Browse Topic: Nitrogen oxides

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NOx Formation Characteristics of Lean Hydrogen Combustion: From 0D Analysis to Comprehensive 3D-CFD Engine Investigations2026-01-0732To be published on 07/01/2026
The transition toward climate-neutral transportation requires powertrain concepts that combine high efficiency with low pollutant emissions. In this context, hydrogen-fueled internal combustion engines represent a promising solution when hydrogen is produced from renewable energy sources. Owing to its specific molecular properties, hydrogen offers new possibilities for influencing and optimizing the combustion process and reducing the emission formation. This paper presents a numerical approach for characterizing the NOx formation in a single-cylinder research engine equipped with port fuel injection and a passive pre-chamber ignition system. The single-cylinder is operated over a wide range of engine loads and speeds, covering air-to-fuel ratios from λ=1.5 to 2.5 and achieving up to 23 bar indicated mean effective pressure. The study focuses on the influence of engine load and mixture composition on NOx emissions. A dedicated look-up table approach in combination with several reaction
Gal, Thomas, Vacca, Antonino, Chiodi, Marco, Schmelcher, Robin, Kulzer, Andre Casal
A Modeling and Experimental Study of the Argon Power Cycle Using Mixing-Controlled Combustion2026-01-50436/19/2026
The closed-cycle hydrogen-fueled argon power cycle is a zero emissions concept that combines a carbon-free fuel with argon as a diluent replacement for nitrogen. The lack of nitrogen in the argon power cycle results in zero NOx emissions on an internal combustion engine platform. There is also massive efficiency improvement because argon is monatomic and has a very high ratio of specific heats. However, this will also result in combustion temperatures and pressures exceeding those normally achieved on an air-standard engine platform. The literature shows conflict between modeling, which promises incredibly high efficiency gains, and experiment, which show more modest efficiency gains. This work combined thermodynamic modeling, literature analysis, and experiments to understand this discrepancy and ultimately understand what level of efficiency gain can be expected for the argon power cycle. It was found that while low compression ratio engines stand to see the largest relative
Gainey, Brian, Ahrling, Christoffer, Tunestal, Per, Tuner, Martin
Accelerated Computational Fluid Dynamics (CFD)-Based Quantitative Prediction of Urea Deposition in Selective Catalytic Reduction (SCR) Systems2026-01-50416/12/2026
Mitigation of harmful emissions from oil-based engines is essential to avoid environmental pollution and comply with various NOx regulations across the globe. This can be partially achieved by injecting urea to produce ammonia (NH3), which reacts with NOx in a catalyst to produce harmless nitrogen (N2) and water vapor (H2O). However, urea deposition in a selective catalytic reduction (SCR) system poses a significant threat to the NOx removal process by not only reducing the urea conversion rate but also blocking the incoming flow and causing an additional pressure drop. Numerical modeling of this urea deposit formation involves multiphase flow physics coupled with accurate heat transfer calculations. Additionally, since urea decomposes into various by-products like biuret, cyanuric acid (CYA), and ammelide, detailed chemical kinetics modeling is equally important. Accurate and fast computational fluid dynamics (CFD) simulations can help accelerate SCR system design cycles, leading to a
Morab, Sumant R., Khalate, Suraj, Ansari, Shoaib, Yang, Pengze
SAE Truck & Off-Highway Engineering: June 202626TOFHP066/11/2026
Hitting the road in the all-new VNR Volvo Trucks' revised VNR brings updated safety tech, improved fuel economy and driver comfort features to the regional haul segment. In fuel control How to ensure off-highway combustion systems operate with sufficient control to meet tightening emissions standards and evolving fuel landscapes without sacrificing reliability. Keeping industrial vehicles secure in a digital landscape OEMs, integrators and suppliers must continuously process, assess and identify platform vulnerabilities to prioritize and implement updates that protect systems from cyberattacks and data breaches. Editorial Diversification key for sustainable fleets ACT 2026: Uncertainty still exists over EPA 2027 NOx limit ZF bets big on hybrid transmissions Moog simplifies off-highway electrification Bosch shows off its first U.S. electrolyzer Microvision fast-tracks adoption of Luminar tech; eyes defense, industrial sectors Future-ready, customizable connectivity powers precision
Investigating the Potential of Two Individually Controlled Injectors per Rotor for a Direct Injection Hydrogen Wankel Engine2026-37-00086/9/2026
Hydrogen-fueled rotary engines offer a promising zero-emission solution for compact commercial powertrains. This study reports experimental results from the further development of a naturally aspirated, direct-injection hydrogen rotary engine by HTM. Initial applications, such as an airport baggage tractor, demonstrated technical feasibility but revealed pre-ignition that limited maximum torque. To address this, mixture formation was investigated using an experimental setup with two independently controlled injectors feeding a single rotor injection channel. The effects on operating behavior, efficiency, and NOx emissions were evaluated. The dual-injector configuration significantly shortens injection duration and improves spatial distribution of hydrogen within the combustion chamber. Enhanced mixture control suppresses pre-ignition and enables higher mean effective pressure. Systematic variation of injection timing under representative steady-state conditions also shows potential for
Endres, Jonas, Beidl, Christian, Herold, Tim, Lavall, Philipp, Schmidt, Marvin, Hofmann, Silas, Kahl, Jonas
Combined EGR-Air Dilution Effects on Performance, Combustion and Emissions of a Single-Cylinder Spark-Ignition Direct-Injection Hydrogen Engine2026-37-00096/9/2026
Hydrogen internal combustion engines (H2ICE) have emerged as a promising solution for decarbonisation of the transport sector, due to low cost and potential for rapid deployment. However, abnormal combustion and high nitrogen oxide (NOx) emissions limit stoichiometric operation, making dilution strategies essential. While lean combustion has been widely studied, combined dilution strategies of air and exhaust gas recirculation (EGR) require further investigation. This work presents experimental results from a boosted 0.5-litre spark-ignition direct-injection single-cylinder research engine equipped with high-tumble ports and cooled high-pressure EGR. Relative air–fuel ratios (lambda) of 1 to 3 and EGR rates of 0 to 40% are evaluated at 5, 10, and 15 bar of indicated mean effective pressure (IMEP) at 2000 rpm to assess effects on net indicated thermal efficiency (nITE), combustion, and emissions. A peak nITE of 43.5% is achieved at 10 bar IMEP, λ = 2.5, and 30% EGR, which can be
King, Aidan, Islam, Reza, Pickering, Simon, Yuan, Hao, Mudge, Henry, Giles, Karl, Goyal, Harsh, Jones, Peter, Akehurst, Sam, Esposito, Stefania
Nitrogen-Based Emissions from Ammonia Combustion in a Heavy-Duty Spark Ignition Engine2026-37-00326/9/2026
Ammonia (NH3) is a carbon-free fuel with strong potential for spark-ignition (SI) engine applications. However, the engine can produce complex nitrogen-based emissions not adequately captured by conventional engine models. This study consolidated the results of experimental and numerical studies on the use of neat NH3 combustion in a heavy-duty compression-ignition engine converted to spark-ignition operation, first for a sweep of equivalence ratios (ϕ) from 0.7 to 1.0, and another from varying the energy substitution ratio of methane (CH4)– NH3 blends from neat CH4 to neat NH3 at constant ϕ = 0.8. Two 0-D two-zone SI engine models with detailed chemistry (called “original” and “extended”) predicted engine thermodynamics and emissions. While the original model reproduced in-cylinder pressure and combustion phasing, it failed to capture the effect of fuel composition or operating condition on NO trends, both under- and over-predicting them for neat NH3 and CH4-rich operations. An
Trujillo Grisales, Juan, Saenz Prado, Stefany, Alvarez, Luis F., Akkerman, Vyacheslav, Dumitrescu, Cosmin E.
An Open-Source Framework to Automate Virtual Optimization of Internal Combustion Engine Calibration Maps through Shape-Based Strategy2026-37-00016/9/2026
The automotive industry is facing increasingly stringent regulatory constraints, driving the need for faster and more efficient powertrain development. This results in higher systems complexity, making internal combustion engine calibration progressively more challenging to meet performance and emissions targets. This, combined with the manual nature of traditional calibration workflows, leads to a time-consuming process that heavily relies on human expertise. Although virtualization can reduce development time and costs, the overall workflow remains largely dependent on manual decision-making and iterative refinement. In this context, this work presents a virtual calibration framework based on a genetic algorithm, aimed at the automated optimization of engine calibration maps to satisfy performance and emissions constraints, while reducing manual effort. Each calibration map is represented through a polynomial parameterization. Specifically, a generic three-dimensional polynomial with
Romano, Gianvito, Aglietti, Filippo, Spedicato, Tonio, Cozza, Ivan Flaminio, Capra, Andrea
Conceptual Design of Hydrogen Fuel-Cell-Based Utility Aircraft2026-26-07836/1/2026
The aviation industry contributes to around 2% of global carbon dioxide emissions. As various sectors of the economy look to reduce their global carbon footprint, the aviation industry is positively acknowledging alternatives to jet fuel. Hydrogen proves to be one such alternative having a high energy density and producing zero carbon emissions on combustion. Hydrogen when used in a jet engine produces water vapour and NOx emissions. In order to reduce the effect of GHGs, the current study aims to develop aircraft concepts suitable with hydrogen propulsion through fuel cells for a short-haul commercial mission profile. Aircrafts such as Metro-23 and Dornier 228-212 were referenced for the requirements of a utility turboprop aircraft. The weight estimation was done to obtain the take-off weight of 10,863 kg following the optimization of thrust to weight ratio and wing loading to calculate the initial dimensions. OpenVSP was used to model the initial structure of the aircraft. For the
Bhattacharya, Anisha, Seetha Ramu, Sree Valli, C N, Lakshmi Manasa, Rohit, Benjamin
ACT 2026: Uncertainty still exists over EPA 2027 NOx limit26TOFHP06_056/1/2026
Though the U.S. EPA has rolled back many emissions regulations surrounding the mobility industry, its HD rules remain intact, meaning manufacturers must hit the world's most stringent NOx requirement. It was clear at a panel of industry experts that the new rule was still causing confusion among operators and fleet owners. The EPA's new limits are set at 0.035 grams per horsepower-hour during normal operation, 0.050 grams at low load and 10.0 grams at idle. A panel immediately following revealed how companies have hit the tough target, which goes into effect in January of 2027.
Clonts, Chris
Experimental Investigation of Diesel, Aqueous Ammonia, and Compressed Natural Gas Mixtures on Performance and Emissions in a Compression Ignition Engine04-19-03-00115/30/2026
Abstract This study investigates and evaluates systematically the combustion, performance, and emissions characteristics of heavy-duty diesel engines fueled by diesel–ammonia–compressed natural gas triple blends. While dual-fuel systems are well-documented, the interactive effects of ammonia and CNG within a single compression ignition (CI) engine remain largely unexplored. Experiments were conducted on a 300 Nm, 660 rpm diesel engine by testing pure diesel, diesel–ammonia blends (10–20 wt.% aqueous ammonia), and triple-fuel mixtures containing 10% of the total energy from compressed natural gas. Pure diesel was first tested to provide baseline data, and subsequently blends were tested for a comparative study. The primary contribution of this work is the identification of a synergistic effect of the fuel triple blends on engine performance and emissions. Results indicate that all fuel blends improve thermal efficiency and reduce fuel consumption compared to conventional diesel. The
Sinkala, Happy, Sarıtaş, Mehmet, Kül, Volkan Sabri, Akansu, Selahaddin Orhan, Ünalan, Sebahattin
Effect of EGR Rate on Cyclohexanol-Diesel Dual-fuel Engines2026-99-17095/22/2026
To reduce high NOx emissions from diesel-cyclohexanol blends, this study employed a marine medium-speed diesel engine as the experimental platform. An in-cylinder combustion model was developed and meshed using AVL - FIRE software, with model validity validated against experimental data. Tests were conducted at four load conditions (25%, 50%, 75%, and 100% load) with a 30% cyclohexanol blend (C30) and four EGR rates (0%, 7.5%, 10%, and 12.5%) to analyze combustion characteristics, emissions, and fuel economy. The results showed that the introduction of EGR had a striking inhibitory effect on NOx emissions. At 100% load with 12.5% EGR rate, NOx emissions were substantially reduced compared to baseline operation without EGR. However, EGR implementation led to delayed ignition timing, reduced in-cylinder pressure, and worsened fuel economy. Therefore, an appropriately calibrated EGR strategy can effectively reduce NOx emissions, though it requires optimization to mitigate adverse effects
Liu, Yuchen, Yang, Chenxi, Fan, Jinyu, Chen, Ke, Ye, Zixiao, Huang, Jialiang
Effect of Burning Biomass Fuel Cyclohexanol on Diesel Engine Performance2026-99-17085/22/2026
Against the backdrop of growing global demands for energy sustainability and stricter emission regulations for diesel engines, this study investigates the performance implications of incorporating cyclohexanol—a renewable oxygenated fuel—into diesel fuel blends. Using a marine medium-speed diesel engine as the experimental platform, the research systematically evaluates engine performance and emission characteristics across a range of cyclohexanol-diesel blend ratios under low, medium, and high load conditions. Experimental findings reveal multifaceted effects of cyclohexanol blending on engine operation. Combustion of the blended fuels enhances the engine’s dynamic performance, particularly under medium and high loads, where the maximum in-cylinder burst pressure exhibits a noticeable increase. This improvement is attributed to cyclohexanol’s oxygen-carrying capacity, which promotes more vigorous and sustained combustion reactions. In terms of emissions, increasing the proportion of
Chen, Ke, Yang, Chenxi, Wang, Yibin, Fan, Jinyu, Liu, Yuchen, Ye, Zixiao, Huang, Jialiang
Research on the Statistical Method of Real Driving Emission Data of Commercial Vehicle under Low Load2026-99-17215/22/2026
Current emission regulation in China (National VI b) adopts the work-based window (WBW) method to statistically analyze PEMS experimental data. This method cannot fully account for experimental data under low load and cold start conditions. In light of this, this paper proposes a statistical method for low-load condition experimental data. Firstly, the adaptability of the WBW method to low-load condition experimental data is analyzed. Secondly, the representativeness and authenticity of statistical results from different methods are compared. The results indicate that when the power threshold of the WBW method is set at 20%, the effective window qualification rate in six experiments is less than 40%. And as the load decreases, the power threshold required to meet regulatory requirements needs to be further reduced, meaning more low-power data points are discarded. The WBW method eliminates many low output power data points with high CO and NOx emissions from test data on an urban road
Tang, Gangzhi, Liu, Jiajun, Wang, Shuaibin, Du, Baocheng, Deng, Xuefei
Emission and Combustion Characteristics of a Hydrogen Direct-Injection Spark Ignition Engine Using EGR2026-01-03254/7/2026
This study experimentally investigates the combined effects of exhaust gas recirculation (EGR) and injection timing on the combustion and emission characteristics of a hydrogen direct injection engine. A single-cylinder 395 cc research engine was used, with injection timing varied from 60° to 180° BTDC and EGR rates from 0% to 30%. In-cylinder pressure, apparent heat release rate (AHRR), NOx, and unburned hydrogen concentrations were measured to analyze the influence of mixture formation and dilution on engine performance. Under non-EGR conditions, retarding the injection timing promoted mixture stratification, resulting in faster flame propagation and shorter combustion duration. However, localized high-temperature regions increased NOx formation, while incomplete combustion in lean or rich zones elevated unburned hydrogen emissions. When EGR was introduced, both ignition delay and combustion duration increased due to reduced oxygen concentration and thermal dilution. Nevertheless
Yang, Heetae, Ki, Youngmin, Kim, Jungho Justin, Kim, Jinsu, Bae, Choongsik, Hwang, Joonsik
Effects of Gasoline Composition and Operating Parameters on the Response of End-Gas Autoignition to Nitric Oxide in a Lean-Burn DI-SI Engine2026-01-03134/7/2026
Lean operation of spark-ignition engines can lead to engine thermal efficiency gains and lower NOx emissions due to reduced combustion temperatures. Yet, lean operation could still face challenges in end-gas autoignition and knock generation due to higher intake pressures and trapped NO in the residual gas. This study evaluates the impact of NO on end-gas autoignition for two gasoline fuels with similar octane rating but different composition: high cycloalkane fuel (HCA) and high olefin fuel (HO). Experiments were performed at stoichiometric and lean (λ = 2) conditions and at two engine speeds of 1400 rpm and 2000 rpm. Accompanying chemical kinetics simulations in CHEMKIN revealed that the mechanisms controlling the effect of NO on autoignition are similar λ = 2 and λ = 1, with NO + HO2 = NO2 + OH being the main pathway for enhancing reactivity by promoting low-temperature heat release (LTHR). The compositionally different fuels reacted differently to NO seeding and engine speed, and
Kim, Namho, Abboud, Rami, Sjöberg, Magnus, Lopez Pintor, Dario, Saggese, Chiara, Matsubara, Naoyoshi, Kitano, Koji, Yamada, Ryota, Sugata, Kenji
Impact of Hydrogen on Methane and Pollutant Emissions over Three-Way Catalysts with Natural Gas–Hydrogen Blends2026-01-03574/7/2026
Blending natural gas (NG) with hydrogen (H₂) can improve combustion and engine performance while potentially facilitating 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 and other pollutants. Experiments were conducted with both degreened and aged catalysts under controlled conditions, systematically varying temperature, the air-to-fuel equivalence ratio (λ), and λ modulation. Test conditions covered λ values from 0.996 to 1.000 to represent nominally stoichiometric engine operation with different λ modulation amplitudes, as well as a range of temperatures to
Prikhodko, Vitaly, Wang, Min, Park, Yeonshil, Chen, Hai-Ying, Pihl, Josh
Experimental Study of Hydrogen Combustion in Argon-Oxygen Mixture Using an Optical Engine2026-01-03284/7/2026
The Argon Power Cycle (APC) is an emerging high-efficiency combustion technology for internal combustion engines. In APC, the conventional air-based working fluid is replaced with an inert argon gas. This substitution inherently increases engine efficiency through thermodynamic properties of argon, in particular a high adiabatic factor ?? ~1.67. A hydrogen-fueled APC engine offers the potential for highly efficient zero emission combustion by also eliminating nitrogen oxide (NOx) formation. In the present paper, hydrogen combustion is studied in an optical heavy-duty research engine, with the objective of providing the first visualization of H2 combustion in an argon–oxygen mixture. A comparative analysis of high-speed optical imaging and in-cylinder pressure measurements is conducted for two different modes: 1) conventional air operation and 2) argon-oxygen mixture operation. The high-speed images reveal a distinctly different combustion process between the two operating modes. The
Kapp, Joakim, Cheng, Qiang, Kaario, Ossi, Vuorinen, Ville
Characterisation of Particle Number and Size from a DI SI Engine Operating on Hydrogen versus Gasoline: Operating Sensitivities and Filtration Effects2026-01-03784/7/2026
Hydrogen Internal Combustion Engines (H₂ICEs) offer the potential for near-zero carbon emissions. However, while nitrogen oxide (NOₓ) emissions have been extensively studied, particulate emissions, specifically particle number (PN), which are widely attributed to in the literature to lubricant oil pyrolysis and exacerbated by hydrogen’s short quenching distance, remain less well understood. This study investigates exhaust-gas particle emission characteristics from a spark-ignition, single-cylinder research engine based on MAHLE Powertrain’s downsizing engine combustion system. The work was carried out at Brunel University of London and compares gasoline and hydrogen direct-injection strategies (central versus side injection) across a wide range of operating conditions, including variations in engine speed, load, air–fuel ratio (λ), rail pressure, and spark timing. While previous studies have investigated hydrogen particle formation mechanisms under isolated operating conditions, the
Harrington, Anthony, Zaman, Zayne, Nickolaus, Chris, Zhao, Hua, Wang, Xinyan, Hall, Jonathan
Model-Based Development of a Heavy-Duty H 2 -ICE and Integrated, Turbogeneration, Electrification, and Supercharging (ITES) System2026-01-04264/7/2026
Changing global economic conditions and efforts to reduce greenhouse gas emissions are driving the need to develop efficient, near-term, alternative propulsion system technologies for heavy-duty vehicles. This study combines a hydrogen internal combustion engine (H2-ICE) with electrically assisted turbocharging, exhaust energy recovery, and mild hybridization to maximize propulsion system efficiency and reduce NOx emissions. To reduce cost and packaging impact of integration of these technologies on an engine, the study presents a model-based development and optimization of an Integrated Turbogeneration, Electrification, and Supercharging (ITES) system that combines the enabling components into a single compact unit. In the first phase of this 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 convert a diesel engine by changing the cylinder head to implement a port fuel
Bustamante, Oscar, Correia Garcia, Bruno, Joshi, Satyum, Franke, Michael
The Influence of Split Injection Ratio on Efficiency and NO x Emissions in a Pilot Diesel-Ignited Hydrogen Direct Injection Engine2026-01-03294/7/2026
This study investigates the impact of the 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 flame developments. Experiments were conducted on a 1-litre single-cylinder diesel engine equipped with an additional hydrogen injector operating at 35 MPa. Hydrogen accounting for 95% of total input energy was injected at 150 and 60 °CA bTDC for the first and second pulses, which were selected as high-efficiency injection timings from previous equal-split injection tests. The 5% diesel energy was injected near TDC to control CA50 at 10 °CA aTDC. 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 significantly affect IMEP/efficiency, which
Zhao, Yifan, Chan, Qing Nian, Kook, Sanghoon
Impact of Hydrothermal Aging and Chemical Poisoning on NOx Reduction Performance of SCR – A Simulation Study2026-01-03724/7/2026
Diesel aftertreatment systems continue to play a critical role in compliance of tailpipe criteria pollutant compliance for commercial transportation applications. Quantification of performance of the aftertreatment system in particular Selective Catalytic Reduction component as a function of aging is critical in ensuring real world tailpipe NOx standard for aged systems. As part of A2CAT-II consortium at Southwest research Institute this aspect of the production AT system was studied for different aging conditions using a set of DAAAC aged components. The performance of these aged components was quantified through a set of steady state reactor tests and transient ECTO burner lab tests that simulate on engine performance. The data was collected at 0, 33 and 100% equivalent aging conditions and this data was used to develop a GT suite-based model with a set of inhibition factors to simulate the loss of Ammonia Storage Capacity and reduced SCR reaction rates caused by thermal load and
Chundru, Venkata Rajesh, Sharp, Christopher, Gankov, Stanislav, Eakle, Scott
Combustion and Emission Characteristics of Biodiesel and Renewable Diesel in a 4-Stroke Locomotive Engine2026-01-03154/7/2026
Rail transportation in North America consumes over 4 billion gallons of diesel fuel [1]. This is 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 drop-in fuels 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, with injection duration adjusted to achieve the targeted engine load and speed. Results indicate that both biodiesel fuels and renewable diesel deliver comparable peak in-cylinder pressure and brake
Ewphun, Pop-Paul, Biruduganti, Munidhar, El-Hannouny, Essam, Longman, Douglas, Fu, Xiao, Subramanya, Raghavendra
Reactivity Controlled Compression Ignition (RCCI) Combustion Engine Characteristics Fuelled with Diesel/Compressed Natural Gas (CNG) and Diesel/Methanol Fuel Pairs2026-01-03194/7/2026
Ultra-low oxides of nitrogen (NOx) and particulate matter (PM) from reactivity-controlled compression ignition (RCCI) combustion have motivated researchers to explore more about low temperature combustion (LTC) engines. In this study, a comparative analysis of combustion, performance, and emission characteristics of RCCI combustion fuelled with diesel/compressed natural gas (CNG) and methanol/diesel fuel pairs has 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. For RCCI combustion experiments, a constant premixed ratio (rp= 0.50) and 15% exhaust gas recirculation (EGR) were used. The results exhibited a significant reduction in NOx emissions and relatively smoother RCCI combustion compared to baseline CI combustion. RCCI mode combustion resulted in relatively superior engine performance compared to baseline CI combustion, especially at higher engine loads. A
Saikia, Bhargav, Kant, Akshay, Gupta, Abhishek, Singh, Akhilendra Pratap
Heavy Duty Hydrogen Internal Combustion Engine Emissions Development to Achieve Ultra-low NOx2026-01-03564/7/2026
This paper presents the emissions development of a heavy-duty hydrogen internal-combustion engine (H₂ICE) targeting ultra-low NOx with a design goal of 20 mg/hp-hr. The approach integrates advanced thermal management of the engine and aftertreatment, including engine out NOx management through air-fuel ratio controls and an electric heater to accelerate catalyst light-off and sustain activity at low-load/idle conditions. A diesel-derived aftertreatment system (ATS) is selected to maximize practicality and component commonality, and an integrated controls strategy spanning the engine and ATS is implemented to demonstrate ultra-low NOx capability over EPA certification cycles. The paper concludes with considerations for periodic SCR regeneration to ensure emission compliance.
Shakya, Bijesh, Xu, Hui, Yang, Zhao, Stetter, John
The Impact of Various Renewable Hydrocarbons on Performance and Emissions in a Super Lean Burn Engine2026-01-03064/7/2026
Compared to regular fuels, biofuels can play a key role as low-carbon 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 enhanced fuel economy and reduced NOx emissions. The Toyota prototype engine used to generate data for this project injects most of the fuel in 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 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
Advanced Multifunctional Catalysts for Emission Control in Hydrogen and Diesel Engines2026-01-03674/7/2026
As hydrogen internal combustion engines (H2-ICE) gain traction, optimizing exhaust aftertreatment technologies for nitrogen oxide (NOx) control has become increasingly critical. While selective catalytic reduction (SCR) systems remain the primary approach for NOx mitigation, oxidation catalysts are also being explored to facilitate hydrogen oxidation and improve overall exhaust treatment efficiency. This work presents a multifunctional catalyst (MFC) concept that combines supported Pd and Cu-zeolite to enable simultaneous NOx reduction and hydrogen oxidation within a single catalytic unit. Preliminary results show that hydrogen oxidation on supported Pd occurs above 300 °C, while Cu-zeolite achieves nearly complete NOx conversion. Experiments on individual components indicate that supported Pd initiates ammonia oxidation only after hydrogen is depleted. In the presence of hydrogen, ammonia conversion remains below 20%, indicating that hydrogen availability suppresses ammonia oxidation
Danghyan, Vardan, Becker, Jan Martin, Hünnekes, Edgar, Patchett, Joseph
The Effects of Ethanol on Combustion in a Super-Lean-Burn Engine2026-01-03034/7/2026
To mitigate global warming, many countries are working toward carbon neutrality. Reducing CO₂ emissions from vehicles requires electrification technologies in hybrid and plug-in hybrid electric vehicles (HEVs, PHEVs) and improving thermal efficiency of internal combustion engines (ICEs). Lean-burn combustion is one approach to improving ICE thermal efficiency. Biofuels and synthetic fuels can also reduce CO₂ emissions in existing vehicles. Ethanol, a bio-derived fuel, is widely used in varying contents worldwide, and its further utilization is anticipated. This study examines the effects of ethanol blending on emissions, thermal efficiency, knocking, and combustion speed in a super-lean-burn engine. Gasoline surrogates with varying ethanol contents were tested at an excess air ratio (λ) of 2.5. Higher ethanol content reduced nitrogen oxides (NOx) emissions due to lower adiabatic flame temperature. Total hydrocarbon (THC) emissions measured by a Flame Ionization Detector (FID) showed a
Sugata, Kenji, Matsubara, Naoyoshi, Yamada, Ryota, Kitano, Koji
Experimental and Kinetic Modeling Study of Aged Natural Gas Three-Way Catalyst Performance2026-01-03734/7/2026
The applicability of three-way catalyst (TWC) models for system-level aftertreatment simulations under transient operating conditions of natural gas engines depend on accurate integration of reaction kinetics as a function of the air-fuel equivalence ratio lambda(λ). A comprehensive global kinetic model has been developed for an aged commercial three-way catalyst (TWC), incorporating key reaction pathways including oxidation of CO, CH₄, C₂H₆, and H₂; reforming of CH₄ and C₂H₆; the water-gas shift reaction; and NO reduction via CO and H₂. The model also accounts for oxygen storage capacity (OSC) and its dynamic interaction with CO and H₂. To calibrate kinetic parameters, systematic bench-scale flow reactor experiments were conducted under lean, stoichiometric, and rich conditions. Performance metrics focused on CH₄ and C₂H₆ oxidation and reforming across varying O₂ and CO concentrations, and NO reduction with CO and H₂ under different oxygen levels. Experimental results revealed that CO
Raj, Richa, Kim, Mi-Young, Aigbiremolen, Grace, Srinivasan, Anand
Simultaneous Reduction of NOx and Fuel Consumption for Off-Road Powertrains2026-01-02964/7/2026
Simultaneously reducing criteria pollutants and fuel consumption is important for clean air and improving vehicle total cost of ownership. The goal of this effort was focused on a 90% NOx reduction and 10% fuel savings for an off-road 407 kW diesel engine. The baseline was a production Fiat Powertrain 13L engine and aftertreatment system meeting 0.4 g/kW-hr NOx. The baseline system was quantified over the NRTC, RMC, new low load cycle and five field cycles. A next generation engine was built incorporating several fuel-efficient design features, including a higher compression ratio, increased fuel-rail pressure, low-friction piston rings, and a high-efficiency variable-geometry turbocharger. Cylinder deactivation and EGR pump technologies were added to this engine as well. The combination was optimized prior to adding advanced aftertreatment systems, showing the trade-off of engine out NOx and exhaust temperature. Two next-generation catalyst technologies were employed into a LO-SCR
McCarthy, Jr.,, James, Wine, Jonathan, Bradley, Ryan, Hasseman, Andy, Prikhodko, Vitaly, Howell, Thomas
Achieving Euro 7 WHSC NOx Emission Targets from a Spark Ignited Engine Using Methanol-Hydrogen Co-Fuelling2026-01-03214/7/2026
E-methanol is increasingly seen as a promising clean fuel because its chemical makeup is close to fossil fuels, making it easier to use in existing engines. It offers a carbon-neutral option to help reduce greenhouse gases in sectors where cutting emissions is especially difficult, such as transportation. However, while e-methanol avoids adding new carbon dioxide, burning it in internal combustion engines still releases harmful gases like oxides of nitrogen (NOx) and other toxic by-products like formaldehyde and formic acid that damage both health and the environment. This report explores a new strategy that combines methanol with hydrogen to run engines under “ultra-lean” conditions and its impact on emissions, performance and efficiency. Experiments were carried out on a single-cylinder spark ignition engine, with directly injected methanol and port fuelled injection of hydrogen. The findings show that adding about 10% hydrogen (energy basis) at low engine loads can extend the lean
Ambalakatte, Ajith, Geng, Sikai, Cairns, Alasdair, Varaei, Amirata, Harrington, Anthony, Hall, Jonathan, Bassett, Mike, Cracknell, Roger
A Pathway to Exceed 50% Indicated Thermal Efficiency for Gasoline Engines with Active Pre-Chamber2026-01-03004/7/2026
Research 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 the compression ratio and excess air coefficient (λ) in naturally aspirated engines via active pre-chamber technology, and further enhancing λ through the synergy of active pre-chamber with intake boosting and Miller cycle technology, on combustion efficiency and pollutant emissions. Experiments were conducted on a high-compression-ratio (up to 16.6) single-cylinder gasoline engine. Under natural aspiration, the effective compression ratio was raised via valve timing, 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
Deng, Jun, Li, Xiaoliang, Miao, Xinke, Xu, Bingxin, Zhang, JianQi, Li, Liguang
Technical Outlook on the Potential of HVO and Biodiesel Blends for Cleaner Combustion2026-01-03164/7/2026
The increasing need to decarbonize the transport sector is accelerating the adoption of renewable and low-carbon fuels such as Hydrotreated Vegetable Oil (HVO) and biodiesel as sustainable substitutes for fossil diesel. These fuels are evaluated as drop-in solutions requiring no engine recalibration, enabling immediate GHG emission reduction in existing diesel fleets. This study experimentally investigates the combustion, performance, and emission characteristics of a turbocharged common-rail two-cylinder diesel engine (Kohler LWD 442 CRS) operated with conventional fossil Diesel, pure HVO (Hydrotreated Vegetable Oil), and an HVOB20 blend (80% HVO and 20% biodiesel produced from waste cooking oil and animal fats). Tests were carried out under steady-state conditions at the DIIEM Engine Laboratory of Roma Tre University. The analysis focused on in-cylinder pressure evolution, brake power, brake specific fuel consumption (BSFC), and both regulated and unregulated emissions. Regulated
Zaccai, Martina, Chiavola, Ornella, Palmieri, Fulvio, Verdoliva, Francesco
CuSCR Catalysts Under H 2 -ICE Exhaust Gas Conditions2026-01-03614/7/2026
In the near to mid-term, hydrogen internal combustion engines (H2-ICE) can be a bridge technology for reducing carbon emissions. A few challenges anticipated under lean-burn H2-ICE operation are the significant drop in turbo-out temperatures, combined with higher water content, and the possible presence of unburned hydrogen in the exhaust, which could have a potential impact on performance and durability of the downstream exhaust aftertreatment system, particularly oxidation and SCR catalysts, as these conditions can suppress low-temperature oxidation activity, perturb Cu-site speciation and redox cycling in SCR catalysts, and exacerbate hydrothermal aging under sustained wet operation. This study examines the impact of excess water and residual hydrogen on Cu-SCR durability, active site chemistry, and stability for the case with and without an upstream oxidation catalyst, through aging tests at 450 °C and 550 °C. Changes in Cu redox cycles were assessed through site quantification
Kim, Mi-Young, Daya, Rohil, Kamasamudram, Krishna
Challenges to Ranking Diesel Fuels for NO x Emissions Using a Constant-Volume Combustion Chamber2026-01-03484/7/2026
The market is witnessing an unprecedented proliferation of low-emission fuel components. To effectively evaluate the suitability of these novel fuels for engine applications, fuel blenders and original equipment manufacturers require rapid and reliable assessment methodologies. Traditionally, such evaluations rely on comprehensive engine testing, which, while thorough, is both time-intensive and costly. In response to the growing diversity of emerging fuel options, this work aims to establish a streamlined screening approach capable of effectively replicating the outcomes of full-scale engine testing. We 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 air at 650°C and 20 bar, where it ignited and burned. The chamber was sampled post-combustion using a chemiluminescence NOx analyzer
Luecke, Jon, Rahimi, Mohammad, Mohamed, Samah, Naser, Nimal, Chausalkar, Abhijeet, McCormick, Robert
On-Road Vehicle Testing and Characterization2026-01-01954/7/2026
Vehicle testing for fuel economy and emissions is typically performed indoors over standard dynamometer drive schedules to minimize variability and maximize repeatability of the results. In contrast, during on-road operation, operational parameters such as vehicle speed and acceleration and environmental factors such as temperature and wind will change unpredictably. These factors influence vehicle fuel economy and emissions, making on-road operation much more variable than dynamometer results. However, even though on-road conditions may be unpredictable, the on-road operational data can still be used to characterize vehicle performance. This paper describes the development of an on-road vehicle test methodology, with a focus on accounting for on-road factors with a high degree of accuracy while requiring only an achievable and reasonable amount of data. To develop this methodology, a 2016 Honda Civic was instrumented and driven multiple times over a route covering urban, rural, and
Moskalik, Andrew, Barba, Daniel
Virtual Sensor Development for Real-Time Estimation of Transient NOx Emissions for Internal Combustion Engine2026-01-03704/7/2026
Accurately measuring NOx emissions under transient engine conditions is becoming increasingly important with upcoming Euro 7 and EPA 2027 regulations. Traditional physical sensors often struggle with cost and response time, especially with aging of sensors in dynamic operation. This paper introduces a machine-learning–based virtual NOx sensor that can provide real-time emission estimates while reducing reliance on hardware sensors. The approach uses multiple machine-learning methods (Random Forest, Bootstrap Aggregating, Adaptive Boosting, Gradient Boosting, Extreme Gradient Boosting) and selected best one to establish correlations between engine operating parameters, measured steady-state data, and transient duty cycle NOx emissions. Validation across different duty cycles has shown strong alignment with physical sensor readings, with R2 values above 99.95% for training cycle data sets and above 95.34% for held-out cycles during training. The model needs to be trained with larger
Kumar, Chandan, Dahodwala, Mufaddel, Thawrani, Kiran
Experimental Evaluation of After-Treatment Solutions for Heavy-Duty Natural Gas Vehicles to Meet Future CNVII Regulations2026-01-03764/7/2026
The heavy-duty truck market in China has seen a significant increase in the adoption of natural gas-powered engines over the past two years. Simultaneously, the anticipated release of the China VII emissions regulation proposal by the end of 2025 is expected to impose stricter emissions limits on all heavy-duty engines, including new particulate number (PN10) thresholds analogous to those in the Euro 7 regulation. While tailpipe oxides of nitrogen (NOx) and methane (CH4) emissions from natural gas engines can be mitigated through tighter lambda control and adjustments to catalyst volume and precious metal (PGM) loading, addressing NOx and particulate number (PN) emissions necessitate more advanced after-treatment solutions. Although natural gas combustion is virtually soot-free, the entrainment of lubricating oil into the combustion chamber, especially during cold-start conditions, poses a challenge, leading to potential exceedance of the proposed future China VII limits. Additionally
Gao, Jiahui, Besch, Marc, Ding, Ning, He, Suhao, Zhao, Yuxin, Yixiao, Li, Shen, Ye
Adaptive Economic Model Predictive Control for Engine Emissions Management with Compensation for Performance Drift2026-01-02874/7/2026
This paper addresses the changes in engine emissions due to in-use component changes through the synergistic application of predictive control, machine learning, and onboard adaptation. In particular, we consider an adaptive economic Model Predictive Control (eMPC) strategy to mitigate the effects of performance drift on Nitrogen Oxides (NOx) and Soot emissions from compression ignition (diesel) engines. A performance drift block, which applies a multiplier and offset to nominal emissions, is integrated with a high-fidelity Neural Network (NN) plant model to simulate these characteristic changes. To counteract variability, two online adaptation methods are integrated within the eMPC framework: One is based on Recursive Least Squares (RLS) and another on a continuously updated online NN. The proposed control architecture is validated through simulations over standard transient cycles. Results demonstrate that while the rate-based eMPC possesses inherent robustness to performance drift
Zhang, Jiadi, Li, Xiao, Kolmanovsky, Ilya, Tsutsumi, Munecika, Nakada, Hayato
Development of an ‘Online’ Combustion System Calibration Method using a Non-Dominated Sorting Genetic Algorithm2026-01-02854/7/2026
Calibration is a major resource bottleneck and source of risk in powertrain technology development. A promising alternative to the typical design-of-experiments (DoE) approach is the use of a ‘Non-Dominated Sorting Genetic Algorithm’ (NSGA) calibration method, where an iterative process is used to directly identify the Pareto Fronts between performance metrics, for example, net mean effective pressure (NMEP) and NOx emission. The goal of the present work was to develop and demonstrate a fully ‘online’ combustion system calibration method based on an NSGA, where the algorithm operates directly on experimental data rather than empirical models as is typical in the literature. This was completed by first designing an optimal NSGA for combustion system calibration and then demonstrating its use for an experimental combustion system calibration on a single cylinder gasoline engine at one operating condition. Results from the design process here indicate that ‘online’ NSGAs have a strong
Mansfield, Andrew
Development of a Zeolite-Based (HC/NOx Trap Type) Cold-Start Catalyst (CSC) for Meeting Tier4/LEV IV Tailpipe Emission Standards, Part IV2026-01-03644/7/2026
This paper is a follow-up study to three preceding reports [1,2,3] that focus on the development of a β-zeolite-based hydrocarbon/nitrogen oxide (HC/NOₓ) trap-type cold-start catalyst (CSC) — a cost-efficient technical strategy for meeting the increasingly stringent vehicle tailpipe emission standards for automotive exhaust systems, including Tier 4 and LEV IV, which are to be enforced in the near future. A core challenge in meeting Tier 4 and LEV IV exhaust emission standards lies in the fact that both the SC03 and US06 test cycles commence from ambient (cold) temperatures, as opposed to the elevated (hot) starting temperatures mandated for the preceding Tier 3 and LEV III standards. In the present study, a hybrid electric vehicle (HEV) fitted with two distinct Tier 3-certified exhaust aftertreatment systems—one officially certified to Bin 30 standards and the other a Bin 20-equivalent system (non-officially certified)—was subjected to testing under the cold SC03, cold US06, hot SC03
Xu, Lifeng, Wei, Hong, Zhao, Pengfei, Ma, Ruibo, Wang, Lin, Qian, Wangmu, Qian, Menghan
Compact, Low-Cost Ultra-Low NOx Solution for 2027 US EPA, Euro VII, China VII and Off-Road2026-01-03634/7/2026
Achieving ultra-low NOx emissions remains a major challenge in diesel emission control industry worldwide, especially as increasingly stringent regulations are introduced globally. Selective Catalytic Reduction (SCR), the leading NOx reduction technology in diesel systems, performs best when “sufficient” heat and ammonia are made available to it. At the same time, any proposed solution must be both low-cost and functionally robust in an industry seeking near 100% NOx removal at the lowest feasible cost. This work presents a low-cost architecture, utilizing a small, highly compact, single heater-mixer unit along with a light-off (close-coupled) SCR for meeting most stringent NOx emission regulations worldwide. It also hinders deposit formation lowering warranty costs and mitigating failure modes. Engine studies using a fully-aged aftertreatment system demonstrate that the proposed solution enables compliance with newer heavy-duty regulations including 2027 US, Euro-VII, China-VII, and
Masoudi, Mansour, Poliakov, Nick
Effect of Exhaust Gas Components on Oxygen Storage Capacity Measurements of Automotive Catalysts2026-01-03604/7/2026
Three-way catalytic converters (TWC) are one of the most popular methods to help reduce harmful tailpipe emissions emitted from internal combustion (IC) vehicles. To help improve conversion efficiency, TWCs can store and release oxygen via an oxygen storage capacity (OSC) mechanism. During engine control unit (ECU) calibration, on board OSC measurements are correlated to TWC and vehicle emissions to monitor emissions performance throughout the full useful life (FUL) of the vehicle. It is known that different test conditions, including temperature, space velocity and background gases in the exhaust stream affect OSC measurement, potentially altering the calculated OSC values and thus the perceived level of OSC and emissions preformance during operation. This study utilises an OMEGA test bench to complete OSC measurements on the full-scale automotive catalyst samples to quantify the effects of different background gases including carbon monoxide, hydrocarbons and nitric oxide on OSC
Mc Grane, Liam, Douglas, Roy, Irwin, Kurtis, Woods, Andrew, Elliott, Matthew, Istrate, Oana, Nockemann, Peter
Combustion Enhancement via Discharge Current Modulation under Turbulence Conditions2026-01-03364/7/2026
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 flame speed. 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 flow chamber is utilized to enhance the turbulence flow, and a custom-built ignition module is utilized to provide boosted discharge current to enhance the ignition stability under flow conditions. An effective spark energy required to enhance the combustion process is investigated under both stoichiometric
Jin, Long, Cong, Binghao, Yu, Xiao, Kong, Xiangxin, Reader, Graham, Zheng, Ming
Experimental Study on the Effect of Ignition Strategy on Combustion and Emissions in a Direct Injection Hydrogen Engine2026-01-03304/7/2026
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 direct injection 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
Effect of Key Operating Parameters on Homogenous Reactivity-Controlled Compression Ignition Concept with Renewable Fuels03-19-02-00094/1/2026
As part of the dTEC MORE project, sustainable powertrain technologies are being explored, including an alternative combustion concept tailored for engines in serial hybrid powertrains. Among the low-temperature combustion strategies, Reactivity-Controlled Compression Ignition (RCCI) is a prominent approach, offering significant reductions in NOx and soot emissions while enhancing combustion efficiency. The dual-fuel nature of RCCI enables improved control over combustion by utilizing fuels of differing reactivities. In this study, a premixed RCCI strategy was implemented using ethanol as a port-injected low-reactivity fuel and octanol as a directly injected high-reactivity fuel. The experimental work was conducted on a single-cylinder research engine with design features that are found in a gasoline passenger car application. Key combustion parameters such as the start of injection (SOI) of the high-reactivity fuel, injection pressure, intake temperature, lambda, premixed fuel ratio
Sundaram, Pravin Kumar, Grundl, Larissa Michaela, Trapp, Christian Thorsten, Tinschmann, Georg
CFD Simulation of Combustion and Emission Characteristics of Pure Spirulina Microalgae Biodiesel in a Single-Cylinder DI Diesel Engine2026-28-00432/12/2026
In this study, the combustion and emission characteristics of a single-cylinder direct injection (DI) diesel engine fueled with Spirulina biodiesel along with diesel blends were examined using a combined CFD and thermodynamic simulation framework. Three test fuels, including pure diesel (D100), Spirulina biodiesel blends (B20 and B40), and pure Spirulina biodiesel (B100), were analysed at 1500 rpm under full load. In the first stage, CFD simulations were performed in ANSYS Fluent, where the Discrete Phase Model (DPM) was applied to capture spray atomization and droplet evaporation, while a non-premixed combustion model coupled with the RNG k-ε turbulence model was employed to resolve in-cylinder flow and heat release dynamics. Subsequently, the Diesel-RK software was utilised to predict engine performance and exhaust emissions based on compression ratios (18.5) and injection timings. Results from the CFD analysis revealed faster atomization and reduced ignition delay for biodiesel
Kumar, B Varun
Enhancing Combustion, Performance and Emission Profiles Using Kapok Methyl Ester Blends with Hydrogen2026-28-00582/12/2026
This study investigates the potential of using a dual green alternative fuel combination, the one is hydrogen fuel and another one is biodiesel for enhancing the Performance, combustion and emission profile of a compression ignition engine. The kapok oil biodiesel was blended with Diesel in proportions of 20% (K20) and 40% (K40) by volume. The hydrogen gas was supplied at a constant flow of 4 liter per minute (LPM). The experimental fuels are neat diesel D100, K20 (80% Diesel and 20 % kapok methyl ester), K40 (60% Diesel + 40 % Kapok methyl ester), K20 + H4L (K20 with 4 LPM hydrogen) and K40+H4L (K40 with 4 LPM hydrogen). These test blends are investigated in a single cylinder direct injection CI engine under 0% to 100% load conditions at a fixed speed of 1500 rpm combustion, and emissions characteristic were evaluated and compared with base fuel. The outcomes indicated that the use of B20 and B40 blends without hydrogen led to reduced BTE because of their lower cetane number and
Anbarasan, B, M, Kumaresan, Balamurugan, S, Rajesh, Munnusamy
3D CFD Combustion Evaluation of Hydrotreated Vegetable Oil (HVO) as a Potential Alternate Fuel for the Future CI Engines2026-26-01131/16/2026
Transportation industry is facing a growing challenge to reduce its carbon footprint and utilize the carbon neutral, more environmentally sustainable fuels to comply with the goal of carbon neutrality. Implementation of carbon free fuels such as Hydrogen, Ammonia and low carbon fuels such as Methanol, Ethanol can significantly reduce the greenhouse gas emissions, but these fuels are suitable for SI engine architecture due to their high-octane ratings. Hydrotreated Vegetable Oil (HVO) is one of the few fuel solutions available today with a high Cetane rating (70-80), that can be used as a drop-in fuel in the existing CI engines, with minimal modifications. The main constituent of HVO is pure alkane and it can be produced from feedstocks such as vegetable oils, animal fats, various wastes and by-products. A closed cycle 3-D CFD combustion simulation using a detailed chemistry-based solver has been conducted with the HVO, on a three cylinder, naturally aspirated water-cooled CI engine at
Tripathi, Ayush, Mukherjee, Nalini, Nene, Devendra
Optimizing Hydrogen Engine Performance a Comparative Study of Lean & Stoichiometric Calibration Approach2026-26-02611/16/2026
Hydrogen combustion in internal combustion engines offers numerous advantages, such as zero CO2 emissions and high flame speed, which make it a promising alternative fuel for green vehicle solutions. In order to maximize the engine performance with hydrogen, however, meticulous calibration of the air-fuel mixture must be performed, particularly when lean and stoichiometric combustion conditions are considered. Lean burning, i.e., excess air, offers better thermal efficiency and lower NOx emissions but can cause lower engine power and combustion instability. Stoichiometric combustion, however, ensures complete combustion of the fuel-air mixture, but at the cost of higher combustion temperatures and consequently, high NOx emissions. Calibration strategies for hydrogen engines are presented in this paper by comparing the lean and stoichiometric strategies and their implications on engine power output, efficiency, and emissions. Test data from several hydrogen engine configurations
Jadhav, Ajinkya, Bandyopadhyay, Debjyoti, Sutar, Prasanna S, Sonawane, Shailesh Balkrishna, Rairikar, Sandeep D, Thipse, Sukrut S
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