Browse Topic: Fuel injection

Items (4,362)

3D Computational Fluid Dynamics Analysis of the Performance and Emissions of an Off-Highway Port Fuel Injection Hydrogen Engine

03-19-04-0018

7/27/2026

To fulfil the global aspiration of achieving net-zero emissions, hydrogen as a fuel seems to be one of the promising candidates. High energy density per unit mass and zero carbonaceous emissions are the two salient advantages that hydrogen offers. In the present study, a set of detailed chemistry-based 3D CFD combustion simulation has been carried on a 3-cylinder turbocharged, water-cooled port fuel injection SI Hydrogen engine to understand its optimum air–fuel ratio, compression ratio, spark timing and combustion chamber geometry. The simulations have been conducted at the full load of the rated power and maximum torque engine rpms. During simulation, the λ zone for study is restricted between 2.1 and 2.7. Two different bowl geometries (spherical and cylindrical), with two compression ratio options (12 and 14) are explored in the simulations. While the spherical bowl seems to accommodate flame front better than the cylindrical bowl, the compression ratio of 12 is a safer choice to control the maximum rate of pressure rise (dp/dθ). At full load and rated speed, the indicated thermal efficiency drops by 7.7% as the λ swings from 2.1 to 2.7, whereas the indicated specific NOx and dp/dθ drop by 99% and 81%, respectively. Similarly, at full load and maximum torque RPM, the indicated thermal efficiency drops by 6.4% with λ swing from 2.1 to 2.7, whereas the indicated specific NOx and dp/dθ drop by 99% and 91%, respectively. Beyond λ = 2.4 NOx reaches almost to zero, however, at a compromise of the thermal efficiency. The dp/dθ remains well within the acceptable limit under this scenario. To account this trade-off between the performance and emission parameters, optimum λ zone has been found out to be between 2.3 and 2.5.

Satre, Santosh Dadasaheb, Mukherjee, Nalini Kanta, Kumar, Sanjeev, Nene, Devendra

Experimental Investigation on Unburned Methanol and Formaldehyde Emissions from a Direct-Injection Diesel / Methanol Dual-Fuel Engine

2026-99-1646

7/24/2026

For large-bore marine methanol / diesel dual-fuel engines, this study investigates the formation characteristics of unregulated emissions through experimental methods and explores the mechanisms by which engine load and injection timing influence the emissions of unburned methanol and formaldehyde. The study was carried out on a supercharged intercooled inline six-cylinder engine, and Fourier Transform Infrared Spectroscopy (FTIR) was used to monitor the exhaust composition in real time. The study shows that methanol released in the exhaust is due to the incomplete combustion of the methanol fuel. In the combustion process of methanol fuel, formaldehyde mainly arises from two pathways, the first of which is the partial oxidation of methanol inside the cylinder; secondly, the unburned methanol in the exhaust gas oxidizes in the exhaust pipe to generate formaldehyde. As the load increased from 25% to 100%, the unburned methanol emissions decreased by 29%, and formaldehyde emissions decreased by 71%. This is mainly attributed to the enhanced oxidation reaction and reduced wall crevice effect due to the increased combustion temperature. Methanol injection timing optimization was effective in controlling unregulated emissions, with methanol emissions lower at -7° CA ATDC and formaldehyde emissions reaching larger values under this condition. Delaying the diesel injection to -16°CA ATDC led to a 38% increase in unburned methanol emissions, caused by fuel spray interactions and longer stagnation, whereas formaldehyde emissions showed minimal change.

Jiang, Yuqi, Li, Hongmei, Zhang, Wenzheng, Li, Xiao, Zheng, Liang, Meng, Yangqian, Gu, Xianan, Hua, Hanqing

Drop Impact Phenomena: An Experimental Study of Isooctane Interaction with Dry Walls and Liquid Films

2026-01-5015

7/13/2026

In this study, high-speed back-illuminated imaging and laser-induced fluorescence (LIF) methods were employed to investigate the impingement behavior of millimeter-sized single isooctane drops on a dry solid wall and various liquid films, including isooctane and glycerol solution films of different concentrations. Various fuel spray impingement scenarios in gasoline direct injection engines were examined. High-speed back-illuminated imaging was primarily used to examine the impact of fuel drops on a dry wall and a fuel film of the same composition as the drops. The LIF method was used to examine the impact of fuel drops on the glycerol solution film, allowing for the distinction between fuel drops and the glycerol solution film. The impingement behavior varied depending on the Weber number of the incident drop and the wall condition. When fuel drops impacted the solid dry wall vertically, they spread into a circular liquid film. The outer edge of the liquid film folded and bulged, and upon reaching the maximum spreading diameter, it maintained equilibrium and did not retract. When isooctane fuel drops impacted the isooctane film, they broke and splashed, with thinner films producing stronger splashes. Additionally, the Weber number of the fuel drops significantly influenced the crown shape and splashing after impact. The impingement behavior of fuel drops on the glycerol solution film was also investigated, focusing on the liquid film morphology after impact. Based on the experimental data, empirical correlations were established between the critical Weber numbers for transitions among different crown morphologies and the dimensionless film thickness under varying film viscosities.

Yang, Tian, Lu, Lili, Guo, Zongwei, Song, Enzhe, Yao, Chong, Ning, Yilin, Ke, Yun

Study on Diesel-Methanol Non-Premixed Combustion Characteristics of a Marine Dual-Fuel Engine at Different Methanol Substitution Rate

2026-99-0517

7/10/2026

Methanol use in marine engines has the potential to reduce nitrogen oxide emissions, particulates, and greenhouse gas emissions. A turbocharged four-stroke marine diesel powerplant was converted to run as a double-DI (direct injection) diesel-methanol hybrid engine. Experimental studies using a non-premixed combustion scheme showed that higher methanol substitution ratios (MSR) led to increased peak heat release rates. The combustion process displayed distinctive two-phase behaviors. Increasing MSR caused retarded ignition timing, shortened combustion duration, and improved thermal efficiency. Combustion stability was significantly improved at higher MSR. Emissions results showed NOX and HC were increased in proportion to MSR, whilst particulate emissions and CO concentrations were inversely reduced. Methanol enrichment was found to enhance NOX and HC formation processes but also accelerate soot particulate decomposition and CO oxidation mechanisms.

Li, Xiao, Jiang, Yuqi, Yan, Ping, Zheng, Liang, Li, Hongmei, Zhang, Wenzheng, Chen, Chao, Man, Zhongguo

NO _x Formation Characteristics of Lean Hydrogen Combustion: From 0D Analysis to Comprehensive 3D-CFD Engine Investigations

2026-01-0732

7/1/2026

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 parameters based on the extended Zeldovich mechanism are evaluated through comparison with experimental data. Furthermore, multiple sampling positions within the CFD mesh are examined. The simulations reproduce measured trends across variations in load and air-to-fuel ratio with good accuracy. At high load and λ=1.5, NOx emissions of up to 6000 ppm are produced, decreasing exponentially with increasing excess air. Finally, potential NOx reduction strategies for the single-cylinder are examined. While influencing the mixture homogenization shows limited effectiveness, temperature-based actions prove to be more effective. Among the investigated approaches, a Miller intake valve strategy yields the largest benefit, achieving approximately 10% NOx reduction by lowering end-of-compression temperatures and increasing residual gas dilution under otherwise identical operating conditions.

Gal, Thomas, Vacca, Antonino, Chiodi, Marco, Schmelcher, Robin, Kulzer, Andre Casal

Experimental Study of Warm-Up And Startability Operations in a Spark Ignition Engine Fueled with Ethanol Gasoline Blends

2026-01-0738

7/1/2026

The mitigation of Greenhouse Gas (GHG) emissions poses a major challenge for the transportation sector, driving the need for renewable fuels. Bioethanol represents a promising fuel for Spark-Ignition (SI) engines, combining a reduced life-cycle CO₂ impact with advantageous combustion properties. However, despite its proven performance under steady-state conditions, the widespread of fuels with high ethanol content is still constrained by significant difficulties during engine cold-start operation. This study aims to experimentally assess the effect of ethanol concentration on cold-start performance and warm-up transient behavior of a Naturally Aspirated (NA), Port Fuel Injected (PFI) SI engine. Warm-up tests were conducted at an operating condition of 2000 rpm engine speed and 20 Nm torque using three fuels with increasing ethanol content: commercial gasoline (E5), E30 and E60. In addition, dedicated startability tests were carried out for E60 and neat ethanol (E100) at different initial engine wall temperatures to evaluate fuel sensitivity to thermal conditions during engine start. The experimental results indicate that increasing ethanol concentration has a negligible effect on the overall duration of the warm-up process, while leading to a modest reduction in both engine wall and exhaust gas temperatures. At the same time, E100 displays severe startability limitations at low initial wall temperatures, requiring repeated cranking attempts before stable operation can be achieved. The same startability issues have been observed for E60 but with limited intensity. Two minimum engine wall temperature ranges were identified for reliable cold-start operation at 20-25 °C for E60 and 25-30°C for E100. Overall, these findings experimentally confirm the dominant influence of engine thermal conditions on the reliable startability of ethanol-fueled spark-ignition engines.

Falbo, Luigi, Falbo, Biagio, Perrone, Diego, Castiglione, Teresa

Spray–Wall Interaction at Thermal Swing Coatings in SI Engines

03-19-03-0014

6/25/2026

As a contribution to the reduction of greenhouse gas emissions in the transportation sector, the indicated efficiency of SI engines can be increased via thermal swing coatings. Thereby, a decrease in greenhouse gas emissions can be achieved, although not at all operating conditions. Here, the often-observed increased hydrocarbon emission partially overcompensates the reduced wall heat losses. The main root cause is always attributed to the increased surface roughness and porosity, leading to an increased crevice volume. Further investigations were performed at a single-cylinder engine equipped with a FTIR for species analysis of hydrocarbon emissions. A comparison of direct injection and port fuel injection were performed for RON95 E10 and methanol to assess the influence of mixture preparation. 3D CFD was used to additionally investigate the in-cylinder processes. The comparison of port fuel injection and direct injection showed a significant influence on the fuel hydrocarbon emissions for the direct injection when the thermal swing coating was applied. The effect is more pronounced for methanol. For port fuel injection nearly the same or reduced fuel hydrocarbon emissions can be observed. This is mainly attributed to an increased wall film agglomeration at the piston for the thermal swing coating in case of direct injection, which can be observed in 3D CFD. Due to the low thermal effusivity of the coating, the droplet impingement leads to a notable decrease in the surface temperature. This results in lower evaporation of the fuel and a longer droplet lifetime. Consequently, a fuel wall film is still present at top dead center after ignition leading to additional hydrocarbon emissions.

Fischer, Marcus, Pischinger, Stefan

Effects of Engine Geometries on the Combustion Characteristics of a Heavy-Duty Hydrogen Spark-Ignition Engine

2026-37-0046

6/9/2026

For heavy-duty applications, hydrogen (H2) internal combustion engines offer a practical solution for future transportation. However, the influence of cylinder head flow characteristics and piston geometry on lean H2 combustion remains insufficiently understood. This study presents a comprehensive computational investigation of three engine configurations characterized by distinct in-cylinder flow dynamics: mild swirl and tumble (Engine a), strong tumble (Engine b), and strong swirl (Engine c). High-fidelity three-dimensional computational fluid dynamics simulations were performed for both port-fuel injection (PFI) and direct injection (DI) strategies. The impact of piston geometry was evaluated by comparing the baseline piston with a flat piston, while the spark timing was optimized to achieve favorable combustion phasing. Combustion and NOx formation were modeled using a G-equation-based combustion framework incorporating diffusive-thermal instability effects and a validated in-house H2 chemical mechanism. Turbulence-flame interactions were further characterized using Borghi-Peters diagrams. Under PFI operation, the strong-tumble configuration (Engine b) generated the highest turbulent kinetic energy (TKE), resulting in faster flame propagation, more advanced combustion phasing, and improved thermal efficiency. The flat piston further enhanced efficiency by reducing mixture confinement within piston-induced recirculation zones. Under DI operation, H2 injection significantly increased turbulence intensity, and a flat piston promoted higher TKE near spark timing in Engines b and c by reducing mixture-wall interaction, leading to faster combustion compared with the baseline piston. In contrast, the original piston produced higher TKE within the piston bowl in Engine a due to stronger recirculation. Additionally, the strong-tumble configuration achieved the most homogeneous mixture distribution under DI conditions. These results demonstrate that in-cylinder flow structure, piston geometry, and DI injection strongly affect turbulence generation, mixture formation, and combustion performance. The strong-tumble configuration shows the greatest potential for achieving high thermal efficiency with controlled emissions in lean H2 spark ignition engines.

Liu, Xinlei, Menaca, Rafael, Cenker, Emre, Silva, Mickael, Qahtani, Yasser A., Pei, Yuanjiang, Turner, James W.G., Im, Hong G.

CFD Modelling of an Asymmetric Hydrogen Injector Cap for Direct Injection Applications: Design Impact on Jets Structure and Momentum Flux

2026-37-0011

6/9/2026

The adoption of hydrogen as a carbon-neutral sustainable fuel for internal combustion is regarded as a promising solution to reduce greenhouse gases and pollutant emissions. In this framework, the injection system plays a crucial role, being responsible for delivering a large amount of fuel to the combustion chamber. Currently, low-pressure direct injection is considered one of the best solutions to ensure the appropriate fuel delivery. The use of caps has proven particularly effective, as they enable a potentially unlimited range of geometries while minimizing modifications to the injector hardware. Experimental campaigns and computational fluid dynamics (CFD) simulations can be used together as complementary tools to speed up the development process and explore multiple combinations of parameters, thereby optimizing the overall design of both the engine and the caps. In the present paper, a single-hole GDI-derived hydrogen prototype injector equipped with a two-hole asymmetric cap and fed with hydrogen is analyzed through both experiments and CFD simulations under two different operating conditions in terms of rail pressure. Cap pressure, overall fuel instantaneous mass flow rate and hole-specific jet momentum have been measured during the experimental campaign. The resulting data were used as boundary conditions and as targets for the validation of steady-state CFD computations, where the same equipment has been simulated. In particular, the momentum flux produced by the two jets emerging from the forming cap was used to validate the numerical methodology against experimental outcomes. Moreover, the exact dimensions of cap holes have been taken by means of optical microscope and applied to the simulation to compare the real geometry against the nominal one. Therefore, the impact of the effective cap geometry is explored, evidencing a noticeable dependence specifically of the cap backpressure and therefore of the injection system performance on the details of the cap design.

Pavan, Nicolo, Breda, Sebastiano, Duni, Andrea, Martino, Manuel, Fontanesi, Stefano, Postrioti, Lucio

Investigation of Influential Parameters on the Integrated Hydrogen Argon Power Cycle

2026-37-0012

6/9/2026

This study investigates hydrogen combustion in an argon–oxygen environment for argon power cycle application using computational fluid dynamics. The numerical framework, developed based on previously validated model, is applied to examine the influence of key operating parameters on combustion efficiency and indicated efficiency under constant cycle pressure conditions. A parametric analysis is conducted to evaluate the effects of excess oxygen ratio, argon rate, start of injection, and injector discharge coefficient on ignition characteristics, combustion efficiency, and engine performance. The results indicate that less fuel injection improves combustion efficiency but leads to a significant reduction in engine load. Increasing the argon rate enhances engine thermal efficiency, primarily due to the higher specific heat ratio of argon, which improves the thermodynamic efficiency of the cycle. However, elevated argon concentrations significantly reduce combustion efficiency because of limited oxygen availability, resulting in increased levels of unburned hydrogen. The analysis further demonstrates that higher injector flow rates improve both combustion and engine efficiency. Overall, unburned hydrogen is identified as a critical limitation for the practical implementation of compression ignition hydrogen engines operating in Ar–O₂ mixtures; however, unburned hydrogen levels up to approximately 8% can be tolerated without significant deterioration in combustion efficiency in next engine cycle. The results revealed that the combustion inefficiency arises due to tale combustion phase and is attributed to inappropriate mixing of fuel and oxidizer.

Chitsaz, Iman, Ahammed, Sajid, Kakoee PhD, Alireza, Salahi, Mohammad Mahdi, Andwari, Amin, Ahmad, Zeeshan, Hyvonen, Jari, Mikulski, Maciej

Comparison of Detailed Chemistry and Flamelet-Based Models for Hydrogen Combustion in a Heavy-Duty PFI Engine

2026-37-0014

6/9/2026

Addressing climate change requires substantial reductions in CO2 emissions from the transportation sector, where alternative fuels for internal combustion engines play a crucial role. Hydrogen stands out as a compelling energy carrier capable of enabling low-carbon combustion while leveraging existing engine technologies. Its adoption can support a transition toward fuel-flexible powertrains and deliver rapid decreases in exhaust carbon emissions. This approach is particularly relevant for hard-to-abate segments, where full electrification remains challenging. Building on this perspective, this numerical study investigates the modelling behaviour of a heavy-duty port fuel injection (PFI) internal combustion engine fuelled with hydrogen. Initially, the mixture was assumed to be fully premixed to avoid uncertainties related to injection and mixing processes and to significantly reduce computational cost; this assumption was subsequently validated through selected injection simulations. A methodology was then developed to ensure robust model responses by analysing convergence over three consecutive cycles and by appropriately defining the initial and boundary conditions, as well as mesh resolution. Three representative experimental operating points were investigated: full load, maximum power, and cruise conditions. Two combustion modelling approaches were then compared. ECFM, a flamelet-based model, demonstrated its ability to match experimental data through a calibration process that accounts for turbulence-chemistry interactions via the adjustment of model parameters. In contrast, SAGE is a detailed chemistry solver that employs a kinetic reaction mechanism to directly compute reaction rates, without requiring calibration. The comparison highlighted certain limitations of SAGE arising from its underlying approach, whereas ECFM showed more stable and reliable behaviour, albeit with the need for case-specific calibration.

Scopelliti, Alex, Misul, Daniela Anna, Baratta, Mirko, Gallo, Alessandro, Rapetto, Nicola, Vargiu, Luca

Experimental Investigation on Cold Start and Warm-Up Phases for an Ethanol Fueled SI Engine

2026-37-0031

6/9/2026

The reduction of Greenhouse Gas (GHG) emissions represents a key challenge for the transportation sector, requiring the adoption of renewable fuels capable of ensuring both environmental benefits and compatibility with existing internal combustion engine technologies. In this context, bioethanol emerges as a viable solution for Spark Ignition (SI) engines, offering a low life-cycle CO₂ footprint and favorable combustion characteristics. Nevertheless, despite its well-known advantages under steady-state operation, the widespread use of high-ethanol-content fuels is still limited by critical issues during engine cold start. The aim of this work is to experimentally investigate the influence of ethanol content on cold-start behavior and idle warm-up transient operation of a Naturally Aspirated (NA), Port Fuel Injected (PFI) SI engine. The experimental campaign was carried out under idle conditions using four fuels with increasing ethanol content, namely commercial gasoline (E5), E30, E60, and neat ethanol (E100). Cold-start and full warm-up tests were performed starting from ambient temperature, while additional dedicated experiments were conducted on E100 to evaluate startability under different initial engine wall temperatures. The results show that increasing ethanol content has a limited impact on the overall warm-up duration, while slightly reducing engine wall and exhaust gas temperatures. Conversely, E100 exhibits pronounced startability issues at low initial wall temperatures, requiring multiple cranking attempts to achieve stable idle operation. A minimum wall temperature threshold in the range of 25-30 °C was identified as necessary to ensure reliable cold start with E100. The outcomes of this study provide experimental evidence of the key role played by engine thermal conditions in enabling stable operation of ethanol fueled SI engines during cold start.

Falbo, Luigi, Falbo, Biagio, Perrone, Diego, Castiglione, Teresa

Investigating the Potential of Two Individually Controlled Injectors per Rotor for a Direct Injection Hydrogen Wankel Engine

2026-37-0008

6/9/2026

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 NOx reduction through differentiated injector operation. In-cylinder pressure analysis and exhaust gas measurements provide detailed insight into combustion characteristics and abnormal events. The dual-injector setup increases torque capability and operational robustness without additional mechanical complexity, supporting the use of hydrogen rotary engines in compact hybrid systems and stationary power applications.

Endres, Jonas, Beidl, Christian, Herold, Tim, Lavall, Philipp, Schmidt, Marvin, Hofmann, Silas, Kahl, Jonas

A Helical Compression Spring Fracture under Impact Velocity in Pump Operation by Theoretical Study and FEA

2026-01-0271

4/7/2026

Helical compression springs have been used widely in various industries from automotive, aerospace and construction to electronics and medical devices. In the automotive industry, they appear in many places such as suspension, valvetrain, etc., as well in the discharge check valve of Gasoline Direct Injection (GDI) pump, which is the subject of study due to a recent fracture in lab testing. A theoretical study is conducted first to establish the equation governing spring dynamic motion under impact velocity, which can be in high magnitude with surging shock wave along spring axis. A new spring shock wave equation is developed for spring axial motion coupled with coil torsional effect. This newly derived shock wave equation has a broader term than the classic spring formula found in most engineering books. In this paper, it shows that the classic spring shock wave equation is only a special case for the general wave equation newly discovered. Then, a theoretical formula on spring shock wave propagation speed and natural frequency are presented, validated by a numerical simulation result by FEA on the spring natural frequency. Next, a FEA tool is employed to study the spring system under transient impact velocity, the spring dynamic stress at fracture location is obtained. It compares closely with the analytical approximate solution. Finally, a fatigue life assessment is performed, back up by the fractured part photo as well as the fatigue life cycles observed in testing. They are found in good agreement.

Pang, Michael L., Gunturu, Srinu, Norkin, Eugene

Development of an ‘Online’ Combustion System Calibration Method using a Non-Dominated Sorting Genetic Algorithm

2026-01-0285

4/7/2026

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 potential to outperform traditional DoEs in the development of Pareto-optimal engine calibrations; however, NSGA performance is highly sensitive to the specific parameters used in the algorithm logic. The highest sensitivity was to the mutation logic within the genetic reproduction process, and second was the number of genes (calibrations) included in the overall process. Inclusion of both the Primary and Secondary non-dominated Pareto fronts in the set of Pareto-optimal calibrations was found to be critical to the success of the NSGA. When demonstrated for an experimental combustion system calibration the NSGA operated effectively and as expected, continually providing ‘upward’ pressure to generate calibrations that maximize NMEP but also ensure the breadth of the Pareto front (NOx) is scanned with high fidelity. In comparison to a traditional DoE approach, the NSGA was nearly twice as accurate in identifying calibrations along the Pareto front for the same number of total experiments. The Pareto-optimal calibrations developed by the NSGA are reasonable for these operating conditions and in excellent agreement with the literature. The present work strongly motivates and supports further development of NSGA methods for use in more complex systems and situations including for electrified and hybrid powertrains.

Mansfield, Andrew

A Novel Chemical Clustering Approach for the Acceleration of 3D CFD Simulations of Internal Combustion Engines with Complex Fuels

2026-01-0495

4/7/2026

Detailed kinetics simulations coupled with 3D CFD offer a powerful analysis tool for combustion and emissions. Such methods allow consistent modeling of multi-component fuels from evaporation to combustion and correctly capture the effects of local inhomogeneities created by preferential evaporation on the performance and emissions of modern powertrains. Such computations are extremely computationally demanding, prompting interest in the development of calculation acceleration techniques that can effectively balance the speed and accuracy of the chemical source calculation terms. Chemical kinetics clustering methods are widely used for that effect. However, such techniques must be not only effective but also robust with respect to the engine conditions and fuel composition changes, to reduce the computational demands introduced by the need to calibrate the parameters of the acceleration method itself. In this paper, an extended chemical kinetics clustering approach is proposed. A calibration methodology for the parameters of this acceleration method is then introduced, based on multi-point single time step optimization for a toluene reference fuel (TRF) surrogate with ESTECO modeFRONTIER, utilizing frozen 3D CFD fields obtained with the Realis Simulation VECTIS code. The optimal clustering parameters thus constructed are then fine-tuned through a DoE exercise performed in VECTIS for the combustion event with the TRF surrogate using a coarse computational mesh. The robustness of the optimal parameters is then evaluated through the application of different perturbations to the species fields. Finally, the optimal clustering parameters are applied to full-load simulations of a typical GDI engine with simple TRF and 8-species E10 gasoline surrogates. The results demonstrate that the acceleration parameters determined by this workflow deliver 2.4× to 4.2× acceleration of combustion source calculation and 1.3× to 1.8× acceleration of the overall simulation while preserving solution accuracy and keeping the resolution of NO and soot emissions within 10% and 15%, respectively. The proposed methodology facilitates the broader use of detailed chemistry in internal combustion engine (ICE) applications, supporting modern powertrain development needs.

Hernandez, Ignacio, Turquand d Auzay, Charles, Shapiro, Evgeniy, Shala, Mehmet, Borg, Anders, Seidel, Lars, Mauss, Fabian

Effect of Pre-Chamber Geometry on Methanol Cold-Start Combustion in an SI Engine

2026-01-0307

4/7/2026

Vehicle pollutant emissions are a major challenge in the development of internal combustion engines. To meet increasingly strict regulations, the automotive sector is exploring alternative fuels and lean-burn strategies. Methanol is gaining importance as a carbon-neutral fuel due to advances in green production technologies. Methanol, despite its potential for renewable production, faces severe limitations due to its inherent poor cold-start performance with conventional ignition systems. In this context, the present study aims to investigate the influence of pre-chamber ignition on cold-start combustion by using high-speed optical diagnostics to visualize flame propagation while simultaneously measuring in-cylinder pressure and engine performance. A major result concerns the significant cyclic variability of conventional spark ignition (SI) under cold-start conditions, which exhibits significant cyclic variability. Instead, passive pre-chamber ignition significantly enhances cold-start combustion stability, lowering CoV IMEP to below 3% at λ = 1.0 and sustaining stability under 5% even in ultra-lean conditions (λ = 1.6), where conventional SI operation fails. Flame visualization quantitatively confirms that this stability stems from distributed, multi-point ignition, which accelerates initial flame propagation by 3-4x compared to SI. These findings demonstrate that pre-chamber ignition can effectively overcome the traditional "cold-start" problem for methanol, enabling stable combustion from the first cycles. This provides an invaluable dataset for CFD model validation, as it captures a highly stable combustion process largely independent of the adverse thermal boundary conditions typical of cold start, thereby simplifying the modeling challenge.

Sementa, Paolo, Altieri, Nunzio, Tornatore, Cinzia

Optimal Strategies for SI H2 Combustion System and Pre-Ignition Investigation through Advanced Optical Techniques

2026-01-0324

4/7/2026

The rapidly transforming mobility sector is confronted with a dual challenge: achieving market expansion while significantly reducing emissions. Even if vehicle electrification tends to be favored in developed nations, it is widely acknowledged that no single solution is universally optimal. Within this context, hydrogen emerges as a compelling energy vector. It can be used both in fuel cells and internal combustion engines. This latter benefits from a well-known architecture and existing production infrastructures constituting a viable short-term and cost-effective solution especially for light or heavy-duty and off-road applications. In this context, investigation on the hydrogen spark-ignited internal combustion engine was performed, focusing especially on critical abnormal combustions. Indeed, during early development phase, abnormal combustion management was a challenge requiring the identification of the root cause of these issues. This work, based on the use of a versatile single-cylinder engine, is dedicated to the optimization of hydrogen combustion through adaptations of injection strategy to minimize the NOx production and improve the combustion efficiency. A dedicated attention was paid to study the effects of different parameters of the hydrogen injection system, such as the location of the injector, the targeting and the injection pressure. Subsequently, a specific cylinder head has been designed to allow endoscopic optical access into the combustion chamber for a visualization of the combustion related phenomena using a high-speed UV intensified camera. The work was especially focused on abnormal combustion analysis such as pre-ignition and allows to analyze the behavior of different spark plugs. Different injection configurations were tested and their effects on combustion were evaluated using both adiabatic heat release rate analysis and in-cylinder movies obtained through the optical setup described above. It provides valuable data about mixture preparation, flame propagation and cycle to cycle fluctuations. Conventional heat release rate analysis gives macro level data of the combustion stroke whereas the endoscopic images provide 2D flame fields that enhance the understanding of the combustion characteristics. This work finally leads to a better understanding of abnormal combustion occurrences and guides towards the choice of relevant injection and ignition strategies, especially at full load.

Londos, Benoit, Bardi, Michele, Serrano, David, Laget, Olivier, Gautrot, Xavier, Bramoullé, Clément, Cordier, Matthieu

Achieving Euro 7 WHSC NOx Emission Targets from a Spark Ignited Engine Using Methanol-Hydrogen Co-Fuelling

2026-01-0321

4/7/2026

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 limit from air-fuel equivalence ratio (λ) of 1.7 to 2. This change cut NOx emissions by 99% and reduced formaldehyde emissions by 18% compared to pure methanol operation at stoichiometric. Furthermore, the NOx emissions were reduced sufficiently that engine could operate within Euro 7 World Harmonic Stationary Cycle (WHSC) limits.

Ambalakatte, Ajith, Geng, Sikai, Cairns, Alasdair, Varaei, Amirata, Harrington, Anthony, Hall, Jonathan, Bassett, Mike, Cracknell, Roger

Challenges of Mixture Formation in Methanol Port Fuel Injection Engines

2026-01-0337

4/7/2026

Port fuel injection (PFI) is an attractive strategy for methanol adoption in both spark-ignition and dual-fuel compression-ignition engines due to its lower cost and simpler hardware compared to direct-injection. However, methanol PFI mixture formation can be challenging due to methanol’s high heat of vaporization, low volatility at cold conditions and high tendency to wall wetting. Understanding and addressing these challenges is critical to ensure robust engine operation. In this study, the effects of injector geometry, coolant temperature, intake temperature and fueling rate on mixture formation of methanol PFI have been investigated for anhydrous methanol and for a blend of 90%vol methanol plus 10%vol water in an optical engine. Mie scattering and infrared imaging were applied to assess the liquid and vapor methanol distribution in the cylinder. For a high-flow injector compatible with methanol, significant amounts of liquid were detected in the cylinder at all conditions tested, leading to poor mixing and high fuel stratification during the compression stroke. This effect was mitigated by using a multi-hole injector that promoted better atomization, indicating that high atomization is preferred over high flow for methanol PFI. The probability of detecting liquid in the cylinder decreased as the coolant temperature or the intake temperature increased or if the fueling rate decreased, with coolant temperature being the dominant parameter to control methanol vaporization. Liquid probability increased with water addition mainly because of the high heat capacity of water. Liquid methanol accumulated in the intake port, decreasing the effective engine intake temperature and limiting fuel vaporization. This accumulation led to a delay of the system response to changes in the PFI settings, with injected fuel requiring one cycle to reach the cylinder and additional 50 cycles required to completely flush the fuel accumulated in the port. Finally, the operating envelope for liquid-free operation was defined.

Lee, Sanguk, Narayanan, Abhinandhan

Experimental Characterisation of Combustion, Performance, and Emissions in a Hydrogen Fueled Opposed Piston Engine

2026-01-0335

4/7/2026

Recent studies have demonstrated that the current Internal Combustion Engine (ICE) can be adapted to operate with hydrogen for the decarbonisation of transport and gensets. This is mostly done by conversion of conventional 4-stroke compression ignition diesel engines or spark ignition gas engines for heavy-duty vehicles or 4-stroke spark ignition gasoline engines for light-duty applications. This study aims to assess the adoption of pure hydrogen direct injection technology on a novel two-stroke opposed-piston engine designed by Carnot Engine Ltd. The engine provides a flexible platform that can operate in both compression ignition and spark ignition modes, allowing it to adopt multiple fuels. For the first time, a single cylinder prototype version of this new engine was operated and tested with hydrogen at Brunel University of London. During the engine experiment, a spark ignition timing sweep was carried out at low and mid-loads up to 10 bar IMEP to identify the Minimum ignition advance for Best Torque (MBT). Then, a complete mapping of the fuel injection strategies and lambda matrix was performed to optimise engine efficiency and combustion stability at low loads. The outcome of this study demonstrates an impressive indicated thermal efficiency of 58.7% at a load of 5 bar indicated mean effective pressure (IMEP) when the engine was operated with an ultra-lean mixture of lambda 3.2. Additionally, the engine-out NOx emissions decreased from the maximum 1863 ppm at lambda 1.38 to less than 20 ppm at lambda 3.2. Furthermore, the steady-state engine-out emissions show near-zero carbon emissions at all operating conditions.

Mohamed, Mohamed, Roeinfard, Nima, Wang, Xinyan, Zhao, Hua, Watts-Farmer, Archie, Rahman, Nadiur, Lempp, Francis

In-Situ Raman Measurements of Fuel Dilution of Lubricant Films in a Direct-Injection Spark-Ignition Engine

2026-01-0355

4/7/2026

To measure the fuel proportion within the lubricant film, an in-situ Raman spectroscopy technique was employed in a specially modified single-cylinder direct-injection spark-ignition engine. The engine block was engineered for optical access with a fused silica window, enabling a focused laser beam to probe the lubricant film on the engine liner under motoring conditions. The lubricant used was GTL8 base oil with ZDDP additive, and iso-octane was injected as a model fuel to study fuel-lubricant mixing. A calibration curve was established by recording Raman spectra of known mixtures of GTL8 oil and iso-octane. The Raman intensity ratio of the iso-octane peak to the oil peak was used as a quantitative indicator of fuel concentration. During engine operation, Raman spectra were acquired in real time, on a cycle-by-cycle basis, through the optical window. Upon iso-octane injection, its characteristic Raman peak appeared in the spectrum, and the intensity ratio was referenced against the calibration curve to estimate the fuel proportion within the lubricant film. Experimental results demonstrated that the iso-octane signal could be detected during and after injection and this allowed for real-time monitoring of fuel dilution dynamics. The main challenge encountered was high fluorescence from oil, which sometimes obscured the Raman peaks and complicated quantification. Despite this, the technique successfully demonstrated the feasibility of direct, in-situ, and real-time quantification of fuel dilution in engine lubricant films, providing a valuable tool for studying fuel-lubricant interactions under operating engine conditions.

Bolle, Bastien, Augoye, Kobi, Wong, Janet, Aleiferis, Pavlos, Hall, Jonathan, Bassett, Mike, Cracknell, Roger

Numerical Study of Gasoline Direct Injection Sprays at Conditions Relevant to Engine Cold-Start Operation

2026-01-0338

4/7/2026

Gasoline direct injection (GDI) remains a key technology for enhancing engine efficiency and meeting regulated engine-out soot limits, particularly when combined with downsizing and boosted operation. The performance of modern GDI engines strongly depends on the in-cylinder spray process, which governs mixture formation and combustion quality under a wide range of operating conditions. In this context, computational fluid dynamics (CFD) is an effective tool for supporting the design and operation of an engine. However, accurately modeling a spray’s evolution —from early to late injections and across varying ambient conditions —remains a major challenge. This study employs a CFD framework with an optimized spray modeling approach to investigate spray morphology and dynamics under various engine cold conditions. Although all simulations are conducted with a single-injection setup, the early- and late-injection cases are designed to emulate different phases of split-injection operation by adjusting the injection duration as well as the ambient pressure and temperature conditions. The analysis spans injection pressures from 100 to 300 bar, incorporating detailed comparisons of two-dimensional projected liquid volume distributions and liquid volume fraction footprint at 15 mm downstream. The results reveal that under late-injection conditions, high pressure suppresses spray penetration, high temperature accelerates evaporation, and increased injection pressure enhances atomization and evaporation. Deviations between the nominal drill angle and the actual plume direction are identified, consistent with the narrower plume orientations observed experimentally. Overall, this work demonstrates the effectiveness of the current CFD framework, with optimized spray modeling, in capturing realistic spray momentum evolution across various engine-relevant operating conditions.

Lien, Hao-Pin (Paul), Torelli, Roberto, Zhao, Le, Park, Ji-Woong, Zhang, Anqi, Pei, Yuanjiang, Hwang, Joonsik, Lee, Kyungwon

Study of Deposit Control Additive Efficacy in Gasoline Direct Injection Engines

2026-01-0349

4/7/2026

There is an increasing adoption of Direct-Injection Spark-Ignition (DISI) engines in the market, which per 2024 US Environmental Protection Agency (EPA) Automotive Trends Report represents 73% of new vehicles sold in the US. And while it is well accepted that DISI offers advantages over Port Fuel Injection (PFI) technology in meeting stringent CO2 emissions and fuel economy requirements set by the EPA, DISI engines are also associated with increased formation of injector deposits. These deposits may foul injectors and accumulate on the injector tip causing distorted spray patterns and diffusive combustion. Ultimately, this leads to engine performance deterioration and increased harmful emissions. To control deposit formation, detergent-type chemistries are added to the fuel in small amounts. Deposit Control Additives (DCAs) function by preventing the formation of deleterious injector deposits as well as removing existing ones. This study used standardized protocols describing the assessment of DCA in controlling injector deposits that have been developed by industry in both the US and Europe. When used at standard concentrations, DCA showed some engine performance and emission benefits over untreated base fuel. This investigation also demonstrated that engine performance can be recovered, in an engine with fouled injectors, with the use of higher DCA concentrations, accompanied by improved fuel economy and reduced particulate and total hydrocarbon emissions. This further confirms previous findings that, although DCA increases gum levels in the fuel, higher concentrations of DCAs improve injector cleanliness enough to outweigh any negative impacts from the increased gum content.

Soriano, Nestor, Williams, Rod, Cracknell, Roger, Lang, Wendy, Chahal, Jasprit

The Influence of Split Injection Ratio on Efficiency and NO _x Emissions in a Pilot Diesel-Ignited Hydrogen Direct Injection Engine

2026-01-0329

4/7/2026

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 consistently achieved a 17.2% increase over the diesel baseline. While CO2 emissions remained at a very low level due to high substitution of hydrogen energy, they showed no dependency on the split ratio. By contrast, NOx emissions were highly sensitive to the hydrogen injection split ratio. Increasing the first hydrogen injection fraction to 30% reduced NOx, attributed to decreased locally rich mixtures formed by late second hydrogen injection and increased lean mixture homogeneity from early first hydrogen injection, leading to a slower burning effect. However, further increasing the first injection fraction led to higher NOₓ emissions due to increased hydrogen compression, which raised TDC and combustion pressure.

Zhao, Yifan, Chan, Qing Nian, Kook, Sanghoon

Analysis of In-Cylinder Flow for Hybrid Gasoline Engine using High-Speed Particle Image Velocimetry

2026-01-0298

4/7/2026

To increase the thermal efficiency of a hybrid inline 4-cylinder direct injection engine, combustion promotion was carried out by enhancing the in-cylinder flow. The intake port and piston top shape were optimized using CFD. In-cylinder flow analysis in steady flow showed that the mean steady flow tumble ratio with the in-cylinder flow enhancement specification increased to 1.7 compared to 1.0 with the previous model and 1.4 with the early development specification. The limit engine speed, which is the engine speed at when the mean flow coefficient decreases due to the choke, and the mean steady flow tumble ratio with the in-cylinder flow enhancement specification were positioned on the trade-off line between the NA and the TC engine. In-cylinder flow analysis on the single-cylinder optical engine showed that the in-cylinder flow entering the cylinder smoothly flowed to the exhaust side, and the in-cylinder flow descending on the exhaust side was smoothly converted to the upward flow by the piston top. Thus, the tumble ratio with the in-cylinder flow enhancement specification in the latter half of the compression stroke increased from 1.0 to 1.7 compared to the early development specification. Turbulent analysis was performed by applying the time filter method, a turbulence decomposition method proposed by the authors, to the in-cylinder flow field. The turbulent kinetic energy with the in-cylinder flow enhancement specification in the latter half of the compression stroke increased by 21.9%. The flame structure was located in the corrugated flamelets region on the turbulent premixed diagram, and the combustion promotion effect by in-cylinder flow enhancement was expected. Evaluation of combustion characteristics on the metal engine showed that the initial combustion duration with the in-cylinder flow enhancement specification decreased by 2.3 deg., the main combustion duration decreased by 4.4 deg., and the time loss decreased by approximately 2%. Therefore, the indicated thermal efficiency increased from 41.9% to 42.2%, proving the concept of combustion promotion by in-cylinder flow enhancement.

Okura, Yasuhiro, Urata, Yasuhiro

Experimental Study on the Effect of Ignition Strategy on Combustion and Emissions in a Direct Injection Hydrogen Engine

2026-01-0330

4/7/2026

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 effectively halved NOx at low load without compromising torque. Increasing spark energy reduced ignition delay by up to 23% and shortened combustion duration by 2–4 °CA at low load, resulting in a torque increase from 48 to 60 N·m; however, the benefits diminished with increasing load. Additionally, higher spark energy led to a moderate NOₓ rise, particularly under medium load. These findings offer valuable insights into the optimization of ignition strategies for H₂ICEs, providing a foundation for improving combustion efficiency while minimizing emissions in zero-carbon hydrogen-powered engine systems.

Zhao, Keqin, Lou, Diming, Zhang, Yunhua, Fang, Liang, Tan, Piqiang, Hu, Zhiyuan

Model-Based Development of a Heavy-Duty H ₂ -ICE and Integrated, Turbogeneration, Electrification, and Supercharging (ITES) System

2026-01-0426

4/7/2026

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 injection (PFI) lean H2 SI combustion system with two-stage turbocharging and no external EGR. The concept was optimized for compression ratio, valve lift profiles, turbocharging, aftertreatment size/specification, and calibration using 1D system simulation in GT-SUITE. In the second phase of this study, the H2-ICE concept performance was further improved by integrating the ITES system and evaluated through 1D simulation. The ITES system replaces the conventional low-pressure stage of the boosting system and adds the capability of electrically assisted turbocharging, turbogeneration from exhaust energy, and P1 mild-hybridization. Applying a model-based approach, the H2-ICE & ITES component sizes were optimized for the best performance and emissions benefit. Using 1D simulation of validated models, the efficiency benefit of the ITES system on engine and vehicle level system was predicted. Finally, a vehicle level simulation was conducted comparing the fuel consumption between a conventional advanced boosting system H2-ICE concept and H2-ICE+ITES concept for Class 6-7 medium heavy duty truck application.

Bustamante, Oscar, Correia Garcia, Bruno, Joshi, Satyum, Franke, Michael

How higher-quality gasoline keeps modern engines CLEAN AND EFFICIENT

26AUTP03_03

3/1/2026

Gasoline direct injection (GDI) engines are the most common technology on American roadways in 2025, and soon, an industrywide gasoline quality standard will better reflect their unique operational needs. Here's why that's important. It's no secret that fuel economy has been one of the greatest driving forces of automotive evolution over the past several decades. As corporate average fuel economy (CAFE) standards have grown increasingly lofty, OEMs eke out new efficiencies from every area of the vehicle. One of those areas, of course, is the engine, and many OEMs have deployed gasoline direct injection (GDI) technology, which is becoming the most common engine technology on American roadways. But while GDI engines proliferate, varying fuel additization throughout North America has not necessarily kept pace with their unique needs and can, in fact, hinder those engines from meeting and sustaining their full fuel economy potential.

Blackburn, Brett

Influence of Lubrication Oil on Hydrogen Fuel-Share Combustion in a Conventional Medium-Speed Marine Diesel Engine

2026-01-5014

2/23/2026

Carbon-free fuels present a potential solution for achieving climate-neutral operation of marine engines. However, their availability is minimal at the moment, though a steady increase can be expected in the coming years. During this transition phase, engine concepts that offer conventional diesel operation and a partial blending of alternative fuels to substitute diesel become interesting. This can be achieved, for example, by blending hydrogen in the intake air of a diesel engine, known as hydrogen fuel-share. Due to the high reactivity of hydrogen, its use in engines is limited by abnormal combustion phenomena (e.g., pre-ignition, knocking combustion), which current research on pure gas engines has shown to be strongly promoted by lube oil reactivity. Building on these fundamental investigations, this paper examines the influence of lubricating oil on the combustion characteristics of a H2 fuel-share medium-speed diesel engine and quantifies the potential to increase the hydrogen share using a less reactive engine oil. For this purpose, single-cylinder engine tests were conducted and supported by 0D/1D simulations with GT-Power and Cantera. The engine was configured as a conventional medium-speed marine diesel, equipped with a hydrogen port fuel injection (PFI) system on the cylinder head. A thermally stable ester-based gas engine oil was used for reducing reactivity compared to a state-of-the-art mineral diesel engine oil. The results show reduced auto-ignition tendency during compression and a mitigation of backfire. An increase in average effective CO2 reduction of up to 17 percentage points is demonstrated, resulting in a total CO2 reduction of 39% on a standard load profile for main propulsion engines. These findings highlight that the choice of lubricating oil can play a key role in increasing the hydrogen share in H2 fuel-share diesel engines, thereby supporting the transition toward climate-neutral propulsion concepts.

Achenbach, Tobias, Meinert, Robert, Mahler, Kay, Kunkel, Christian, Rösler, Sebastian, Prager, Maximilian, Jaensch, Malte

CFD Simulation of Combustion and Emission Characteristics of Pure Spirulina Microalgae Biodiesel in a Single-Cylinder DI Diesel Engine

2026-28-0043

2/12/2026

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 blends compared with pure diesel, supported by enhanced cylinder pressure development. Diesel-RK simulations indicated that Spirulina biodiesel blends (B20) generally improved brake thermal efficiency at higher compression ratios while increasing brake specific fuel consumption due to their lower calorific value. Emission analysis showed consistent reductions in CO, HC, and smoke capacity with higher biodiesel content, while NOx emissions exhibited a rising trend. The findings confirm Spirulina biodiesel (B20) as a viable renewable fuel and highlight simulation-driven strategies for optimising compression ratio and injection timing in CI engines..

Kumar, B Varun

Enhancing Combustion, Performance and Emission Profiles Using Kapok Methyl Ester Blends with Hydrogen

2026-28-0058

2/12/2026

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 calorific value. Additionally, higher viscosity of the blends resulted in increased BFSC. However, the introduction of hydrogen and the K20H fuel blend demonstrated notable emission improvements compared to conventional diesel, achieving reductions of 9–11% in unburned hydrocarbons, 5.3% in carbon monoxide, and approximately 8% in nitrogen oxides (NOₓ). These findings highlight the potential of K20H as a cleaner alternative fuel.

Anbarasan, B, M, Kumaresan, Balamurugan, S, Rajesh, Munnusamy

Research on Active Predictive Speed Control of Dual-Fuel Engine for Hardware Real-Time Applications

03-19-01-0004

2/9/2026

The present article proposes an active observation speed prediction control algorithm architecture for embedded applications, with the aim of addressing the problems of complex operating conditions, strong perturbations, and high control real-time requirements of high-pressure direct injection (HPDI) dual-fuel engines. A nonlinear speed prediction model with diesel and natural gas injection mass as inputs has been established, and the nonlinear model predictive control (NMPC) method is used to realize the optimized control of engine speed. In order to enhance the operational efficiency of the algorithm on the embedded platform, a system has been developed that includes an event triggering mechanism and a warm-start strategy. These mechanisms work in tandem to dynamically adjust the computation cycle. Additionally, a torque reduced-order expansion state observer (RESO) has been integrated to improve the accuracy of perturbation estimation and computational efficiency. The model-level experiments and hardware verification were carried out under the sudden load change operating condition and World Harmonized Transient Cycle (WHTC) test, respectively. The simulation results demonstrate that the proposed optimization strategy can effectively reduce the peak-to-peak value of speed control error to 118.73 rpm and shorten the stabilization time to 3.48 s. Furthermore, the tracking accuracies of the controller on the speed and torque targets in the hardware test reach 0.994 and 0.997, respectively, thereby substantiating the high accuracy and robust performance of the proposed algorithm.

Yang, Xinda, Li, Yunhua, Chen, Dongdong, Li, Yao, Zhang, Shutao, Zhao, Feiyang, Yu, Wenbin

Potential of a Hydrogen Fuel-Share Combustion Concept for a Conventional Medium-Speed Marine Diesel Engine

2026-01-5007

2/2/2026

To meet the International Maritime Organization’s (IMO) short-term greenhouse gas (GHG) reduction targets, partial decarbonization of the existing fleet, often powered by medium-speed diesel engines, is required. One approach for reducing CO2 emissions is to enrich the charge air with hydrogen to substitute diesel. However, hydrogen’s high reactivity can lead to combustion abnormalities such as backfire, pre-ignition, and knocking, thus limiting the feasible admixture rates. These challenges are particularly relevant in medium-speed diesel engines designed for high power output and efficiency at low rpm. While hydrogen fuel-share has previously been tested in small-bore engines at moderate loads, this study investigates the influence on combustion and achievable hydrogen admixture rates in a medium-speed, 4-stroke diesel engine operating with up to 30 bar net indicated mean effective pressure (net IMEP). To minimize retrofitting efforts and to preserve diesel performance, the investigations were conducted on a single-cylinder engine with representative design features of a conventional diesel engine: a high compression ratio, Miller valve timing, valve overlap, and a piston with deep valve pockets. The piston ring system is suited for heavy fuel oil (HFO) operation. Hydrogen was supplied via a port fuel injection (PFI) system. 0D/1D process simulations supplement the experimental data. Findings indicate that energetic hydrogen admixture rates of up to 43% are achievable at low loads, limited by an advancing start of combustion, and up to 15% hydrogen share at high loads, constrained by backfire. This results in an average CO2 reduction of ~22% on the E2 cycle for constant-speed main propulsion engines. Due to rising NOx emissions, the results are only applicable when meeting IMO Tier II limits with selective catalytic reduction (SCR). The results demonstrate that conventional medium-speed diesel engines are suited for hydrogen fuel-share operation and that CO2 reductions comparable to liquid natural gas (LNG) conversions are feasible.

Achenbach, Tobias, Meinert, Robert, Mahler, Kay, Kunkel, Christian, Rösler, Sebastian, Prager, Maximilian, Jaensch, Malte

Rolls-Royce pursues pure methanol for marine engines

26TOFHP02_05

2/1/2026

Rolls-Royce has successfully tested the world's first high-speed marine engine powered exclusively by methanol on its test bench in Friedrichshafen, Germany. The company began this engine-development journey six years ago when it gathered experts to determine what the future fuel of the maritime industry should be, according to Denise Kurtulus, senior vice president of global marine at Rolls-Royce. “For us, it's clear. It's methanol,” she said. Rolls-Royce worked with industry partners as part of the joint project meOHmare, which is funded by the German Federal Ministry for Economic Affairs and Energy. Injection system specialist Woodward L'Orange and the WTZ Roßlau technology and research center contributed their expertise. Their goal was to not only develop a comprehensive concept for a CO2-neutral marine engine based on green methanol, but also to run it on the test bench by the end of 2025.

Gehm, Ryan

Increasing the Efficiency of Hydrogen Direct Injection Internal Combustion Engines through the Use of Miller Cycles and Water Injection

03-19-01-0001

1/31/2026

Hydrogen-fueled reciprocating engines typically feature reasonable efficiencies and low engine-out emissions but low power density, compromising their utility and economics. Previous hydrogen engine research has found efficiency and anti-knock benefits when using either Miller cycles or water injection. This article therefore studies, for the first time, a directly injected (DI), spark-ignited, heavy-duty, turbocharged and hydrogen-fueled engine operated with both Miller cycles and water injection. Miller cycles, with either early or late intake valve closure, and water injection combine to achieve high engine efficiencies approaching 50%, which is significantly higher than the same engine with standard valve timing. The increased susceptibility of hydrogen autoignition in these Miller cycles is overcome by water injection, which simultaneously increases the charge density, counteracting both lean-burn hydrogen’s and Miller cycles’ commonly observed power loss. This demonstrates that the combination of DI, Miller cycles, and water injection is a pathway toward highly efficient, low-emission, hydrogen-fueled engines with power densities that are comparable to conventional engines.

Mortimer, Joel, Poursadegh, Farzad, Brear, Michael, Yang, Yi

Establishing a High-Pressure Direct Injection Hydrogen Engine Test Facility with Integrated Ammonia Fuel Capability: Technical Considerations, Safety Framework, and Best Practices

2026-26-0267

1/16/2026

The transition toward zero-carbon propulsion technologies has highlighted the urgent need for specialized test infrastructure to support hydrogen and alternative fuel research. This paper presents the conceptualization, design, and operation of a High-Pressure Direct Injection (HPDI) Hydrogen Internal Combustion Engine (H2 ICE) test facility with integrated ammonia fuel testing capability, marking a significant advancement in India’s sustainable automotive research efforts. Drawing from practical experience, it outlines crucial technical specifications, safety protocols, and best practices for establishing robust, adaptable, and secure testing environments. Addressing the industry’s need for dedicated infrastructure, it is engineered for adaptability across various engine types including heavy-duty, light-duty, and multi-utility vehicles while aligning with global technical standards. Key technical considerations include a transient dynamometer with an advanced automation system for precise control of both hydrogen and ammonia test cycles. Emission measurement systems such as hydrogen analyzer, ammonia-specific FTIR, particle number counter, and particle size distribution analyzer, are essential for analyzing regulated and unregulated emissions that are critical to sustainable fuel development. The hydrogen fuel storage and distribution system support up to 500 bar pressure, incorporating certified components. Three distinct supply lines operating at 350 bar (for HPDI), 100 bar (for Low Pressure Direct Injection), and 20 bar (for Port Fuel Injection) to accommodate diverse engine configurations. A separate ammonia delivery system ensures dual-fuel testing while addressing its specific chemical and safety needs. Safety remains a cornerstone of the facility's design due to hydrogen’s flammability and ammonia’s toxicity. Essential measures include a high-capacity ventilation, ATEX-rated electricals, real-time gas detection, inert-gas fire suppression, remote monitoring using CCTV, thermal imaging and acoustic sensors. The facility serves as a benchmark for hydrogen and ammonia ICE research in emerging markets, providing practical insights, and technical recommendations and guidance for aligned infrastructure development in support of a zero-carbon mobility future.

Dhyani, Vipin, Kurien, Caneon, Subramanian, Balaji, Khandai, Chinmayananda, Muralidharan, M

Performance and Emission Characteristics of a Lean-Boosted Direct Injection Hydrogen Combustion System for Retrofitting Heavy Duty Diesel Engines

2026-26-0268

1/16/2026

To address the imperative for decarbonizing the heavy-duty transport sector and advancing sustainable energy solutions, this paper presents a novel lean-boosted Direct Injection (DI) Hydrogen Internal Combustion Engine (H2 ICE) combustion system. This system is developed to retrofit existing flat-deck Diesel engines, offering a viable pathway towards drastically reduced emissions. Building on consolidated expertise from prior production-oriented Port Fuel Injection H2 engine development (DUMAREY 6.6ℓ V8), this research focuses on leveraging the distinct advantages of DI for hydrogen. An experimental assessment, supported by 1D and 3D-CFD analyses, demonstrates the system's capability to achieve highly efficient operation in Spark Ignition (SI) mode under ultra-lean and EGR-diluted conditions. The study confirms the elimination of combustion anomalies such as backfiring, pre-ignition, and knock, while achieving ultra-low engine-out NOx emissions and near-zero CO2, HC, CO, and PM. The authors discuss the optimization of key combustion drivers and the beneficial effects of dilution strategies. The findings reveal the significant potential of this DI H2 system, particularly when applied to the swirling cylinder head designs typical of common Diesel engines, to facilitate a rapid and cost-effective transition to cleaner freight mobility. Additionally, a specific flat-deck based tumble motion design has been investigated as a mixing improver versus swirl design, showing further margin for enhancing efficiency and effectiveness of the combustion process.

Gessaroli, Davide, Golisano, Roberto, Pesce, Francesco, Boretto, Gianmarco, Accurso, Francesco

Development of a Passive Regeneration Diesel Particulate Filter System for an Agricultural Tractor Engine

2026-26-0217

1/16/2026

This paper presents the development and evaluation of a passive regeneration Diesel Particulate Filter (DPF) system for a 4-cylinder, 3.18-liter naturally aspirated agricultural tractor engine based on the mDI engine family. The primary objective is to significantly reduce particulate matter (PM) emissions while maintaining optimal engine performance and fuel economy. The passive regeneration DPF system leverages the engine's operating conditions to generate sufficient heat for the oxidation of trapped particulate matter, eliminating the need for active regeneration techniques. The paper details the design process, including the selection of DPF material, filter geometry, and integration into the exhaust system. Rigorous experimental testing was conducted to assess the performance of the DPF system under various engine load and speed conditions. Results demonstrate substantial reductions in PM emissions without compromising engine power, torque, or specific fuel consumption. This novelty of this work lies in developing a new engine capacity from a legacy engine architecture and then develop the engine from an inline pump fuel injection system to make it compatible for Common rail technology and at the same time integrate a DOC+DPF after treatment system. The development also enhanced the maximum torque capability and improved the noise characteristics of the engine. The work also included developing the engine with two different after treatment system suppliers, two different EGR system suppliers, two different Fuel injection system suppliers and yet meet the engine performance and efficiency requirements. Thus, a legacy Mahindra Engine Platform was successfully made ready for future emission norms without compromising on fuel efficiency and performance requirements of the application.

Maddali, Varun Suman, Jidigonti, Shashank, Kannan, S, Ramesh, Natrajan

Development of above 500 kW Diesel Engine & After Treatment System to Meet CPCB-IV+ Emission Norms

2026-26-0234

1/16/2026

The CPCB-IV+ emission compliance for genset application is applicable with effect from 1st July 2023 as per as per GSR 804(E). The CPCB-II to CPCB-IV+ changeover in very stringent in emission front by almost 90 % emission reduction. It’s a significant advancement in environmentally sustainable powertrain technology. To meet the CPCB-IV+ Emission, combustion development & ATS technology plays an important role. First is the base engine need to optimize enough with combustion & associated parts. Second is the after treatment system which will carry the battle further to the engine emission with minimum margin of 10 % engineering target. This paper present the systematic approach followed to meet CPCB-IV+ emission norms for upgradation of 21 litre TCIC engine for the power range (56 < P ≤ 560). Here the challenge to avoid major changes in the existing CPCB-II FIE recipe & meet the CPCB-IV+ emission with ECU calibration & ATS system calibration with its potential. Here interesting parts unique communication architecture built with genset controller in leading role due to time line constraints. The engine integrates with advanced combustion strategies, improved fuel injections systems, and robust after treatment technology including DOC, DPF & SCR system to significantly reduce NOX, PM, HC & CO Emission. Phase-I (Base engine Calibration): - Baseline engine optimization with existing CPCB-II recipe & ECU calibration feature. Here we have used the 1600 bar rail pressure potential along with optimized fuel timing. The pilot & post injection strategy plays vital role to meet the targeted base engine emission. Phase-II (ATS system selection & its calibration): - To meet the CPCB-IV+ emission norms, stringent limits of NOX, PM introduces in India for genset application. For achieving this a highly optimized after treatment system (ATS) comprising DOC, DPF, SCR, and ASC is essential however our strict target is to avoid the DPF. These strategies collectively help to meet the CPCB-IV+ emission targets with optimum engine performance & fuel economy with potential of ATS architecture and a structured calibration methodology. The DOC enables rapid HC/CO oxidation, while the SCR system, controlled via open-loop urea dosing, achieves >95% NOx conversion. The ASC prevents ammonia slip beyond 10 ppm, ensuring exhaust pipe compliance. This project completed within very low stipulated time month effectively. Phase-III (OBD): - The OBD part of CPCB-IV+ contains the following Check on Torque Reduction & Shutdown Strategy Components wise diagnostic calibration on first proto Report on final diagnostic calibration Phase-IV (Engine Consistency & TA Certification):- Emission consistency trial.

Rane, Vikas, Jagtap, Shailesh, Gothekar, Sanjeev, Pawar, Narendra V, Khedkar, Prasad, Kagade, Samadhan, Kendre, Mahadev, G Bhat, Prasanna, Thipse, S

Experimental Evaluation of Energy and Exergy of Hydrogen, CNG and Gasoline Fuelled High-Speed Spark Ignition Engine

2026-26-0258

1/16/2026

The maximum power is recorded with Gasoline than CNG and Hydrogen fuel. The maximum exergy and energy efficiency is with Hydrogen, followed by CNG and then Gasoline. Hydrogen fuel has a maximum potential to convert into energy. The maximum energy destruction of 48.7kW for gasoline fuel at 3000 rpm and followed by CNG and hydrogen. The maximum entropy generation of 85.5 W/K with Gasoline and 60.72 W/K and 29.39W/K for CNG and hydrogen engine respectively at 10000 rpm. The entropy generation rate increase with engine speed. The highest rate of heat release is from hydrogen fuel, followed by Gasoline and CNG.

Shinde, Apurwa Balasaheb, Kadam, Tushar, karunamurthy, K, SHINDE, DR BALU

Comparitive Study of Hydrogen Internal Combustion Engine Performance for Port Fuel Injected and Direct Injected Technology Routes using 1D Simulation

2026-26-0250

1/16/2026

Hydrogen Internal Combustion Engine (HICE) has the promise of zero carbon solution for the mobility industry. The key beneficiary would be the medium and heavy-duty segment of transportation which are likely to adapt the battery electric or fuel cell electric solution in longer term. This particular segment of engines need high low end torque, peak torque and rated power which cannot be compromised. Additionally, a competitive thermal efficiency w.r.t diesel engines would be advantageous. Direct Injection (DI) of hydrogen gives higher specific power and thermal efficiency as compared to Port Fuel Injection (PFI). This study focuses on the performance characteristics of these technology routes to aid in the HICE development process. Current work involves the use of 1-D thermodynamic simulation using GT-SUITE for modeling the performance of HICE. Both predictive and non-predictive methodologies of modeling the combustion were employed. Initially, the model validation of the PFI engine model was carried out with the HICE baseline experimental data for a heavy-duty commercial truck engine. Subsequently, a DI engine model was created and with similar combustion modeling methodology, the performance assessment was carried out. The study presents all aspects of full throttle performance of both the PFI and DI technology routes for HICE. The simulation results show that DI methodology is advantageous as it gives a minimum of 3 to 5% increased torque as compared to PFI route with the same turbocharging system. Using a DI methodology helps to enhance the volumetric efficiency of the engine unlike PFI where the hydrogen gas displaces air in the intake system. DI strategy is also less susceptible to knocking combustion. Various combustion behavior insights namely, the combustion duration, mass burned fraction, peak combustion pressures and temperatures are also obtained as a part of the study.

Parthiban R, Varun, Karthikeyan, K R, Narayana Reddy, J, Paramasivam, Prakash, Manjunath, M, Kumar D, Kishore, N R, Varatharaj, Suresh, K, G, Yogesh Bolar, Sadagopan, Krishnan, Pandey, Sunil Kumar

Strategic & Frugal Technology Approach to Meet the Stringent CPCB-IV+ Emission Norms

2026-26-0059

1/16/2026

In CPCB-IV+ Emissions regulations NOx & PM are reduced by 90% from CPCB-II limits in the power band 56 < kW ≤ 560. Obvious technology approach adopted by industry to meet this requirement is the introduction of CRDI fuel injection system & DOC+SCR+ASC aftertreatment technology, leading to substantial modifications at both engine & genset level. This result into huge development expenditure, high incremental product cost, timelines and increased total cost of ownership. This paper describes the frugal technology approach to keep development cost, product cost, development time to the minimum using electronically governed, high pressure mechanical fuel injection equipment, with DOC+SCR+ASC without any external thermal management strategy while comfortably achieving target CPCB-IV+ emission levels. This integrated approach also helped in completing the entire development in < 12 months. 1D-thermodynamic & 3D-combustion simulation approach was adopted to predict the engine out emissions and to optimize combustion hardware. This was followed by Virtual Test Bench (VTB) or closed loop HiL system simulation to integrate the engine, after-treatment plant models, actuators, sensors, ECU, ACU, GCU & RMS. In VTB lab, all the corresponding software’s communication was established and most of the NCD functionalities were verified before moving on to the actual test bed activities. The matured dataset from VTB and hardware selected through simulation were further taken up on the engine testbench and engine out calibration. As per the engine out & tailpipe emissions targets and engine out performance conditions, required exhaust aftertreatment was selected through benchmarking, technology potential analysis, which is to be DOC+SCR+ASC and without any external thermal management strategy i.e. intake throttle valve, HC dozer etc. same was taken care by engine out optimization and TC to DOC inlet exhaust gas temperature drop by thermal insulation. Further, DOC+SCR+ASC system was optimized through 1D & 3D CFD simulations for Uniformity index, back pressure, thermal mapping, Urea deposits and SCR conversions prediction etc. After freezing the EATS design, tailpipe/ SCR calibration was carried out. Through this approach CPCB-IV+ emission norms could be met with NOx emissions min. of 50% margin, PM emissions min. of 30% margin. NCD regulations met with single NCD family, while maintaining best in class fuel & DEF consumption levels.

Arde, Vasundhara, Juttu, Simachalam, Kadam, Atit, Gothekar, Sanjeev, Karthick, K, Vandana, Suryanarayana, Thipse, S, Kendre, Mahadev

Combustion Noise Quality Improvement in a Common rail Diesel Engine at Low Idle using Taguchi DOE

2026-26-0329

1/16/2026

Noise quality at idle condition is an important factor which influences customer comfort. Modern diesel engines with stringent emission norms together with fuel economy requirements pose challenges to noise control. Common rail engine technology has advantage of precise fuel delivery and combustion control which needs optimization to achieve the conflicting requirements of noise, emission and fuel efficiency. Engine noise at low idle condition is dominated by combustion noise which depends on rate of pressure rise inside the cylinder during combustion. The important parameters which influence cylinder pressure rise are fuel injection timing, pilot injection quantity and its separation, rail pressure and EGR valve position. The study on effect of these parameters at varying levels demand large no of experiments. Taguchi design of experiments is a statistical technique which can be used to optimize these parameters by significantly reducing no of experiments needed to achieve the desired results. These five CR parameters are varied at five different levels using an L25 Taguchi orthogonal array and noise measurements are conducted. The results of experiment have indicated that rail pressure has the highest effect on noise quality with 5dBA difference between the lowest and highest level of rail pressure. The second most significant parameter is pilot quantity with 3 dBA improvement by introducing pilot injection and the quantity of pilot injection needs to be kept minimum. Main injection timing has the potential of 1dBA and EGR valve position and pilot separation has very less influence. Engine calibration is optimized based on above inputs to meet the emission requirements and with the optimized calibration noise is improved by 5dBA at low idle

P, Priyadarshan, Chavan, Amit, A, Kannanswamy, Patil, Sandeep, Chaudhari, Vishal V

Technologies and Strategies for High Brake Thermal Efficiency Gasoline Engine to Meet the Future CO ₂ Emission Targets in India

2026-26-0072

1/16/2026

The Indian automobile industry is experiencing a significant shift, propelled by environmental necessities and national climate obligations set at the CoP26 summit, aiming for a 45% decrease in CO₂ emissions by 2030 and reaching carbon neutrality by 2070 [1]. Transportation continues to be a significant source of air pollution; consequently, India is enhancing its regulatory frameworks with BS VI Stage 2 regulations, CAFE Phase III norms set for 2027, and CAFE Phase IV by 2032 [2]. Furthermore, the transition from MIDC to WLTP driving cycle is meant to increase the accuracy of the efficiency and emissions assessments [2]. To comply to these upcoming regulations, the automotive industry is moving toward producing high efficiency engines in India. A naturally aspirated (NA) 1.5L, 4-cylinder inline gasoline engine was selected from Indian market for this study. Maximum Brake Thermal Efficiency (BTE) of this engine is around 37%. Assessment of new technologies were performed by implementing them stepwise to see the impact on BTE. A well calibrated 1D GT-SUITE model was considered from FEV database to perform the simulation-based approach to increase the BTE by improving the stroke/bore (s/B) ratio, increasing the compression ratio, implementing Atkinson cycle with variable valve timing (VVT) / variable valve lift (VVL) optimization, and charge motion refinement for optimal in-cylinder combustion. Low temperature cooled EGR (TEGR < 70°C) and pre-catalyst pick-up distributed EGR strategies were simulated to improve the combustion stability and pumping loss for BTE improvement. Friction losses were further minimized by implementing the polished surfaces, electrification of auxiliary components, and other advanced surface treatments. Advanced technologies including Dual Port Fuel Injection (Dual PFI) system, high energy ignition system with thermal swing coatings, and system designed to operate with highly diluted mixture are required to achieve maximum BTE. These technologies would also be explored in this study. This paper also covers the rivals' restrictions put on engine geometry and number of cylinders concerning possible max. BTE level with which the engine can achieve. With the completed study, the efficiency step walk document indicated BTE improvement from each technology step to achieve a target max. BTE for the engine.

Garg, Shivam, Fischer, Marcus, Emran, Ashraf, Jagodzinski, Bartosch, Franzke, Bjoern

1D Simulation Approach for Common Rail Injection Systems for a Marine 2 Stroke Diesel Engine

2026-26-0395

1/16/2026

This study presents a comprehensive 1D simulation approach of an automotive solenoid-based diesel fuel injector and a common rail injection system for a marine engine using Simcenter AMESim. The injector model was developed to analyse the injection rate and total injected fuel at various solenoid actuation durations (1.2 ms and 2.0 ms) and common rail pressures. The experimental results from a well-established research study are used for validating the simulation results of the solenoid-based injector. Overall error in total fuel injected ranges from -6.14 percent to 1.93 percent, while timing errors for the start of injection vary from 1.7° crank angle (CA) to 0.08° CA and the end of injection from 2.8° CA to 0.20° CA at 1200 rpm demonstrating strong agreement at higher rail pressures (above 1000 bar) and solenoid actuation times. Building on this validated injector model, a detailed marine common rail system was developed incorporating key hydraulic components: a check valve to maintain pressure inside the rail, flow limiting valves to prevent overpressure in the fuel injector, and a combination pressure relief valve. The simulation was used to study rail pressure dynamics at 50 percent of the engine load for varying rail lengths, diameters, and injector flow rates. The experimental results for the common rail pressure test match closely with the simulated common rail pressure dynamics. Parametric studies reveal sensitivity of rail pressure to geometric variations, which in turn influence injection characteristics. The developed model serves as a useful tool for assessing design changes in high-pressure injection systems and optimizing performance in marine engine applications.

Bhoware, Yash, Pise, Uday, Saha, Dipta, Gaikwad, Nilesh

Misfires Detection in Bi-Fuel Engines – A Brief Note

2026-26-0120

1/16/2026

With the expansion of compressed natural gas (CNG) filling station in India, bi-fuel vehicles are gaining popularity in recent times. Bi-fuel engine runs on more than one fuel, say in both CNG and petrol. Hence, the engine must be optimized in both the fuel modes for performance and emissions. However, due to the inherent differences in combustion characteristics: ignition dynamics and fuel properties, they pose a significant challenge in case of detection of misfires. Misfires are caused because of faulty injection systems and ignition systems and incorrect fuel mixture. Accurate detection is essential as misfires deteriorate the catalysts performance and may impacts emission. Misfires (or engine roughness) is calculated from engine crankshaft speed signal. In this study, the effectiveness of crankshaft-based misfires detection method, comparison of misfire signals magnitude in bi-fuel modes and practices developed for accurate detection of misfires is presented.

Thiyagarajan, Abhinav, N, Gobalakrishnan, R, Hema

Development of a CNG-Diesel Dual Fuel Tractor with Mechanical Fuel Injection System

2026-26-0114

1/16/2026

Identification of renewable and sustainable energy solutions remains a key focus area for the engine designers of the modern world. An avenue of research and development is being vastly dedicated to propelling engines using alternate fuels. The chemistry of these alternate fuels is in general much simpler than fossil fuels, like diesel and gasoline. One such promising and easily available alternate fuel is compressed natural gas (CNG). In this work, a 3-cylinder, 3-liter naturally aspirated air-cooled diesel engine from the off-highway tractor application is converted into a CNG Diesel Dual fuel (CNG-DDF) engine. Part throttle performance test shows the higher NMHC and CO emissions in CNG-DDF mode which have been controlled by an oxidation catalyst in C1 8-mode emission test. A comparative performance shows that the thermal efficiency is up to 2% lower with CNG-DDF with respect to diesel. However, it has shown the benefit of 44% in Particulate Matter, while retaining the same NOx + NMHC levels as the baseline diesel engine. The cycle average CO emission has been found to increase by 6%. Average exhaust gas temperature has been found to be lower by up-to 54°C with CNG-DDF. To control the particulate and HC levels of the baseline NA engine, the CNG injection has been confined from 20% to 85% engine loads, across all engine speeds. The peak firing pressure and in-cylinder temperature are lower by ~3% and ~7%, and the SoC got retarded by max 4°CA with CNG-DDF which is in-agreement with drop in thermal efficiency. The outcome from the engine dyno level testing has been successfully validated through the tractor testing.

Choudhary, Vasu, Mukherjee, Nalini, Kumar, Sanjeev, Tripathi, Ayush, Nene, Devendra

Performance Optimization of 2 Cylinder Flex Fuel Engine for Small Commercial Vehicle – A STEP TOWARDS SUSTAINABILITY

2026-26-0119

1/16/2026

Increasing ethanol blending in gasoline is significant from both financial (reducing dependency on crude oil) and sustainability (overall CO2 reduction) points of view. Flex Fuel is an ethanol-gasoline blend containing ethanol ranging from 20% to 85%. Flex Fuel emerges as an exceptionally advantageous solution, adeptly addressing the shortcomings associated with both gasoline and ethanol. Performance optimization of Flex Fuel is a major challenge as fuel properties like knocking tendency, calorific value, vapour pressure, latent heat, and stoichiometric air-fuel ratio change with varying ethanol content. This paper elaborates on the experimental results of trials conducted for optimizing engine performance with Flex Fuel for a 2-cylinder engine used in a small commercial vehicle. To derive maximum benefit from the higher octane rating of E85, the compression ratio is increased, while ignition timing is optimized to avoid knocking with E20 fuel. For intermediate blends, ignition timing is suitably interpolated. Fuel injection pressure is increased to address the higher fuel flow requirement, and a fuel heater is added to address cold starts with E85 fuel. Ethanol content detection is done through software, and by suitable interpolation, fuelling and ignition timing are optimized for the entire range of Flex Fuel in a single calibration file. Engine performance with E20 & E93 fuel is optimized considering all mechanical and thermal limits of the engine through various iterations. The experimental results are analysed using the first principle method.

Kulkarni, Deepak, Malekar, Hemant A, Upadhyay, Rajdip, Katkar, Santosh, Undre, Shrikant

Correlation of Particulate Matter Species on Gasoline Direct Injection (GDI) Vehicle with Ethanol Blended Gasoline: Real Drive Emissions based Portable Emission Measurement System

2026-26-0216

1/16/2026

On the way to net zero emissions and to cut the oil import bills, NITI Aayog, Government of India and Ministry of Petroleum & Natural Gas (MoP&NG) has rolled out roadmap for ethanol blending in India during 2020-2025. Also, National Policy on Biofuels – 2018, provides an indicative target of 20% ethanol blending under the Ethanol Blended Petrol (EBP) Programme by 2030. Considering these Government’s initiatives current studies were performed on BSVI compliant gasoline direct injection vehicle on RDE compliant route (Route formulated by Indian Oil R&D Centre) with different ethanol blended gasoline fuel formulations i.e., E0 (Neat Gasoline), E10 (10% Ethanol in gasoline) & E20 (20% Ethanol in gasoline). The study aims to determine the compliance of Conformity Factor (C.F.) for ethanol blended gasoline fuel on Direct Injection gasoline engine. The conformity factors were calculated in each case for CO, NOx & PN using moving window average evaluation method. For reference CO2 characteristics curve, CO2 values were measured over Modified Indian Driving Cycle (MIDC) on chassis dynamometer. The study suggests that the use of oxygenated fuel formulations (E10 & E20) impacts tail pipe emissions in a greater way and without any change in the hardware of after treatment devices of the vehicle tail pipe emissions can be reduced. Paper presents RDE as well laboratory mass emissions data collected. However, all the emission values are well below the typical BSVI/Euro6d limits and the C.F for NOx is also below than stated limit of BS_2.0 IRDE (Indian Real Driving Emissions).

Kant, Chander, Arora, Ajay, Saroj, Shyamsher, Kumar, Prashant, Sithananthan, M, Chakradhar, Dr Maya, Kalita, Mrinmoy

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