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

Effect of Ignition Condition and Fuel Octane Number on Knock Intensity in a Small 2-Stroke Engine

2025-01-0211

To be published on 06/16/2025

Internal combustion engines (ICEs) remain widely used in automotive transportation for their high energy storage system efficiency and economic benefits. The 4-stroke engine has dominated all other forms to date, because the Otto cycle is relatively simple to understand. However, the significant benefits such as less pumping work and friction, lighter construction of 2-stroke engine, are attractive for applications that prioritize the simplicity and power density as well as meet the emission regulations. The disadvantages of the 2-stroke engine are mainly caused by the lack of sufficient scavenging process. Also, the overlap of the intake and exhaust phases results in charge short-circuiting, more fuel consumption and high unburned hydrocarbon emissions. For these reasons, it is difficult for 2-stroke engines to achieve stoichiometric combustion, making them incompatible with 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

Experimental Analysis of Performance and Durability Using Ethanol 27% Fuel Blend in a Turbocharged Gasoline Direct Injection Engine

2025-01-0245

To be published on 06/16/2025

India aims to achieve 20% ethanol blending (E20) in petrol by 2025 under its National Biofuels Policy to reduce carbon emissions, enhance energy security, and support the agricultural economy. Building on this, E27 (27% ethanol in gasoline) is being evaluated as an advanced mid-level blend to further lower greenhouse gas emissions and reduce reliance on fossil fuels. This study investigates the performance, emissions, and combustion characteristics of a turbocharged gasoline direct injection (TGDI) engine using E27 fuel over 20,000 km in real-world driving conditions, as part of a broader research program accumulating over 100,000 km across multiple vehicle categories. Key findings indicate that E27 achieves an optimal balance of emissions reduction and performance, with NOx and THC emissions decreasing by 12% and 5%, respectively, compared to E10, while CO and CO₂ levels remained stable, reflecting ethanol’s oxygenation effect and lower carbon intensity. Power output and acceleration

D R, Vigneshwar, Bhakthavachalu, Vijayabaskar, Muralidharan, M.

Higher Content n-Butanol Blending Ratios in Diesel Fuel Spray and Combustion Characteristics: Addressing Oxygenated Fuel Challenges with Spark-Assisted Combustion Strategies

2025-01-0210

To 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

An Experimental Study on Aqueous Ammonia and Diesel Dual-Fuel Combustion with Ignition Improving Additives in a Compression Ignition Engine

2025-01-0231

To 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 has health risks 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 and, 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 co-combustion and pollutant emissions of burning such a fuel remain less understood. This study therefore explores the potential of using

Han, Yanlin, Hellier, Paul, Schonborn, Alessandro, Ladommatos, Nicos

Hydrogen Jet Characteristics of an Outward-Opening Injector Based on Schlieren Imaging

2025-01-0228

To be published on 06/16/2025

Hydrogen was considered as a promising carbon-free fuel for future society. The application of hydrogen in internal combustion engines has drawn more and more attention. Jet performance of hydrogen injection plays a crucial role in characteristics of the hydrogen fuelled engines, in terms of mixture preparation, combustion and heat release in cylinder. In this research, an outward-opening injector was developed for hydrogen direct-injection applications. The jet performance was studied using high-speed schlieren imaging in a constant volume chamber and the effects of injection and ambient pressures on jet characteristics were investigated. The results show that, the hydrogen jet exhibits a conical structure in the near-field and overall presents a bell-shaped appearance under relatively low ambient pressure, which differs from the irregular structure under relatively high ambient pressure. The pressure ratio, defined as the ratio of injection pressure to chamber pressure, significantly

Hu, Chaoqun, Hu, Longbiao, Chen, Haie, Li, Liguang, Wu, Zhijun, Deng, Jun

Effects of Injection and Intake Timing on Atomization and Combustion in a Hybrid Gasoline Direct Injection Optical Engine under the Low-Speed Low-Load Condition

2025-01-0203

To 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 at BMEP of 6 to 10 bar, low-to-mid speed of 2000 to 3000 rpm to achieve optimal fuel economy. However, these engines inevitably operate under low-speed, low-load conditions, such as during engine startup and low-speed cruising, 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 was used. The engine featured a compression ratio of 15.0:1 and was 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

Cui, Mingli, Fu, Jinhong, Man, Xingjia, Nour, Mohamed, Zhang, Weixuan, Li, Xuesong, Xu, Min

Influence of Fuel Surface Tension and Viscosity on Internal Flow Bubble Formation and Atomization in Flash Boiling Sprays

2025-01-0221

To be published on 06/16/2025

Flash boiling atomization is considered a promising atomization technique for combustion applications in automotive powertrains. It can potentially address the deteriorated atomization issue for alternative fuels (such as methanol) in internal combustion engines. However, it has been observed that flash boiling spray atomization for methanol fuels is not as effective as that for traditional alkane-based fuels. This work aims to explain such phenomena using transparent nozzles to reveal the impact of internal vaporization on external spray breakups. Three different working fluids, including methanol, ethanol, and pentane, are tested with elevated temperatures. The flow patterns and external liquid breakup are shown with the high-speed imaging technique. It is found that the internal phase change of the base working fluid is suppressed when ethanol or methanol is used instead of pentane. Consequently, the external liquid breakup is also hindered due to insufficient vapor phase inside the

Zhang, Yijia, Li, Yilong, Wang, Shangning, Zeng, Tingxi, Xu, Min, Hung, David, Li, Xuesong

Morphology Experiment of Icing Effect on Spray Propagation

2025-01-0222

To be published on 06/16/2025

The working conditions of combustion systems have been going extreme under the desire of human beings exploring the unknown. Cold environments can be a significant impact on the spraying of fuel not only by changing the fuel properties including viscosity and surface tension, but also by freezing the parts. In the present study, methanol spray from a commercial injector is studied via high-speed imaging, with the liquid fuel being frozen to sub-zero degrees at the injector tip. It is observed that water components from the environment will freeze at the injector tip, creating crystal structures on the surface. During the injection, the ice components will be flushed by the liquid, and the spray morphology of the starting cycle will be strongly altered, resulting in wider spray angles, much shorter penetrations, and particle structures can be observed in the downstream of the flow field. The results of the experiment provide a clear view and quantified evaluation of the freezing impact

Zeng, Tingxi, Wang, Shangning, Zhang, Yijia, Hung, David, Xu, Min

Overview of Indian Government Policies, Regulations and Automotive Company Strategies toward Net-zero Emissions

2025-01-0184

To be published on 06/16/2025

The automotive sector in India is undergoing a transformation, driven by government policies and regulations aimed at achieving net-zero carbon emissions. In alignment with global climate goals, the Indian government has set ambitious targets to reduce greenhouse gas emissions, with a focus on promoting Electric Vehicles (EVs) and Hydrogen Fuel Cell Vehicles (FCVs). Initiatives like the Faster Adoption and Manufacturing of Hybrid and Electric Vehicles (FAME) Scheme, along with tax incentives, subsidies, and charging infrastructure development, are designed to accelerate the adoption of cleaner vehicles. The introduction of stricter emission standards and the National Electric Mobility Mission Plan (NEMMP) further underscores the push toward sustainable mobility. In response, Indian automotive companies are shifting strategies to align with these government directives. Major players are significantly increasing investments in EV technology, focusing on enhancing battery performance

Patil, Nikhil Nivrutti, Saurabh, Saurabh, Bhardwaj, Rohit, Gawhade, Ravikant, Gadve, Dhananjay, Amancharla, Naga Chaithanya

Techno-Economic Analysis of an Integrated E-Methanol Production Plant Utilizing First and Second Generation Biomass Resources

2025-01-0182

To be published on 06/16/2025

This study presents a comprehensive techno-economic assessment (TEA) of an integrated e-methanol production system building upon previously published foundational research utilizing Aspen Plus modeling for e-methanol production from sugar cane and sugar beet biomass. The established integrated system converts biomass into ethanol through fermentation and synthesizes e-methanol using both captured CO2 and syngas derived from biomass residue gasification. This approach maximizes CO2 and biomass utilization, promoting a circular carbon economy. The TEA quantifies capital expenditures (CAPEX), operational expenditures (OPEX), and levelized costs of Methanol (LCOM), providing a detailed economic analysis of the potential for commercializing e-methanol. A sensitivity analysis evaluates the impact of feedstock prices and Technology Readiness Levels (TRL), identifying key leverage points affecting financial viability. The study aims to explore the potential of utilizing existing agricultural

Fernandes, Renston Jake, Shakeel, Mohammad Raghib, Nguyen, Ducduy, Im, Hong G., Turner, James W.G.

Comparison of HRD and Petro Diesel in Industrial Engine Applications

2025-01-0243To 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

Life Cycle Assessment of Hydrogen Generation through Steam Methane Reforming: A Focus on Co-Product Allocation between Steam and Electricity

2025-01-0181

To be published on 06/16/2025

This research presents a numerical analysis of the environmental impacts associated with using hot steam as a co-product in hydrogen production through Steam Methane Reforming (SMR) of renewable gas sources. As hydrogen production technology advances rapidly, reducing emissions and addressing environmental concerns, particularly greenhouse gas (GHG) emissions, have become essential. This study examines the SMR process with a focus on the environmental effects of utilizing hot steam as a co-product for electricity generation or facility heating. The analysis evaluates renewable feedstocks, including landfill gas, animal waste, food waste, and wastewater sludge, to determine their viability for sustainable hydrogen production. Key pollutants, such as carbon monoxide and nitrogen oxides, along with GHGs, are assessed to identify the most environmentally advantageous feedstock options. This work aims to provide insights to promote sustainable hydrogen production practices.

Rosyadi, Ahmad Adib, Lim, Ocktaeck

3D-Printed Porous Media Combined with Biomimetic Distributor for Small-Scale Polymer Electrolyte Membrane Fuel Cells

2025-01-0196

To be published on 06/16/2025

This study presents a novel biomimetic flow-field concept that integrates a triply periodic minimal surface (TPMS) porous architectures with a hierarchical leaf-vein-inspired distribution zone, fabricated through 3D printing. By mimicking natural transport systems, the proposed design enhances oxygen delivery and water removal in proton exchange membrane fuel cells (PEMFCs). The results showed that I-FF and G-FF significantly improved mass transport and water management compared to conventional CPFF. The integrated design I-FF-LDZ achieves up to 32% improvement in power density at 1.85 A/cm2@0.4 V and delays the onset of mass transport losses. The study also reveals that optimizing the volume fraction Vf significantly affects gas penetration, with lower Vf (30%) improving performance in the mass-limited region. These findings underscore the promise of nature-inspired, 3D-printed flow-field architectures in overcoming key transport limitations and advancing the scalability of next

Ho-Van, Phuc, Lim, Ocktaeck

Enhanced Equivalent Consumotion Minimization Strategy Based on Bayesian Optimization

2025-01-0194

To be published on 06/16/2025

The Equivalent Consumption Minimization Strategy (ECMS) is an effective approach for managing energy flow in hybrid electric vehicles (HEVs), balancing the use of electric energy and fuel consumption. The strategy’s performance depends heavily on the Equivalent Factor (EF), which governs this trade-off. However, the optimal EF varies under different driving conditions and is influenced by the inherent randomness in factors such as traffic, road gradients, and driving behavior, making it challenging to determine through traditional methods. This paper introduces Bayesian Optimization (BO) as a solution to address the stochastic nature of the EF parameter tuning process. By using a probabilistic model, BO efficiently navigates the complex, uncertain performance landscape to find the optimal EF parameters that minimize fuel consumption and emissions across variable conditions. Simulation results under WLTP cycles show that the proposed method reduces fuel consumption by 0.9% and improves

Zhang, Cetengfei, Zhou, Quan, Jia, Yiqi, Xiong, Lu

An Experimental and Numerical Study of Ultra-Lean Combustion Characteristics of Methanol Direct Injection using Various Coil Spark Ignition Strategies

2025-01-0200

To 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

Thermal Efficiency Improvement and Emission Reduction of Methanol Spark Ignition Engine Using Lean-Burn Strategy

2025-01-0224

To 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. These characteristics make methanol well-suited for lean-burn strategies, which reduce pumping losses and enhance thermal efficiency. However, there remains a lack of studies on the influence of injection timing under different lean conditions, particularly in a wall-guided spark ignition engine. Wall-guided systems use the chamber wall or piston surface to redirect and stratify the fuel-air mixture near the spark plug at the time of ignition. The combustion performance of lean-burn engines in highly sensitive to variations in injection and excess air ratio. In this study, experiments were conducted on a single

Lee, Seungwon, Kim, Hyunsoo, Hwang, Joonsik, Bae, Choongsik

Understanding How Blending Different Ratios of Renewable Fuels with Diesel Impacts the Toxicity of Exhaust Particulates to Human Health

2025-01-0207

To be published on 06/16/2025

The urgent need to decarbonise transport has increased the utilisation of renewable fuels blended 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, oils and biomass. Particulates from diesel combustion are known to be toxic due to the presence of polycyclic aromatic 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

Hailwood, Emma, Hellier, Paul, Ladommatos, Nicos, Leonard, Martin

Evaluation of Jet Fuels on Thermal Efficiency, NO _X Emissions, Particulate Matter, and Particle Size Distribution in a Heavy-Duty Compression Ignition Engine

2025-01-0244

To 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 the important sustainable aviation fuels (SAFs) for future transportation. However, these alternative fuels often vary in their characteristics, depending on their feedstock and fuel production processes. Therefore, a detailed analysis of these alternative fuels' combustion, emissions, and efficiency must be performed under controlled experiments to understand the impact of fuel properties and operating conditions. This study used a single-cylinder research engine (SCE) with a compression ratio of 17:1. Extensive operating conditions were performed to determine the effect of each fuel on the engine performance, which can be fundamentally understood by fuel properties (e.g., cetane number, heat of combustion, and density) in comparison with Jet-A fuel. The experimental setup includes high-speed data acquisition for combustion analysis and gaseous

Cung, Khanh, Miganakallu Narasimhamurthy, Niranjan, Khalek, Imad, Hansen, Greg

Numerical Investigation into the Combustion and Emission Characteristics of Ammonia Direct Injection Mechanism

2025-01-0241

To be published on 06/16/2025

The effects of diesel and the ammonia ratio on the emissions and combustion characteristics of ammonia utilized in AMMONIA direct injection (AMMONIA-Di) engines were investigated through experimental and numerical investigations. A rapid compression expansion machine (RCEM) modified to facilitate the dual direct injection fuel (diesel-ammonia) - compression ignition (CI) method was used to conduct the experiment. A compression ratio (CR) of 19 and an ammonia energy percentage ranging from 10% to 90% were used in the experiment. Changes were made to the start of injection (SOI) from 0o to 40o before top dead center (BTDC) in order to find the best auto-ignition properties of ammonia. In order to facilitate auto-ignition, the diesel’s SOI was maintained at 10o BTDC. Computational fluid dynamics (CFD) modeling was used to establish the detailed emission propagation during the combustion process. During the expansion step, ammonia goes through a second stage of combustion, demonstrating

Setiawan, Ardhika, Lim, Ocktaeck

Analysis of Diesel-Ethanol Blends: Impact on Spray Behavior and Combustion Properties under Various Injection Parameters in CI Settings

2025-01-0208

To be published on 06/16/2025

With rising fuel consumption across road transportation, there is growing interest in expanding the market share of renewable fuels, such as ethanol. Ethanol can be produced from raw materials from various starch-rich plants. In CI engines, ethanol cannot be utilized on its own, largely due to its low cetane number. In this study, a constant volume combustion chamber (CVCC) is employed to investigate the effects of adding ethanol in diesel with different proportions (10%, 20%, 30% v/v) on the spray and combustion characteristics. Optical techniques, such as shadowgraph and direct photography using high-speed imaging methods, were employed to reveal the spray and flame development process. This study examines the effects of varying fuel injection pressures (50, 80, and 110 MPa) and ambient pressures (1.5 and 3 MPa) on diesel-ethanol (DE) fuel blends. The study emphasizes the impact of DE blending ratios on the spray’s macroscopic features, while the microscopic characteristics are

Putra, I Komang Gede Tryas Agameru, Lim, Ocktaeck

Decarbonisation of GDI Engines Utilising On-Board Hydrogen Production in an Improved Design Thermochemical Exhaust-Assisted Fuel Reformer

2025-01-0186

To be published on 06/16/2025

Engine intake charge enrichment with hydrogen (H2) is one way to enhance engine thermal efficiency and decrease 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 decrease 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 between 78% and 86% in the critical exhaust gas temperature range of 410°C to 520°C with gas hourly space velocities (GHSVs) in highly demanding engine operating conditions ranging from

Lee, Seung Woo, Wahbi, Ammar, Herreros, Jose, Zeraati Rezaei, Soheil, Tsolakis, Athanasios, Millington, Paul

Comparison of Methanol and Gasoline Fuel Spray Vaporization Using Direct-Injection Technology

2025-01-0225

To 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

Development of After-Treatment Systems and Control Strategy for a Hybrid-Dedicated Homogeneous Lean Burn Engine

2025-01-0217

To be published on 06/16/2025

The development of lean-burn gasoline engines has continued due to their significant improvements in thermal efficiency. However, challenges associated with NOx emissions have hindered their mainstream adoption. As a result, the development of an effective NOx after-treatment system has become a key focus in lean-burn engine research. Additionally, HC emissions pose another challenge, as they tend to increase under lean combustion conditions while their conversion efficiency simultaneously declines. This study presents a novel after-treatment system incorporating a lean NOx trap(LNT) and a passive SCR(pSCR) system. This configuration enables efficient NOx reduction at a competitive cost while maintaining operational simplicity. Moreover, conventional catalyst technologies, including three-way catalysts (TWCs) and fuel-cut NOx traps (FCNTs), were optimized to maximize conversion performance under lean operating conditions. To further enhance system performance, various control

Oh, Heechang, Lee, Jonghyeok, Sim, Kiseon, Lim, SeungSoo, Park, Jongil, Park, Minkyu, Kang, Hyunjin, Han, Donghee, Lee, Kwiyeon, Song, Jinwoo

SAE Truck & Off-Highway Engineering: June 2025

25TOFHP0606/12/2025

Developing next-gen diesels to last decades John Deere's newest combustion engines are designed to accommodate alternative fuels and evolving technologies as requirements demand. New Volvo D13 VGT utilizes 24V architecture Volvo Trucks North America launches the all-new VNR with standard D13 VGT engine and announces an upcoming CARB-24 Omnibus compliant engine variant. Next reman up: The role of engine remanufacturing While new sustainability efforts aim to curb the carbon footprint of the commercial vehicle industry, old methods continue to be among the most effective. Challenges and opportunities for electrifying machines The switch to electrified off-highway vehicles can help reduce reliance on hydraulic components that decrease system efficiency via parasitic losses. Editorial Tech - and tariffs - top of mind at tradeshows ACT Expo 2025: Battery experts fret tariffs, encourage specific designs How HVAC systems can adapt to the needs of electric off-highway vehicles Clarios brings

Automated Fiber Placement: Status, Challenges, and Evolution

R-51106/11/2025

Discover the cutting-edge technology driving the next generation of aerospace, automotive, and space exploration. Automated Fiber Placement: Status, Challenges, and Evolution offers a comprehensive dive into AFP—an innovative method that’s transforming how complex, lightweight structures are built. Over the last 50 years, fiber-reinforced composites have revolutionized industries, particularly aerospace, with carbon fiber reinforced polymers at the forefront. AFP has enabled lighter, more durable aircraft with reduced fuel consumption and improved longevity. As the aerospace industry advances with new platforms like the Boeing 787 and Airbus A350, AFP continues to evolve, integrating machine learning and automation to deliver higher efficiency and lower costs. This book serves as an essential guide, presenting a decade of research in clear, accessible language. Whether you're a student, engineer, or industry professional, you'll gain a thorough understanding of AFP and its

Harik, Ramy, Brasington, Alex

Automotive Engineering: June 2025

25AUTP0606/05/2025

Balancing the scales in Dakar Here's how M-Sport engineers removed some weight - and added some elsewhere - to produce a podium-winning vehicle. Sealing the future of in-wheel motors: low friction and maximum protection V-seals and cassette seals offer critical protection from environmental influences and are helping in-wheel motors set new benchmarks. Taiwan suppliers look around the world for solutions Tariffs are forcing Taiwanese companies to rethink their plans, but it could be worse. U.S. states focus on Taiwan as trade war continues Taiwan's role in the global automotive supply chain continues to increase, which is one reason so many U.S. states are on site. Tariff challenges, EV advances at 360 Mobility We check in on Foxconn, Master Bus, PEWC and NUK at Taiwan's big trade show for the transportation industry. Editorial Off we go Supplier Eye Investment certainty is critical GM picks LMR as its future affordable battery technology Slate unveils bare-bones EV mini truck for

Multi-Objective Robust Optimization for a Parallel Link Steering System: A Six Sigma and Monte Carlo Approach

2025-01-5036

06/03/2025

The steering system is one of the most important assemblies for the vehicle. It allows the vehicle to steer according to the driver’s intention. For an ideal steering system, the steering angle for the wheel on the left and right side should obey the Ackman equation. To achieve this goal, the optimization method is usually initiated to determine the coordinates of the hard points for the steering system. However, the location of hard points varies due to the manufacturing error of the components and wear caused by friction during their working life. To decrease the influence of geometry parameter error, and system mass, and improve the robust performance of the steering system, the optimization based on Six Sigma and Monte Carlo approach is used to optimize the steering system for an off-road vehicle. At last, the effect is proved by the comparison of other methods. The maximum error of the steering angle is decreased from 7.78° to 2.14°, while the mass of the steering system is

Peng, Dengzhi, Deng, Chao, Zhou, Bingbing, Zhang, Zhenhua

Impact of Copper Contamination on the Thermal Stability of Jet Fuels

AIR6443A (Current)

05/27/2025

This SAE Aerospace Information Report (AIR) discusses the sources of copper in aviation jet fuels, the impact of copper on thermal stability of jet fuels and the resultant impact on aircraft turbine engine performance, and potential methods for measurement of copper contamination and reduction of the catalytic activity of copper contamination in jet fuels. This document is an information report and does not provide recommendations or stipulate limits for copper concentrations in jet fuels.

AE-5B Aircraft and Engine Fuel and Lubricant Sys Components

Enabling Neat Alcohol Combustion in a Heavy-Duty Diesel Engine with Exhaust Rebreathing

13-06-03-0022

05/23/2025

In this study, a strategy for MCCI combustion of a novel alcohol fuel is demonstrated. The novel fuel, “GrenOl”, is the result of the catalytic upgrade of sustainable ethanol into alcohols of higher molecular weight. The composition of GrenOl includes approximately 70% 1-butanol, 15% 1-hexanol, and 5% 1-octanol by mass, resulting in a cetane number around 18. In order to achieve mixing-controlled compression ignition with GrenOl, an exhaust rebreathing strategy is employed. In this strategy, the exhaust valve reopens for a part of the intake stroke, inducting hot exhaust into the cylinder and preheating the fresh air. This study investigates the feasibility of operating with such a valve strategy from idle to peak torque. At idle, the primary challenge is ensuring stable combustion by inducting adequate exhaust to achieve ignition. Under load, when cylinder temperatures are higher, the primary challenge is ensuring sufficient air is inducted to achieve the target torque. It was found

Trzaska, Joseph, Xu, Zhihao, Boehman, André L.

Assessing the Performance of a Modified Fuel Injection System–Equipped Dimethyl Ether-Fueled Genset/Tractor Engine

04-18-03-0014

05/21/2025

Ethers are emerging as suitable mineral diesel replacements. A customized mechanical fuel injection system was used to investigate the dimethyl ether–fueled genset/tractor, and ~75% rated engine load was achieved over diesel. The in-cylinder pressure rise rate was about half for the dimethyl ether engine. However, the lower pressure generated in the high-pressure dimethyl ether line reduced brake thermal efficiency for the dimethyl ether engine. Dimethyl ether engines emitted lower nitrogen oxide emissions than baseline diesel except at higher loads and reduced nozzle opening pressure. Carbon monoxide emissions increased due to prolonged and incomplete combustion at higher loads with reduced nozzle opening pressure. Blowby gas leakage was lower for dimethyl ether than for baseline diesel engines. Overall, the genset/tractor engine could perform satisfactorily using a customized fuel injection system and will help achieve carbon neutrality from the various sectors using this technology.

Agarwal, Avinash Kumar, Pal, Manojit, Valera, Hardikk

Experimental Investigation of Carbon Nanotube Additives Effect on Performance and Emission of a High-Injection Pressure Common Rail Diesel Engine

03-18-03-0020

05/16/2025

Due to the continuous decrease in fossil fuel resources, and drawbacks of some biofuel properties, in addition to restricted environmental concerns, it becomes a vital manner to innovate some approaches for energy saving and emission reduction. One of the promising approaches is to enhance the fuel properties via adding nanoparticles. Carbon nanotubes (CNTs) blended with biofuels get extensive investigations by researchers using conventional diesel engines at relatively limited operating regimes. The objective of this work is to extend these studies using diesel fuel, rather than biofuels, on a high-injection pressure (1400–1600 bar) common rail diesel engine at wide operating conditions and higher CNT concentrations. Experimental results show an increase in peak pressure up to 24.46% than pure diesel when using 100 ppm CNTs concentration. Also, BSFC has decreased by 33.19%, and BTE increased by 54.2% compared to pure diesel fuel at high speeds and loads. NOx and CO2 emissions raised

Moaayet, Sayed, Neseem, Waleed Mohamed, Amin, Mohamed Ibrahim, Shahin, Motasem Abdelbaky

Methodology for Selection of Gasoline Catalytic Convertor & Oxygen Sensor Position, Study on Oxygen Storage Capacity for 1.2L Turbocharger MPFI Engine

2025-01-5022

05/16/2025

The results published in this paper emphasize on the study of three-way catalytic convertor for a 1.2 L turbocharged multi-point fuel injection gasoline engine. This paper takes us through the findings on methodology used for finalizing the brick configuration for catalytic convertor along with downstream oxygen sensor placement for emission control and methods applied for catalytic convertor selection with actual testing. The advantages of dual brick configuration over single brick with downstream sensor placed in between the bricks to enable faster dew point of sensor is explained using water splash test and design confirmation of better exhaust gas flow vortices concentration at the sensor tip for better sensing. Selection of catalytic convertor loading by testing its emission conversion capability and light-off behavior. NOx conversion capability across stoichiometric ratio (14.7:1 for petrol) on selected most operational zone was tested (±5% lambda) for the design-finalized

Arun Selvan, S. A., Paul, Arun Augustine, Selvaraj, Manimaran

Experimental Quantitative Analysis of Spray Velocity Field Characteristics of Four Compression-Ignition Engine Oxygenated Alternative Fuels

03-18-03-0021

05/10/2025

As the suitable substitutes for diesel in compression-ignition (CI) piston engines, hydrotreated vegetable oil (HVO), polyoxymethylene dimethyl ethers (PODEs), and bio-aviation fuel (BAF), among other oxygenated alternative fuels have been widely recognized due to higher cetane values. To explore the in-cylinder fuel spray dynamics and subsequent fuel–air entrainment of these fuels, experimental studies on near-field and full-field spray characteristics were carried out by the diffuser back-illumination imaging (DBI) method within a constant-volume chamber. The local velocity was inferred by momentum flux conservation and Gaussian radial profile assumption, and the dimensionless Jet number was introduced to qualify the strength of interaction within two-phase flow. It was found that the initial spray transitions from a “needle” to a larger spray head structure as injection pressure rises, especially with PODE3-5 exhibiting a stable “mushroom” structure due to its higher surface tension

Chen, Houchang, Jiang, Junxin, Hu, Yong, Yu, Wenbin, Zhao, Feiyang

Experimental Evaluation of Direct and Port Fuel Injection Strategies on a Heavy-Duty Liquefied Petroleum Gas Engine

03-18-03-0022

05/09/2025

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

A Computational Process to Predict and Mitigate Liftgate Gap Noise

2025-01-0028

05/05/2025

This study introduces a computational approach to evaluate potential noise issues arising from liftgate gaps and their contribution to cabin noise early in the design process. This computational approach uses an extensively-validated Lattice Boltzmann method (LBM) based computational fluid dynamics (CFD) solver to predict the transient flow field and exterior noise sources. Transmission of these noise sources through glass panels and seals were done by a well-validated statistical energy analysis (SEA) solver. Various sealing strategies were investigated to reduce interior noise levels attributed to these gaps, aiming to enhance wind noise performance. The findings emphasize the importance of integrating computational tools in the early design stages to mitigate wind noise issues and optimize sealing strategies effectively.

Moron, Philippe, Jantzen, Andreas, Kim, Minsuk, Senthooran, Sivapalan

Prediction and Optimization of Noise radiation from a Heavy-Duty Commercial Vehicle Transmission using Statistical Energy Analysis

2025-01-0051

05/05/2025

Heavy Duty (HD) linehaul vehicles are majorly used in transportation of goods and heavy loads between different cities or long distances. Considering the current trend, payload capacity of these heavy-duty trucks are increasing due to constant increase in the load demand. Due to which engine torques of these HD vehicles are increasing which in turn increases the transmission input torque. At higher torque levels, gear excitation also increases and transmission becomes more susceptible towards higher noise radiation. The transmission is an integral part of the driveline in a heavy duty commercial vehicle. Along with speed and torque conversion, the transmission design is crucial to achieve better fuel economy. Important factors to consider in the transmission design are duty cycle, torque capacity, fuel economy and overall weight. Global vehicle pass-by noise regulations for HD commercial vehicles are becoming more stringent and transmissions are expected to be very quiet. Historically

Rastogi, Sarthak, Milind, T. R.

Optimization of HEV Vehicle’s Engine Modulated Noise

2025-01-0084

05/05/2025

One 1.5L Miller-cycle turbocharged four cylinder gasoline hybrid engine is installed on a certain hybrid vehicle. When accelerating at low to medium speeds with a small throttle, there is a "da da" knocking noise inside the car, which seriously affects the overall sound quality of the vehicle. By analyzing the vibration and noise data of the engine, it was found that the frequency of the abnormal knocking sound is 200-2000Hz, 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

Simulation of Pass-by Fan Noise Emissions and Advancing Test Regulations for Heavy-Duty Electric Vehicles

2025-01-0086

05/05/2025

The rapid adoption of electric vehicles (EVs) necessitates updates to the automotive testing standards, particularly for noise emission. This paper examines the vehicle-level noise emission testing of a Nikola Class 8 hydrogen fuel cell electric semi-truck and the component-level noise emission testing needed to create a predictive simulation model using Wave6 software. The physical, component-level noise emission testing focused on individual cooling fans in a semi-anechoic chamber to assess their isolated noise contributions. With this data, an initial model was developed using spatial gradient statistical energy analysis, which successfully predicted pass-by noise levels based on varying fan locations and speeds. Real-world pass-by testing confirmed the model's accuracy across different cooling fan speeds. By leveraging advanced simulation techniques, engineers aim to enhance the accuracy and reliability of pass-by noise predictions through cost-effective studies of architectural

Passador, Stephen, Woo, Sangbeom, Liu, Ting-Wei, De La Vega Alonso, Gerardo, Kim, James

Flow-Induced Noise Prediction and Validation of a Heavy-Duty Electric Vehicle’s HVAC System Using the Lattice Boltzmann Method

2025-01-0057

05/05/2025

Within automobiles, the HVAC is a critical system to regulate the occupants’ thermal comfort. However, at its high operating speeds, it can contribute significantly to the overall sound levels perceived by the cabin occupants, impacting their experience. This is especially true in the case of electric vehicles due to their overall quieter operation. This work has the intention to validate HVAC noise predictions using computational fluid dynamics (CFD) simulations. In addition, CFD simulations provide detailed flow field insights which are essential to identify and rank the main noise sources, and it ultimately allows a better understanding of the physical mechanisms of noise generation on similar systems. These insights are very difficult, if not impossible, to obtain with physical testing and are key to designing a quiet and efficient HVAC system. Sound levels were measured experimentally at eight different locations inside of a Class-8 Nikola TRE hydrogen fuel cell electric semi

Ihi, Rafael, Fougere, Nicolas, Passador, Stephen, Woo, Sangbeom, Kim, James, Desouky, Mohamed

Experimental Analysis of Pressure Pulsation Noise Phenomenon in a CNG-Powered Passenger Vehicle

2025-01-0112

05/05/2025

Compressed Natural Gas (CNG) engines are emerging as a viable alternative to gasoline and diesel in heavy commercial and passenger transport worldwide. They offer reduced CO₂ emissions and support energy independence in regions rich in natural gas. In India, enhanced CNG infrastructure and strict emission regulations have driven OEMs to develop CNG vehicles across all segments. Moreover, from a noise and vibration standpoint, CNG vehicles are expected to deliver cabin refinement comparable to that of their fossil fuel counterparts. However, one of the major challenges associated with CNG vehicles is the excitation due to additional components like CNG Pressure Regulator, Injector et al. The operational metallic/pulsation noises are generally higher as compared to liquid fuels like gasoline due to dry nature of the CNG fuel. This paper describes in detail the pulsation noise phenomena encountered during one of the late-stage vehicle development projects. An experimental root cause

Chatterjee, Joydeep, Ravindran, Mugundaram

Plug-In Hybrid and Range Extender NVH – Challenges and Solutions

2025-01-0101

05/05/2025

The automotive industry continues to develop new powertrain and vehicle technologies aimed at reducing overall vehicle-level fuel consumption. While the use of electrified propulsion systems is expected to play an increasingly important role in helping 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

Process to Simulate Active Tuned Mass Dampers to Reduce Interior Noise during Cylinder De-Activation Events

2025-01-0110

05/05/2025

During cylinder deactivation events, high amplitude torque pulsations are generated at the crankshaft of the engine over a wide frequency range creating a potential risk for noise, vibration and harshness (NVH) performance of the vehicle. As passive tuned mass dampers are effective only in a narrow frequency range, active tuned mass dampers (ATMD) have become a popular choice to mitigate the risk. Often, engineers rely on finite element (FE) models of vehicle structures to make design decisions during the early stages of vehicle development. However, there is limited literature on the simulation of ATMD using FE techniques. Consequently, several details related to the ATMD design are decided through physical testing at the latter stages of vehicle development which is not ideal. To address these issues, a novel methodology to simulate an ATMD during cylinder deactivation events using FE technique is presented here. In this study, an ATMD based on force feedback control method was

Maddali, Ramakanth, Mogal, Akbar Baig, Haider, Syed, Jahangir, Yawar

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