Browse Topic: Hydrogen fuel

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2025 International Conference on Solid Mechanics and Materials2026-99-1600To be published on 07/24/2026
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Tobolski, Sue
Modeling and Simulation Analysis of Liquid Hydrogen and Power Systems Based on Amesim2026-99-1608To be published on 07/24/2026
Hydrogen-powered aircraft primarily utilize the conversion of liquid hydrogen into gaseous hydrogen to replace aviation kerosene, where hydrogen is directly combusted to provide propulsion. This study applied Amesim software to establish a complicated model simulating the liquid hydrogen to gaseous hydrogen conversion and ignition combustion processes. The simulation contains converting liquid hydrogen into gaseous hydrogen through a heat exchanger and simulating the mixture of gaseous hydrogen and air in the engine combustion chamber, and then igniting the mixture. The pressure, temperature, and flow rate of gaseous hydrogen and air during the ignition and combustion process in the engine combustion chamber, as well as the outlet temperature of the combustion chamber, are simulated and analyzed. The results demonstrate that during the simulation process, the internal pressure of the liquid hydrogen storage tank, the outlet pressure and flow rate of the liquid hydrogen pump, and the pressure and flow rate of gaseous hydrogen meet the requirements of the ignition combustion test. In addition, varying gaseous hydrogen flow rates had significant impacts on the temperature of the combustion chamber during combustion.
Gao, Pengfei, Wang, Lijian
EUROCAE/SAE WG80/AE-7AFC Hydrogen Fuel Cells Aircraft Fuel Cell Safety GuidelinesAIR6464 (Current)7/17/2026
This document defines the technical guidelines for the safe integration of Proton Exchange Membrane (PEM) Fuel Cell Systems (FCS), fuel (considered to be liquid and compressed hydrogen storage types only), fuel storage, fuel distribution and appropriate electrical systems into the aircraft. Editorial Note: Today PEM systems and fuel storage represent the most mature FCS technology and currently forms the basis for this standard. Other types of fuel cell systems and fuels (including reforming technologies and electrolyzers), may be covered by a further update to this document.
AE-7F Hydrogen and Fuel Cells
Temperature Control Technology for Solid-state Hydrogen Proton Exchange Membrane Fuel Cell2026-99-05287/10/2026
The global trend towards green and low-carbon development is that hydrogen fuel cells, as a new type of green power device, have the characteristics of zero emissions and no pollution. Its basic principle is that hydrogen fuel directly converts chemical energy into electrical energy through electrochemical reactions, achieving energy conversion between fuel cells and internal combustion engines, thereby providing sustained and stable power. The PEMFC has attracted significant attention due to advantages such as fast start-up times and long lifespans. However, excessive temperature during the reaction process of solid-state hydrogen proton fuel cells can lead to a decrease in efficiency. This article studies the temperature control device of solid-state hydrogen fuel cells and finds that active temperature control technology can achieve precise temperature regulation, but it consumes more energy; the passive temperature control scheme can reduce energy consumption, but the response speed to low-temperature start-up is limited; The application of intelligent algorithm fuzzy PID significantly improves the temperature control accuracy under dynamic loads and effectively enhances the hydrogen release rate.
Ma, Yueyue, Liu, Jingyi, Shi, Jian, Lu, Zhaona, Bao, Xueqin
Impact of Compression Ratio and Stroke on Hydrogen Requirement for Emission-Optimized Operation of an Ammonia-Fuelled Spark-Ignition Engine2026-37-00306/9/2026
Ammonia (NH3) fuelled engines have emerged as a promising route toward net-zero emission targets due to NH3’s carbon-free nature, ease of storage, and established handling infrastructure. However, the low laminar burning speed and narrow flammability limits of NH3 pose a significant combustion challenge, which can be addressed through hydrogen (H2) co-fuelling. For practical implementation, on-board H2 production via thermal catalytic cracking of NH3 is an attractive solution, as it eliminates the need for external H2 storage and associated handling and capital costs. Previous studies by the present authors identified a lean operating strategy that achieves an equimolar ratio of NOx and unburned NH3 (α NH3NOx ≈ 1), enabling complete conversion to nitrogen and water vapour when coupled with a Selective Catalytic Reduction (SCR) system. This strategy was further validated using cracked NH3 derived H2 in place of bottled H2 through an on-board cracker, thereby representing a practical system configuration. However, the required H2 fraction, and consequently the size and power demand of the onboard cracking system, is strongly influenced by engine architecture and operating conditions. The present study investigates the effect of compression ratio (CR) and stroke length, on H2 fraction requirements to achieve an optimum α of unity in an externally boosted SI engine. Results demonstrate that the high CR = 17.5, long stroke configuration reduces H2 enrichment by 50–60% compared to a low CR = 12.5, short-stroke engine architecture, allowing smaller onboard H2 generation systems. At high-speed, high-load conditions, it achieves over 45% thermal efficiency with stable NH3 combustion and no H2 supplementation, maintaining an α ≈ 1. Across the full operating map, NOx emissions comply with IMO Tier III and EPA Tier 4 norms, demonstrating near-zero-emission operation.
Yadav, Neeraj Kumar, Ambalakatte, Ajith, Geng, Sikai, Gopakumar Suja, Gagan, Birch, Alexander, Cairns, Alasdair, Harrington, Anthony, Hall, Jonathan
Bosch shows off its first U.S. electrolyzer26TOFHP06_086/1/2026
Two of the biggest hurdles to adoption of hydrogen fuel cells are still the availability of hydrogen and its affordability. Now Bosch has taken what is a small step toward addressing availability at its Farmington Hills, Michigan, engineering center, where the company just unveiled its new electrolyzer, which uses electrical current to split water into oxygen and hydrogen to power fuel cells.
Clonts, Chris
Weight Estimation of Novel Aircraft Configurations in Early Design Phase2026-26-07736/1/2026
Initial weight estimation from Top Level Aircraft Requirements (TLAR) is a critical first step in aircraft design, yet existing empirical methods are inadequate for novel configurations such as those using Liquid Hydrogen (LH2) or Sustainable Aviation Fuels (SAF). This paper presents a hybrid methodology for top-level weight estimation of such unconventional aircraft. The approach is based on modifying a conventional baseline aircraft, integrating a new statistical model with component-specific weight estimations. A multivariate regression model to estimate the empty weight fraction (We/W0) was developed from a dataset of 44 conventional aircraft, yielding an R-squared value of 0.833. This statistical model was integrated with physics-based models for novel components, including cryogenic fuel tanks and fuel systems. The methodology accounts for iterative changes to fuselage structure and parasitic drag. Four configurations were analyzed: fuel types being Jet A1, SAF, LH2 with aft-fuselage tanks, and LH2 with under-wing podded tanks. The results demonstrate that while LH2 configurations introduce weight penalties for tanks and systems, these are significantly offset by a reduction in fuel weight, resulting in a final Maximum Takeoff Weight (MTOW) comparable to or lower than the conventional baseline. The modular nature of this methodology makes it a viable tool for exploring the design space in early-stage conceptual design.
Goyal, Tushar
Model-based Optimization of Fuel Cell Powered Vertical Take-Off and Landing (eVTOL) AircraftF-0082-2026-02265/5/2026
Electric Vertical Take-Off and Landing (eVTOL) aircraft are poised to transform urban and regional mobility by offering zero-emission, congestion-free transportation. As regulatory frameworks evolve and advanced air mobility (AAM) gains traction, manufacturers are exploring propulsion strategies that improve range, power delivery, and overall system efficiency. A key challenge in eVTOL development is balancing range with payload capacity. While larger battery packs can extend range, they also increase system weight, reduce payload, and prolong charging times, limiting operational flexibility and turnaround time. Hydrogen fuel cells, supported by liquid hydrogen (LH₂) present a promising alternative for eVTOL propulsion. This study proposes a methodology for optimizing fuel cell propulsion systems tailored to eVTOL applications. A multi-physics modeling framework for eVTOL flight dynamics and propulsion system was developed, representing the target eVTOL configuration. For a defined flight path including vertical takeoff, hover, cruise, and landing, a Genetic Algorithm (GA) based optimization was conducted on propulsion system. The algorithm down-selected battery size, fuel cell stack specifications, and hydrogen tank capacity to meet mission requirements while minimizing propulsion system weight. The modeling framework was also used to evaluate trade-offs between payload and performance as functions of component sizing, battery chemistry and energy distribution strategy.
Garcia, Bruno, Paul, Sumit, Zeigler, Sophia, Franke, Michael, Joshi, Satyum, Araujo, Joao
Bosch shows off its first U.S. electrolyzer in support of hydrogen research26AUTD05_095/1/2026
Two of the biggest hurdles to the adoption of hydrogen fuel cells are still the availability of hydrogen and its affordability. Bosch recently took a small step toward addressing availability at its Farmington Hills, Michigan, engineering center, where the company unveiled a new electrolyzer that uses electrical current to split water into oxygen and hydrogen to power fuel cells.
Clonts, Chris
The Influence of Split Injection Ratio on Efficiency and NO x Emissions in a Pilot Diesel-Ignited Hydrogen Direct Injection Engine2026-01-03294/7/2026
This study investigates the impact of the hydrogen split injection ratio on the combustion of pilot diesel-ignited hydrogen direct-injection engines, which is expected to affect hydrogen-air mixture conditions and thus flame propagation and diffusion flame developments. Experiments were conducted on a 1-litre single-cylinder diesel engine equipped with an additional hydrogen injector operating at 35 MPa. Hydrogen accounting for 95% of total input energy was injected at 150 and 60 °CA bTDC for the first and second pulses, which were selected as high-efficiency injection timings from previous equal-split injection tests. The 5% diesel energy was injected near TDC to control CA50 at 10 °CA aTDC. While varying the split ratio between the two hydrogen injections, in-cylinder pressure/aHRR profiles, engine efficiency/power output and engine-out emissions of NOx and CO2 were evaluated. Results showed that the hydrogen split ratio does not significantly affect IMEP/efficiency, which 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
Effects of the Spark Location and Timing in a Heavy-Duty Hydrogen-Fueled Engine2026-01-03314/7/2026
The use of hydrogen in internal combustion engines offers a promising route to lower-carbon propulsion in heavy-duty transportation. However, its distinct combustion characteristics as high flame speed, wide flammability limits, and susceptibility to abnormal combustion, necessitate careful engine and ignition system design. This study numerically investigates the combined effects of spark plug (SP) location and ignition timing on the performance of a heavy-duty diesel engine converted to spark-ignition and operated with hydrogen as fuel at reduced compression ratio. The numerical study aims to guide engine design. Three-dimensional computational fluid dynamics simulations with detailed hydrogen chemistry were conducted to evaluate flame development, and relevant combustion metrics under different loads. Model validation against engine combustion data and hydrogen injection from a low-pressure, high-mass-flow direct injector are also presented. The results demonstrate that SP placement is pivotal to control for combustion stability and efficiency due to the complex in-cylinder mixing and stratification associated with direct hydrogen injection. For each load, optimal ignition timings were identified. Highlights demonstrate the feasibility of installing the SP close to the jet-forming cap (injector tip) to exploit local enrichment and enhance flame propagation.
Menaca, Rafael, Shakeel, Mohammad Raghib, Panithasan, Mebin, Liu, Xinlei, Qahtani, Yasser, AlRamadan, Abdullah, Cenker, Emre, Silva, Mickael, Pei, Yuanjiang, Turner, James, Im, Hong
Optimization Strategies of Gliding Arc Plasma-Based Ammonia Cracker towards Onboard Applications2026-01-02924/7/2026
Ammonia has emerged as a viable hydrogen energy carrier owing to its superior hydrogen density and mature industrial utilization. However, ammonia faces critical challenges including inadequate ignition characteristics and sluggish combustion kinetics, necessitating supplementary high-reactivity fuels for optimizing combustion. Onboard ammonia decomposition technology resolves this problem through on-demand hydrogen real-time production. Among existing ammonia decomposition methods, gliding arc plasma (GAP) demonstrates exceptional promise for onboard hydrogen production given its high processing flow rate，decent hydrogen conversion rate, and transient response capability. Prevailing research predominantly relies on experimental approaches, with insufficient understanding of the effects of specific electrical field parameters and inlet pressure on system performance. This study established a quasi-one-dimensional numerical model for GAP-assisted ammonia decomposition. A comprehensive analysis was conducted to examine the influence of key electric field parameters, such as reduced electric field strength (REFS) and electron density (De), on ammonia conversion rate and energy efficiency. Furthermore, the study explored the synergistic effects of inlet pressure and electric field parameters on system performance under constant mass flow rate conditions. The results indicate that increasing REFS and De significantly substantially elevates ammonia conversion rate, but energy efficiency decreases as these parameters increase. Keeping a constant NH3 inlet mass flow rate, the gas velocity decreases when the inlet pressure increases and then extends the residence time. Consequently, the ammonia conversion rate significantly improves while the energy efficiency slightly decreases. By increasing inlet pressure and simultaneously reducing REFS or De, system energy efficiency can be effectively enhanced without altering ammonia conversion rates. This study demonstrates the synergistic regulation mechanism of electric field parameters and inlet pressure on hydrogen production performance, providing optimization strategies for GAP reactor design.
Dong, Guangyu, Li, Xian, Zhou, Yanxiong, Xu, Jie, Li, Liguang
Effect of Ignition Timing on Combustion Characteristics in Ammonia-Hydrogen Blended Fuel Engine with Passive Pre-Chamber2026-01-03234/7/2026
Against the backdrop of energy structure transformation and upgraded environmental protection requirements, ammonia has been gaining significant traction for its potential application as a zero-carbon fuel. However, it faces challenges such as difficult ignition, slow combustion rate, and low heating value. Thus, researching efficient combustion strategies suitable for ammonia as a fuel holds great significance. In this study, a two-cylinder diesel engine was modified into an ammonia-hydrogen blended fuel engine. Experimental study coupled with numerical simulations were carried out to investigate the effects of varying ignition timing on the combustion characteristics employed a passive pre-chamber ammonia-hydrogen fuel engine. The results show that the peak in-cylinder pressure exhibits a "first increase then decrease" trend as the ignition timing is retarded, reaching a maximum value of 7.42 MPa at the ignition timing of -27.5°CA ATDC. When the ignition timing is retarded beyond -15°CA ATDC, a double-peak phenomenon appears in the in-cylinder pressure curve. The peak heat release rate (HRR) gradually increases with the retardation of ignition timing, but excessively retarded ignition diminishes the proportion of constant-volume combustion in the combustion process. The combustion rate is the fastest when the ignition timing is -20°CA ATDC under the operating conditions of an engine speed of 1800 r·min-1, a hydrogen energy fraction (HEF) of 11.6%, and a λ of 1.0, with the shortest combustion duration (CA10~CA90) of 22.5°CA, which leads to the highest indicated thermal efficiency of 42.5%.
Deng, Jun, Luo, Mingyu, Shang, Quanbo, Tang, Yongjian, Qin, Jie, Li, Liguang
Optimized Design and Economic Evaluation of a Renewable Hydrogen Refueling Station for Public Transport on Elba Island14-15-01-00042/13/2026
The aim of this study is to develop a methodology to significantly reduce emissions in bus fleet renewal scenarios by investigating both technical and economic aspects. This work presents a case study based on Elba Island, Italy, which investigates optimal solutions for replacing existing Diesel buses through a total cost of ownership analysis. The investigation is carried out for four different potential scenarios: renewing the fleet with Diesel buses, renewing the fleet with electric buses, adopting fuel cell buses, and implementing a hybrid solution. The latter represents a synergistic solution that integrates fuel cell buses with the development of a hydrogen refueling station driven by a proton exchange membrane electrolyzer, unlocking the techno-economic potential of self-producing green hydrogen for bus refueling. The novelty of this study is its integrated methodology that combines a total cost of ownership analysis with a tailored design of a green hydrogen production network optimized for continuous fleet operation. A constrained optimization algorithm was employed to determine the optimal configuration of key plant components, including the proton exchange membrane electrolyzer system size, the amount of photovoltaic panels and wind turbines, and the capacity of the hydrogen storage tank. The grid-based alternative offers a simple payback period under 4 years and a total cost of ownership of 6 M€, making it more cost-effective than the 6.5 M€ electric and 7.5 M€ Diesel options. These results provide a scalable, replicable roadmap for accelerating sustainable public transport adoption in similar contexts.
Bove, Giovanni, Sorrentino, Marco, Baldinelli, Arianna, Desideri, Umberto
Enhancing Combustion, Performance and Emission Profiles Using Kapok Methyl Ester Blends with Hydrogen2026-28-00582/12/2026
This study investigates the potential of using a dual green alternative fuel combination, the one is hydrogen fuel and another one is biodiesel for enhancing the Performance, combustion and emission profile of a compression ignition engine. The kapok oil biodiesel was blended with Diesel in proportions of 20% (K20) and 40% (K40) by volume. The hydrogen gas was supplied at a constant flow of 4 liter per minute (LPM). The experimental fuels are neat diesel D100, K20 (80% Diesel and 20 % kapok methyl ester), K40 (60% Diesel + 40 % Kapok methyl ester), K20 + H4L (K20 with 4 LPM hydrogen) and K40+H4L (K40 with 4 LPM hydrogen). These test blends are investigated in a single cylinder direct injection CI engine under 0% to 100% load conditions at a fixed speed of 1500 rpm combustion, and emissions characteristic were evaluated and compared with base fuel. The outcomes indicated that the use of B20 and B40 blends without hydrogen led to reduced BTE because of their lower cetane number and 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
Total Cost of Ownership Analysis of Fuel Cell and Hydrogen-Powered Commercial Vehicles for Cost Competitiveness with ICE and BEV2026-26-02541/16/2026
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, the 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 commercial vehicle categories are analysed to assess the vehicle classes and use cases where hydrogen fuel cell-powered vehicles can be a cost-effective alternative to conventional ICE and battery electric vehicles (BEV). The analysis also determines the factors that contribute most to TCO, which will help identify the areas that require improvement/development or policy support to make fuel cells and hydrogen power more widespread. The paper also analyses the sensitivity of TCO to different cost factors, such as hydrogen cost, which helps in establishing cost targets to make hydrogen-powered vehicles a cost-effective solution in the transition to zero-emission transportation. Finally, different market trends are analysed to predict the timelines in which fuel cell-powered vehicles can become cost-competitive with ICE and BEV.
Jacob, Joe, Chougule, Abhijeet
Testing Methodology to Calculate the Fuel Economy in Km/Kg of Hydrogen Fuel Cell Electric Vehicle (FCEV) based on Current (Ampere) Method and Flow Method2026-26-02481/16/2026
The globe is looking headlong to set up new benchmarks for the reduction of GHG (Green House Gases) considering short-term and long-term strategies. Efforts in the Internal Combustion Engines (ICE) domain have been accelerating to find an alternative way to reduce harmful emissions. Hydrogen is considered as a promising fuel to leapfrog this transition. Hydrogen fuel can be categorized into vast mobility areas viz. ICE and Fuel Cell Electric Vehicle (FCEV). Hydrogen fuel has attracted global attention from engine researchers due to the crude oil crisis and its rise in prices in recent years. This will serve the nation's goal towards carbon neutrality. Hydrogen has a few advantages such as less fueling time, higher heating value and more efficiency making it an eye-touching fuel for the automotive industry. In the contemporary FCEV segment, many fuel cell technologies have evolved, wherein the development of Proton Exchange Membrane (PEM) fuel cell technology has taken a new height for heavy-duty commercial vehicle applications due to its significant interest in the non-existent tailpipe CO2 emissions. Since electric vehicles are also being combined with hydrogen fuel and the opportunity persists to convert it into a hybrid system or FCEV. There is always a keen curiosity of the end user to know the mileage of a vehicle as a distinguishing measure of fuel economy. Thus, it is pertinent to determine the hydrogen fuel economy of the FCEV vehicle. This paper provides an insight into fuel cell fundamentals, the working principle of hydrogen fuel cell vehicles, vehicle operation modes and testing methodology to determine the fuel economy of FCEV based on the electric current method and pressure method. The vehicle (e-Bus) has been validated on a chassis dynamometer based on the prescribed DBDC Cycle in the AIS 049 standard to calculate the hydrogen fuel economy of the FCEV Bus. The multiple stacks of PEM fuel cells connected in series has been used along with the electric powertrain vehicle and estimation of its fuel economy are the focus of this paper.
Joshi, Ashish Rajendra, Kandalgaonkar, Siddhesh, Sontakke, Rushikesh
Experimental Evaluation of Energy and Exergy of Hydrogen, CNG and Gasoline Fuelled High-Speed Spark Ignition Engine2026-26-02581/16/2026
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
Challenges for Truck Decarbonization: Load Distribution Evaluation According to Contran Resolution N° 882/20212025-36-019212/18/2025
The road transport mode is predominant in Brazil, representing more than 50% of greenhouse gas (GHG) emissions from energy sector [1]. Currently, trucks use internal compression combustion engine (ICCE) with fuel Diesel as propulsion, considering the reference for technical and economic studies for alternative propulsions such as: electrification or hydrogen (H2) as fuel. Both technologies are extremely important to achieve the goals defined by Brazilian nationally determined contribution (NDC) (commitment to Paris agreement target) to avoid climate changes catastrophic issues due climate temperature risk to exceed 2°C. In addition, several companies have announced sustainability compromises to contribute with reduction of GHG emissions in scopes 1,2 and 3, focusing on Environmental, Social and governance (ESG), where road transportation has a larger contribution to achieving the target. Contran Resolution (CR) n° 882/2021 defines the maximum weights and dimensions of vehicles to be authorized to circulate in Brazilian roads. A major challenge is the eligibility of the system to be installed, as well as the layout arrangement in the vehicle. In the context, during the concept phase, it is necessary to evaluate the load distribution on the axles, maximum weights and maximum dimensions of the vehicle complying with the legal requirements. Legal requirements modifying has been started in some countries, for example Chile where recently had public a resolution n° 181/2025 allowing to increase 350 kilograms (kg) in a single front axle, probably part of new policies to make feasible alternatives propulsions to reduce GHG emissions. The proposal of this work will evaluate the impact of load distribution through the assessment of possible layouts for purely electric propulsion or hydrogen fuel propulsion using software as tool, searching for greater agility in concept evaluation. The challenge is to create a model where it is possible to modify the gravity of center (CoG) along the vehicle considering curb weight, implementation, gross weight and payload, checking if it possible to follow the same premises of ICCE and current CR without miss customer by criteria. The results show the impact of reduced payload by 15-34% due to mass added in vehicle for zero emission vehicle (ZEV) using alternative propulsion (electric and hydrogen) in all scenarios simulated, considering the same dimensions of ICCE complying with CR. As conclusion, has been observe challenges for truck decarbonization due to payload reduction, generating direct impacts in customers due the possible total cost operation (TCO) increase. In additional this work can contribute to new decarbonization mobile polices discussion in the future (technical or compensation rules), where the tool used can contribute to build Fastly many different scenarios for decision. As recommendation, the CR updated n°1015/24 does not comply all decarbonization truck scenarios and will need be discussed how reduce the impact for ZEV concepts, resulting in CR updates to make the plan feasible for the truck decarbonization,
Ferreira, Bruno Francisco, Oliveira Da Silva, Laura de
Analysis of Combustion Process in HVO-Hydrogen Dual-Fuel Operation Using Simultaneous Imaging of OH* and CH* Chemiluminescence2025-32-005311/3/2025
This study investigated the combustion process in a hydrotreated vegetable oil (HVO)–hydrogen dual-fuel operation using simultaneous imaging of the OH* and CH* chemiluminescence in a rapid compression and expansion machine (RCEM). In this operation, hydrogen served as the primary fuel, ignited by a small quantity of pilot fuel. CH* chemiluminescence was primarily detected in the pilot fuel combustion regions, whereas OH* chemiluminescence was detected in both the pilot fuel and hydrogen combustion regions, enabling the separation of pilot ignition and hydrogen flame propagation. The combustion mechanism was found to proceed through four distinct stages: autoignition of the pilot fuel, combustion of the mixture in the lean pilot fuel region, propagation of the hydrogen–air premixture flame, and flame propagation toward the wall and squish area. Furthermore, the effects of the pilot injection parameters on the combustion characteristics were systematically evaluated by varying the injection quantity, injection pressure, and nozzle specifications (hole diameter and number of holes). Increasing the pilot injection quantity improved the degree of constant volume of combustion but intensified the combustion near the wall, potentially increasing the cooling loss. Reducing the injection pressure shifted the autoignition location toward the center of the piston bowl, potentially reducing cooling loss but prolonging the combustion duration. With smaller injection quantities, fewer nozzle holes resulted in a higher second heat release rate peak, owing to the increased space for hydrogen flame propagation. Conversely, with larger injection quantities, a greater number of nozzle holes led to a shorter combustion duration while maintaining the combustion away from the wall.
Yukitani, Takumi, Une, Naoto, Mukhtar, Ghazian, Horibe, Naoto, Kawanabe, Hiroshi, Koda, Kazuyuki, Hiraoka, Kenji
Validation of an Integrated Ignition-Combustion Model for Premixed Hydrogen-Air Flames under Lean Conditions2025-32-005611/3/2025
Recent climate changes, driven by greenhouse gas emissions, along with global regulations aimed at mitigating these effects, have intensified research on carbon-free fuels. Among these, hydrogen stands out as one of the most promising options. In this study, use is made of a recent 1D kernel expansion model developed by the authors, which is based on the conservation equations of mass, energy and deficient reactant. The theory of transient thermo-diffusion is also adopted to estimate the reactant and temperature gradients at the outer flame surface. The kernel expansion model accounts for the variability of thermodynamic properties both inside and outside the flame volume, including high-temperature ionization and dissociation effects. The kernel expansion model is used until the non-linear stretch effects are sufficiently relaxed. Subsequently, the propagation of the premixed flame is described by means of a two-zone combustion model. During both phases, the effects of hydrodynamic and thermo-diffusive instabilities are accounted for. The former are modeled considering the flame wrinkling produced by the density discontinuity across the flame, evolving towards a self-similar fractal-like behavior. The latter, induced by a less-than-unity Lewis number, are modeled introducing an equivalent flame consumption speed to quantify the increase in flame expansion velocity. The model is validated against experimental data from literature obtained for premixed hydrogen-air flames propagating in an optically accessible spherical bomb. The data used for model validation refer to quiescent conditions at multiple lean equivalence ratios (from 0.45 to 0.97). The capabilities of the present model are assessed with reference to the measured time histories of chamber pressure, flame radius and expansion speed. A good agreement is achieved across all the test cases considered, confirming the consistency of the integrated ignition-combustion model proposed in this work.
Pretto, Marco, Bozza, Fabio, Giannattasio, Pietro, De Bellis, Vincenzo, Ugliano, Emanuele
Analysis of Flame Propagation Characteristics in a Hydrogen Engine using an Optically Accessible Engine2025-32-006111/3/2025
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 directly in the lean region. In future studies, it will be necessary to reduce the shooting speed or to conduct investigations based on spectroscopic measurements. Regarding hydrogen combustion, it was found that the combustible range of hydrogen was broad even when the experimental conditions were substantially varied. It was also found that the combustible period was much shorter than that of the existing hydrocarbon fuel. Misfiring and after-firing were observed in hydrogen combustion where the ignition timing was close to top dead center as well as under a lean condition. This confirmed that there are issues concerning hydrogen combustion stability under such conditions.
Arai, Yuto, Ueno, Takamori, Suda, Ryosuke, Sato, Ryoichi, Nakao, Yoshinori, Ninomiya, Yoshinari, Matsushita, Koichiro, Kamio, Tomohiko, Iijima, Akira
A Study of Knocking Characteristics in a Hydrogen SI Engine under High Compression Ratio2025-32-006311/3/2025
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 ratio of 17:1. High-intensity knocking was observed while operating the engine under various ignition timings and equivalence ratios. The knocking intensity and knocking mode characteristics were examined based on the observed knocking data.
Ishihara, Hiromasa, Kishibata, Shunsuke, Miyake, Shota, Iida, Tomoya, Kuwabara, Kenta, Yoshihara, Shintaro, Miyamoto, Sekai, Iijima, Akira
Experimental Study on Hydrogen-Methane Co-Combustion in Small Gas Engines2025-32-005511/3/2025
Hydrogen fuel has garnered significant attention as a key method for adapting internal combustion engines to a carbon-neutral society. Hydrogen is a carbon-free fuel that does not produce CO2 emissions during combustion. However, its wide flammability range and extremely low ignition energy present technical challenges when applied to internal combustion engines, such as the frequent occurrence of abnormal combustion phenomena like pre-ignition and knocking. Furthermore, the low energy density of hydrogen makes it difficult to achieve high power output. Additionally, hydrogen’s high adiabatic flame temperature and short quenching distance result in increased NOx emissions and cooling loss, which are further obstacles to its use. To address these issues, this study focuses on methane blending as a remedial approach. Experiments were conducted using a naturally aspirated engine with a premixed intake method to investigate the effects of methane-hydrogen blending. The following key findings were obtained: 1 The heat release rate can be controlled by adjusting the blending ratio. 2 Pre-ignition and knocking can be suppressed. 3 Power output can be improved. 4 NOx emissions can be reduced. 5 Thermal efficiency can be enhanced by optimizing the blending ratio based on engine load conditions. The insights gained through this study demonstrate the potential of internal combustion engines in achieving a low-carbon and decarbonized society.
Tanaka, Kenta, Tani, Toshihiro, Sako, Takahiro
Study on CO 2 Absorption via Atomization Utilizing Surface Texturing and Surface Energy for Small Engine Applications2025-32-007611/3/2025
In response to the stringent CO2 regulations set to be enforced in Europe in 2030, there is a global demand for innovative technologies to significantly reduce CO2 emissions from internal combustion engines used in trucks, ships, and other applications. For this reason, future power sources are anticipated to adopt a three-pronged approach: electrification; hydrogen fuel used in fuel cells or internal combustion engines; and synthetic fuels (e-fuels) produced from renewable energy-sourced hydrogen, as approved by the European Commission (EC), and from raw materials that capture CO₂ directly from the atmosphere via the Direct Air Capture (DAC) method, combined with internal combustion engines. In this study, we aimed to absorb and capture “Green” CO₂ emissions from e-fuel and carbon-neutral (CN) fuels combined with internal combustion engines by investigating a method that atomizes a CO₂-absorbing solution. This approach involved spraying the solution and impingement the droplets within the exhaust pipe to promote surface absorption reactions with CO₂ in the gas flow. By spraying an amine-based CO2 absorbent onto an impingement plate that has been especially surface textured and further treated with heating, we were able to enhance the surface area and control the surface energy of the CO2 absorbent. This approach opens up new possibilities for improved CO2 absorption reactions.
Nohara, Tetsuo, Nara, Shotaro, Kawamoto, Yuki, Fukushima, Naoya, Ochiai, Masayuki
Hydrogen-Assisted Renewable Fuels RME and HVO in the Compression-Ignition Engine2025-32-004811/3/2025
The article presents the research results on performance, thermodynamic parameters, and toxic exhaust emissions from the combustion in a compression-ignition engine fueled optionally by the hydrotreated vegetable oil (HVO) or the rapeseed methyl ester (RME), both with hydrogen addition. Furthermore, regular diesel fuel was used to obtain the reference data for making comparisons between HVO, RME, and diesel fuel. Hydrogen was injected into the intake manifold of a compression-ignition (CI) engine. Typically, diesel fuel combustion in a CI engine initiates through its self-ignition, usually simultaneously occurring at many points across the engine cylinder. Hydrogen, as a very chemically reactive substance, can promote pre-ignition reactions and accelerate flame kernel formation, shortening the ignition lag. This is crucial for the smooth running of the compression-ignition engine. Hydrogen was added at amounts not exceeding 7% by volume (35% energy content) referred to air sucked into the engine cylinder. As observed, a slightly positive trend in NOx vs. hydrogen addition was observed. It was also found that hydrogen added in small amounts does not form the so-called knock originating from hydrogen rapid combustion, regardless of the diesel knock.
Szwaja, Stanislaw, Juknelevicius, Romualdas, Pukalskas, Saugirdas, Rimkus, Alfredas, Szymanek, Arkadiusz
SAE TOMORROW TODAY - Fast-Tracking Hydrogen's Role in Aviation1354110/31/2025
If you still think hydrogen was the cause of the Hindenburg disaster, allow Danielle McLean, Founder and Executive Director of HYSKY Society, to debunk that myth for you. What first began as a hydrogen-powered eVTOL startup quickly revealed a bigger challenge for the aerospace engineer: the need for scalable, affordable clean hydrogen. In response, Danielle united engineers, entrepreneurs, and energy experts to form HYSKY Society -- a global nonprofit advancing hydrogen aviation through collaboration, education, and advocacy. Listen in as Danielle busts myths about the Hindenburg disaster, explains why regional airports could be the launchpad for hydrogen-powered planes, and details what it will take for hydrogen to go mainstream by 2045. You'll also get a sneak peek at FLYING HY, the world's largest hydrogen aviation event, and learn why "I want my hydrogen" just might be the future slogan of the aviation. We'd love to hear from you. Share your comments, questions and ideas for future topics and guests to podcast@sae.org. Don't forget to take a moment to follow SAE Tomorrow Today--a podcast where we discuss emerging technology and trends in mobility with the leaders, innovators and strategists making it all happen--and give us a review on your preferred podcasting platform. Follow SAE on LinkedIn, Instagram, Facebook, Twitter, and YouTube.
Patterson, Lori
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 achievable load among all the oils ranged from IMEP = 19–21 bar, while at 4000 1/min, it ranged from IMEP = 12–15 bar. The performance of the oils showed significantly more disparity at the elevated engine speed. While the impact of different lubricating oils on gasoline engines is rather limited, the outcome of this experiment indicates that in the case of hydrogen engines, oils can have a significant impact on PI. In addition to the oil formulation, different viscosities were also investigated. A lower relative calcium content leads to a much higher PI rate, a lower relative calcium content combined with a higher viscosity did not impact the PI rate. The base oil composition came second in terms of PI influence. The sulfated ash content did not show differences in terms of PI rate. In contrast to gasoline engines, the PI tendency increases with increasing engine speed.
Pehlivanlar, Benjamin, Torkler, Michael, Fischer, Marcus, Göbel, Christoph, Pischinger, Stefan, Maulbetsch, Theo, Nübling, Fritz, Neumann, Stephan
Scalable Hydrogen Storage and Transport Systems2025-01-05029/16/2025
Advances in conformable tank technology have resulted in opportunities to harness and deploy hydrogen energy in a variety of operational environments. Various use cases are described, and the benefits of these unique storage systems in vehicular, stationary, and bulk storage applications are illustrated. The impressive scalability of conformable hydrogen tank production is also explained, as it relates to the cost effective and broad application of these storage systems.
Johnston, Stephen, Kondogiani, Chris
CFD-Driven Optimization of Diesel Injection for a Hydrogen-Diesel Dual Fuel Engine2025-24-00459/7/2025
Among the alternatives to the use of fossil diesel fuel, dual fuel combustion, leveraging hydrogen as the low-reactivity fuel, represents a promising approach for both reducing pollutant emissions and improving brake thermal efficiency. In addition, this innovative combustion mode requires minimal modifications to the existing Diesel engines architecture. This study was conducted on a Diesel engine (naturally aspirated, 3-cylinder, 1 L, direct injection), properly modified by the authors to operate in dual fuel mode with port fuel injection of hydrogen. A set of experimental data was used to calibrate the 1D and the 3D-CFD models for both Diesel and diesel-hydrogen dual fuel configurations. The AVL FIRE M 3D-CFD software was employed to model diesel injection and combustion, while the gas exchange process was analyzed by GT-Power. The validated 3D-CFD model was then leveraged to optimize the baseline diesel injection strategy in dual fuel mode, minimizing diesel consumption while maintaining stable combustion and comparable performance with respect to the baseline Diesel engine. Notably, the analysis highlights that, at low loads, where hydrogen energy fraction is limited, a diesel injection strategy consisting of two fuel pulses is required to ensure stable ignition. However, as the hydrogen contribution increases, the main injection can be reduced or eliminated, with the pilot injection alone being sufficient to ignite the premixed charge, without compromising engine efficiency. This optimized strategy enabled a simultaneous reduction in diesel usage, up to −62.6%, and a marked decrease in emissions, with the best reductions reaching −62.5% for CO₂, −81.1% for CO, and −31.6% for NOₓ.
Rinaldini, Carlo, Pisapia, Alfredo Maria, Scrignoli, Francesco, Volza, Antonello, Rossetti, Salvatore, Mancaruso, Ezio
High-Pressure Hydrogen Flows through Single- and Multi-Hole Nozzles: A Computational Study13-06-03-00249/1/2025
Efficient propulsion technologies that utilize alternative fuels are becoming increasingly critical to achieve high efficiency at the vehicle scale while fulfilling global regulations in terms of emissions and criteria pollutants. In this scenario, hydrogen (H2) represents an important and appealing part of the solution due to its molecular composition and unique physical and chemical properties. With reference to internal combustion engines, much research is needed to overcome technical challenges that make H2 use not yet viable at the industrial scale. This work focuses on the computational modeling of some of the fundamental aspects of H2’s physical behavior, which can be useful to the development of high-pressure H2 injection systems. Computational fluid dynamics simulations are discussed with the goal of understanding the near- and far-nozzle behavior of H2 using single- and multi-hole nozzles. This study presents the validation of the computational framework against literature data, followed by its extension to a multi-hole geometry relevant to the automotive industry. The role of parameters such as ambient gas composition, minimum allowable temperature in the domain, different turbulence models, and grid strategies are all discussed in detail while keeping into consideration computational costs. The authors’ goal is to provide a series of best practices and guidelines that can be useful to researchers in the automotive industry who are interested in understanding the behavior of H2 injectors by means of numerical simulations.
Torelli, Roberto, Park, Ji-Woong, Pei, Yuanjiang
High Lambda Boosting for Hydrogen Internal Combustion Engine02-18-03-00238/29/2025
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 architectures together for steady-state and transient regime performance is the novelty for this study, which is a gap in the existing literatures. Base diesel power curves from both 13L and 15L engines were studied, having maximum brake mean effective pressures (BMEP) from 18 to 21 to 23 bar with λ ≥ 2.2. The VGT+SC was studied with multiple variants including splitting the charge air cooler (CAC) into two parts to provide cooling both pre and post SC, a SC clutch, and a SC bypass. The results show that the VGT (upstream) + SC variant utilizes the SC at low engine speed and high torque, along with all transient regimes from low to high load. The VGT+SC architecture, besides its complexity with clutch and bypass, successfully supports high λ operation (≥2.4), achieving a peak BTE of 43%, and significantly reduces NOx emissions without the need for EGR or large aftertreatment systems. This variant shows the fastest transient response relative to all other configurations in time-to-torque and acceleration cycles while rivaling the highest BTE. VGT+SC can also meet 5500 ft altitude performance with λ ≥ 2.2, leading to low NOx with the same SCR size equivalent to diesel engines and without EGR. Transient response and high BTE are essential to showing that this zero-carbon H2-ICE solution is viable for the commercial vehicle market.
Gurjar, Shubham, McCarthy, Jr., James E., Manickavasagan, Thirumoolan, Chaudhari, Amol S., Nimeshkumar, Parmar, Bachu, Pruthvi, Bitsis, Christopher
EDITORIAL: Hydrogen's humming in power generation25TOFHP08_048/1/2025
Two issues ago in this space I wrote about some high-profile struggles hydrogen-technology companies had encountered, including Nikola and Hyzon both ceasing operations. I also recognized, however, that despite legitimate challenges, many OEMs and suppliers continue development efforts, confident that hydrogen - be it in combustion engines or fuel cells - will eventually make its mark on the industry. One segment where this is coming closer to reality is power generation in stationary applications.
Gehm, Ryan
Experimental Investigation of Performance and Emission Characteristics of a Diesel Light-Duty Engine Fuelled with Pure Hydrogen2025-01-03147/2/2025
Transitioning to zero-carbon fuels is pivotal for expediting the reduction of carbon emissions. Hydrogen demonstrates significant adaptability and emerges as a principal zero-carbon alternative fuel for fossil fuel internal combustion engine (ICE) platforms. Implementing hydrogen in both spark ignition (SI) and compression ignition (CI) engines has proven to be both economically viable and timely. In this study, a conventional diesel engine was operated with pure hydrogen with minimal modification to engine hardware. It features a proactive, automated shutdown system to mitigate intake backfire risks associated with hydrogen port fuel injection (PFI) systems. A comprehensive engine characterisation was conducted using a lambda sweep test, measuring values from 1.5 to 4.5 with an integrated in-cylinder pressure transducer for high-resolution data. The study used an advanced Bandpass, Rectify, Integrate, Compare (BRIC) knock detection method for engine health monitoring and assessed stability through various metrics over 300 cycles. The performance and emission characteristics of a 100% hydrogen engine were analysed. Additionally, other low-carbon fuels, including methane and hythane (a blend of gaseous fuel with 80 % methane and 20% hydrogen by volume), were used for engine experiments to compare their performance with hydrogen. The results indicate that hydrogen can function effectively in a diesel light-duty engine utilising a port-fuel injection and spark ignition system, achieving an indicated thermal efficiency of approximately 40%. The engine operates with exceptional stability, reflected in a Coefficient of Variation of Indicated Mean Effective Pressure (COVIMEP) of less than 1.6% at a maximum lambda of 4.2. Additionally, it maintains a high combustion efficiency of 97.4%, with minimal hydrogen slip observed in the exhaust. The hydrogen fuel demonstrates nearly zero carbon emissions, with NOx levels recorded below 50 ppm at lambda 2.5 and approaching zero NOx at lambda 3. Compared to methane and hythane, hydrogen can achieve better emission characteristics with near zero NOx and unburnt hydrocarbon. However, the power output of pure hydrogen operation is lower than that of methane and hythane, as a result of leaner operating conditions.
Mohamed, Mohamed, Zaman, Zayne, Lu, Enshen, Feng, Yizhuo, Wang, Xinyan, Zhao, Hua
Hydrogen Jet Characteristics of an Outward-Opening Injector Based on Schlieren Imaging2025-01-02286/16/2025
Hydrogen was considered as a promising carbon-free fuel for future society. The application of hydrogen in internal combustion engines has drawn more and more attention. Jet performance of hydrogen injection plays a crucial role in characteristics of the hydrogen fuelled engines, in terms of mixture preparation, combustion and heat release in cylinder. In this research, an outward-opening injector was developed for hydrogen direct-injection applications. The jet performance was studied using high-speed schlieren imaging in a constant volume chamber and the effects of injection and ambient pressures on jet characteristics were investigated. The results show that, the hydrogen jet exhibits a conical structure in the near-field and overall presents a bell-shaped appearance under relatively low ambient pressure, which differs from the irregular structure under relatively high ambient pressure. The pressure ratio, defined as the ratio of injection pressure to chamber pressure, significantly influences the jet characteristics. The increase in the pressure ratio leads to greater axial and radial penetration of the jet, and an increase in the cross-sectional area. The penetration constant of outward-opening injector gas jets is 1.10 ± 0.02 at a pressure ratio ranging from 2 to 10. Separately, elevating the injection pressure enhances its mass flow and improves mixture formation. While increasing the chamber pressure hinders the development and expansion of the jet, resulting in a reduction in the jet entrainment rate.
Hu, Chaoqun, Hu, Longbiao, Chen, Haie, Li, Liguang, Wu, Zhijun, Deng, Jun
Conceptual Design of a Superconducting Aero Electric Engine System2025-01-01465/2/2025
The goal of the development of an electric aircraft engine is to create an aircraft system that achieves ultimate efficiency using hydrogen fuel instead of fossil fuels. Therefore, it is necessary to focus on reducing weight as much as possible, and this paper describes the approach to such fuel cell-powered aircraft. The authors have adopted a superconducting coreless rotating electric machine with an integrated hydrogen tank and are pursuing a target of 70kg or less for the main components of a 2MW rotating electric machine. High-temperature superconducting cables have zero electrical resistance and can carry a very high current density, but the alternating current (AC) loss generated when used in AC has been an issue in their application to rotating electric machines. In 2023, The SCSC cable was developed to be a low-AC-loss, robust, and high current cable concept, in which copper-plated multifilament coated conductors are wound spirally on a core. In addition to using this superconducting cable, the structure is designed to minimize the weight required to maintain the cryogenic state, and it consists of a single structure that combines a hydrogen tank and a rotating electric motor. This new type of superconducting rotating machine combines flux concentrated type field rotor technology and canned motor technology and provides a seal structure and bearings that make it practical. To put superconducting rotating machines to practical use in electric aircraft engines, it is necessary to transmit high currents from fuel cells, and this system proposes a flexible superconducting cable for power transmission with a hydrogen supply function that combines light weight and flexibility. As a result of performance estimation, we have confirmed that this superconducting rotating machine has the potential to improve performance by more than 10 times compared to our conventional products.
Oyori, Hitoshi, Sakurai, Sho, Kusase, Shin, Yoshida, Yukihiro, Yoshinaga, Seiichiro, Nose, Hiroyuki, Amemiya, Naoyuki
Vehicle Decarbonization: Vol. 3EPRCOMPV0720244/30/2025
Lin, Rui, Adas, Camilo Abduch
Aerospace Developments: Vol. 3EPRCOMPV0920244/30/2025
Muelaner, Jody Emlyn, Moran, Matthew, Phillips, Paul
Enhancements in Hydrogen Low Pressure Injection on Small Two-Stroke Engines2024-32-00474/18/2025
The use of small 2-stroke crankcase scavenged engines running on hydrogen is very attractive for low power rates, when low cost and compact dimensions are the fundamental design constraints. However, achieving optimal performance with hydrogen fuel presents challenges, including uneven air-fuel mixtures, fuel losses, and crankcase backfiring. This research focuses on a small 50cc 2-stroke loop-scavenged engine equipped with a patented Low-Pressure Direct Injection (LPDI) system, modified for hydrogen use. Experimental results demonstrate performance comparable to the gasoline counterpart, but further optimizations are needed. Consequently, CFD-3D simulations are employed to analyses the injection process and guide engine development. The numerical analysis focuses on a fixed operating condition: 6000 rpm, Wide Open Throttle (WOT), with a slightly lean mixture and injection pressure fixed at 5 bar. A numerical model of the entire engine is set up with the primary objective of improving injection efficiency by modifying the position and orientation of the injector, along with the piston dome shape. Seven configurations under the same operating conditions and injected mass are investigated to assess the impact of these modifications and find the best compromise. The methodology considers the following parameters: fuel trapped within the cylinder, fuel lost through the exhaust, fuel mass in the crankcase, and mixture uniformity before spark ignition. The best-performing configuration, featuring a standard piston dome but with a repositioned injector, achieves a notable reduction in fuel short-circuiting (up to 20%), while ensuring a relatively uniform air-fuel mixture at spark timing.
Caprioli, Stefano, Schoegl, Oliver, Oswald, Roland, Kirchberger, Roland, Mattarelli, Enrico, Rinaldini, Carlo Alberto
Enhancing Low Temperature Lean Combustion of CH4-H2 Blends through a Prechamber Equipped Engine2024-32-00444/18/2025
The use of hydrogen as a sustainable fuel in the short term is hampered by the impossibility of large scale use due low availability. In order to promote decarbonization, complementary solution for a smooth transition is to dilute it in a mixture with methane, in a current Port Fuel Injection (PFI) internal combustion engine (ICE). This can be done as a retrofit after limited structural modifications, such as the introduction of a passive prechamber. Such a solution allows a reduction of the carbon footprint of traditional ICEs through more efficient combustion (both the prechamber technology and the hydrogen fuel properties promote an increase in combustion speed) and a reduced carbon content in the fuel. The present research activity has been carried out through numerical investigation based on three-dimensional CFD analyses to simulate the behavior of a natural gas engine fueled with CH4-H2 blends. The combustion mechanism for the fuel blend was validated against measurements of the flame front propagation carried out on an optical engine. The focus of the work is to evaluate the effect of both the hydrogen share and the charge dilution. The introduction of a passive prechamber was necessary to stabilize the mixture ignition and increase the combustion speed. In particular, simulations were carried out for increasing hydrogen content, from 0% to 30% in volume, and increasing excess air from stoichiometric (λ=1.0) to ultra-lean (λ=1.8), in order to achieve a Low Temperature Combustion (LTC). For each operating condition investigated, the ignition advance was optimized in order to maximize the gross indicated mean pressure (GMEP). The results show that, at λ = 1.4, 20% H2 is sufficient to obtain a slightly higher GMEP than using pure CH4, while at the same time guaranteeing a 40% reduction of raw NOx emissions. When further increasing the value of λ up to 1.8, slow combustion is obtained even with 30% share of H2. In this case, hot EGR is needed to increase the reactivity of the mixture and allow achieving a complete combustion.
Balduzzi, Francesco, Ferrara, Giovanni, Di Iorio, Silvana, Sementa, Paolo
Optimization-Oriented Adaptive Equivalent Consumption Minimization Strategy for Fuel Cell Hybrid Electric Vehicles2025-01-85524/1/2025
Fuel economy and the ability to maintain the state of charge (SOC) of the battery are two key metrics for the energy management of a full-power fuel cell hybrid vehicle fitted with a small-capacity battery pack. To achieve stable maintenance of SOC and near-optimal fuel consumption, this paper proposes an adaptive equivalent consumption minimization strategy (PA-ECMS) based on power prediction. The strategy realizes demand power prediction through a hybrid deep learning model, and periodically updates the optimal equivalent factor (EF) based on the predicted power to achieve SOC convergence and ensure fuel economy. Simulation results show that the hybrid deep learning network model has high prediction accuracy with a root mean square error (RMSE) of only 0.733 m/s. Compared with the traditional ECMS based on SOC feedback, the PA-ECMS effectively maintains the battery SOC in a more reasonable range, reduces the situation of the fuel cell directly charging the power cell in the high-power-demand scenarios, and reduces the equivalent hydrogen fuel consumption by 1.77% to 6.66 g/km.
Gao, Xinyu, Ju, Fei, Chen, Gang, Zong, Yuhua, Wang, Liangmo
Numerical Investigation on Behaviors of Under-Expanded Hydrogen Jets: Influence of Straight Nozzle Geometry2025-01-84594/1/2025
In internal combustion engines, hydrogen is considered as one of the most promising alternatives to replace fossil fuels and reduce CO2 emissions. In such a context, traditional injectors for hydrocarbon fuels are currently being tailored to be used with hydrogen, or a single-hole/multi-hole cap mounted at the injector tip was used to obtain better mixing and air utilization. Nevertheless, the hydrogen injection can be accompanied by the formation of highly under-expanded jets and will significantly influence the downstream mixing process. Therefore, in order to achieve a better understanding on hydrogen-air mixture, this work aims to numerically investigate the influence of the nozzle geometry on the jet behaviors in the near nozzle region. The nozzle diameter ranges from 0.1 mm to 2.0 mm and the nozzle length is from 1mm to 2mm. The injection pressure ranges from 10 bar to 70 bar. As the boundary condition varied, differences in both the internal flow of different nozzle structures and the development of external jets through these nozzles were found, as well as the close connection between the internal flow and the external under-expanded jet development. This work will provide a theoretical basis for the design of hydrogen injectors.
Jiahui, Lang, Li, Yanfei, Xu, Lubing, Xiao, Ma, Shuai, Shijin
Operating the Tour Split-Cycle Engine on Hydrogen/Methane Fuel Blends to Achieve High Efficiency and Reduction of Both GHG and NOx Emissions2025-01-84224/1/2025
Decarbonized or low carbon fuels, such as hydrogen/methane blends, can be used in internal combustion engines to support ambitious greenhouse gas (GHG) emission reduction goals worldwide, including achieving carbon neutrality by 2045. However, as the volumetric concentration of H2 in these fuel blends surpasses 30%, the in-cylinder flame propagation and combustion rates increase significantly, causing an unacceptable increase in nitrogen oxides (NOx) emissions, which is known to have substantial negative effects on human health and the environment. This rise in engine-out NOx emissions is a major concern, limiting the use of H2 fuels as a means to reduce GHG emissions from both mobile and stationary power generation engines. In this study, an experimental investigation of the combustion performance and emissions characteristics of a 4th generation Tour split-cycle engine was undertaken while operating on 100% methane and various hydrogen/methane fuel blends (30%, 40%, and 50% by volume of hydrogen). Taking advantage of the Tour engine’s superior operating flexibility and its inherent capability to manipulate combustion phasing, the results demonstrate that the Tour split-cycle engine operating on hydrogen/methane fuel blends is capable of high brake thermal efficiency and reduced GHG emissions, while at the same time exhibiting reduced engine-out NOx emissions.
Bhanage, Pratik, Cho, Kukwon, Anderson, Bradley, Kemmet, Ryan, Tour, Gilad, Atkinson, Chris, Tour, Hugo, Tour, Oded
Effect of Hydrogen Addition on Abnormal Combustion of Pre-Chamber Natural Gas Engine at High Load2025-01-84264/1/2025
In cogeneration system, the pre-chamber natural gas engine adopts combustion technologies such as ultra-high supercharged lean burn and Miller cycle to increase the theoretical efficiency by increasing the specific heat ratio and the mechanical efficiency by improving the specific power. In recent years, the use of hydrogen fuel has been attracting attention in order to achieve carbon neutrality, and it is required to operate existing high-efficiency natural gas engines by appropriately mixing hydrogen. For this purpose, it is important to have natural gas and hydrogen co-combustion technology that allows combustion at any mixture ratio without major modifications. The authors mixed hydrogen into the fuel of an ultra-high supercharged lean burn pre-chamber natural gas engine (Bore size: 200mm) that has already achieved high efficiency and performed combustion experiments at BMEP (Brake mean effective pressure) of 2 MPa or more. The engine load and hydrogen mixture ratio were used as operating parameters to search for the optimal air excess ratio and ignition timing. Abnormal combustion such as pre-ignition and thud occurs in the high load and high hydrogen mixture regions, but the occurrence regions may or may not overlap, and it was found that this limits the operable limit on the high load and high hydrogen mixture sides. We reported on the operating range in which each type of abnormal combustion occurs, the relationship between the frequency of occurrence and operating conditions, the fact that the pattern of abnormal combustion occurrence is not continuous, the relationship and continuity with the cycles before and after, and the fact that pre-ignition is less likely to occur when the pre-chamber excess air ratio is large. Furthermore, we investigated a method of separating the main chamber pressure oscillation caused by the ejection jet from pre-chamber combustion, known as ringing, from the pressure oscillation caused by knocking. We have set a threshold for the maximum amplitude of high-frequency components and separating knocking from ringing by the frequency of occurrence.
Morikawa, Koji, Kimura, Shin, Sakai, Shunya, Moriyoshi, Yasuo
Green Hydrogen Production: Progress, Challenges and Proposed Solutions2025-01-86014/1/2025
Recently, global interest in hydrogen as a powerful, promising and clean source of energy has increased. Green hydrogen production (GHP) is considered one of the most important modern projects worldwide, as it is the way to achieve a clean, healthy and sustainable environment. GHP plays a major role to improve public health. There are several methods for producing or harvesting green hydrogen, the most famous of which are: 1) The electrolysis of water using a proton exchange membrane and metal foam at low temperatures and 2) Flash Joule Heating (FJH) method for heating plastic waste at high temperatures using low-carbon emissions technology. However, both methods still suffer from some difficulties. This calls for the need to search for scientific solutions to make hydrogen available at reasonable prices. While the first method is considered better for producing high-purity hydrogen compared to the second method, it faces challenges in collecting hydrogen on the surface of the negative electrode (cathode) in a suitable manner (catalyst) to collect it in a less expensive way. While the second method is considered the cheapest, but it is complex and requires very high temperatures to produce graphene with hydrogen harvesting. Graphene can be used in the manufacture of digital processors, electronic cells and conductors. Green hydrogen is used sparingly in some applications such as automotive research and some metallurgical and chemical industries. The paper focused on monitoring and understanding the current situation and challenges to provide proposed solutions for enhancing hydrogen production based on advanced engineering materials and metrology techniques. These solutions aim to develop the cathode material and its surface in the first method. Furthermore, the use of SEM and AFM in both methods was proposed to improve the characterization process of both the cathode material with its surface and GHP. Adopting such approach is essential to contribute for reducing the costs of GHP with the aim of providing clean and sustainable energy, in addition to enhancing the role of doctors in performing their medical duties towards raising the level of health awareness of community members and maximizing the treatment and recovery of patients in a healthy environment.
Hamed, Maryam Salah, Ali, Salah H. R.
Improving Modal Frequencies in Class 5 Truck Fuel Cell Tank Structure through Topology Optimization2025-01-86484/1/2025
In addition to electric vehicles (EVs), hydrogen fuel cell systems are gaining attention as energy-efficient propulsion options. However, designing fuel cell vehicles presents unique challenges, particularly in terms of storage systems for heavy hydrogen tanks. These challenges impact factors such as NVH (noise, vibration, and harshness) and safety performance. This study presents a topology optimization study for Hydrogen Energy Storage System (HESS) tank structure in Class 5 trucks, with a focus on enhancing the modal frequencies. The study considers a specific truck configuration with a HESS structure located behind the crew cab, consisting of two horizontally stacked hydrogen tanks and two tanks attached on both sides of the frame. The optimization process aimed to meet the modal targets of this hydrogen tank structure in the fore-aft (X) and lateral (Y) directions, while considering other load cases such as a simplified representation of GST (global static torsion), simplified side impact, and angled impact. By utilizing solid and shell elements, as well as Frequency Response Function (FRF) analysis, various load paths and configurations were explored to identify efficient designs that meet the modal targets and structural requirements. The optimized structure was verified and translated into a feasible and manufacturable design.
Yoo, Dong Yeon, Chavare, Sudeep, Viswanathan, Sankar, Mouyianis, Adam
Combustion Characterization and Heat Release Rate Modeling of a Heavy-Duty Hydrogen-Diesel Dual-Fuel Engine2025-01-84184/1/2025
Introducing hydrogen (H2) into the intake air of diesel engines provides a near-term approach to reducing tailpipe CO2 emissions from heavy-duty commercial vehicles. The premixed hydrogen results in a complex H2-Diesel dual fuel (H2DF) combustion process, where H2 can both participate in the non-premixed diesel combustion and result in a propagating H2/air combustion. These interactions influence engine combustion characteristics, including in-cylinder pressure and heat release rate (HRR), as well as emissions. The nature and extent of the impact depends on the amount of H2 introduced as a function of the total fuel energy (H2 energy share ratio - HES), the trapped air mass, and engine operating conditions. To optimize the HES ratio under different conditions, it is crucial to understand how H2DF combustion differs from diesel combustion and how this limits engine operation and impacts emissions. To investigate these effects, a heavy-duty class 8 truck fitted with an H2DF system developed by Hydra Energy Corp. was tested on a chassis dynamometer. The engine was fitted with a suite of instrumentation, including in-cylinder pressure, air system pressure and temperature, exhaust flow rate, and emissions measurement equipment. Tests were conducted over three loads and speeds at fixed HES ratios, and detailed HES ratio studies were conducted at low- and mid-load cases at 1200 RPM. The results show that H2 introduction significantly impacts combustion characteristics and emissions, primarily influenced by the H2 equivalence ratio, with the engine control unit’s adjustments to boost pressure and diesel injection timing playing a critical role in combustion characteristics and engine-out emissions. At higher H2 equivalence ratios than 0.1, an H2/air premixed flame forms, advancing combustion phasing, which increases the maximum rate of pressure rise and reduces PM while raising NOx emissions. The Pcyl and HRR data are used to develop a semi-predictive combustion model imposing the net HRR profile using a multi-Wiebe function. A four-curve Wiebe function model can accurately capture the HRR and combustion characteristics across engine operating points, providing a reliable predictive tool at a given speed/load for various HES ratios. The developed understanding and combustion model provides valuable insight and techniques for future studies to further improve H2 utilization strategies tailored for the retrofit of heavy-duty H2DF truck applications.
Farzam, Reza, Guan, Mang, Gmoser, Raine, Steiche, Patrick, Kirchen, Patrick, McTaggart-Cowan, Gordon
HYDROGEN WON'T ACCEPT ‘NO’ FOR AN ANSWER25AUTP03_013/1/2025
From automakers to companies in the wider mobility industry, hydrogen power is seeing no shortage of investment and research even as some remain unconvinced of its future. Most outsiders to the transportation industry don't know much about rapid developments in hydrogen fuel-cell and hydrogen internal-combustion. There just aren't the large-scale commercial and public efforts to inform the public as exist for the battery-electric vehicle market. Still, 50% of people in a recent Department of Energy survey said they understood that hydrogen has a chance to be a clean alternative source of power for vehicles and even for homes. Spotlight or no, progress is being made. And though much of it is outside the United States, American cities and companies have absolutely not given up on the technology. SAE Media wanted to check in and note recent transportation developments that use the earth's most abundant element.
Clonts, Chris
Hydrogen storage: Not everything need look like a sausage25AUTP03_063/1/2025
Since the 1860 Hippomobile, hydrogen has been a part of powered mobility. Today, most hydrogen storage applications use cylindrical tanks, but other solutions are available. At a recent Bosch-sponsored event, SAE Media noted Linamar's Flexform conformable storage, which the company says uses the same or less material for a given storage volume while delivering anywhere from 5-25% more volumetric efficiency than conventional cylindrical tanks within that volume. “We see space as a regular bounding box where all you're losing is this area around the corners, closer to five to 10% [loss]. Where Flexform really shines and where the value proposition really is, is irregular spaces, such as between frame rails,” said representatives from the Linamar engineering team.
Cannell, Thom
High-Flow Prescriptive Fueling Protocols for Gaseous Hydrogen Powered Medium and Heavy-Duty VehiclesJ2601/5_202502 (Current)2/7/2025
This TIR establishes high-flow fueling protocols, including their process limits for fueling of compressed gaseous hydrogen vehicles at peak flow rates from 60 to 300 g/s with compressed hydrogen storage system (CHSS) volume capacities between 248.6 and 7500 L which have been qualified to UN GTR #13. This document is initially being published as a TIR due to limited field testing of the fueling protocols. Once the fueling protocols have been field tested, the SAE Fuel Cell Standards Committee Interface Task Force intends to publish a revision to this document as an SAE Standard.
Fuel Cell Standards Committee
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