The clearance between the impeller and pump head is a critical parameter of the hydrogen recirculation pump used in proton exchange membrane fuel cell (PEMFC) systems, and it significantly affects performance, efficiency, and reliability. This study investigates the impact of clearance on the performance of a hydrogen recirculation pump applied in PEMFC systems. Both numerical simulation and experimental methods are employed to systematically evaluate the effects of symmetric circular clearances ranging from 0 to 0.4 mm, as well as asymmetric clearance configurations representative of manufacturing tolerances and assembly deviations. According to the research results, the pressure rise increases with the clearance decreasing under a given flow rate, and a smaller clearance would show a stronger capability to cover a larger flow rate range. The clearance impact on the performance of the hydrogen recirculation pump is found to be in the lower flow rate zone. In addition, the pressure

Xie, Lu, Zhong, Hao, Tsoi, Jeffrey

Evaluation of Flamelet-Based Combustion Models for Hydrogen-Ammonia Spark-Ignition Engines

2026-37-0027

6/9/2026

Besides the electrification of the transport sector, the growing interest in alternative fuels for internal combustion engines represents a promising pathway to effectively decarbonize transportation over the coming decades. Predictive combustion models implemented within CFD frameworks are a critical tool to guide the design of next-generation internal combustion engines fuelled with alternative fuels. Accurate prediction of the combustion heat release process is influenced by multiple interacting parameters, requiring combustion models that can reliably adapt to variations in fuel chemical properties and operating conditions. In this study, two well-established combustion models considered to model combustion development in Spark-Ignition engine, namely the Extended Coherent Flame Model (ECFM) and the G-equation model, are compared to assess their capability to adapt to changes in fuel chemical composition. Both models, based on the flamelet formulation are deliberately tested beyond

Sola, Riccardo, Baratta, Mirko, Misul, Daniela, Rousselle, Christine, BREQUIGNY, Pierre, Colin, Olivier

Comparative Toxicological Assessment of Exhaust Emissions from Modern Low-Emission Passenger Vehicles

2026-37-0005

6/9/2026

As vehicle technologies evolve toward electrification and advanced aftertreatment, understanding the biological implications of their exhaust emissions remains essential. This study presents a harmonized comparative toxicological assessment of five Euro 6 vehicles representing gasoline, hybrid, plug-in hybrid, compressed natural gas (CNG), and diesel technologies. Vehicles were tested under realistic driving conditions on a chassis dynamometer. Diluted exhaust was delivered directly to human lung epithelial cells (A549) using a controlled air–liquid interface (ALI) exposure system. Solid and total particle number emissions were measured, and deposited particle mass was estimated from size-resolved distributions and deposition efficiency. Vehicles equipped with particulate filtration showed lower solid particle emissions overall, while differences between gasoline particulate filter-equipped vehicles indicated that hybridization can further influence emission levels. Diesel operation

Tsakonas, Georgios, Stamatiou, Rodopi, Lazou, Antigone, Samaras, Zissis, Elihn, Karine

Nitrogen-Based Emissions from Ammonia Combustion in a Heavy-Duty Spark Ignition Engine

2026-37-0032

6/9/2026

Ammonia (NH3) is a carbon-free fuel with strong potential for spark-ignition (SI) engine applications. However, the engine can produce complex nitrogen-based emissions not adequately captured by conventional engine models. This study consolidated the results of experimental and numerical studies on the use of neat NH3 combustion in a heavy-duty compression-ignition engine converted to spark-ignition operation, first for a sweep of equivalence ratios (ϕ) from 0.7 to 1.0, and another from varying the energy substitution ratio of methane (CH4)– NH3 blends from neat CH4 to neat NH3 at constant ϕ = 0.8. Two 0-D two-zone SI engine models with detailed chemistry (called “original” and “extended”) predicted engine thermodynamics and emissions. While the original model reproduced in-cylinder pressure and combustion phasing, it failed to capture the effect of fuel composition or operating condition on NO trends, both under- and over-predicting them for neat NH3 and CH4-rich operations. An

Trujillo Grisales, Juan, Saenz Prado, Stefany, Alvarez, Luis F., Akkerman, Vyacheslav, Dumitrescu, Cosmin E.

Development of a Diesel Combustion System for Next-Generation Heavy-Duty Engines Using a Synergistic Analysis-and-Testing Approach

2026-37-0004

6/9/2026

Regulators and policymakers have introduced increasingly stringent limits on tailpipe CO₂ and pollutant emissions to accelerate the decarbonization of heavy-duty vehicle applications. The development of innovative propulsion technologies — such as advanced combustion systems, low-friction reciprocating components, and improved aftertreatment solutions — combined with hybridization and the adoption of alternative fuels (e.g., biogas, HVO, green hydrogen), is a key pathway for meeting future emission and GHG targets. In this study, advanced combustion systems were developed for a 13-liter diesel engine for heavy-duty truck applications, with the objective of meeting forthcoming Euro VII regulations while maximizing thermal efficiency. The combustion system architecture—including open-bowl geometry with high aspect ratio, injector nozzle with wider spray opening angle, and reduced swirl ratio—was optimized using a Machine Learning–algorithm trained on high-fidelity 3D CFD combustion data

Belgiorno, Giacomo, Centini, Maria Pia, Pezza, Vincenzo, Cozza, Ivan F., Pesce, Francesco C., Vassallo, Alberto, Colombo, Giovanni, Gallo, Alessandro, Mirzaeian, Mohsen, Borg, Jonathan

Alcohol-Based Energy Carriers in Transportation: Status, Standards, and Outlook

2026-37-0042

6/9/2026

The global transport sector accounts for approximately 30 % of total final energy consumption and 15.9 % of worldwide greenhouse gas (GHG) emissions, with road transport alone accounting for the largest share at 11.8 %. Decarbonizing this sector requires energy sources that combine scalable generation from renewable sources with compatibility with various modes of transportation and existing infrastructure. Methanol and ethanol emerge as promising alternative energy carriers that can leverage existing logistics infrastructure while reducing dependence on fossil fuels. Global methanol production reached 112 million metric tons, and global ethanol production totaled approximately 93.5 million metric tons in 2024, compared to more than 2 billion metric tons of gasoline and diesel produced annually. The review assesses production pathways and cost trajectories for both alcohols, evaluates fuel requirements across multiple transport modes, including passenger vehicles, light- and heavy-duty

Fitz, Patrick, Fellner, Felix, Rößlhuemer, Raphael, Härtl, Martin, Jaensch, Malte

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

2026-37-0031

6/9/2026

The reduction of Greenhouse Gas (GHG) emissions represents a key challenge for the transportation sector, requiring the adoption of renewable fuels capable of ensuring both environmental benefits and compatibility with existing internal combustion engine technologies. In this context, bioethanol emerges as a viable solution for Spark Ignition (SI) engines, offering a low life-cycle CO₂ footprint and favorable combustion characteristics. Nevertheless, despite its well-known advantages under steady-state operation, the widespread use of high-ethanol-content fuels is still limited by critical issues during engine cold start. The aim of this work is to experimentally investigate the influence of ethanol content on cold-start behavior and idle warm-up transient operation of a Naturally Aspirated (NA), Port Fuel Injected (PFI) SI engine. The experimental campaign was carried out under idle conditions using four fuels with increasing ethanol content, namely commercial gasoline (E5), E30, E60

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

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

2026-37-0008

6/9/2026

Hydrogen-fueled rotary engines offer a promising zero-emission solution for compact commercial powertrains. This study reports experimental results from the further development of a naturally aspirated, direct-injection hydrogen rotary engine by HTM. Initial applications, such as an airport baggage tractor, demonstrated technical feasibility but revealed pre-ignition that limited maximum torque. To address this, mixture formation was investigated using an experimental setup with two independently controlled injectors feeding a single rotor injection channel. The effects on operating behavior, efficiency, and NOx emissions were evaluated. The dual-injector configuration significantly shortens injection duration and improves spatial distribution of hydrogen within the combustion chamber. Enhanced mixture control suppresses pre-ignition and enables higher mean effective pressure. Systematic variation of injection timing under representative steady-state conditions also shows potential for

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

Numerical Simulation of Spark-Ignited Flame Kernels towards Prospective Application to Hydrogen SI Engines

2026-37-0015

6/9/2026

The ongoing energy transition demands the decarbonization of the transport sector, for which the use of premixed hydrogen in spark-ignition (SI) engines appears very promising. However, modeling the combustion of the lean hydrogen/air mixtures required for safe, efficient, and low-NOx engine operation involves multiple open issues. Correct prediction of flame kernel initiation and growth is a difficulty that hydrogen shares with hydrocarbon fuels, while properly accounting for the instabilities that characterize lean hydrogen flames is an additional demanding task. In this work, a 1D kernel expansion model of general validity recently proposed by the authors is implemented into OpenFOAM, an open-source 3D CFD software package, to enable numerical simulation of expanding spark-ignited flame kernels. Firstly, the OpenFOAM framework is presented focusing on XiFluid, its flame propagation model based on a regress variable whose evolution depends on the laminar flame speed. Then, the

Dotteschini, Enrico, Pretto, Marco, Giannattasio, Pietro, Gadalla, Mahmoud

On Natural Gas Combustion Split into Diesel Like Architecture of a Compression Ignition Engine Retrofitted for Spark Ignition Operation

2026-37-0029

6/9/2026

In commercial areas that no longer favor diesel engines, such as Europe, it might be interesting to convert an existing compression ignition engine to the spark ignition operation and to use natural gas (NG) because of its advantages: availability of still abundant supplies worldwide and environmental benefits compared to conventional liquid fossil fuels. This paper first presents experimental results on NG combustion inside such a converted engine with diesel-like architecture dedicated to light-duty vehicles and passenger cars. Particularly, our study carried out at the engine test bed revealed that in certain operating points (low speed and load, stoichiometric mixture and rather high spark advance), the combustion is split into two distinct events (first, a fast combustion inside the cylinder and piston bowl and then, a slower combustion occurring outside the bowl-in combustion chamber, in other words, in the squish region), which is not specific to the standard spark ignition

Clenci, Adrian F., Popa, Robert, Berquez, Julien, Iorga-Siman, Victor, Magheru, Catalin, Punov, Plamen, Niculescu, Rodica

Development and Validation of a One-Dimensional Model for an Opposed-Piston Free-Piston Engine Generator with Parametric Analysis

2026-37-0021

6/9/2026

Opposed-piston free-piston engine generators (OFPEGs) are emerging as a promising technology for next-generation hybrid and electrified transportation systems due to their high efficiency, reduced mechanical complexity, and improved noise, vibration, and harshness (NVH) characteristics. However, due to eliminating the conventional crankshaft mechanism and directly coupling a free-piston engine with linear generators, performance of OFPEG systems is governed by a strong coupling between piston dynamics, in-cylinder combustion processes, and electrical loading conditions. This coupling presents substantial challenges for system design, control, and optimization, limiting the further development and application of OFPEGs. Existing researches lack a comprehensive numerical model that integrates detailed in-cylinder thermodynamic process with control system of linear generator, and quantitative analysis of the effect of piston motion trajectory on system performance remains insufficiently

Wang, Jiayu, Morandi, Nicola, Lucchini, Tommaso, FENG, HUIHUA, Jia, Boru, Ren, Peirong

Methane Emission Mitigation in Large-Bore Dual-Fuel Engines via Negative Valve Overlap Diesel Injection: Thermochemical Pathways and Reactivity Control

2026-37-0045

6/9/2026

Low-load natural gas–diesel reactivity controlled compression ignition (RCCI) in medium-speed marine engines is constrained by an insufficient charge thermal state. This limitation leads to partial fuel oxidation, producing high methane emissions. This work evaluates the use of negative valve overlap (NVO) combined with NVO diesel injection as an in-cylinder reactivity enhancement strategy. The simulation study was performed using the University of Vaasa’s advanced thermo-kinetic multi-zone model (UVATZ), extended for reactive simulations during NVO. The extended framework was validated against test-bench data from a prototype Wärtsilä 6L20 dual-fuel engine operating in RCCI mode. The baseline low-load operating point for reforming simulations was defined by reducing the intake manifold temperature to replicate conditions close to partial misfire with 52% combustion efficiency. The parametric sweeps of NVO injection timing and ratio showed that the strategy can be used for in-cycle

Soleimani, Amir, Nurmi, Mikael, Hunicz, Jacek, Kim, Jeyoung, Hyvonen, Jari, Mikulski, Maciej

Development and Experimental Validation of a 1D Model for Performance and Emissions Analysis of Oxygenated Fuel Blends in a CI Engine

2026-37-0028

6/9/2026

Emissions reduction remains a major concern for internal combustion engines in view of increasingly stringent environmental regulations. To address these challenges while maintaining acceptable engine performance, a wide range of alternative fuels and fuel blends have been investigated to ensure the continued viability of CI engines. This study reports the effects of blending the oxygenated fuel diethylene glycol diethyl ether (DGDE) with hydrotreated vegetable oil biodiesel (HVO) on engine performance and emissions. The investigation is conducted on a 2.3-liter, four-cylinder, common-rail diesel engine, equipped with a variable geometry turbocharger and a high-pressure exhaust gas recirculation system. The objectives of this study are achieved by developing a one-dimensional predictive engine model using the commercial GT-SUITE software. The engine model is developed and experimentally validated, at various operating conditions and HVO–DGDE fuel blends, to predict their effects on

Arain, M Wajahat Rasool, Foglia, Antonio, Frasci, Emmanuele, Vitek, Oldrich, Pianese, Cesare, Arsie, Ivan

Hybridized Diesel Powertrains - An Important Enabler for Commercial Applications on the Long Journey towards Full Electrification

2026-37-0022

6/9/2026

The ongoing efforts for reduction of the traffic-related greenhouse gas emissions and, at the same time, the mitigation of harmful pollutant emissions from vehicle exhaust emissions are important development tasks for the entire automotive industry worldwide according to demand to provide clean and efficient products. Further tightened fleet average FE standards and ultra-low limits for exhaust emissions require the continuous development of new propulsion system types. Due to the given reluctance of the end customer and corresponding low acceptance of fully electrified vehicles, especially in the commercial vehicle segment, new and innovative topologies are needed to meet regulatory requirements and maintain the high versatility of today’s dominating solutions. For further optimization of operating conditions with enhanced fuel efficiency, the technical strategy is also determined by uplifting the attractiveness of electric driving incl. the avoidance of areas with poor ICE efficiency

Koerfer, Thomas

An Open-Source Framework to Automate Virtual Optimization of Internal Combustion Engine Calibration Maps through Shape-Based Strategy

2026-37-0001

6/9/2026

The automotive industry is facing increasingly stringent regulatory constraints, driving the need for faster and more efficient powertrain development. This results in higher systems complexity, making internal combustion engine calibration progressively more challenging to meet performance and emissions targets. This, combined with the manual nature of traditional calibration workflows, leads to a time-consuming process that heavily relies on human expertise. Although virtualization can reduce development time and costs, the overall workflow remains largely dependent on manual decision-making and iterative refinement. In this context, this work presents a virtual calibration framework based on a genetic algorithm, aimed at the automated optimization of engine calibration maps to satisfy performance and emissions constraints, while reducing manual effort. Each calibration map is represented through a polynomial parameterization. Specifically, a generic three-dimensional polynomial with

Romano, Gianvito, Aglietti, Filippo, Spedicato, Tonio, Cozza, Ivan Flaminio, Capra, Andrea

An Along-the-Channel Pseudo-2D Approach for Spatially Resolved PEM Fuel Cell Dynamics

2026-37-0010

6/9/2026

The longevity of proton-exchange membrane fuel cells is governed by degradation processes whose rates depend on local operating conditions such as temperature, humidity, liquid-water saturation, and reactant availability. Along-the-channel gradients imposed by the flow field can therefore be relevant when interpreting operating behavior and when formulating models intended to support control and system studies. The AlphaPEM framework provides a dynamic through-plane description of electrochemical and water-management states, but in its baseline form does not resolve how these states vary along the gas channels. This paper presents a pseudo-2D (1+1D) extension of AlphaPEM that couples a discretized along-the-channel gas-channel model to a segment-wise MEA submodel. For each axial segment, the MEA equations are evaluated with local boundary conditions obtained from the channel (e.g., reactant and vapor concentrations), while retaining the key dynamic states of the original formulation

Ringeisen, Björn, Günthner, Michael, Kargl, Pascal

Development of a 0D – 1D Numerical Model for the Thermal Management of a Heavy – Duty PEMFC

2026-37-0006

6/9/2026

The rising concerns on climate change is accelerating the transition from fossil fuel-based technologies to sustainable energy systems. In this framework, Proton Exchange Membrane Fuel Cells (PEMFCs) are gaining an increasing interest due to their high efficiency and wide range of applications. Nevertheless, these systems experience significant performance losses under high loads, associated with significant heat generation, making thermal management a fundamental design aspect. In this study, a 200-kW low temperature PEMFC was investigated through the development of a 0D – 1D model of a simplified cooling circuit implemented in GT – SUITE environment. The model was used to evaluate the influence of design parameters on the effective efficiency of the system to dissipate the excessive heat. Additionally, a detailed stack-only model, comprehensive of the Membrane Electrode Assembly (MEA) subcomponents, was developed to verify the temperature differences between coolant fluid and

Cecere, Giovanni, Antetomaso, Christian, Irimescu, Adrian, Merola, Simona

Impact of Compression Ratio and Stroke on Hydrogen Requirement for Emission-Optimized Operation of an Ammonia-Fuelled Spark-Ignition Engine

2026-37-0030

6/9/2026

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

Yadav, Neeraj Kumar, Ambalakatte, Ajith, Geng, Sikai, Gopakumar Suja, Gagan, Birch, Alexander, Cairns, Alasdair, Harrington, Anthony, Hall, Jonathan

Potential of ORC-Based Waste Heat Recovery in Conventional and Hybrid Heavy-Duty Powertrains

2026-37-0018

6/9/2026

Heavy-duty vehicles significantly contribute to greenhouse gas emissions and urban air pollution, especially during cold-starts and transients when engine and aftertreatment efficiencies drop. Waste heat recovery (WHR) via Organic Rankine Cycle (ORC) systems offers a practical solution to improve fuel efficiency and cut CO₂ in real-world heavy-duty operations. This study examines ORC-based WHR integration into conventional and hybrid powertrains of an Isuzu FTR850 truck, analyzing four configurations: Shell-and-Tube or Plate heat exchangers with simple or regenerative ORC layouts. For hybrids, it compares two engine sizes and energy management strategies: an optimized fuzzy logic approach versus constant-power operation to enhance exhaust heat recovery. A validated quasi-static simulation framework is used to predict fuel consumption and exhaust properties over representative duty cycles. 2D performance maps using exhaust temperature and mass flow as inputs are used to model the WHR

Donateo, Teresa, Morrone, Pietropaolo

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

2026-37-0014

6/9/2026

Addressing climate change requires substantial reductions in CO2 emissions from the transportation sector, where alternative fuels for internal combustion engines play a crucial role. Hydrogen stands out as a compelling energy carrier capable of enabling low-carbon combustion while leveraging existing engine technologies. Its adoption can support a transition toward fuel-flexible powertrains and deliver rapid decreases in exhaust carbon emissions. This approach is particularly relevant for hard-to-abate segments, where full electrification remains challenging. Building on this perspective, this numerical study investigates the modelling behaviour of a heavy-duty port fuel injection (PFI) internal combustion engine fuelled with hydrogen. Initially, the mixture was assumed to be fully premixed to avoid uncertainties related to injection and mixing processes and to significantly reduce computational cost; this assumption was subsequently validated through selected injection simulations. A

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

Performance and Combustion Characteristics of Coryton SUSTAIN Classic Super 80 Carbon-Neutral Fuel versus EN 228 in a 1980s Fiat 500 Engine

2026-37-0033

6/9/2026

The energy transition requires a rapid reduction in the use of fossil fuels, whose combustion generates substantial greenhouse-gas emissions. In Europe, transport alone accounts for roughly a quarter of total greenhouse-gas emissions, with road transport being the predominant component. In this context, the use of biofuels has emerged as a potential solution for limiting further increases in CO₂ emissions. However, most studies available in the literature evaluate the performance of these fuels on modern engines, while their effects on historic carburetted engines remain largely unexplored. This is particularly significant given the large fleet of historic vehicles across Europe, supported by a long-standing tradition of vehicle preservation, associations, and classic car collectors. The main historic-vehicle federations advise caution and the use of low-ethanol formulations so as not to damage elastomers, fuel tanks, and carburettor float bowls. For this reason, a few suppliers have

Tarchiani, Marco, Fossati, Federico, Raspanti, Sandro, Baroni, Alberto, Ferrara, Giovanni, Romani, Luca

Investigation of the Combustion of Stearic Acid-Coated Pure Aluminum Powder as Additives in Biodiesel and Diesel Blends

04-19-02-0010

6/8/2026

In the present study, research was conducted to increase the combustion efficiency in a diesel engine by adding 100 and 200 ppm aluminum powder to diesel and biodiesel (produced from 10% spent coffee ground oil and 90% waste cooking oil) blends. Aluminum powder is a flammable metal. Due to this feature, it has been used as an additive to liquid fuels in many studies in the literature. In general, it has been reported that thermal efficiency increases with the addition of aluminum particles. However, the high explosion sensitivity of aluminum can affect its stable combustion. In addition, Al is a metal that can be easily oxidized. Therefore, coating aluminum is considered a good solution. Stearic acid has been suggested in the literature as a suitable material for coating aluminum. In this study, stearic acid, a saturated fatty acid, was used to coat aluminum particles. Stearic acid is a good surfactant, hydrophobic substance, and plasticizer. It is also a more environmentally friendly

Kül, Volkan Sabri, Akansu, Selahaddin Orhan, Sarıtaş, Mehmet

Heavy-Duty Nonroad Material Handler Electrification Part 2: Energy Efficiency and Performance Evaluation

02-19-03-0016

6/2/2026

Decarbonization efforts achieved through electrification in nonroad mobile machinery can realize a reduction in fuel consumption of more than 20%, thanks to concepts familiar to light-duty passenger vehicles. This case study compares the results of a hybrid-electric material handler to its conventional counterpart, utilizing machine-specific drive cycles presented in part one of this paper series. The hybrid prototype features an extended-range electric vehicle (EREV) powertrain that demonstrated substantial energy efficiency improvements. Specifically, there was a reduction in equivalent fuel consumption of 75% when operating in electric-only mode, and 33% when maintaining the battery by charging with an on-board generator. Together, the efficiency improvements can be extrapolated over a low-intensity, 8-h shift characterized by significant idle time and highly dynamic engine load for a 47% reduction in net energy consumption. Key technologies that led to this improvement included

Czarnecki, Alexander, Goodenough, Bryant, Worm, Jeremy, Robinette, Darrell, LaTendresse, Phil, Westman, John, Subert, David, Heath, Matthew, Kiefer, Dylan, Black, Andrew

Weight Estimation of Novel Aircraft Configurations in Early Design Phase

2026-26-0773

6/1/2026

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

Goyal, Tushar

Conceptual Design of Hydrogen Fuel-Cell-Based Utility Aircraft

2026-26-0783

6/1/2026

The aviation industry contributes to around 2% of global carbon dioxide emissions. As various sectors of the economy look to reduce their global carbon footprint, the aviation industry is positively acknowledging alternatives to jet fuel. Hydrogen proves to be one such alternative having a high energy density and producing zero carbon emissions on combustion. Hydrogen when used in a jet engine produces water vapour and NOx emissions. In order to reduce the effect of GHGs, the current study aims to develop aircraft concepts suitable with hydrogen propulsion through fuel cells for a short-haul commercial mission profile. Aircrafts such as Metro-23 and Dornier 228-212 were referenced for the requirements of a utility turboprop aircraft. The weight estimation was done to obtain the take-off weight of 10,863 kg following the optimization of thrust to weight ratio and wing loading to calculate the initial dimensions. OpenVSP was used to model the initial structure of the aircraft. For the

Bhattacharya, Anisha, Seetha Ramu, Sree Valli, C N, Lakshmi Manasa, Rohit, Benjamin

Quantum-Inspired Optimization for Trajectory Planning of Reusable Launch Vehicles across Diverse Missions

2026-26-0725

6/1/2026

Trajectory optimization for reusable launch vehicles is a critical challenge in space mission design, aiming to determine fuel-efficient paths for spacecraft during ascent, hover, and descent phases. Minimizing fuel consumption not only enhances cost-effectiveness but also improves mission sustainability. The optimization process is governed by nonlinear orbital mechanics, gravitational perturbations, atmospheric drag, and operational constraints such as thrust limits and collision avoidance. These factors make the problem highly non-convex and discontinuous, posing significant difficulties for classical gradient-based approaches, which often fail to identify global optima. In this work, we formulate the trajectory optimization problem for a reusable rocket executing an ascent–hover–descent cycle. The vehicle must ascend to a specified target altitude, maintain a stable hover for a given duration, and then return to the launch site. The primary decision variable is the throttle control

Eswara Sai Kumar, Kandula, Singh, Utkarsh, Pohankar, Pritam, A, Anoop, Maharana, Priyabrata, Lineswala, Rut

Data-Driven Air Traffic Management: Forecasting Demand, Modeling Delay Propagation, and Demand Capacity Balancing

2026-26-0772

6/1/2026

Air Traffic Management (ATM) must be familiar with the exact Aircraft Take-off Weights (ATOWs) of airplanes to make the most use of runways, maintain safety margins high, and keep utilization and resources in balance. This paper aims to present a dependable ATOW forecasting methodology that can assist the air transport industry in enhancing operational decision-making. This research used datasets acquired from the EUROCONTROL Performance Review Commission (PRC) 2024 Aircraft Take-Off Weight Estimation dataset featuring 527,000 flights over Europe containing aircraft details, air trips and flight conditions. Technique comprises structured data input, inspection of missing data, timestamp aggregation to identify demand cycles over time, and domain-specific feature engineering using distance_per_minute, block_minutes, taxiout_ratio, and a strong wake turbulence metric The two supervised learning models used were Linear Regression (LR) for understanding and XGBoost for performance

Senthilkumar, N., S, Gopalakrishnan, Gopinath, S

Thermal Management System in Commercial Aircraft: A Case Study on Passenger Egress System

2026-26-0760

6/1/2026

It is known fact that Thermal management systems are essential to the safety, operational efficiency, and structural integrity of present-day commercial aircraft. Very critical insulation and thermal protection materials are utilized across various aircraft zones to mitigate extreme temperature challenges, ranging from cryogenic conditions at high altitude to pyrotechnic conditions at low altitude/ sea level. Some of the examples where specific materials at their functional role are, In engine pylons and nacelles, high temperature alloys such as Titanium and Inconel, along with ceramic Matrix composites (CMCs) serve as firewalls and heat shields, which are designed to contain fires and protect primary structures. In bleed air ducting, fiberglass or silica insulations blankets are employed to prevent thermal degradation of surrounding aluminum and composite components, when air at temperatures above 200 degree C flows. This paper focuses on the critical insulation and thermal protection

Govindaraju, Parthasarathy, Nanjundegowda, Harshavardhana

Experimental Investigation of Diesel, Aqueous Ammonia, and Compressed Natural Gas Mixtures on Performance and Emissions in a Compression Ignition Engine

04-19-03-0011

5/30/2026

Abstract This study investigates and evaluates systematically the combustion, performance, and emissions characteristics of heavy-duty diesel engines fueled by diesel–ammonia–compressed natural gas triple blends. While dual-fuel systems are well-documented, the interactive effects of ammonia and CNG within a single compression ignition (CI) engine remain largely unexplored. Experiments were conducted on a 300 Nm, 660 rpm diesel engine by testing pure diesel, diesel–ammonia blends (10–20 wt.% aqueous ammonia), and triple-fuel mixtures containing 10% of the total energy from compressed natural gas. Pure diesel was first tested to provide baseline data, and subsequently blends were tested for a comparative study. The primary contribution of this work is the identification of a synergistic effect of the fuel triple blends on engine performance and emissions. Results indicate that all fuel blends improve thermal efficiency and reduce fuel consumption compared to conventional diesel. The

Sinkala, Happy, Sarıtaş, Mehmet, Kül, Volkan Sabri, Akansu, Selahaddin Orhan, Ünalan, Sebahattin

Potential of an In-Cylinder Pressure–Based Combustion Control for Compression Ignition Aviation Engines Operated with Sustainable Aviation Fuels

2026-01-5028

5/29/2026

The aviation industry represents a significant greenhouse gas emitter and aims to reduce net CO2 emissions to zero by 2050. The deployment of sustainable aviation fuel (SAF), alongside measures such as increasing engine efficiency and enhancing ground handling processes, represents a key driver to reach this ambitious goal. SAF exhibits significantly different physical and chemical properties compared to conventional kerosene. The corresponding fuel specification (ASTM D7566 [1]) currently only defines fuel parameters relevant for the use in jet engines. To assess the suitability of SAF for the use in compression ignition (CI) aviation engines, a collaborative project was conducted at TU Wien—Institute of Powertrain and Automotive Technology, together with Austro Engine. ASTM D7566-certified fuels like Hydrotreated Vegetable Oil (HVO), Fischer–Tropsch–Kerosene (FTK), and Alcohol-to-Jet (AtJ) have been investigated on the engine test bench at TU Wien. The core contribution of this study

Kleissner, Florian, Hofmann, Peter

Effect of EGR Rate on Cyclohexanol-Diesel Dual-fuel Engines

2026-99-1709

5/22/2026

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Liu, Yuchen, Yang, Chenxi, Fan, Jinyu, Chen, Ke, Ye, Zixiao, Huang, Jialiang

Simulation Study on the Impact of Porous Media Microstructure on Gasoline Particulate Filter Performance

2026-99-1740

5/22/2026

Stricter environmental legislation is driving ever-more-demanding performance targets for gasoline particulate filters (GPFs). This study constructs a multi-scale filtration model based on fractal characteristics, taking into account particle size distribution and particle deposition, to investigate the influence of the microstructure of porous media on GPF performance and analyze the impact of structural parameters on capture efficiency and pressure drop. The results show that: (1) Increasing the wall thickness can improve the capture efficiency and pressure drop, and a thicker wall has a stronger inertial interception capacity for larger particles. (2) A reduction in porosity markedly alters both filtration efficacy and flow pressure drop. For particles in the intermediate size range (0.1-0.5 μm), the capture efficiency of a low-porosity structure is more sensitive to the diffusion deposition of small particles, while the inertial collision efficiency of large particles is higher. (3

Xiong, Xianyang, Qing, Ze, Zhang, Jian, Li, Ting

Effect of Burning Biomass Fuel Cyclohexanol on Diesel Engine Performance

2026-99-1708

5/22/2026

Chen, Ke, Yang, Chenxi, Wang, Yibin, Fan, Jinyu, Liu, Yuchen, Ye, Zixiao, Huang, Jialiang

Research on Carbon Emission Calculation Algorithm for Trucks on Expressways in Xinjiang

2026-99-1718

5/22/2026

In the field of measuring carbon emissions from road traffic, the carbon emission factor method has remarkable advantages in terms of standardization, operational simplicity, and adaptability. Backed by the IPCC international standard framework, this method offers convenient access to a dynamic factor database and incorporates an adaptive adjustment mechanism for real-world scenarios, such as technological advancements and regional disparities. Against this backdrop, this study employs the carbon emission factor method to establish refined measurement models based on load capacity and fuel consumption, respectively. These models are then applied to quantify carbon emissions from trucks on specific sections of the G30 highway in Xinjiang. The load-based model calculates emissions by integrating truck axle weight and driving distance, while the fuel-based model analyzes fuel consumption data in conjunction with driving mileage. A comparison of the two models in terms of measurement

Li, Maowen, Han, Dongchen, Gao, Yansen, Bai, Haotian, Dai, Xiaomin

Risk Assessment of Bunkering Process for LNG River Powered Ship

2026-99-1722

5/22/2026

At present, with the rapid development of LNG powered ships, China’s LNG powered ships have formed a certain scale, but the speed of infrastructure construction such as bunkering stations restricts the development of LNG powered ships. In this process, “tank truck-to-ship bunkering”(TTS) has become one of the most widely used bunkering methods in China because of its flexible, fast and convenient characteristics, but there are many hidden dangers in the bunkering process. According to the characteristics of TTS, fault tree method is used to identify the risk of bunkering process, and the leakage of pipeline system is listed as the basic risk factor. The leakage probability of different aperture is analyzed by industry statistics. Three different leakage scenarios are selected and the consequences are simulated by PHAST software. The study shows that the failure of the valve and flange can easily lead to the leakage of LNG in the TTS process, and the leakage of the medium aperture and

Dong, Yuanchao

Multi-Physics Modeling of Aircraft Hybrid Propulsion Systems Integrating Batteries, SOFC, and Jet Engine

2026-99-1703

5/22/2026

This paper presents a multi-physics modeling approach for a hybrid propulsion system designed for High-Altitude Long-Endurance Unmanned Aerial Vehicles (HALE UAVs), integrating solid oxide fuel cells (SOFCs), lithium-ion batteries, and a jet engine. A dynamic model was developed to analyze the coupled characteristics of pressure, temperature, and power under steady-state conditions. Simulation results demonstrate that the internally integrated system achieves efficient fuel and waste heat recovery, delivering a net power output of 300–700 kW, sufficient to meet the operational demands of HALE UAVs. Key innovations include a heat exchanger maintaining SOFC stack inlet temperatures above 850 K for optimal performance and a compressor-fan subsystem enhancing gas compression efficiency. Experimental validation confirmed the accuracy of the SOFC model, with simulated electrical characteristics aligning closely with empirical data. The proposed hybrid system addresses limitations in specific

Zhang, Lin, Zhang, Di, Zhao, Lulu, Li, Xi

Research on Hole Enlargement Process and Modeling Optimization for Type III Hydrogen Storage Tanks

2026-99-0720

5/15/2026

The global automotive industry is accelerating its transition toward low-carbon solutions, with hydrogen fuel cell vehicles offering core advantages of zero emissions and extended range. Their critical component is the Type III fiber-wound hydrogen storage tank, whose performance directly impacts vehicle operational safety and driving range. This technology has now achieved widespread adoption. However, two significant challenges persist in the dome region of these tanks: first, modeling accuracy is difficult to control due to dynamic variations in thickness and winding angles; second, fiber thickness buildup frequently occurs near the pole holes. These issues compromise both the design reliability and manufacturing quality of hydrogen storage tanks. Therefore, this study adopted a combined approach of theoretical analysis and numerical simulation. First, based on composite mechanics theory and calibrated with experimental data (Tensile, Compression, and Shear Tests on NOL and

Wang, Jianguo, Zhang, Qian, Cao, Xuewen, Zheng, Xuanxuan, Li, Jiajie

Development of a Variable Interface Finite Volume Method for Simulating One- and Three- Dimensional Unsteady Gas Flow and Performances of Underwater Marine Diesel Engines

03-19-03-0012

5/6/2026

Diesel engines used for the main power supplier of submarine normally run in high back pressure and low intake pressure, causing unstable performances. Furthermore, when a submarine runs under the sea the exhaust pipe of the diesel engine is under the seawater. Once the lowest pressure in the exhaust pipe is not sufficient to push all the water out, the water will flow into the exhaust pipe and damage the diesel engine. Modeling can provide a useful guide for designing diesel engines, intake and exhaust pipes, and turbocharging systems to avoid water flowing into diesel engine. However, existing simulation methods cannot well simulate the exhaust system of an underwater diesel engine, in which the interface between the liquid water and the exhaust gas is variable. To overcome the drawbacks of existing simulation methods in handling the variable interface between the two phases, a variable interface finite volume method (FVM) is proposed, and a corresponding model is developed in this

Guo, Dongshao, Zhang, Licheng, Yang, Shiyou, Sun, Yong, Abidin, Zainal, Lin, Shujun

A Comparative Assessment of Fuel Cell and Battery Powertrains for Formula Student Electric Applications

2026-01-5032

4/27/2026

The organizers of the most prominent Formula Student competitions have recently initiated a preliminary feasibility study on the application of hydrogen-based propulsion technologies in future single-seater race vehicles. These include electric powertrains with electrochemically converted hydrogen in fuel cell–powered vehicles, competing within the electric championship league. Based on the initial set of regulations, this study presents a model-based comparison between battery-powered (BEVs) and fuel cell–powered electric vehicles (FCVs) for Formula Student. The analysis is conducted using energy, power, and efficiency metrics from four candidate models of propulsion systems, implemented in an open and publicly available MATLAB script: two BEVs with varying battery capacities, and two FCVs employing different hybridization strategies. The aim of this study is to pinpoint and quantify the advantages and disadvantages of each technology for the Formula Student use case, and to identify

Martoccia, Lorenzo, Breda, Sebastiano, Fontanesi, Stefano, d’Adamo, Alessandro

Experimental Study of Knock Resistance Offered by Direct Water Injections in a Single-Cylinder Spark Ignition Engine

03-19-02-0011

4/11/2026

Stochastic end-gas autoignition in spark ignition (SI) engines, commonly called “knock,” limits attainable engine efficiencies. Multiple pathways to extend SI engine operation into knock-limited regions have been studied, including direct water injection (DWI). This study employs single-cylinder engine experiments with a centrally mounted water injector to investigate the knock resistance offered by compression stroke water injections, which, through incomplete mixing, can thermally stratify the cylinder. In SI, thermally stratifying injections are expected to forcibly widen the cylinder temperature distribution by preferentially cooling the cylinder periphery. The end-gas is in the cylinder periphery. A cooler end-gas would result in longer ignition delays, thus providing knock resistance. The difference between intake temperature required to match knock-limited CA50 and a baseline intake temperature at the load of 8 bar IMEPg (gross indicated mean effective pressure) was used to

Datar, Aditya, Vedpathak, Kunal, Gainey, Brian, Lawler , Benjamin

Embedded Real-Time Control of a Distributed Trailer Propulsion System with Regenerative Braking for Net Neutral Load Towing

2026-01-0065

4/7/2026

Towing imposes substantial efficiency penalties on both battery-electric vehicles (BEVs) and internal combustion engine (ICE) vehicles, reducing range by 30-50%. This paper presents a proof-of-concept embedded control architecture for distributed trailer propulsion that actively regulates drawbar force to reduce towing loads. Unlike proprietary e-trailer systems requiring specialized hardware, the proposed implementation demonstrates feasibility using commercial off-the-shelf (COTS) components and open-source software. The distributed architecture employs dual Raspberry Pi 4B single-board computers communicating via ROS 2 at 20 Hz. The trailer-mounted controller executes a Simulink-generated control node coordinating load cell acquisition (HX711 ADC), motor CAN bus telemetry, and throttle commands to a 5 kW BLDC traction motor powered by a 5 kWh LiFePO4 battery pack. A vehicle-mounted controller logs OBD-II/CAN validation data. The control pipeline implements cascaded EWMA/Hampel

Joshi, Gaurav, Adelman, Ian, Liu, Jun, Donnaway, Ruthie

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