Browse Topic: Hydrogen engines

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Analysis of the Indian Patent Landscape on Alternative Fuels with a focus on Hydrogen Fuel Cells and Hydrogen Internal Combustion Engines2026-26-0262To be published on 01/16/2026
This paper presents an analysis of the Indian patent landscape concerning alternative fuels, with a specific focus on hydrogen fuel cells and hydrogen internal combustion engines (H2 ICEs). The study aims to provide insights into the innovation trends, key players, white spaces and technological advancements, in this evolving sector within the Indian context. The study is based on the granted patents and disclosures in the said area, and also focuses on the key problems and solutions. Based on a review of patent publications from January 2024 to March 2025, it was observed that a significant number of patent records pertain to the broader domain of hydrogen internal combustion engine disclosures. Specifically, 540 extended families patent publications were screened focusing on hydrogen internal combustion engine as a domain of disclosure. Further analysis revealed that greater 75 % of applicants were from the industry sector, indicating a strong commercial interest in these
Nikam, Mahesh Suresh, Sutavane, Ila, V, Ajay, Aghav, Yogesh
Performance and Emission Characteristics of a Lean-Boosted Direct Injection Hydrogen Combustion System for Retrofitting Heavy Duty Diesel Engines.2026-26-0268To be published on 01/16/2026
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
Gessaroli, Davide, Golisano, Roberto, Pesce, Francesco, Boretto, Gianmarco, Accurso, Francesco
COMPARITIVE STUDY OF HYDROGEN INTERNAL COMBUSTION ENGINE PERFORMANCE FOR PORT FUEL INJECTED AND DIRECT INJECTED TECHNOLOGY ROUTES USING 1D SIMULATION2026-26-0250To be published on 01/16/2026
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 not likely to adapt the battery electric or fuel cell electric solution in the immediate 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 base 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-Power for modeling the performance of HICE. Both predictive and non-predictive methodologies of modeling the combustion were employed. Initially, the model validation of
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
Data-Driven Modeling for Hydrogen ICE Emission Prediction and ATS Performance Benchmarking2026-26-0386To be published on 01/16/2026
This study presents a novel methodology for benchmarking Hydrogen Internal Combustion Engine (H2E) emissions against diesel vehicle configurations, emphasizing Real-Drive Emission (RDE) test procedures. By leveraging Artificial Neural Networks (ANN) and Long Short-Term Memory (LSTM) models, emission profiles for legal cycles and RDE scenarios are predicted. Integrated data pipelines and physics-based modeling enable virtual evaluations of Selective Catalytic Reduction (SCR) system performance, ammonia dosing accuracy, and exhaust temperature dynamics. Key results demonstrate high prediction accuracy across models, including temperature (R² > 0.94, RMS error <25°C), air flow (92% accuracy, RMSE = 28 kg/h), upstream NOx (93% accuracy, RMSE <10 mg/s), and SCR (TP NOx accuracy = 85%, dosing accuracy = 90%). This approach significantly reduces the need for extensive on-road driving tests, as the model performs most of the work, thereby lowering development costs and supporting OEMs in
S, Manoj Kumar, Shah, Jash Vipin, Ratnaparkhi, Aditya, H, Shivaprakash
Design Optimization of Hydrogen Engine Vanity Cover for PSHA Compliance using CFD leakage analysis2026-26-0263To be published on 01/16/2026
Abstract: The integration of hydrogen (H2) as a fuel source in internal combustion engines (ICE) necessitates stringent design measures to mitigate leakage risks and ensure operational safety. This study focuses on the design optimization of vanity cover for hydrogen engines which only serves the purpose for hiding fuel system, wire harness & engine aesthetic else there is no engineering function like sealing, load factor associated with it. This paper addresses the challenges and risks of using Vanity cover on Internal combustion engines, if fuel joints inside the cover start leaking and forms hydrogen cloud which if not ventilated or diluted properly will have safety risk considering low ignition of hydrogen. Computational fluid dynamics (CFD) analysis is carried out to assess and control hydrogen leakage through fuel rail connections, injector interfaces and associated high pressure fuel system components. Detailed modelling of hydrogen flow behavior, diffusion characteristics of
Veerbhadra, Swati Ashvinkumar, Sahu, Abhay Kumar, Singh, Rahul
COMPUTATIONAL STUDY OF HYDROGEN BASED SCR TECHNOLOGY AS AN ALTERNATIVE TO UREA SCR IN HYDROGEN-FUELLED ENGINES2026-26-0213To be published on 01/16/2026
Air pollution from vehicle exhaust emissions is a growing issue in major cities around the world. Hydrogen is a clean and carbon-free fuel that presents a promising alternative to the fossil fuels. However, despite its environmental advantages, hydrogen internal combustion engines still produce some nitrogen oxides as a by-product due to high combustion temperatures. This study investigates the effectiveness of current exhaust after-treatment technologies designed to reduce NOx emissions in hydrogen-powered engines. A comparative analysis is conducted between the conventional urea-based selective catalytic reduction used in diesel engines and emerging hydrogen-based selective catalytic reduction technologies for hydrogen engines. The analysis is performed using CFD simulation in ANSYS Fluent, focusing on NOx reduction efficiency and other operational parameters. The results provide valuable insights into the feasibility and effectiveness of hydrogen SCR in achieving reduced NOx
KASHYAP, KESHAV, Khandagale, Anup, Petale, Mahendra
Controls Solutions for Commercial Hydrogen Engines2026-26-0112To be published on 01/16/2026
India’s commitment to carbon neutrality is significantly shaping the future architecture of commercial vehicle powertrains. While the use of CO₂-free technologies such as battery-electric drivetrains has already been successfully demonstrated across various applications, challenges related to limited range and the lack of high-power charging infrastructure continue to hinder widespread adoption, particularly for productivity-critical commercial vehicles. This has shifted the spotlight toward sustainable fuels, which offer the advantage of fast refueling times. Among these, hydrogen internal combustion engines (H₂ ICE) have gained increasing attention in recent years. In regions such as the European Union, the primary motivation for hydrogen is CO₂ reduction. In contrast, for markets like India, hydrogen also presents a strategic opportunity for reducing dependency on fossil fuel imports. Over the past four years, AVL has carried out multiple performance and emission development
Arnberger, Anton, Danninger, Alois, Mannsberger, Stefan, Breitegger, Bernhard
Comprehensive Validation Methodologies for Hydrogen IC Engines: Combustion Analysis and Performance Metrics2026-26-0256To be published on 01/16/2026
The validation of hydrogen-fuelled internal combustion engine (H2 ICE) is critical to assess its feasibility as sustainable transportation with zero carbon emissions. Validation of H2 ICE necessitates a specialized testing & analysis methodologies to achieve reliable test results. This study shows the adverse effects on engine performance due to barometric pressure variation, turbo compressor out temperature variation due to increase in ambient temperature. The analysis also shows experimental results of engine performance variation based on hydrogen gas quality. Charge air quality reduces due to presence of nitrogen and moisture content in hydrogen gas and has direct impact on combustion. Engine Performance variation also observed due to engine components detoriation like valve seat wear & spark plug gap expansion. This study emphasizes the significance of precise instrumentation of thermocouples across engine on cylinder head, intake manifold & exhaust manifold, to detect performance
Vasudevan, Sindhuja, J, Narayana Reddy, Bolar, Yogesh Ganesh, Pandey, Sunil, N, Harish, N R, Varatharaj, Karthikeyan, K, Kumar D, Kishore
Optimising Hydrogen Engine Performance: A Comparative Study of Lean and Stoichiometric Calibration Approach2026-26-0261To be published on 01/16/2026
Hydrogen combustion in internal combustion engines offers numerous advantages, such as zero CO2 emissions and high flame speed, which make it a promising alternative fuel for green vehicle solutions. In order to maximize the engine performance with hydrogen, however, meticulous calibration of the air-fuel mixture must be performed, particularly when lean and stoichiometric combustion conditions are considered. Lean burning, i.e., excess air, offers better thermal efficiency and lower NOx emissions but can cause lower engine power and combustion instability. Stoichiometric combustion, however, ensures a complete fuel-air mixture but at the cost of higher combustion temperature and high NOx emissions. Calibration strategies for hydrogen engines are presented in this paper by comparing the lean and stoichiometric strategies and their implications on engine power output, efficiency, and emissions. Test data from several hydrogen engine configurations demonstrate that lean burn with EGR
Jadhav, Ajinkya, Bandyopadhyay, Debjyoti, Sutar, Prasanna S, Sonawane, Shailesh Balkrishna, Rairikar, Sandeep D, Thipse, Sukrut S
Establishing a High-Pressure Direct Injection Hydrogen Engine Test Facility with Integrated Ammonia Fuel Capability: Technical Considerations, Safety Framework, and Best Practices2026-26-0267To be published on 01/16/2026
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 the use of a transient dynamometer that features an advanced
Dhyani, Vipin, Kurien, Caneon, Subramanian, Balaji, Khandai, Chinmayananda, Muralidharan, M
Experimental evaluation of Energy and Exergy of Hydrogen, CNG and Gasoline fuelled High-Speed Spark Ignition Engine2026-26-0258To be published on 01/16/2026
HIGHLIGHTS 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.   ABSTRACT- The analysis was performed on a single Cylinder, Multivalve, Electronic Fuel Injection, high-speed motor fuelled engine with Gasoline, CNG and Hydrogen to assess energetic and exegetic performance. The engine was evaluated from 3000 rpm to 10000 rpm on each of the three fuels. All tests are led at Wide Open Throttle condition.The Gasoline and CNG
shinde, Apurwa Balasaheb, SHINDE, DR BALU, Kadam, Tushar, karunamurthy, K
3D CFD simulation methodology for safe and efficient hydrogen refueling for hydrogen internal combustion engines2026-26-0252To be published on 01/16/2026
As conventional fossil fuels are on the verge of depletion, the search for alternative fuel for automotive applications has intensified. Among these, hydrogen stands out due to its high energy content per unit mass, high octane number, and compatibility with Internal combustion engines (ICE). However, the volatility of hydrogen (H2) presents challenges, particularly during the refueling process, where uncontrolled temperature rise occurs because of negative Joule-Thomson (JT) effect. This brings an alarming bell for the safety of fueling stations, vehicles and mankind. This paper investigates the physics involved in hydrogen tank filling, focusing on maintaining the hydrogen gas temperature below 85 °C during the process. A 3D Computational Fluid Dynamics (CFD) analysis was performed to model the temperature and pressure behavior of hydrogen during filling. The study provides insights into the optimal fill rates, temperature distribution, and the evolution of peak temperature locations
Khanna, Gourav, Veerbhadra, Swati, Sahu, Abhay Kumar
Total cost of ownership analysis of fuel cell and hydrogen-powered commercial vehicles for cost competitiveness with ICE and BEV2026-26-0254To be published on 01/16/2026
Worldwide, the automotive industry is pivoting towards electrification and zero-emission vehicles (ZEV) to address greenhouse gas emissions and to meet net-zero emission goals. Although pure electric vehicles with rechargeable high-voltage batteries seem to be the most popular choice to achieve climate goals, hydrogen-powered vehicles are also seen by many as a viable technology to clean up the transportation sector. Hydrogen fuel cells and fuel cell-powered vehicles have been in development for a long time, and hydrogen internal combustion engines (ICE) have seen rapid development in the past few years. While the technological feasibility of hydrogen fuel cells and H2 ICE is being proven, mass adoption of these technologies depends, along with other factors such as hydrogen infrastructure, upon financial feasibility as well. This paper presents a systematic analysis of the total cost of ownership (TCO) of hydrogen-powered vehicles, especially fuel cell electric vehicles. Different
Jacob, Joe, Chougule, Abhijeet
Investigation of Active Pre-Chamber Ignition on an Optically Accessible Ultra-Lean DI Hydrogen Engine2025-01-0524To be published on 11/25/2025
Hydrogen is a promising alternative to conventional fuels for decarbonizing the commercial vehicle sector due to its carbon-free nature. This study investigates the ignition and flame propagation characteristics of hydrogen in a 2-liter single-cylinder optical research engine representative of the commercial vehicle sector. The main objective was to enable high power density operation while minimizing NOx emissions. For that, ultra-lean combustion was employed to lower in-cylinder temperatures, addressing the challenge of NOx formation. To counteract delayed and unstable combustion under lean conditions, an active pre-chamber ignition system was implemented. It uses a gas-purged pre-chamber with separate hydrogen injection and spark plug ignition. Turbulent hot gas jets from the pre-chamber ignite the fresh mixture in the main combustion chamber, enabling faster and more stable ignition compared to conventional spark plugs. Additionally, the low volumetric energy density of hydrogen
Borken, Philipp, Bill, Daniel, Link, Lukas, Dinkelacker, Friedrich, Hansen, Hauke
Transient Helium Jet Evolution Using High Speed Schlieren Imaging2025-32-005711/03/2025
The accelerating global shift towards decarbonised energy systems has positioned hydrogen as a highly promising carbon-free fuel. This study comprehensively investigates the macroscopic characteristics and temporal evolution of vortex ring trailing helium jets, serving as a surrogate for hydrogen, injected into a quiescent ambient environment using high-speed Schlieren imaging. This research addresses critical insights into fuel-air mixing dynamics essential for optimising hydrogen direct injection (DI) internal combustion engines. Analysis of helium jet tip’s topology revealed a three-stage evolution from an initial pressure-insensitive phase, dominated by pressure wave structures, to a momentum-driven, vortex-dependent growth stage, then to a fully developed stage. Specifically, the lower-pressure cases showed increased Kelvin-Helmholtz instability and distinct head vortex pinch-off at the final stage. Jet tip velocities transitioned from initial high, rapid pressure wave development
Dong, Shuo, Shi, Hao, Zhang, Gengxin, Feng, Yizhuo, Lu, Enshen, Wang, Xinyan, Zhao, Hua
Clarification of the Mechanism of Abnormal Combustion in Hydrogen Engines -Investigation of Abnormal Combustion Location by Visualization Measurement-2025-32-006411/03/2025
Hydrogen internal combustion engines present a promising path towards carbon neutrality, yet their development is challenged by abnormal combustion phenomena like backfire and pre-ignition. These phenomena limit engine torque and reduce component reliability. This study is aimed to elucidate the mechanisms behind these phenomena in hydrogen internal combustion engines. We utilized a multi-cylinder engine with optical access for direct high-speed imaging of in-cylinder processes to visualize backfire and pre-ignition. Initial analysis, combining visualization data with one-dimensional (1D) simulations, indicated that high temperatures of the ground electrode of the spark plug could be a key trigger factor for abnormal combustion. To investigate this hypothesis, the surface temperature of the ground electrode was measured under firing conditions using a two-color thermometry system. The measurements revealed that the electrode temperature exceeded the compressed gas temperature near Top
Muramatsu, Keiji, Tokuhara, Satoshi, Kadu, Pravin, Yoshimura, Kei, Nakama, Kenjiro
A Study of Knocking Characteristics in a Hydrogen SI Engine under High Compression Ratio2025-32-006311/03/2025
This study investigated the knocking characteristics of a hydrogen spark ignition engine for the purpose of increasing efficiency and expanding the operating range. In recent years, research focused on carbon neutrality has been vigorously conducted, and hydrogen has attracted attention as a next-generation fuel for internal combustion engines (ICEs). The combustion characteristics of hydrogen are vastly from those of existing gasoline. It is essential to have a sufficient understanding of the combustion characteristics of hydrogen in order to develop next-generation ICEs designed to operate on hydrogen fuel. There are especially many aspects of the knocking mechanisms of hydrogen that are unclear. Consequently, those characteristics and mechanisms must be clarified for the purpose of expanding the operating range of hydrogen engines and enhancing their efficiency. In this study, experiments were conducted using a single-cylinder hydrogen engine that was operated at a high compression
Ishihara, Hiromasa, Kishibata, Shunsuke, Miyake, Shota, Iida, Tomoya, Kuwabara, Kenta, Yoshihara, Shintaro, Miyamoto, Sekai, Iijima, Akira
Analysis of Flame Propagation Characteristics in a Hydrogen Engine using an Optically Accessible Engine2025-32-006111/03/2025
This study focused on the effects of hydrogen on the flame propagation characteristics and combustion characteristics of a small spark-ignition engine. The combustion flame in the cylinder was observed using a side-valve engine that allowed optical access. The fundamental characteristics of hydrogen combustion were investigated based on combustion images photographed in the cylinder with a high-speed camera and measured cylinder pressure waveforms. Experiments were conducted under various ignition timings and equivalence ratios and comparisons were made with the characteristics of an existing hydrocarbon liquid fuel. The hydrogen flame was successfully photographed, although it has been regarded as being difficult to visualize, thus enabling calculation of the flame propagation speed. As a result, it was found that the flame propagation speed of hydrogen was much faster than that of the existing hydrocarbon fuel. On the other hand, it was difficult to photograph the hydrogen flame
Arai, Yuto, Ueno, Takamori, Suda, Ryosuke, Sato, Ryoichi, Nakao, Yoshinori, Ninomiya, Yoshinari, Matsushita, Koichiro, Kamio, Tomohiko, Iijima, Akira
Experimental Study of hCNG on Single Cylinder 395cc Spark Ignition Engine for Performance and Exhaust Emission2025-32-005011/03/2025
There is growing demand for energy utilization due to stricter environmental emission norms to reduce greenhouse gases and other threats posed due to the emissions are major motivation factors for researchers to adopt on strategic plans to decrease the usage of energy and reduce the carbon contents of fuels, the usage of hydrogen or blend of hydrogen with CNG as a fuel in internal combustion engines is the best option. As hydrogen has lower volumetric energy density and higher combustion temperature, pure hydrogen-fueled engines produce lower power output and much higher NOx emissions than gasoline-fueled engine at stoichiometric air-fuel ratio. Blending of hydrogen with CNG provides a blended gas termed as hydrogen-enriched natural gas (hCNG). hCNG stands for hydrogen enriched compressed natural gas and it combines the advantages of both hydrogen and methane. The addition of Hydrogen to CNG has potential to even lower the CNG emissions and is the first step towards promotion of a
Syed, Kaleemuddin, Chaudhari, Sandip, Khairnar, Girish, Sajjan lng, Suresh
Effect of In-Cylinder Hydrogen Mixture Formation on Hydrogen Combustion2025-32-006511/03/2025
Global efforts to mitigate climate change include ambitious long-term strategies by countries to achieve net-zero greenhouse gas emissions by 2050. The automotive sector is exploring carbon-free powertrains, with hydrogen emerging as a key technology. Its zero-emission potential positions it for widespread adoption in power generation, transportation, and industry. Hydrogen engines, particularly direct injection engines offering high power and efficiency, are gaining traction due to their adaptability using existing engine components. However, in a hydrogen direct injection engine, achieving proper mixing of hydrogen and air in the cylinder is challenging, making in-cylinder mixture formation a crucial factor for ensuring stable combustion. To predict hydrogen mixture formation in the cylinder, we conducted a Schlieren visualization experiment of the hydrogen jet. Based on the results, a detailed hydrogen jet model for the direct injection injector was developed. This model was then
Hisano, Atsushi, Saitou, Masahito, Sakurai, Yota, Ichi, Satoaki
Development of the Hydrogen Fueled Internal Combustion Engine for Off-Road Applications2025-32-006611/03/2025
This paper focuses on the potential application of hydrogen fueled internal combustion engine (HICE) in the off-road market, examining HICE based on a diesel engine. In the transition to HICE, priority was given to compatibility with existing systems, minimizing changes from the base engine. By adopting a PFI (Port Fuel Injection) method for fuel injection, low-pressure hydrogen supply was achieved. To address the issue of backfire associated with PFI, optimization of injection pressure using a variable pressure control valve, along with adjustments to valve timing and injection timing, was implemented to suppress backflow of residual gases into the intake system and minimize hydrogen retention. Regarding pre-ignition, in addition to suppressing hotspots, the relationship between the homogenization of the air-fuel mixture and NOx emissions was examined, revealing a correlation. This engine was mounted on a generator, and efforts were made to improve the important characteristic of
Shiraishi, Kentaro, Kishi, Shinji, Kato, Daichi, Mitamura, Kenta, Murakami, Kei, Mikuni, Yusuke
Advanced Multi-Fidelity Simulation of Piston Oil Jet Cooling in High-Performance Engines2025-32-008111/03/2025
The development of next-generation hydrogen-fueled engines introduces critical challenges related to thermal loads within the combustion chamber, particularly in high-performance applications. To address the extreme temperatures encountered, effective piston cooling strategies, such as oil jet impingement, are essential. Accurately predicting thermal stresses to prevent component failure is therefore crucial. However, numerical simulations often come with significant computational costs. This paper presents a comprehensive multi-fidelity modeling approach to predict the thermal behavior of pistons under these demanding conditions. The model integrates a simplified 3D thermal representation of the piston, a lumped-parameter mechanical model of the piston-liner assembly, and convective boundary conditions obtained at various levels of fidelity, from high-level Computational Fluid Dynamics (CFD) simulations to literature correlations. Additionally, the study examines the influence of
Sassoli, Andrea, Romani, Luca, Ferrara, Giovanni, Paolicelli, Giovanni, Balduzzi, Francesco
Thermal Management in Electrified Transportation: A Comparative Study of Different Powertrain Technologies2025-28-041210/30/2025
The transition towards sustainable transportation necessitates the development of advanced thermal management systems (TMS) for electric vehicles (EVs), hybrid electric vehicles (HEVs), hydrogen fuel cell vehicles (FCVs), and hydrogen internal combustion engine vehicles (HICEVs). Effective thermal control is crucial for passenger comfort and the performance, longevity, and safety of critical vehicle components. This paper presents a rigorous and comparative analysis of TMS strategies across these diverse powertrain technologies. It systematically examines the unique thermal challenges associated with each subsystem, including cabin HVAC, battery packs, fuel cell stacks, traction motors, and power electronics. For cabin HVAC, the paper explores methods for minimizing energy consumption while maintaining thermal comfort, considering factors such as ambient temperature, humidity, and occupant load. The critical importance of battery thermal management is emphasized, with a focus on
K, Neelima, K, Anisha, Ch, Kavya, C, Somasundar, Satyam, Satyam, P, Geetha
Impact of Oil Composition on Pre-Ignition in a Hydrogen Engine04-18-03-001810/10/2025
Pre-ignition (PI) is a common issue in internal combustion engines (ICE) with spark ignition. While the various causes have been identified with conventional fuels (such as gasoline or gasoline blends), the causes with hydrogen in ICE are not yet fully understood. This article presents the results of investigations into the influence of seven different lubricating oils on PI in a single-cylinder hydrogen research engine. The variation of two different parameters at two engine speeds were investigated: load and air/fuel mixture. For both variations, the tests start at the same conditions and run until the operating limit of the engine is reached (peak firing pressure, or maximum intake manifold pressure). The PI and knocking PI are investigated, while classifying them according to the peak cylinder pressure. It has been observed that enleanment above λ = 2.4 can lead to higher PI rates, while simultaneously reducing the knocking PI. During the load sweep at 2000 1/min, the highest
Pehlivanlar, Benjamin, Torkler, Michael, Fischer, Marcus, Göbel, Christoph, Pischinger, Stefan, Maulbetsch, Theo, Nübling, Fritz, Neumann, Stephan
Developing Custom Engine Test and Solutions for Handling Water in Lubricants for Hydrogen Internal Combustion Engines2025-01-040010/07/2025
Hydrogen internal combustion engines (H2–ICEs) are being evaluated as a potential pathway for lowering the CO2 emissions intensity of the transportation and the power generation sectors as well as off-road applications such as agriculture and construction industry. H2–ICEs offer several advantages to the Original Equipment Manufacturers (OEMs); such as retaining the existing engine architecture and hardware, whilst achieving a lower emissions intensity than diesel engines. Some of the key challenges for the H2–ICEs operation are managing excessive amounts of water build-up in the oil under certain operating conditions and pre-ignition which have significant impact on the engine life and durability. In the current study, the authors developed a custom test cycle using a 7.4-litre 6-cylinder turbo-charged hydrogen engine designed for combined heat and power applications. The test cycle was created with the purpose of accumulating significant amounts of water (hydration phase) in the oil
Bansal, Dinesh, Weimar, Hans-Joachim, Berlet, Peter
Approaches for Mechanical Development and Validation of Hydrogen Internal Combustion Engines2025-01-039810/07/2025
Hydrogen Internal Combustion Engines (H2 ICEs) are seen as a viable zero-emission technology that can be implemented relatively quickly and cost-effectively by automotive manufacturers. The changed boundary conditions of a hydrogen-fueled engine in terms of mechanical and thermal aspects require a review and potential refinement of the design especially for the 'piston bore interface' (liner honing, ring and piston design) but also for other engine sub-systems, e.g. the crankcase ventilation system. The influence of oil entry into the combustion chamber is even more important in hydrogen engines due to the risk of oil-induced pre-ignition. Therefore, investigations of the interaction between friction, blowby and oil transfer into the combustion chamber were performed and are presented in this paper. During the investigations, experimental tests were carried out on a single-cylinder engine ('floating liner') and on a multi-cylinder engine. The 'floating liner' concept allows the crank
Plettenberg, Mirko, Gell, Johannes, Grabner, Peter, Gschiel, Kevin, Hick, Hannes
CFD and FE Toolset for Predicting Structural Temperatures in a Hydrogen Internal Combustion Engine2025-01-038310/07/2025
Hydrogen has been identified as a promising decarbonization fuel in internal combustion engine (ICE) applications in many areas including heavy-duty on- and off-road, power-generation, marine, etc. Hydrogen ICEs can achieve high power density and very low tailpipe emissions. However, there are challenges; designing systems for a gaseous fuel with its own specific mixing, burn rate and combustion control needs, which can differ from legacy products. Being able to determine the thermal distribution and temperatures of the power cylinder components has always been critical to the design and development of ICE. SAE-2023-01-1675 [1] presented an analytical FE-based tool, and validation using both FE and CFD methods for a Euro VI HD Diesel engine converted to operate on hydrogen gas using direct injection. In this study, updated methods and investigations are presented for Hydrogen ICE including applicability of the Woschni heat transfer correlation, use of CFD thermal wall functions and a
Bell, David J., Shapiro, Evgeniy, Turquand d Auzay, Charles, Hernandez, Ignacio, Hynous, Jan, Kohutka, Jiri, Osborne, Richard, Penning, Richard, Tomiska, Zbynek
Water Injection Effects on a Heavy-Duty Hydrogen Spark Ignition Engine2025-24-005009/07/2025
Hydrogen engines have gained interest recently, as they present a promising alternative for decarbonizing heavy-duty transport, aligning with carbon neutrality regulations. This study investigates the effects of inlet manifold water injection on a heavy-duty hydrogen-fueled spark ignition single-cylinder engine, focusing on moderating abnormal hydrogen combustion and its impact on performance, thermal efficiency, and exhaust emissions. Water injection has been identified as a potential solution to mitigate the challenges associated with hydrogen combustion, such as pre-ignition and knock, by reducing the reactivity of the mixture (lowering temperature and increasing the dilution). The lower reactivity of the mixture allows running richer lambdas or higher compression ratios without spontaneous preignition, mitigating boosting requirements for full load and transient performance. Experimental results demonstrate that water injection significantly improves engine performance, thermal
Peñin Garcia, Alfonso Jose, Valls Claramunt, Carles, Rivas, Manuel, Birnstingl, Johannes, Wieser, Martin, Martin, Jaime, Novella, Ricardo
Exploring the Emission Spectrum of Pure Hydrogen Combustion in Spark Ignition Engines: A Comprehensive Experimental Study2025-24-005109/07/2025
Hydrogen internal combustion engines (H2ICE) have shown enormous potential for zero-carbon emissions, aligning with the European zero-carbon targets in 2050. Adopting hydrogen as a zero-carbon fuel offers a time- and cost-effective approach to directly replacing carbon-based and fossil fuel-powered ICEs. The study aims to provide comprehensive data on the H2ICE engine during steady-state operations of a single-cylinder spark ignition engine with a direct hydrogen injection system. It focuses on emissions, including carbon monoxide (CO) and unburnt hydrocarbons (HC), utilising ultra-fast analysers positioned close to the exhaust valves to minimise signal delay. Particulate matter (PM) emissions are also measured to evaluate the potential for zero-carbon emissions from the H2ICE. Additionally, NO and NO2 emissions are analysed against air-fuel ratios (AFR) to estimate combustion temperature and NOx mechanisms. Water vapour and oxygen emissions are captured to assess their quantities
Mohamed, Mohamed, Zaman, Zayne, Wang, Xinyan, Zhao, Hua, Hall, Jonathan
Experimental Study of the Lubricating Oil Impact on the Unsteady Performance of an Automotive Turbocharger2025-24-007809/07/2025
Turbocharging technique is a key technology for the development of hydrogen engines, allowing high lambda values to reach low NOx emissions. In ultra-lean mixture conditions, the thermal management of the lubricating oil and its cold condition becomes a crucial aspect that cannot be neglected. Accordingly, the impact of different lubricating oils and different lubricant thermal conditions is highlighted referring to the performance of a turbocharging system for automotive application. To this aim, an experimental campaign is conducted at the test bench for components of propulsion systems of the University of Genoa. Tests are performed on a turbocharger equipped with a variable geometry turbine under both steady and unsteady flow conditions, considering different positions of the turbine regulating device. A 4-cylinder engine head was coupled to the turbocharger in order to reproduce the pulsating flow related to the opening and closing of the engine valves. The influence of the
Marelli, Silvia, Usai, Vittorio, Cordalonga, Carla
Experimental Assessment of Different NO x Storage Catalysts for Transient Emission Management in DI H 2 Fueled ICE2025-24-007909/07/2025
One of the emerging technologies to effectively decarbonize the transportation sector in the Heavy-Duty and Non-Road segment is the Hydrogen fueled Internal Combustion Engine (H2-ICE). Although completely free of carbon content, and therefore CO2, the H2-ICE exhaust still releases NOx as harmful byproducts of the combustion process. Furthermore, it is well known that H2-ICE NOx emissions are very sensitive to combustion air-to-fuel ratio (λ) and hence are much higher during load increase when λ is lowered (λ<2) to reach the target level of performance. Therefore, to comply with most stringent emission regulations, it is paramount to equip the H2-ICE with an aftertreatment system capable to handle the NOx peaks generated during transient operations with extremely high efficiency. The present work provides indication for the transposition of catalyst formulations well-known for compression-ignited ICE to Direct Injection H2-ICEs for effectively storing and converting NOx within their
Blangetti, Nicola, Pozzi, Chiara, Ciaravino, Claudio, Deorsola, Fabio, Galletti, Camilla
Combustion System Optimization of Commercial Vehicle Hydrogen Engines via 3DCFD Simulations and Single Cylinder Engine Measurements: Injector Cap, Injection Strategy and Intake Duct Design2025-24-000809/07/2025
The development of hydrogen fueled engines has dramatically accelerated in recent years. They have gained much in operating reliability and the specific power outputs is at least comparable to those of current natural gas engines. This has been made possible by combining specific development tools derived from the development of compression-ignition and spark-ignition engines. These include jet visualization techniques (Schlieren, PIV, and LIF), video endoscopy on engine, and 3-D fluid dynamics simulations. In hydrogen engines for commercial vehicles, efforts have so far been made to keep engine components as unchanged as possible from similar diesel or gasoline versions. Similarly, some manufacturers have favored the port fueled injection (PFI) solution because it is easier to implement than the in-cylinder (DI) injection one. The present work concerns the evaluation of the further improvement potential made possible by using direct injection (DI) technology, and intervening on both
Gaballo, Maria Rosaria, Iacobazzi, Marino, Burtsche, Thomas, Cornetti, Giovanni
Combustion Characteristics and Efficiency of a Turbocharged Hydrogen-Fueled Internal Combustion Engine Under Ultra-Lean, High-Load Conditions2025-24-004809/07/2025
The transportation industry seeks sustainable alternatives to fossil fuels, and hydrogen internal combustion engines (H₂ICE) have emerged as a practical solution. They offer near carbon-free operation while integrating with existing engine technology and infrastructure. Thanks to hydrogen’s specific properties, lean combustion can be achieved, significantly reducing NOx emissions. However, operating a commercial engine under ultra-lean conditions at high load presents challenges, particularly in maintaining volumetric efficiency and power density. This study analyzes the combustion behavior, NOx emissions, and loss mechanisms in a four-cylinder, direct-injection, hydrogen-fueled engine, equipped with a variable geometry turbine (VGT). The engine was tested at three BMEP levels (8, 10, and 12 bar) under ultra-lean conditions, with lambda varied between 2.2 and 3.6. Unlike conventional approaches, fuel mass was held constant at each load, and lambda was adjusted by varying intake air
Azizianamiri, Sobhan, Tauzia, Xavier, Maiboom, Alain, Perrot, Nicolas
LES and RANS Modeling of a Hydrogen Low-Pressure Direct-Injection Injector2025-24-006609/07/2025
Hydrogen direct injection is a promising strategy for enabling high-efficiency, low-emission powertrains. However, challenges related to mixture stratification and jet modeling persist, particularly under engine representative conditions. This study numerically investigates a simplified injector model, focusing on the downstream hydrogen jet behavior from of a hydrogen low-pressure direct-injection jet-forming cap under both constant-volume chamber (CVC) and engine conditions. The primary objective is to evaluate numerical methodologies and explore model simplification strategies that remain computationally feasible while preserving physical fidelity—particularly relevant for early-stage hydrogen injector development. Experimental data serve as validation benchmarks across operating regimes. In the CVC platform, large eddy simulations (LES) provide turbulence-resolving insights that inform the refinement of Reynolds-averaged Navier–Stokes (RANS) models. RANS simulations are then
Menaca, Rafael, Liu, Xinlei, Silva, Mickael, Wu, Hao, Ben Houidi, Moez, Mohan, Balaji, Cenker, Emre, AlRamadan, Abdullah, Syed, Iltesham, Pei, Yuanjiang, Roberts, William, Im, Hong G.
Condensate Formation in Exhaust Systems during Cold Start2025-24-008109/07/2025
In order to minimize tailpipe emissions of vehicles with combustion engines, highest conversion rates of exhaust gas aftertreatment systems are indispensable. At low ambient temperatures, gaseous emissions increase due to inhomogeneous mixture formation and incomplete combustion. Simultaneously, formation of condensate on exhaust gas-carrying components is stimulated due to temperatures dropping below the dew point. The acidic condensates contain more than 95 vol.-% water and a small fraction of aliphatic and aromatic hydrocarbons. In acidic environments these hydrocarbons can be polymerized, forming insoluble deposits that become progressively less reactive with time. These deposits may harm components of exhaust systems by fouling. As low temperature conditions are particularly promoting condensate formation, the aim of this study is to investigate condensate formation and composition during cold start and early warm-up phases in the exhaust duct of state-of-the-art internal
Knapp, Sebastian, Hagen, Fabian P., Wagner, Uwe, Bockhorn, Henning, Trimis, Dimosthenis, Koch, Thomas
Development of a Compact Hydrogen Engine for Commercial Applications2025-24-006009/07/2025
As the individual and commercial vehicle industries seek sustainable alternatives to conventional internal combustion engines (ICEs), hydrogen-fueled rotary engines are emerging as a promising solution for several applications. This paper presents an innovative approach for the development of a hydrogen rotary engine that is integrated within a hybrid system. By exploiting the unique characteristics of rotary engines, such as compact size and high power-to-weight ratio, the electric machine, the battery and the rotary engine can be accommodated in the installation space of a conventional ICE with comparable power, despite the reduced power density of hydrogen as a fuel in ICEs. As a first step, the hydrogen engine is naturally aspirated and equipped with direct injection. To develop a suitable calibration for the engine’s application, the influence of calibration parameters such as ignition and injection are investigated. The study examines the influence of these on operating behavior
Endres, Jonas, Beidl, Christian, Hofmann, Silas
Understanding and Qualifying Hydrogen Combustion Related Phenomena for Low-Carbon Mobility2025-24-005709/07/2025
The reduction of the overall greenhouse gas and pollutant emissions from ground vehicles is mandatory to fight against global warming and health issues. Moreover, regarding the increasing demand related to the population growth, the energy requirement for mobility may significantly increase during coming years. Meeting greenhouse gas emission targets is not only about commitment to regulations but also fundamentally about enhancing human well-being. Consequently, the diversification of low-carbon energy sources is of huge interest. The use of Hydrogen (H2) as a sustainable energy source in ground transportation is an alternative or a complementary solution to the full electric vehicles. Hydrogen for mobility can be used in two types of energy converters: The Proton-Exchange Membrane Fuel Cell or the H2 adapted Internal Combustion Engine (H2-ICE). This last has the advantage of its strong maturity with the reuse of existing production infrastructures from conventional ICE and low raw
Laget, Olivier, Bardi, Michele, Quintens, Hugo, Giuffrida, Vincent, Bramoullé, Clément, Sikic, Ivan
A Study on Sensitive Spots in Hydrogen Engines2025-24-005909/07/2025
Premature self-ignitions in hydrogen internal combustion engines have been associated with the presence of hot spots. However, local increases in charge reactivity may be triggered not only by elevated temperatures but also by composition inhomogeneities. Such non-uniformities, in addition to imperfect mixing (e.g., in the case of direct hydrogen injection), may result from external contamination by more reactive components, such as lubricant oil. The present study aims to shed light on the mechanism through which lubricant oil contamination leads to the formation of sensitive spots, by analysing the behaviour of an isolated droplet suspended in a hydrogen/air environment. The “HyLube” chemical kinetic mechanism was employed to reproduce the chemical behaviour of lubricant oil, as it was specifically developed for this purpose. A one-dimensional numerical model was used to simulate the heating, vaporization, and combustion of the droplet. Zero-dimensional simulations were also
Distaso, Elia, Baloch, Daniyal Altaf, Amirante, Riccardo, Tamburrano, Paolo
Lifting the Key Functional Figures Concerning Performance and Efficiency for 2nd Gen. H 2 Engines for On- and Off-Highway Installations by Tailored Engineering Measures2025-24-004909/07/2025
To curb global warming and meet stricter greenhouse gas emission standards all over the globe, it is essential to minimize the carbon footprint of applications in the mobility and transport segment. The demands on mobility, transportation and services are constantly increasing in line with worldwide population growth and the corresponding need for economic prosperity. This ongoing trend will lead to a significant increase in energy requirements for mobility-related applications in the upcoming time, despite all efficiency improvements. The timely introduction and accelerated spread of low-carbon/carbon-neutral energy sources is therefore of crucial importance. In addition to the switch to electric propulsion systems, particularly in the light-duty vehicle sector, the use of advanced and optimized hydrogen (H2)-powered internal combustion engines (ICE) represents a parallel, compatible technical option, as these applications will also meet the most stringent requirements in terms of
Koerfer, Thomas, Zimmer, Pascal, Li, Zhengling, Pischinger, Stefan, Lückerath, Moritz
CFD Simulation of Combustion in an Optically Accessible Hydrogen Engine: Comparison between Lean and Diluted Stoichiometric Operations2025-24-000909/07/2025
The reduction of CO2 emissions from anthropogenic activities is pushing the green energy transition, prompting the search for alternative and more environmental-friendly solutions compared to traditional technologies based on fossil fuels. One of the most affected sectors is transportation, which is undergoing a significant change to increase sustainability. To achieve this goal, development of hybrid and electric propulsion systems has taken hold over the past decade, but electrification is proceeding slower than expected due to many challenges related to charging infrastructure, cars range and cost, thus pushing the European automotive sector into a potential crisis. To reverse this trend and simultaneously accelerate the transition to sustainable transportation, further development of ICEs technology aimed at enhancing efficiency when using alternative fuels like hydrogen, is staging a comeback. Thanks to the possibility to retrofit existing units, benefiting from a strong know-how
Madia, Manuel, Boehm, Benjamin, Fontanesi, Stefano, Ye, Pedro, Magnani, Mauro, Breda, Sebastiano
Waste Heat Recovery in Hydrogen Fueled Internal Combustion Engines2025-24-010809/07/2025
Waste Heat Recovery is one of the most investigated and promising technologies for energy efficiency in the transportation sector. It consents to maintain the high-level technology of the present propulsion systems, based on Internal Combustion Engines, while increasing the overall engine and vehicle system efficiency. At the same time, the use of alternative fuels, like hydrogen, has the same crucial role to reduce harmful and greenhouse emissions, without overturn the existing mature technology. A hydrogen-fueled Internal Combustion Engine is proposed in this paper, equipped with waste heat recovery consisting in an additional radial turbine downstream the turbocharger of the engine (Turbo-Compound). The aim is to have a reduction of the specific consumption in most of the operating points of the engine, considering the effect of the recovery and the engine equilibrium rearrangement. The use of hydrogen increases recoverable enthalpy at the engine exhaust, which is intended to be
Di Battista, Davide, Cipollone, Roberto, Corti, Enrico, Brancaleoni, Pier Paolo, Di Prospero, Federico, Ravaglioli, Vittorio
Testing and Modeling of a Passive SCR System for Hydrogen Engines2025-24-008209/07/2025
Heavy-duty vehicles powered by hydrogen internal combustion engines (H2-ICEs) present a compelling solution for sustainable transportation. When optimized for ultra-lean operation, H2-ICEs are capable of meeting the most stringent contemporary legislative emission standards. However, achieving optimal drivability necessitates occasionally an enriched operating mode, thereby presenting significant challenges in maintaining ultra-low emissions. In this context, the implementation of advanced exhaust after-treatment technologies becomes essential to ensure near-zero tailpipe emissions with minimal impact on fuel efficiency and drivability. This paper investigates the potential of a passive Selective Catalytic Reduction (SCR) exhaust configuration for a heavy-duty hydrogen (HD H₂) engine, employing testing and modeling of a Lean NOx Trap, utilized as an ammonia (NH3) generator, in conjunction with a downstream Selective Catalytic Reduction system. We underscore the complexities associated
Zafeiridis, Menelaos, Alexiadou, Panagiota, Koltsakis, Grigorios
Numerical Analysis of the Combustion Process in a Hydrogen-Fueled Pre-Chamber Combustion Engine2025-24-001209/07/2025
Direct injection hydrogen internal combustion engine (ICE) has emerged as a promising alternative fuel due to its potential to enable clean and sustainable energy systems. However, the rapid injection of low-density hydrogen leads to strong mixture stratification and strong flame-turbulence-wall interactions. This challenge is exacerbated in the high-performance engine under study operating at a high engine load (indicated mean effective pressure of about 20 bar) and speed (7500 revolutions per minute). Furthermore, to target high efficiencies, restrict abnormal combustion behaviors, and inhibit oxides of nitrogen emissions, a lean-burn combustion strategy with a global equivalence ratio of 0.4 was applied, where diffusive-thermal (DT) instability effects further complicate the flame characteristics. Additionally, to promote engine performance, the pre-chamber (PC) combustion concept was applied, further complicating the turbulent flame dynamics. To address the modeling challenges and
Mortellaro, Fabio Santi, Menaca, Rafael, Liu, Xinlei, Im, Hong G., Tonelli, Roberto, Medda, Massimo
Calorimetric Study of the Influence of Spark Ignition System Parameters on the Energy Transfer to the Gas2025-24-003309/07/2025
Achieving a robust ignition with minimal spark plug wear is challenging in heavy duty engines fueled with gaseous fuels like biogas and hydrogen. Thermal energy deposition from the spark to the gas was studied in a 10.9 milliliter custom-built spark calorimeter. An AC capacitive ignition system was used along with a dual-nickel standard J-gap spark plug and the influence of multiple physical and electrical parameters was investigated in an experimental design including five factors: spark plug center electrode diameter, electrode gap, glow current, glow duration, and gas density. The aim was to maximize energy transfer to the gas and reduce heat losses to the spark plug electrodes, thus extending spark plug service life and reducing the risk of pre-ignition in hydrogen engines caused by overheated electrodes. The results show that the electrode gap has the dominating influence on energy transfer to the gas. Both the gas density and the glow current contribute to increased energy
Saha, Anupam, Tunestal, Per, Aengeby, Jakob, Andersson, Oivind
Experimental Investigation of the Comparison between Helium and Hydrogen Jets Exiting a DI Outward-Opening Injector via Schlieren Technique2025-24-006809/07/2025
This paper deals with the hydrogen-to-helium jets comparison within the framework of the assessment of helium as a potential hydrogen surrogate. The comparison is centred on the assessment of the combined action of pressure ratio with gas properties on the dynamics of the jet exiting an outward-opening injector. The shots are performed at injection pressures and backpressures ranging from 21 to 36 bar and from 1.2 to 5 bar, respectively. The Schlieren technique is deployed to capture the jets images. The study demonstrates that at certain pressure ratios helium is an appealing solution bridging the lab safety with fidelity to hydrogen-like jet behaviour. Decreasing pressure ratio minimizes the hydrogen-to-helium difference in axial penetration and area, enabling helium to yield a hydrogen-like development. The findings underscore the impact of the pressure ratio on how the gas properties, such as density and diffusivity, dictate the evolution of the axial propagation and area
Coratella, Carlo, Tinchon, Alexis, Hespel, Camille, Dober, Gavin, Foucher, Fabrice
Numerical Study of Mixing, Combustion and NOx Emissions in a DI High Performance Hydrogen Engine Operated at Stoichiometry2025-24-001009/07/2025
The roadmap towards carbon neutrality by 2050 makes necessary drastic reduction of road vehicle tailpipe carbon emissions. One viable approach to reach the abatement of carbon monoxide and dioxide is to fuel internal combustion engines (ICEs) with hydrogen. The burning of a hydrogen-air mixture inside the combustion chamber reduces to minimal amount the production of carbon emissions and particulate matter that are only produced by the presence of lubricant oil. However, the high temperatures reached by the end-gases promote the formation of nitrogen oxides. In high-performance ICEs, the pursuit for high-specific power by means of the adoption of stoichiometric mixtures is hindered by the need to reduce NOx - as this pollutant drastically drops when moving towards ultra-lean mixtures. The paper aims to present a CFD-3D framework to simulate the full engine-cycle of a high-performance Spark-Ignited (SI) Direct-Injection (DI) ICE fuelled at stoichiometric conditions. The methodology is
Baudone, Antonio Denny, Marini, Alessandro, Sfriso, Stefano, Falcinelli, Francesco, Mortellaro, Fabio, Tonelli, Roberto, Breda, Sebastiano
Integrated CFD-Experimental Methodology for Hydrogen-Fuelled Small Loop Scavenged Two-Stroke Engines2025-24-001409/07/2025
This paper presents an integrated methodology for the analysis of hydrogen-fueled 2-Stroke engines, combining experimental data, 1D-CFD simulations, and 3D-CFD combustion calculations. The proposed approach aims to enhance the understanding of scavenging, injection, and combustion processes in a 50 cm3 loop-scavenged engine with low-pressure direct hydrogen injection, experimentally studied on a test bench. The hydrogen-fueled engine was capable of achieving a maximum power output of 3.1 kW, using a slightly lean air-to-fuel ratio (lambda = 1.3). The maximum engine speed for stable combustion without knocking was achieved at wide open throttle at 7119 RPM. The developed 1D-CFD model, based on the engine layout at the test bench, was calibrated using average experimental data and specific full load operating points. 3D-CFD simulations were performed for one full load operating point, focusing on combustion dynamics and fuel distribution within the chamber, with combustion model
Caprioli, Stefano, Ferretti, Luca, Scrignoli, Francesco, Fiaschi, Matteo, D'Elia, Matteo, Oswald, Roland, Schoegl, Oliver, Nambully, Suresh Kumar, Rothbauer, Rainer, Mattarelli, Enrico, Kirchberger, Roland, Rinaldini, Carlo
Investigation of a Lambda Leap Strategy for Hydrogen Internal Combustion Engines to Balance Efficiency with Performance and Vehicle Packaging2025-24-007009/07/2025
The paper reports an investigation into employing a “lambda leap” (λ leap) strategy for hydrogen internal combustion engines (H₂ICEs), wherein inherently low emissions of oxides of nitrogen (NOx) are afforded at light load via operation at lambda 2.5, and at higher load by operation at stoichiometry utilizing a three-way catalyst (TWC) for NOx control. This approach means it is necessary under transient operation to “leap” between high values of lambda and stoichiometry from one cycle to the next, in order to avoid completely the λ ≈ 1.3 area where high combustion NOx is generated away from lambda equal to 1; this is because lean catalysis of NOx will be extremely challenging at the rate that it is generated there. To achieve this, a short cam profile was introduced to reduce air mass flow by 57.5%, enabling this leap without changing the fuel injection amount, while preserving favorable combustion characteristics via an early Miller cycle. The study models a 2.0 L inline four-cylinder
Fong Cisneros, Eric J., Kodaboina, Raghu Vamsi, Vorraro, Giovanni, Turner, James W. G.
A Computational Study of Hydrogen Mixing and Combustion in a High-Speed Direct-Injection Spark-Ignition Engine2025-24-000409/07/2025
Hydrogen has emerged as a promising alternative fuel due to its potential to enable clean and sustainable energy systems. Direct injection is the preferred fueling strategy for hydrogen engines, as it enhances power density while addressing safety concerns. However, the low density of hydrogen necessitates a large molar quantity of fuel, leading to strong fuel-air stratification and posing challenges for mixing in a confined chamber with complex turbulent flow and jet/wall interactions. This challenge is exacerbated in the present study, where the evaluated high-performance engine operates at a high engine load (indicated mean effective pressure of about 20 bar) and an extremely high speed (7500 revolutions per minute). Furthermore, to target high efficiencies, restrict abnormal combustion behaviors and inhibit oxides of nitrogen emissions, a lean-burn combustion strategy with a global equivalence ratio of 0.4 was applied, where diffusive-thermal (DT) instability effects would matter
Menaca, Rafael, Liu, Xinlei, Mortellaro, Fabio, Medda, Massimo, Im, Hong G.
High Lambda Boosting for Hydrogen Internal Combustion Engine02-18-03-002308/29/2025
The commercial vehicle industry continues to move in the direction of lower emissions while reducing its carbon footprint. This study focuses on hydrogen internal combustion engines (H2-ICE) since it offers a zero-carbon solution to the industry while showing very low NOx emissions when coupled to a conventionally sized aftertreatment SCR system. This work highlights modeling efforts for analyzing key boosting configurations to operate a hydrogen engine at high lambda (relative air–fuel ratio) for lowering NOx, maintain the aftertreatment system reasonable in size, and improving brake thermal efficiency (BTE). GT-Power was used to model H2-ICE engines from 13L to 19L in displacement with different boosting architectures. Key configurations include a variable geometry turbine (VGT) turbocharger coupled with a supercharger (SC), a VGT with higher engine displacement, and a VGT coupled in series with a fixed geometry turbine (FGT) turbocharger. An exhaustive study comparing these boosting
Gurjar, Shubham, McCarthy, Jr., James E., Manickavasagan, Thirumoolan, Chaudhari, Amol S., Nimeshkumar, Parmar, Bachu, Pruthvi, Bitsis, Christopher
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