Internationaler Motorenkongress 2025

Inhaltsverzeichnis

1. Frontmatter

2. Technology Concept of the Engine Family TCD4.0 for the Worldwide Emission Legislation in Mobile Machinery

   Heiner Bülte, Philipp Hundertmark, Adrian Troeger, Paul Grzeschik

   Abstract

   DEUTZ has developed a diverse portfolio of drive technologies for mobile machines, in which the combustion engine continues to be an important factor. This also results from load profiles for which electric drives or fuel cells are not an economically viable alternative.

   For this reason, DEUTZ has developed a new TCD3.9 and TCD4.0 engine series, primarily for use in mobile machines, but also for other non-road applications, which replaces the established TCD3.6 and TCD4.1 engines. Care was taken to ensure that the TCD3.9/4.0 is compatible with the installation of the TCD3.6. Due to the increased displacement, increased peak pressure, high turbocharger efficiency and the elimination of exhaust gas recirculation, the output can be increased to 130 kW and thus exceeds the values of the predecessor TCD4.1, which has a larger displacement. Both engine dynamics and fuel consumption can be improved.

   After the engine was presented at the ATZ Congress in Eisenach with a focus on its design features, this paper will focus on thermodynamics and emission behavior. This concept not only serves the highly regulated EU Stage V and US EPA/CARB Tier 4 emission markets with a very powerful SCR system that avoids the use of exhaust gas recirculation, but also includes a variant for those markets where ECE R49 Stage III A certification is sufficient, which requires exhaust gas recirculation but no exhaust gas aftertreatment. Due to the modular design, the engine has the potential to comply with future emission standards such as the announced CARB Tier 5.

3. Innovating Hybrid Power

   Simulation, Testing, and Regulatory Compliance of a Patented Series-Parallel Heavy-Duty Truck Geir Brudeli, Geraldo Francisco de Souza Rebouças, Baard Vestgaard, Håvard Fagerås

   Abstract

   The patented Brudeli Powerhybrid™ hybrid powertrain is currently undergoing testing on Norwegian roads to demonstrate its emission reduction potential. A series-parallel hybrid powertrain is installed on a DAF CF 410 tractor, combining an 11-L diesel engine with two electric motors power (2 × 130 kW continuous). Extended electric driving will be obtained with a 200-kWh battery, replacing otherwise low efficiency engine operation and optimizing fuel use.

   Power boosting, energy harvesting, and pure electric driving will be tested and their individual contributions to improving efficiency will be discussed and compared against simulations.

   Initial analysis shows that Brudeli’s Powerhybrid can meet the latest European and American emission regulations. Different CO₂ credits (VECTO) can be obtained, based on which system configuration is used for certification on the European market. Additionally, the relevance of Brudeli’s systems will be considered in the context of their attractiveness for meeting EPA’s 2027 Greenhouse Gas (GHG) Phase 3 requirements in the US market.

   Long haul routes, where trucks need to drive 30+ tons of cargo for 300+ km daily, emit a substantial CO₂ and present serious challenges for the range capabilities of BEVs. With hybrids, CO₂ emissions can be reduced significantly or even eliminated in congested areas. Alternative fuel engines can be integrated into the Brudeli Powerhybrid™ system, contributing to gradual scaling of production and distribution capabilities of such fuels.

   The Brudeli Powerhybrid™ will create a cost competitive business opportunity for carbon neutral trucks with green fuels against diesel trucks. Optimally combining Brudeli Powerhybrid™ to downsized combustion engines running on green fuels, provides a feasible strategic pathway to reduced energy consumption and emissions in heavy duty trucking. Brudeli Powerhybrid™ offers 50–80 % CO₂ reduction for diesel trucks, meeting European and American regulations, without overlooking operational and economical aspects.

   From the simulations it is plausible to conclude that even with a battery as small as 200 kWh to target fuel saving in the range of 50% is realistic. Results from the testing of the pilot truck give clear indications that targeting 50% fuel saving would be within reach for specific use cases.

4. HVO100—The Pathway to a CO2-neutral Future for Diesel Engine Drives

   Matthias Tzschentke, Thomas Garbe, Matthias Diezemann, Dr.-Thomas Kemski

   Abstract

   This article describes the potential and usability of hydrotreated vegetable oil (HVO) for passenger cars and light commercial vehicles with Diesel engine drive.

   In the context of engine and vehicle tests, the CO₂ and emission potential at partial load and full load was investigated on various vehicle concepts.

   The aim of the investigation was to prove on a random basis that the end customer can operate his vehicles in the existing fleet in the field with HVO100 without application and hardware changes and without negative effects on CO₂ and emissions.

   The article describes the influence of HVO100 compared to Diesel B7 on the identical vehicle concept with regard to the combustion process, the DPF loading and unloading model, the vehicle individual regeneration contribution and the cold start behavior.

   Furthermore, the potential of HVO100 for adjusting the emission control in the case of monovalent fuel use is discussed.

5. Chassis Dynamometer and Road Pollutant Emissions Assessment on Gasoline Hybrid Vehicles with E-Gasoline based Advanced Fuels

   Clément Larrieu, Christophe Chaillou, David Préterre, Julien Hinault

   Abstract

   To limit climate change, the European Commission (EU) has set new objectives for GHG emissions for the transport sector, the EU Green Deal and the FitFor55 package. E-fuels, derived from low-carbon hydrogen and carbon dioxide captured or taken from unavoidable industrial point sources, are one of the sustainable solutions available to reduce the carbon footprint of the transport sector compared to conventional fuel. In parallel, an upcoming Euro 7 regulation has been proposed in order to limit the impact of the transport sector on pollutant emissions and air quality.

   A study was conducted using five gasoline Hybrid Electric Vehicles (HEV), from standards Euro 6d-temp and up, to assess the impact of conventional fuel and accurately simulated, surrogate advanced fuels with renewable hydrocarbons upon exhaust emissions. All the vehicles were equipped with aged TWC, and most of them with fresh GPF as well. Chassis dynamometer and on-road tests were performed to ensure a complete picture of emissions under both laboratory- and real-world conditions. State-of-the-art measurement equipment was used both on chassis dynamometer and on road, including FTIR giving access to insights into hydrocarbon and nitrogen compound speciation, as well as PN size distributions down to 10 nm in both engine-out and tailpipe positions via ELPI on chassis dynamometer.

   A detailed analysis of non-regulated and Euro 7 regulated pollutant emissions was performed for each of the vehicles. An assessment of the impact upon emission levels of the surrogate fuels compared to a reference conventional fuel was then made. Certain vehicles displayed specific sensitivities to certain fuels with regards to emissions of some pollutants, that were discussed with their respective manufacturers. Despite that, no major differences were observed between regular and e-fuels, showing the drop-in capability and the absence of impact on pollutant emissions of the low carbon e-fuels in addition to their reduced carbon footprint from a life cycle standpoint.

6. Special Requirements of Alternative Fuels for the Selection of Suitable Materials in the Lubricating Oil and Fuel Circuit

   Christof Schleusener, Andreas Dworog

   Abstract

   Despite the initial aim of “phasing out” the combustion engine, the industry has retained a certain openness to technology, especially as the combustion engine has an intact (further) development, production and operating infrastructure. The combustion engine will remain the most widely used drive system for many years to come, particularly in heavy commercial vehicles and in the off-highway sector. The market share of alternative fuels or blends on a biogenic and synthetic basis will increase and make an important contribution to climate protection. Many studies to date have focused on the thermodynamic side of the combustion process. The subject of this study is the influence of alternative fuels and their decomposition products on the durability and stability of the materials used in the fuel circuit of seals, plastics and filter media. The influence of gaseous fuels such as hydrogen on the lubricating oil circuit is greater than is usually expected. The materials can be validated using suitable test methods. Suitable filter systems and separators help to reduce wear on the combustion engine and the sensitive injection system.

7. Defossilization Perspectives with Sustainable Alkylate Fuel for Outdoor Power Tools

   Kai W. Beck, Jens Melder, Armin Kölmel, Holger Lochmann

   Abstract

   Off-road applications, which include handheld equipment, are among the areas that are difficult to fully electrify for a variety of reasons. STIHL products, especially handheld power tools, are used worldwide to shape and maintain the environment and are daily assistants in forestry and construction, operated under very demanding environmental conditions. In the power equipment sector, as elsewhere, the shift from petrol to battery-powered products is already well underway, especially for consumer applications. However, for professional power tool users who demand the highest levels of power and energy density from their equipment, internal combustion engines will continue to be essential.

   Biofuels and RFNBOs possess the potential to be green alternatives, especially for this group of users. STIHL has already taken the first steps towards sustainable fuels with the market launches of MotoMix Eco and MotoMix Eco 20 containing a 20% biofuel content in 2025. Like the fully fossil MotoMix, Eco 20 is a premium alkylate fuel, meeting the requirements of the EN 17867 standard. With MotoMix Eco 20, an overall CO₂ reduction of at least 25% compared to a fully fossil gasoline can be achieved.

   The continuous optimization of engine technology and its overall system, including cutting tools (saw chain, cutting wheel and blades), is another important component. Hence, the combination of our new, more efficient combustion technology with our sustainable MotoMix Eco 20 fuel, results in even higher CO₂ reductions. The right choice of powertrain and tool, and the effective use of our products by the user, are the final building blocks for the most sustainable use of our equipment.

8. Der neue LC8 Motor/Antriebsstrang von KTM

   Helfried Sorger, Michael Viertlmayr, Christian Mayrhofer, Sebastian Faistauer

   Zusammenfassung

   Die deutliche Verbesserung der Nachhaltigkeit in der Zweiradindustrie ist ökologisch ein Muss und ökonomisch ein Erfolgsfaktor.

   Die Elektrifizierung des Antriebsstranges wird neben der Erfüllung zukünftig weiter verschärfter Emissionsvorgaben (inklusive CO₂ und NVH) ein wesentlicher Schritt sein, um die „Powered Two Wheelers“ (PTW) in der öffentlichen Wahrnehmung positiver zu besetzen.

   Der Schlüssel zur erfolgreichen Umsetzung dessen für die Zweiradindustrie ist die Technologieoffenheit. Im Sinne einer nachhaltigen Dekarbonisierung wird es deshalb notwendig sein, die Wirkungsgrade der Verbrennungsmotoren deutlich zu verbessern sowie den Einsatz von CO₂-neutralen Kraftstoffen – wie eFuels – in allen Anwendungen sicherzustellen. Darüberhinaus sind die wachsenden Komfortansprüche der Zweiradkunden zu berücksichtigen.

   Wie KTM diesen Weg beschreitet, wird in diesem Beitrag am Beispiel des neuen LC8 Motors beschrieben. Traditionell stellt der V2 bei KTM die Speerspitze der Technologieentwicklung dar. In dem seit 2024 in Serie produzierten Motor mit nunmehr 1350 ccm Hubraum konnten gegenüber dem Vorgänger weitere Verbesserungen in der Performance, bei den Emissionen und in der Fahrbarkeit – sowohl in der Variante „Sport“ als auch in der Variante „Travel“ – erzielt werden. Zum ersten Mal bei KTM kommt ab 2025 auch ein automatisiertes Schaltgetriebe zum Einsatz, das hinsichtlich Funktionalität und Fahrkomfort einen zusätzlichen Freiheitsgrad offeriert. Der mechanische Aufbau, die Thermodynamik sowie die Kalibration des Antriebsstranges sowie dessen Fahrzeugintegration werden im Detail dargestellt.

9. Electrified Motorcycle Powertrains—Hybrid Concepts Paving the Way to Future Technologies

   Wolfgang Schöffmann, Christian Hubmann, Gernot Fuckar, Christian Martin, Manuel Gruber

   Abstract

   The main drivers for powertrain electrification in two-wheelers, motorcycles and ATVs are increasingly stringent emission and noise limitations along with the growing demand for carbon neutrality. Two-wheeler applications face unique challenges, including packaging and mass constraints, limited urban charging infrastructure and stringent cost targets.

   Whereas battery electric two wheelers are the ideal choice for transient city driving with limited range requirements, hybridization offers significant advantages and extends operational limits. In addition to improving efficiency, silent and zero-emission modes enable fully electric driving, while combined boosting enhances performance and transient response.

   In general, hybrid powertrains for two-wheelers can be divided into two main categories: motorcycles with frame-integrated internal combustion engines (ICE) and transmission units, paired with secondary drives via chain or belt; and scooters with integral single-sided swingarm power units, featuring an internal combustion engine and a continuously variable transmission (CVT).

   A promising hybrid scooter powertrain concept combines efficiency improvements with additional benefits of electric driving by utilizing a power-split electrified variable transmission (e-VT) with a planetary gearset.

   For sports and touring bikes, customers prioritize fun-to-ride dynamics, handling, and low weight, necessitating significantly different hybrid concepts. An integral dedicated hybrid transmission (DHT) with minimized packaging and mass penalty, aimed at achieving a neutral performance-to-mass ratio, is specified for a HEV or P-HEV performance hybrid with minimized battery mass and size.

   The paper explains the hybrid concepts for two key target applications: the e-VT layout and the DHT concept evaluation. It covers the selection criteria for ICE and e-motor performance, while addressing the applicable hybrid operation modes. Performance and efficiency evaluations were conducted in the relevant drive cycle sections.

10. The Heavy-Duty Engine in Negative Torque Regime: Engine Motoring and Braking

    Jonathan Borg, Yifei Tong, Mathias Binder, Konstantinos Priftis, Christof Strässle

    Abstract

    Ever more stringent emissions and fuel consumption legislations require OEMs to introduce engine measures which reduce emissions and improve the operating conditions of the After Treatment System (ATS) at all engine operating points. The heavy-duty engine, for diesel or alternative fuels, runs extensively also in negative torque operating modes, particularly for on-road applications. In this paper we review the fuel cut-off engine operation, and how various measures introduced for operation in positive torque modes can be optimized for engine performance in negative torque regime. During engine motoring, performance criteria may include low motoring torque, reduced cooling of the ATS as well as priming of the turbine for the case of an eventual load request. We review and analyze, based on experimental data from a typical HD on-road engine, the impact of various measures, including Cylinder Deactivation (with various combinations of deactive cylinders), Miller camshafts, intake and exhaust throttling, and Exhaust Gas Recirculation. We will then extend the focus of negative torque to the need for engine braking, and we review the braking performance capability comparing the utilization of throttling in standard four-stroke operation, and the improvements obtained for high-power engine brake with the introduction of decompression humps in the valve lift profile. We introduce a quasi two-stroke brake system, which can reach very high braking power without requiring changes to the standard intake valve lift as pure two-stroke brake would. It completes each breathing, compression and decompression cycle in every consecutive two engine strokes, but whereas the first of each pair of cycles breathes and brakes with fresh air, the second re-breathes, compresses and decompresses brake gas.

11. H2-ICE: Optimization Potential of Heavy-Duty Engines with Homogenous Lean LPDI Combustion Based on Variable Valvetrain Technologies

    Steffen Pfeiffer, Piergiacomo Traversa, Nicola Morelli, Philipp Müller

    Abstract

    First hydrogen combustion engines will most likely go into series applying SI port-fuel injection, based on Diesel engine hardware. But it is already obvious that direct injection concepts will represent the second generation of mixture formation systems. Homogeneous-lean and spark ignited concepts based on low pressure direct injection (LPDI) represent a promising approach in this regard. Beside the challenges of injection nozzle design for mixture formation with good levels of homogeneity, the focus likewise is on high specific power density at best brake thermal efficiency and dynamic response. Variable valvetrain technologies can help to overcome those somehow opposing targets. This paper and presentation will discuss the layout process and optimization results of a H₂-ICE with homogenous lean LPDI combustion based on a GT-Power simulation model derived from a state-of-the-art Diesel engine and by applying a fully variable valvetrain system on the intake. The fuel consumption reduction potential for relevant driving cycles will be presented and compared to the base configuration and a setup with fixed reduced valve lift profile on the intake (i.e., fixed Miller strategy), respectively. Furthermore, a second focus will be laid on the dynamic response of these investigated different configurations by an analysis and discussion of their Time-to-Torque performance capability in comparison to the Diesel reference. Further means to improve the dynamic response in addition to the benefits derived from a variable valvetrain (e.g., late injection, late combustion, or innovative turbo-charging bearing technologies) are presented and likewise evaluated.

12. Life Cycle Assessment: Different Approaches and The Need for Industry Partnership

    Quentin Gauthier, Sari Kuusisto

    Abstract

    This paper explores the application of Life Cycle Assessment (LCA) in the transportation sector, emphasizing the importance of a comprehensive approach that encompasses all stages of a vehicle’s life cycle and the complexities of energy sources. The methodology of LCA, including goal and scope definition, inventory analysis, impact assessment, and interpretation, is outlined. The paper details the specific challenges and considerations of LCA in the context of vehicle manufacturing, use phase, end-of-life, and diverse energy sources (fossil fuels, electricity, biofuels, and e-fuels). It underscores the influence of geographical, technological, methodological, and policy factors on LCA outcomes. The critical role of industry partnerships in overcoming data silos, enhancing data quality, and fostering collaborative solutions for sustainable transportation is highlighted. The paper concludes by emphasizing the need for continued research, data transparency, and cross-sectoral collaboration to advance sustainable transportation and achieve a holistic understanding of its environmental, social, and economic impacts.

13. Bosch DFT—Digital Fuel Twin as Solution for Carbon Footprint Tracking of Fuels

    Michael Storch, Marko Babic, Erik Schünemann, Florian Hoffmann, Matthias Horn, Matthias Biehl, Jens Olaf Stein

    Abstract

    The Bosch digital fuel twin (DFT) provides an effective market mechanism for transparency of CO₂ emissions along the entire fuel supply chain. DFT digitalizes the supply chain from fuel production, storage, distribution into vehicle, with the aim of providing the end customer with an accurate, certified proof of the CO₂ footprint of the fuel quantities consumed. The CO₂ footprint certificate can be utilized for sustainability reporting, as support to proof if applications comply with contractual CO₂ reductions or as a marketing and advertising instrument. DFT includes plausibility monitoring checks and quantifies blending of different fuels along the fuel supply chain up to the filling station, as well as in the vehicle’s tank. This way intended mixed refilling of lower carbon and fossil fuels for fleet operation is also supported.

    In this work the DFT working principle will be explained in detail and advantages for different stakeholders will be highlighted. Furthermore, potential applications beyond carbon tracking will be presented. For example, an established digital connection between filling station and vehicle would allow for the transfer of fuel batch specific properties to the vehicle powertrain level. Such data could improve on board fuel consumption monitoring (OBFCM) for diesel applications. It can further allow for better pre control of engine ignition parameters by octane number leading to significant engine efficiency gain in gasoline powertrains. Finally, large engine segments fuel quality monitoring is described as well as the application for Carbon Neutral Fuel only vehicle monitoring both enabled by DFT.

14. Transforming Waste to Value—Life Cycle Analysis of Sustainable Methanol Production from Sewage Sludge

    Jannik Kexel, Benedikt Schroeder, Andreas Balazs, Robert Maurer, Thorsten Schnorbus, Andreas van Sloun, Benedikt Heuser, Johannes Buchmann, Tilo Brandt, Daniel Neumann, Hagen Wegner

    Abstract

    In the context of climate change, the European Union (EU) has established a roadmap for achieving climate neutrality by 2050 through the European Green Deal. This initiative requires an urgent and major shift towards alternative chemical energy carriers to achieve the sustainability targets. Renewable methanol emerges as a major building block for both transportation and the chemical industry and is anticipated to play a significant role in the future energy transition. However, a common argument against methanol is the carbon contained in its lifecycle. This raises the question: How sustainable is this renewable energy carrier throughout its entire production cycle, when considering upstream processes as well?

    This paper presents research that examines the sustainability impacts of a decentralized renewable methanol production plant in the 10–20 MW power range, which utilizes sewage sludge as green carbon input. In terms of sustainability, the focus lies on Global Warming Potential and water consumption. For this purpose, a Life-Cycle Sustainability Assessment is performed. This assessment follows the methodology of DIN EN ISO 14040/44 and the EU Product Environmental Footprint procedure. This includes not only the operation phase in the Life-Cycle Inventory, but all aspects from cradle to grave.

    In contrast to other studies, an integrated approach is used to aggregate the Life-Cycle Inventory data. This approach combines internal and publicly available databases with FEV’s model-based system design including physical-empiric simulations models, transient operation with fluctuating renewable energy and a DoE based techno-economic optimization. To deal with uncertainties, a comprehensive sensitivity analysis is conducted and discussed.

15. eFuels and Their Contribution to Climate-Neutral Mobility

    Ralf Diemer, Tobias Block, Eric Christoph Nebel

    Abstract

    eFuels, synthetic fuels produced using renewable energy, represent a groundbreaking solution for achieving climate-neutral mobility.

16. Exhaust Gas Aftertreatment Concept for a H2 Engine Hybrid Powertrain

    Christian Tomanik, Jan Niklas Geiler, Tobias Rabe, Klaus Moritz Springer, Markus Kirzinger

    Abstract

    Within the joint public funded project “H₂ ICE Democar”, funded by the Federal Ministry for Economic Affairs and Climate Action, Ford, Bosch, MAHLE, Umicore, Institute of Automotive Engineering (IFS, University of Stuttgart), Research Institute for Automotive Engineering and Powertrain Systems (FKFS), Chair of Thermodynamics of Mobile Energy Conversion Systems (tme), DHL, Purem by Eberspächer and Shell are identifying the key requirements for a hydrogen (H₂) engine hybrid powertrain in a light commercial vehicle. This powertrain technology enables the CO₂-free operation, long driving ranges, fast refueling and zero-impact exhaust emissions in combination with a high thermal efficiency of the H₂ engine.

    This paper focuses on the optimization of the exhaust gas treatment (EGT) concept for the H₂ engine serial hybrid powertrain. An efficient EGT system is the key to combine low tailpipe emissions with high engine thermal efficiency. Even though the lean combustion concept (λ > 2) provides already relatively low engine-out exhaust emissions, a dedicated H₂ EGT system has been implemented to reduce the tailpipe emissions even further. Suitable catalyst technologies have been identified at a model gas test bench.

    In addition to the requirements of the lean H₂ operation engine concept, the EGT optimization has to fulfill the demands of the vehicle package.

    During the project the preselected catalyst technologies have been verified by engine tests under stationary and transient conditions. This supports the holistic assessment and optimization of the EGT system in the “H₂ ICE Democar” project. A further important aspect is the serial hybrid vehicle operating strategy that offers additional degrees of freedom to further reduce emission especially with respect to transient engine operation.

    The results demonstrate the potential of a lean-burn H₂ engine combustion concept equipped with an appropriate EGT system. Tailpipe emissions have been minimized without compromising engine efficiency.

17. Challenges in Exhaust Gas Aftertreatment of Lean-Burn H2 Combustion Engines on the Way to Zero Impact Emissions

    Alexander Lampkowski, Stefan Sterlepper, Patrick Recker, Stefan Pischinger

    Abstract

    The transition to sustainable energy is crucial for defossilizing the transport sector, with hydrogen (H₂) emerging as a viable option for carbon-free fuel. However, while H₂ combustion primarily produces water vapor, it also generates nitrogen oxides (NO_x) emissions and potential carbon-based emissions from lubricant combustion. To achieve zero impact emissions and to maximize the environmental benefits of H₂, an efficient exhaust gas aftertreatment system (EATS) is crucial.

    This study characterizes various catalysts – including oxidation catalysts (OCs), selective catalytic reduction (SCR) catalysts, and NO_x storage catalysts (NSCs) – under close-to-real exhaust conditions using a synthetic gas test bench (SGB). The results reveal that OCs with differing platinum loadings exhibit significant variations in performance. Specifically, the higher-loaded OC demonstrates a substantially lower light-off temperature and higher H₂ conversion efficiency compared to the ultra-low loaded OC.

    Moreover, while SCR catalysts show high NO_x conversion efficiencies, they form secondary emissions such as nitrous oxide (N₂O). A combined catalyst approach derived from a V₂O₅-WO₃-TiO₂ and a Cu-SSZ-13 catalyst is used to enhance NO_x reduction while minimizing secondary emissions. The NSC effectively stores NO_x during lean operation and low exhaust gas temperature. The thermal decomposition can be utilized to empty the NO_x storage under lean conditions. A H₂-rich operation can be employed to reduce stored NO_x, although this approach tends to result in the formation of secondary emissions.

    In summary, this study shows that achieving zero impact emissions requires minimizing not only NO_x and H₂ but also N₂O formation to effectively reduce overall greenhouse gas emissions.

18. Durability Assessment of a Heavy-Duty Hydrogen Engine Exhaust Aftertreatment System for Euro 7 Emission Compliance

    Neil Kunder, Hannes Noll, Anton Arnberger, Cheikh Diouf, Emmanuel Laigle

    Abstract

    Hydrogen is gaining traction as a potential substitute for traditional fuels, offering a viable solution in significantly reducing carbon emissions in the heavy-duty transport industry. Engines powered by hydrogen could be instrumental in creating a more sustainable future, particularly in the heavy-duty vehicle sector, which is predominantly dependent on internal combustion engines (ICEs) fueled by carbon-based fossil fuels.

    While hydrogen engines are advantageous because of their near-zero CO₂ emissions, they do generate some pollutants, including nitrogen oxides (NO_X) and trace amounts of particulate matter due to unwanted side-reactions and lube-oil consumption respectively. Therefore, the implementation of an Exhaust Aftertreatment System (EAS) remains necessary for these engines to adhere to the emission standards outlined in the upcoming Euro 7 regulations. It’s crucial that the EAS not only meets emission standards at the beginning of its life but also retains its effectiveness throughout the vehicle’s lifespan, ensuring consistent emission reduction even as it ages. This research delves into the performance of the EAS in a hydrogen engine exhaust over a period of durability testing.

    The study examined the EAS in the exhaust system of a 13L class inline-six heavy-duty hydrogen engine, evaluating its ability to convert emissions under various driving conditions, with a focus on meeting Euro 7 emission standards. The EAS was also subjected to approximately 500 hours of durability testing under a range of operating conditions, including various steady-state and transient cycles that mimic real-world usage.

    The findings offer valuable understanding into how the EAS’ performance evolves over the testing period. They also highlight anticipated challenges in achieving Euro 7 compliance over the vehicle’s lifespan and suggest possible strategies for overcoming these obstacles.

19. E-Fuels in German Road Transport: Assessing Market Potential and Global Supply Limitations

    Samuel Hasselwander, Özcan Deniz, Benjamin Frieske

    Abstract

    In 2021, the German road transport sector emitted over 145 million tons of CO₂-equivalents, with 92% of energy consumption coming from fossil fuels like petrol and diesel. To meet net climate neutrality by 2045, fossil fuel use must be phased out. This transition requires technological solutions such as zero-emission vehicles, but can also be supported by the use of synthetic fuels. Synthetic fuels provide a high energy density similar to fossil fuels, enabling large vehicle ranges and compatibility with existing infrastructure. In order to estimate the market potential of these fuels, an e-fuel scenario was being created using DLR’s vehicle technology scenario model VECTOR21 simulating yearly passenger and commercial vehicle purchase decisions. Based on forecasts for large-scale e-fuel production, costs are estimated to fall to 2.62 Euro/l by 2050.

    The possibility of registering e-fuel only vehicles would result in 10 % fewer battery electric vehicles in the fleet in 2040, resulting in a maximum demand for synthetic fuels in the e-fuel scenario of up to 133 TWh/year. As this is 2.8 times more than the projects announced worldwide for the production of synthetic fuels and also considering other sectors that are highly dependent on the use of synthetic energy sources, such as aviation or shipping, the use of electricity-based fuels on this scale in road transport is currently not to be expected. Without the potential approval of e-fuel only vehicles, the additional fuel demand of 48 TWh/year for these vehicles in the e-fuel scenario could be eliminated, which would cut the need for synthetic fuels to defossilize road transport in half in 2050.

20. The Next Evolutionary Stage of the V6 TFSI Engines—Engine Development Within the Conflicting Goals of Performance & Sustainability

    Marc Deblaize, Matthias Schober, Gerd Seifried, Anton J. Kerckhoff

    Abstract

    In 2024, Audi has launched the so-called Premium Platform Combustion (PPC). To this end, conventional drives as well as hybrid powertrains are being comprehensively further developed at Audi. In addition to complying with future legal emission limits, increasing performance and comfort, while at the same time reducing fuel consumption, are key development goals.

    The new 3.0l V6 TFSI EA839evo represents the logical evolution of the V6 TFSI EA839-engine, which was launched in 2015. Newly designed exhaust-gas turbochargers with variable turbine geometry, indirect charge air cooling, DoE-supported optimisation of charge exchange, Miller combustion process and fuel injection system form the basis for achieving these ambitious goals. The engine develops a full torque curve of up to 550 Nm and a nominal output of 270 kW (367 hp) and achieves in combination with the 48V mild hybrid system with powertrain generator very attractive characteristics in terms of driving dynamics, comfort and CO2 emissions.

    The new V6 TFSI EA839evo generation initially started production in 2024 as a 3.0 liter mono-turbo in the Audi S5 and SQ5. It forms the high-performance basis for future S and RS models at Audi and will later also be used in other Group models.

21. System Solutions for Fulfilling Future Exhaust Gas Emission Legislations with Gasoline Passenger Cars

    Domagoj Zovak, Frank Meier, Alexander Hettinger, Erik Schünemann

    Abstract

    In major automotive markets such as Europe, USA and China, more stringent emission regulations are introduced starting from model year 2026 (e.g. EU7, EPA Tier 4, CARB LEV IV) or are in preparation (CN7). The aim is to further reduce traffic-related criteria pollutant emissions. This presents an additional challenge for the automotive industry alongside the introduction of powertrains with reduced CO₂ emissions. The objective is to meet future emission limits under stricter and real-world driving conditions with reasonable additional costs, ensuring affordable future mobility, especially for cost-sensitive market segments like entry-level vehicles. BOSCH has already demonstrated significant exhaust emission reductions for diesel and gasoline vehicles with a comprehensive system approach. This paper focuses on further developed hardware and software solutions for gasoline hybrid powertrains, as well as adapted calibration for the corresponding market requirements. The functional principles of these solutions will be explained, and emission results will be demonstrated on a vehicle level. Within this paper we will focus on US specific requirements and therefore set segment specific targets for an Upper Class (UC) 2,0L TGDI 48V vehicle with SULEV20 and a large SUV 3,0L TGDI with a plug-in hybrid (P2) powertrain with SULEV30. Emission performance is assessed in the US legislative driving cycles on the roller dynamometer, including future additional testing requirements set by EPA and CARB, such as e.g. partial soak and quick drive away FTP75. The results demonstrate emission feasibility for the stringent US emission levels and even provide potential measures for further emission reduction.

22. DI-Strategies and Combustion System Design: A Combined Numerical and Experimental Approach for Hydrogen Engines Development

    Magda Elvira Cassone Potenza, Thomas Middel, Giovanni Cornetti, Stefan Bareiss, Dirk Naber, Andreas Kufferath, Michael Krüger, Nicola Rapetto, Sergio Giordana, Andre Kulzer Casal

    Abstract

    In the automotive industry, hydrogen (H₂) fueled engines are nowadays gaining increasing attention as promising technology for the upcoming CO₂-neutral environment scenario, especially for commercial vehicle applications. In this framework, H₂ direct-injection (DI) systems play a key role in the development of suitable mixture preparation mechanisms aiming at meeting the power and torque targets set by the hydrocarbons fueled engines.

    To this purpose, the many degrees of freedom allowed by the H₂-DI systems such as e.g., injector position and geometry as well as injection pressure and timing, can be successfully used to promote the mixture formation, for a given intake ports configuration and depending on the combustion chamber geometry. Thus, the challenge of the combustion system development resides in providing the optimal combination of jet targeting and injection strategy over the whole engine map.

    This paper suggests a combined numerical and experimental approach aiming at disclosing the effects of the jet-charge motion interaction provided by the H₂-DI injection system integrated in an originally NG-fueled single cylinder engine (SCE). Different intake port designs, allowing for increasing swirl levels, have herein been simulated by means of 3D CFD U-RANS and subsequently tested on the thermodynamic SCE for establishing a correlation between in-cylinder mixing processes and engine test bench results. The obtained characterization of the engine behavior is extended to DI-operation strategy variations for further improvement of engine-out emissions and performance of the adopted combustion system.

23. Liebherr’s Alternative Fuel Injection Platform Strategy: Innovations and Developments for Modern Powertrain Technologies

    Giovanni Corbinelli, Dennis Herrmann, Patrick Send, Richard Pirkl

    Abstract

    This paper explores the potential of an alternative fuel injection platform strategy focusing on hydrogen, methanol, ethanol, and liquid ammonia. The Liebherr approach offers a versatile platform solution to the diverse requirements in various sectors, including off-road vehicles, commercial and industrial machinery, gensets, and marine transportation. The flexibility to use different fuels with one platform approach could lead to significant advancements in the decarbonization of sectors that are traditionally challenging to electrify, such as heavy-duty transportation and industrial applications. Additionally, this approach covers different infrastructure and logistics requirements of the various industry segments.

    An overview on the status of development on the Liebherr fuel injection system for alternative fuels will be provided and accompanied by the latest test results. Furthermore, this paper outlines potential solutions for different market segments from flexible retrofit dual-fuel applications to mono-fuel applications.

24. Obstacles to the German reFuels strategy

    Olaf Toedter, Alexander Heinz, Thomas Koch

    Abstract

    The use of synthetic fuels from renewable sources (reFuels) is an elementary building block on the way to greenhouse gas-neutral mobility. There is a broad consensus on the necessity of these fuels, but the potential prioritization of their use and the conditions under which this ramp-up should take place are part of the ongoing discussion. This paper presents a wide range of obstacles and proposes ideas for dealing with them. A distinction is made between technical barriers in the historical context of the technologies that require technical solutions, regulatory barriers that require political and social consensus and barriers that become particularly relevant during the ramp-up of industrialization and need to be addressed financially.

25. Analysis of the Availability of Sustainable, Biogenic Gasoline in Europe

    Lars Knaup, Friedemar Knost, Niko Weimer, Christian Beidl, Patricia Thornley, Mirjam Röder, Jalil Yesufu, Kornél Szalay, Ravi Teja Ganti, Constantin Fuchs, Ulrich Arnold, Jörg Sauer

    Abstract

    In order to reduce greenhouse gas emissions in road traffic, different technologies can be considered. Besides electrification, alternative fuels offer the possibility to reduce the climate impact of vehicles using combustion engines. Thereby, they can be used to reduce greenhouse gas emissions in the existing car fleet. By using biomass as raw material, biofuels offer the possibility to create a closed carbon cycle as the plants used for their production absorb CO₂ from the atmosphere. In this paper, the potential to produce sustainable, biogenic gasoline with second generation biomass in Europe is evaluated. The considered potentials are only based on second generation biomass that is currently not used for other purposes. The biomass potentials include residual and waste materials, as well as perennial crops cultivated on unused marginal lands. With the considered biomass amounts, the potential gasoline that could be produced is calculated. Therefore, different pathways using ethanol and methanol as an intermediate product are considered. Besides the estimation of the mass potentials, a cost estimation as well as an outlook on future potentials is included in this study.

26. CO2 and Emission Evaluation of a Future Truck Concept—Methods and First Results

    Michael Conin, Lars Knaup, Tim Herold, Alexander Stalp, Patrick Noone, Chistian Beidl

    Abstract

    The goals to reduce greenhouse gas emissions in the heavy-duty vehicle segment require the use of alternative powertrain systems and improvements of existing technologies. One option that is discussed in this paper is the use of electrified semi-trailer systems. These systems can help to reduce the in-use greenhouse gas emissions of heavy-duty trucks in combination with conventional tractor vehicles. The paper shows the potentials of this technology based on simulation studies and testbed measurements. The influence of the electrified trailer system on the behavior of the combustion engine in the tractor vehicle is taken into account including an assessment of the influence on the exhaust gas aftertreatment system and the resulting pollutant emissions. Based on the testbed results the potentials of a pre turbo catalyst (PTC) system for the considered vehicle are evaluated using an AI-based modelling approach for the thermal behavior of the catalyst. In a final well-to-wheel-analysis the CO₂ saving potentials of the electrified trailer system are shown for the use of conventional diesel as well as for the use of hydrotreated vegetable oil (HVO) in the tractor vehicle.

27. Backmatter