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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, AmirNurmi, MikaelHunicz, JacekKim, JeyoungHyvonen, JariMikulski, Maciej
Thermal safety in lithium-ion batteries is a critical aspect due to their increasing use in energy storage systems and electric vehicles. To investigate thermal abuse conditions, numerous studies employ specialized equipment to accurately measure physical variables during thermal runaway events. However, such tests typically require robust equipment which limit their availability in conventional laboratory environments. In this context, the present study proposes and evaluates an experimental methodology based on the use of a climate chamber combined with an instrumented reduced-volume container, to reproduce severe external heating conditions. The thermal behavior and gas emissions associated with thermal runaway events were characterized in six cylindrical lithium-ion batteries of two different chemistries. Six cylindrical cells with NMC and NCA cathode chemistries were subjected to thermal abuse tests. In addition, gaseous emissions and mass loss were quantified after the event
Penagos Vásquez, Diego AlejandroMarco-Gimeno, JavierMonsalve-Serrano, JavierGarcia, AntonioPerez Balastegui, Jose
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
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, MarcoFossati, FedericoRaspanti, SandroBaroni, AlbertoFerrara, GiovanniRomani, Luca
Vehicle fleet decarbonization is a key objective for the coming years, with electrification representing the primary pathway to achieving the targets set by the European Union. The share of battery electric trucks in new registrations has been gradually increasing especially in light and medium size trucks. The replacement rate of diesel long-haul trucks with zero emission trucks is still low due to challenges posed by added complexity and limitations of battery charging. Depot overnight charging is not sufficient to cover the energy needs of a truck covering large distances and careful planning of the route using public charging infrastructure is crucial for an optimized route minimizing extra costs and range anxiety. The current work aims to develop a methodology to propose the optimal charging locations for a given route of a battery electric truck based on nearby stations along the route. Our study uses an open-source optimization algorithm for the fixed route vehicle charging
Perdikopoulos, MichailDoulgeris, StylianosLivitsanos, GeorgiosKazakis, ThomasMellios, GiorgosNtziachristos, Leonidas
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 KumarAmbalakatte, AjithGeng, SikaiGopakumar Suja, GaganBirch, AlexanderCairns, AlasdairHarrington, AnthonyHall, Jonathan
This study investigates the structural improvement of recycled carbon fibre composites through hybridisation with continuous flax fibres to address sustainability concerns and performance limitations. Recycled carbon fibres, while environmentally beneficial, suffer from short, randomized orientations and lower mechanical properties limiting their application beyond decorative uses. This research explores whether incorporating unidirectional flax fibres can enhance rCF behaviour for structural applications. Six hybrid composite layup variants and two plain composites were manufactured using cold compression moulding with Ampro Bio Resin. Each hybrid configuration comprised eight layers, divided into four layers of recycled carbon and four layers of flax fibres oriented at 0°. Complete mechanical characterization was performed following ISO standards for tensile (ISO 527), flexural (ISO 178), and impact (ISO 179) testing. Results demonstrated significant performance improvements in
Hnatyk, DawidChrysanthou, AndreasDe Vuyst, TomIsmail, Sikiru
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, GiovanniAntetomaso, ChristianIrimescu, AdrianMerola, Simona
In recent years, especially in high-performance spark-ignition engines, the thermal stress of pistons has gradually increased due to the implementation of various technologies, aimed at meeting emission reduction and specific power increase requirements. If the heat is not properly dissipated, cracking and plastic deformation of the material as well as formation of hot spots triggering pre-ignition in the combustion chamber mixture can occur. This last aspect is even more true considering innovative fuels such as hydrogen. To overcome these problems, one or more jets of oil are directed towards the piston under-crown region, impacting at high speed. This technique ensures immediate cooling and allows the engine performance to be increased without compromising the useful life. In order to optimize the oil jet effectiveness, 3D-CFD can be proficiently adopted. In this regard, the aim of this work is to define a robust numerical methodology able to simulate oil jet impingement and piston
Duni, AndreaBerni, FabioBreda, SebastianoFontanesi, StefanoGilioli, Filippo
An increase in compression ratio has been widely recognized as one of the essential technologies for improving the thermal efficiency of heavy-duty diesel engines. However, a higher compression ratio tends to result in increased cooling loss, which could diminish the thermal efficiency gains. It was found that an offset orifice nozzle, in which the orifices are drilled with a small offset from the radial center of the nozzle, improves thermal efficiency and reduces cooling loss simultaneously. This study investigates the mechanism of cooling-loss reduction associated with changes in flame distribution when using an offset orifice nozzle, through in-cylinder combustion observations, two-color method image analysis, and local heat-flux measurements. High-speed combustion visualization was conducted to capture the growth of luminous flames. Radial profiles of the mean and standard deviation were computed at each crank angle to quantify spatial temperature non-uniformity. Furthermore
Mukayama, TomoyukiEnomoto, YoshiteruMikami, NaotakaNomoto, ShigeruUchida, Noboru
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, GianvitoAglietti, FilippoSpedicato, TonioCozza, Ivan FlaminioCapra, Andrea
Hydrogen is emerging as a viable energy carrier for the decarbonization of internal combustion engines (ICEs), representing a necessary step toward the long-term sustainability of this technology. In particular, hydrogen direct injection (DI) operation is receiving increased attention due to its inherent advantages over port fuel injection (PFI), such as reduced risks of abnormal combustion, higher specific power, and improved thermal efficiency. However, the mixture preparation process in DI operation generally leads to a stratified charge, especially under intermediate-to-late injection strategies, which in turn strongly affects ignition, combustion performance, and engine-out emissions. Therefore, investigating mixture formation, its key influencing parameters, and the resulting effects on the combustion process is essential for the proper design and optimization of hydrogen-fuelled DI ICEs. In this context, computational fluid dynamics (CFD) emerges as a powerful tool to address
Capecci, MarcolucioLucchini, TommasoSforza, LorenzoPezza, VincenzoTosi, Sergio
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, JiayuMorandi, NicolaLucchini, TommasoFENG, HUIHUAJia, BoruRen, Peirong
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, BjörnGünthner, MichaelKargl, Pascal
Many high-end electric vehicles use an automatic two-speed transmission. The ability of the drivetrain to switch between two gear ratios improves vehicle performance and increases driving range. The aim of the presented research work is to transfer these advantages to small and lightweight battery-electric vehicles, which face significant cost and weight constraints and therefore cannot rely on highly sophisticated electric motors. Direct-drive systems are widely used in this vehicle class due to their simplicity and high baseline efficiency. However, they offer limited flexibility in adapting the operating point of the electric motor under varying load conditions. A two-speed transmission can overcome this limitation by enabling load point shifting, allowing the motor to operate closer to its optimal efficiency region during both urban and extra-urban driving. This results in improved energy consumption without adding substantial system complexity. Currently, only actuated
Napetschnig, ChristofTromayer, JuergenStückler, David
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, TeresaMorrone, Pietropaolo
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 RasoolFoglia, AntonioFrasci, EmmanueleVitek, OldrichPianese, CesareArsie, Ivan
With the United Kingdom’s goal to achieve a fully decarbonised energy sector by 2035 and achieve net zero greenhouse gas emissions by 2050, the transition of the UK’s passenger car fleet to battery electric vehicles (BEVs) plays a crucial role in reaching this goal. This study evaluates the environmental and energy impact of large-scale BEV adoption by modelling future uptake scenarios using historical fleet data combined with assumed impact of future policy such as the 2030 ban on the sale of new petrol and diesel vehicles. Three predictive models have been developed: fast uptake, in which approximately 100% of the passenger car fleet is replaced by BEVs; moderate uptake, where a large majority of passenger cars are BEVs; and slow uptake, in which BEV adoption does not reach a majority. The results have shown that, if a medium- or large-scale adoption is possible by 2040 predicting nearly 37 million BEVs on the road, the associated electricity demand is predicted to rise close to 110
Burke, BradleyKateregga, SunnySodre, Jose Ricardo
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, AlexMisul, Daniela AnnaBaratta, MirkoGallo, AlessandroRapetto, NicolaVargiu, Luca
This work presents the development of a user-oriented software tool for the cradle-to-grave Life Cycle Assessment (LCA) of passenger cars, enabling robust comparisons of greenhouse gas emissions across heterogeneous vehicle configurations. The tool supports informed decision-making by quantifying and visualizing environmental impacts associated with alternative mobility choices over the full vehicle life cycle, including production, use, maintenance, and end-of-life stages. The proposed framework allows key parameters describing both the vehicle and its usage to be explicitly defined, including powertrain type, dimensions and weight, ownership profile (new or second-hand vehicles, partial ownership periods, leasing scenarios), annual mileage, vehicle lifetime assumptions, and the carbon intensity of fuels or electricity sources. Country-specific energy mixes are incorporated, enabling the same vehicle to be assessed under different geographic contexts and highlighting the strong
Gastaldi, ChiaraCibrario, Luca
This work investigates the integration of a Sorption Thermal Energy Storage (TES) into the Heating, Ventilation and Air Conditioning (HVAC) system of electric vehicles. The proposed device reduces the energy demand for cabin heating under winter conditions, leading to a driving range increase. The TES dehumidifies the cabin air through a desiccant bed (zeolite 4A), preventing window fogging, enabling higher air recirculation rates, and consequently reducing the required heating power. An experimentally validated numerical model was used to analyze the adsorption and regeneration processes and to identify suitable operating conditions. Regeneration was found to be effective at moderate temperatures (from 120°C), with a counter-current airflow configuration providing faster and more efficient desorption compared to parallel-flow one. A simplified model integrating TES, HVAC unit and cabin was developed and used to compare different configurations. Heating energy consumption with and
Verlingieri, RebeccaCalabrese, LuigiFreni, AngeloMarocco, LucaScudeler, GabrieleDe Antonellis, Stefano
The adoption of hydrogen as a carbon-neutral sustainable fuel for internal combustion is regarded as a promising solution to reduce greenhouse gases and pollutant emissions. In this framework, the injection system plays a crucial role, being responsible for delivering a large amount of fuel to the combustion chamber. Currently, low-pressure direct injection is considered one of the best solutions to ensure the appropriate fuel delivery. The use of caps has proven particularly effective, as they enable a potentially unlimited range of geometries while minimizing modifications to the injector hardware. Experimental campaigns and computational fluid dynamics (CFD) simulations can be used together as complementary tools to speed up the development process and explore multiple combinations of parameters, thereby optimizing the overall design of both the engine and the caps. In the present paper, a single-hole GDI-derived hydrogen prototype injector equipped with a two-hole asymmetric cap
Pavan, NicoloBreda, SebastianoDuni, AndreaMartino, ManuelFontanesi, StefanoPostrioti, Lucio
For heavy-duty applications, hydrogen (H2) internal combustion engines offer a practical solution for future transportation. However, the influence of cylinder head flow characteristics and piston geometry on lean H2 combustion remains insufficiently understood. This study presents a comprehensive computational investigation of three engine configurations characterized by distinct in-cylinder flow dynamics: mild swirl and tumble (Engine a), strong tumble (Engine b), and strong swirl (Engine c). High-fidelity three-dimensional computational fluid dynamics simulations were performed for both port-fuel injection (PFI) and direct injection (DI) strategies. The impact of piston geometry was evaluated by comparing the baseline piston with a flat piston, while the spark timing was optimized to achieve favorable combustion phasing. Combustion and NOx formation were modeled using a G-equation-based combustion framework incorporating diffusive-thermal instability effects and a validated in-house
Liu, XinleiMenaca, RafaelCenker, EmreSilva, MickaelQahtani, Yasser A.Pei, YuanjiangTurner, James W.G.Im, Hong G.
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, RiccardoBaratta, MirkoMisul, DanielaRousselle, ChristineBREQUIGNY, PierreColin, Olivier
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, PatrickFellner, FelixRößlhuemer, RaphaelHärtl, MartinJaensch, Malte