based sensing of combustion phasing for compression-ignition engines. Ten accelerometer locations were studied on a light-duty compression-ignition engine for a set of conditions varied in engine load, speed, injection timing and injection strategy. Start of combustion (SOC) was identified from filtered acceleration signals. Each location was assessed using both signal quality metrics, including magnitude squared coherence (MSC) with in-cylinder pressure, passband intensity, signal to noise ratio, and spectrogram shape, as well as SOC outcome metrics such as detection success rate. Results demonstrate that the mounting location has a significant impact on the ability to extract relevant combustion phasing information from the accelerometer signal. Sensors mounted on the front face of the engine produced the strongest signals for an individual cylinder. For multi-cylinder sensing, a side mounted location delivered
Hegge, Graydon, Hanson, Reed, Kim, Kenneth, Rothamer, David
Effects of the Spark Location and Timing in a Heavy-Duty Hydrogen-Fueled Engine2026-01-0331To be published on 04/07/2026
The use of hydrogen in internal combustion engines offers a promising route to low-carbon propulsion in heavy-duty transportation. However, its distinct combustion characteristics as high flame speed, wide flammability limits, and susceptibility to abnormal combustion, necessitate careful engine and ignition system design. This study investigates the combined influence of spark plug location and ignition timing on the performance of a heavy-duty Volvo Diesel engine modified to operate in a spark-ignited mode with hydrogen fuel at low compression ratio under different load conditions. Three-dimensional computational fluid dynamics simulations with detailed hydrogen chemistry, including diffusive-thermal effects, were conducted to evaluate flame development, combustion efficiency, and heat release under different loads. Model validation against combustion behavior and jet characteristics from a low-pressure, high-mass-flow direct injector is also presented. The results demonstrate that
Menaca, Rafael, Shakeel, Mohammad Raghib, Panithasan, Mebin, Liu, Xinlei, Qahtani, Yasser, AlRamadan, Abdullah, Cenker, Emre, Silva, Mickael, Pei, Yuanjiang, Turner, James, Im, Hong
The impact of various renewable hydrocarbons on performance and emissions in a super lean burn engine2026-01-0306To be published on 04/07/2026
Biofuels can play a key role as carbon-neutral transitional energy sources for ICE vehicles as the fleet moves towards increasing electrification. Blending of ethanol plays a key role in enhancing the anti-knock properties of the fuel and also allows renewable hydrocarbons (such as bio-naphtha) to be incorporated into the blend whilst maintaining an acceptable overall fuel quality. Super lean burn ICE technology with λ between 2 and 3 can lead to significantly enhanced fuel economy and reduced NOx emissions. The Toyota prototype engine used to generate data for this project injects most of the fuel in a PFI mode to generate a homogeneous super-lean charge in the cylinder, but just before spark ignition the DI injector sprays a small amount of fuel towards the spark plug to create a richer charge near the spark plug to promote flame kernel development. Various fuel formulations with a high biofuel content were tested in both conventional and super lean burn engines. Certain fuel
Aradi, Allen, Krueger-Venus, Jens, Jain, Sandeep Kumar, Cracknell, Roger, Kolbeck, Andreas, Shibuya, Masahiko, Yamada, Ryota, Matsubara, Naoyoshi, Kitano, Koji
Upstream Oxygen Sensor Signal Improvement Using the DFSS and Virtual Validation Approach2026-01-0486To be published on 04/07/2026
Combustion stability and emission control remain key challenges for gasoline engines, requiring robust oxygen sensing strategies. The primary function of the upstream exhaust oxygen sensor is to detect the oxygen concentration in exhaust gas for accurate air–fuel ratio control. However, poor signal visibility from individual cylinders across engine speeds can lead to improper combustion prediction and reduced engine efficiency. This work applies a Design for Six Sigma (DFSS) approach to optimize the upstream oxygen sensor configuration in a 2.0 L four-stroke gasoline engine. Conventionally, sensor placement is completed by iterative testing and calibration, which is both time-consuming and cost intensive. The DFSS framework uses input, output, control, and noise factors. Exhaust gas mass flow rate from engine cylinders at different speeds is treated as the input, while the detected oxygen mass fraction is the output. Design parameters such as pipe length, pipe diameter, sensor
Dixit, Manish, Raja, Vinayak, Annabattula, Pallavi
Control Strategy and Dynamic Characteristics of a Hydrogen Opposed-Cylinder Free-Piston Engine Generator2026-01-50172/23/2026
Free-piston engine generator (FPEG), as a novel energy conversion device, has the advantages of good fuel adaptability and high energy utilization. Combustion variation between cycles poses a significant challenge to the running control of an FPEG. A hierarchical control strategy, including motion, combustion, and generation power controllers, is designed in this paper to achieve the stable and efficient running of a hydrogen-fueled opposed-cylinder FPEG prototype. Piston motion is controlled by adjusting the generation current, which is adjusted through iterative learning using piston displacement feedback and adaptive control using piston velocity feedback. Generating power is regulated by controlling the throttle opening angle, which is adjusted through iterative learning. A multidisciplinary joint mathematical model is developed to simulate the dynamic characteristics and verify the control strategy. The simulation results reveals that the dead center position accuracy can be
Wang, Jiesheng, Liu, Liang, Xu, Zhaoping
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