Hydrogen-fuelled internal combustion engines are a potential carbon-free propulsion solution for high-power applications such as construction machinery and heavy-duty commercial vehicles. However, compared to conventional diesel engines, hydrogen engines exhibit limitations in transient operation and at full load, primarily due to the high reactivity of hydrogen. In spark-ignited hydrogen engines, combustion anomalies represent the main constraint during performance-oriented operation, particularly during transient phases that require mixture enrichment to meet dynamic torque demands. Water injection is investigated in this study as a means to mitigate these limitations. The paper describes the implementation of a port water injection system on a heavy-duty commercial hydrogen engine and evaluates its influence on engine performance with a focus on transient operating conditions. A combustion anomaly evaluation method developed in-house is applied to quantify the effect of water injection on abnormal combustion behavior. The results show that water injection shifts the combustion anomaly limit toward richer air–fuel ratios, thereby enabling mixture enrichment up to stoichiometric conditions or under during transient load changes. Water is injected cyclically into each intake port to achieve a defined water-to-hydrogen ratio during load steps. Even at low water injection rates, a significant reduction in engine response time is observed, leading to transient torque response comparable to that of a diesel reference engine. Improved torque demand tracking is demonstrated in dynamic test cycles. In steady-state operation, the application of water injection also extends the achievable full-load operating range. Overall, the results indicate that port water injection is an effective measure for suppressing abnormal combustion in heavy-duty hydrogen engines and enables more aggressive yet stable engine calibration with minimal water consumption, contributing to diesel-like performance characteristics.

Für Off-Road Fahrzeuge und Maschinen, die häufig unter extremen Bedingungen betrieben werden, ist zusätzlich zu den gesetzlichen Vorgaben für die Schadstoffemissionen mittelfristig eine zwingende Reduktion der Treibhausgasemission absehbar. Für die Bewertung einer effektiven Reduktion ist sowohl der Betrieb, der ohne Einsatz fossiler Energieträger stattfinden muss, als auch der gesamte Lebenszyklus zu betrachten. Um diese Ziele zu erreichen, bestehen verschiedene Konzepte zur Nutzung erneuerbarer Kraftstoffe und elektrischer Energie, welche im Beitrag vorgestellt werden. Besonders die direkte Nutzung von grünem Wasserstoff in Brennstoffzellen oder Verbrennungsmotoren bietet große Chancen, da sie nicht nur CO2-frei, sondern emissionsarm oder emissionsfrei arbeiten können. Allerdings sind dafür noch einige Herausforderungen bei Speicherung, Infrastruktur, Robustheit und Kosten zu bewältigen. Einige ausgeführte Beispiele, wie elektrische Schwerfahrzeuge, Brennstoffzellenfahrzeuge und Hybridlösungen mit Verbrennungsmotoren, die sowohl operativ als auch als Demonstratoren im Einsatz sind, werden vorgestellt. Es kann auch gezeigt werden, dass die entscheidende Voraussetzung für eine signifikante CO2-Reduktion die Nutzung erneuerbarer Energie und erst in zweiter Linie der Energiewandler ist. Die Wahl des wirksamsten und bestgeeigneten Antriebskonzepts hängt von Anwendung, Rahmenbedingungen und Infrastruktur ab. Eine offene, technologieübergreifende Herangehensweise ist notwendig, um die besten Lösungen für den Einsatz unter extremen Bedingungen zu finden.

This research investigates the deactivation phenomena of oxidation catalysts in exhaust gas aftertreatment systems of hydrogen internal combustion engines (H2-ICEs). The study observes an unexpected catalyst deactivation during extended cold start operation, which is partially reversible through lambda variation and increased exhaust temperatures. Light-off tests on a synthetic gas bench (SGB) reproduce these deactivation effects during the absence of carbon-based and nitrogen oxide emissions, showing that preconditioning with nitrogen oxide (NO) can aid partial reactivation. Additionally, conditioning at higher temperatures effectively prevents significant deactivation. The findings suggest that state-of-the-art oxidation catalysts from diesel engines are applicable for H2-ICEs if suitable engine operating modes are employed to mitigate catalyst deactivation.

Hydrogen internal combustion engines have the potential to become a key zero-emission propulsion system of the future. Especially the use in heavy-duty applications seems promising. However, some challenges remain, one of them being the tendency of these engines towards combustion anomalies. The present paper proposes a methodology for the quantification and evaluation of combustion anomalies occurring under varying operating conditions on an engine test bench. For this, a test procedure is defined to detect irregularities in a systematic way. The classification of the anomalies is conducted through a post-processing routine, which utilizes appropriate parameter limit values. The findings of this study indicate that engine anomaly behavior is strongly influenced by ambient conditions, most notably by elevated charge air and coolant temperatures. Furthermore, ignition timing exerts a significant additional effect. This paper also addresses the reproducibility and validity of the test procedure for real-life operation. All research activities conducted in this paper were performed under the scope of the COMET project Hylley.

The thermal management system and the balance-of-plant (BoP) in fuel cell electric vehicles (FCEV) are characterized by a particularly high level of complexity and a number of interfaces. Optimizing the efficiency of the overall vehicle is of special importance to maximize the range and increase the attractiveness of this technology to customers. This paper focuses on the optimization potential of the air supply system in the BoP, whereby the charging concepts of the electric supercharger (ESC) and the electrically assisted turbocharger (EAT) as well as the integration of water spray injection (WSI) at the compressor inlet are investigated in the framework of an FCEV complete vehicle co-simulation. As a benchmark for the integration of these optimization measures, the complete vehicle co-simulation is designed for a fuel cell electric passenger car of the current generation. Here, thermo-hydraulic fluid circuits in the thermal management software KULI are coupled with mathematical-physical models in MATLAB/Simulink. Applying advanced simulation methodologies for the components of fuel cell, powertrain and vehicle cabin enables the mapping of the effects of realistic operating conditions on the FCEV characteristics. The EAT offers the advantage over the ESC that, due to the arrangement of an exhaust gas turbine, a part of the exhaust gas enthalpy flow downstream of the fuel cell stack can be recovered, which reduces the electrical compressor drive power. Moreover, an additional reduction of this power consumption can be achieved by WSI, as the effect of evaporative cooling lowers the initial compression temperature. For analysis and comparison, these concepts are again modeled with high degree of detail and integrated into the benchmark overall vehicle simulation. The results indicate considerable reductions in the electric compressor drive power of the EAT compared to the ESC, with noteworthy potential for reducing the vehicle’s hydrogen consumption. At an operating point in Worldwide harmonized Light Duty Test Cycle (WLTC) under 35 ^∘ C ambient temperature and 25 ^∘ C ambient temperature and 25

An unmodified series-production fuel cell city bus is measured on a heavy-duty roller chassis dynamometer. The two main research questions are. center dot The development and comparison of different methods to measure hydrogen consumption without the use of special measuring instruments (the bus should not be modified). center dot The influence of the heating, ventilation and air conditioning (HVAC) system on the fuel consumption of the bus. For the measurements we use a heavy-duty roller chassis dynamometer. Four different transient driving cycles are selected to represent typical city bus driving patterns. The ambient temperature is controlled within certain limits to simulate different weather conditions. Different HVAC settings and simulated passenger numbers are also used to imply variation in HVAC energy consumption. Three different methods to measure the hydrogen consumption of the bus are evaluated. They are based on the measurement of fuel cell current (A), hydrogen storage pressure (B) and product water mass (C). The methods are compared with each other and with the consumption reported by the vehicle. Based on the available validation options, we conclude that methods A and B give the most reliable results. Both show a difference of less than +/- 5 % for the majority of the results. The measured hydrogen consumption (method A) is between 5 and 8 kg/100 km depending on the cycle. The efficiency of the fuel cell system is measured to be between 58 % and 50 % at low and high load, respectively, with the BoP responsible for up to 5 % point loss. We also find that a full bus requires almost 30 % more traction power and that the heat dissipation from the passengers has a significant impact on the HVAC system. Different settings of the HVAC system are responsible for an increase in fuel consumption of up to 15 %.

Hydrogen fuelled internal combustion engines (H 2 -ICEs) are a promising zero-carbon propulsion solution. Although their steady-state performance has been investigated widely, sufficient transient performance is still challenging, especially for lean-burn, turbocharged configurations. This paper presents an experimental investigation into the transient behaviour and identifies key parameters for engine response and emission behaviour of a lean-burn turbocharged H 2 -ICE. The engine control unit features dedicated strategies for transient operation: an acceleration enrichment function that temporarily allows a richer $$\lambda$$ hence more fuel mass to improve engine response and an ignition retard function to mitigate combustion anomalies. Both functions are activated based on the difference between requested and calculated actual torque. These functions were the enabler to create calibrations with different transient performance. Besides known Non-Road Transient Cycle and World Harmonized Transient Cycle the transient performance was evaluated using a custom test cycle consisting of load steps at various engine speeds. The engine response time from the beginning of the load step until 70% of the full load torque was reached—the t 70% —was used as a key metric. The results highlight the trade-off between fast torque response and emission control and demonstrate the importance of transient engine control. Especially the difference to diesel transient performance shows the need for further development. All tests were conducted within the COMET Research Project Hylley.

Hydrogen-fueled internal combustion engines are a promising CO2-free and zero-impact emission alternative to battery or fuel cell electric powertrains. Advantages include long service life, robustness against fuel impurities and a strong infrastructural base with existing production lines and workshop stations. In order to make hydrogen engines harmless in terms of pollutant emissions as well, NOX emissions at the tailpipe must be reduced as low as the zero-impact emission level. Here, the application of selective catalytic reduction (SCR) catalysts is a promising solution that can be rapidly adopted from conventional diesel engines. This paper therefore investigates the influences of the hydrogen concentration in the raw exhaust gas, of the NO2/NOX ratio and of the space velocity on the performance of two different SCR technologies. The results show that both types of SCR, copper-zeolite and vanadium-based, have their advantages and drawbacks. Copper-based SCR catalysts have an early light-off temperature and reach maximum efficiencies of up to >99%. On the other hand, vanadium systems promise almost no secondary N2O emissions. As a result, we combined both approaches to create a superior solution with high efficiency and lowest secondary emissions.

Emission legislation limits have tightened in recent years. With regards to the European Union, the new Euro 7 legislation is expected to come into force within 2025. Furthermore, discussions on zero-impact emission levels are ongoing, which in addition are relevant for the assessment of future propulsion systems. In this study, the exhaust aftertreatment system (EAS) of an SI DI 2 l hydrogen engine with dedicated emission control is experimentally evaluated in stationary operation. After that, transient experiments with both low- and high-load RDE driving cycles are conducted. A special focus is put on the heat-up phase of the EAS. Various heat-up measures, including retarded ignition timing, load point shifting and an electrically heated catalyst (EHC) are considered. The 3 kW EHC showed good performance and was further used for the EAS heat-up. The driving cycles are then experimentally conducted with an EAS consisting of an EHC, an SCR catalyst, an ammonia slip catalyst (ASC) and a particulate filter (PF). In the WLTC, NOx tailpipe emissions as low as 1.7 mg/km are achieved, which means a reduction rate of 98

Hydrogene in Automotive Engineering introduces in the topic of hydrogen and deepens the application in automotive engineering.

Aufgrund seiner spezifischen Vorteile ist der Verbrennungsmotor der am weitesten verbreitete Energiewandler in der automotiven Anwendung. Der Verbrennungsmotor kann unterschiedliche flüssige und gasförmige Kraftstoffe verarbeiten und ist hinsichtlich Leistungsdichte, Kosteneffizienz und Robustheit anderen Antrieben überlegen. Weltweit sind über 1 Mrd.

In this paper, we will show the potentials of reducing NOx emissions of an H2-ICE to an ultra-low level by hybridizing the H2-ICE in an NRMM powertrain. Real-world measurement data of NRMM together with a simulated hybrid powertrain and operating strategy form the input data for the H2-ICE on the test bench. We have modified a turbocharged four-cylinder in-line gasoline engine for use with directly injected hydrogen. Within several iteration loops, we obtained measurement data that shows that, depending on the operating strategy, ultra-low NOx emissions are reachable. The combination of hybridization, which implies the possibility of recuperation, and the CO2 emission-free H2-ICE leads to a highly efficient, robust, and economic drivetrain with the lowest emissions, perfectly suitable for Non-Road Machinery. Additionally, we will discuss the overall coupled measurement and simulation setup and the reachable NOx emission levels in our tested setup. We will give an outlook for additional NOx emission reduction potentials with exhaust after-treatment systems and other methods of further reducing nitric oxides, which can take the H2-ICE to near zero NOx emissions.

In battery electric vehicles (BEV), thermal management is a key technique to improve efficiency and lifetime. Currently, manufacturers use different cooling concepts with numerous architectures. This work describes the development of a co-simulation framework to optimize BEV thermal management on system level, using advanced simulation methodologies also on component level, merging simulation and testing. Due to interactions between multiple conditioning circuits, thermal management optimization requires an overall vehicle approach. Thus, a full vehicle co-simulation of a BEV is developed, combining 1D thermal management software KULI and MATLAB/Simulink. Within co-simulation, the precise modeling of vehicle’s subsystems is important to predict thermal behavior and to calculate dynamic heating and cooling demands as well as exchanged energy flows with the thermal management system. Here, different methodologies are applied for cabin and battery modeling and simulation, with this paper primarily focusing on the battery and its cooling system. Inhomogeneous coolant flow within complex channel geometries complicates the simulation of temperature distribution and heat exchange in the battery, so simulation and testing are merged. The inner cell structures are modeled with detailed thermal networks, followed by scaling and extrapolation methods to estimate the thermal behavior at pack level. In parallel, a novel thermal dummy cell is developed, designed and realized in a hardware prototype, which reproduces heat generation due to electrochemical processes by inner heating elements. Furthermore, the co-simulation is extended to a hardware-in-the-loop (HIL) simulation by coupling battery simulation with thermal dummy cell hardware prototypes on test bench. This configuration enables the validation and correction of simulated thermal behavior and heat flows by measured heat transfer data.

Proton exchange membrane fuel cells are gaining increasing importance in vehicle applications. The exhaust gas composition regarding the water and oxygen content and the mass flow are important parameters in fuel cell research (e.g., for designing the test bed, quantifying the hydrogen loss in the exhaust, performing experiments with air pollutants, and monitoring degradation). The exhaust gas composition is also important for vehicle applications (e.g., ensuring safe hydrogen levels in the exhaust). Performing direct measurements of the exhaust mass flow and the relative humidity is challenging due to the high-humidity environment. This article presents a mathematical thermodynamic model used to calculate the exhaust gas mass flow and relative humidity, validated by balancing the gas species composition between cathode inlet and exhaust and by using data measured at the fuel cell system test bed. Four calculation model variations and their analyses are discussed. Furthermore, the exhaust gas composition throughout the fuel cell system operating range is presented. The results of air pollutant experiments provide comprehensive examples for the application of the calculation model. These results demonstrate the suitability of the model for its application in fuel cell system research.

Air contaminants can have detrimental effects on the performance and durability of proton exchange membrane (PEM) fuel cell vehicles. This research focuses on the experimental investigation of the effect of nitrogen monoxide (NO) in the cathode gas stream, which provokes a cell voltage decrease due to the partially reversible adsorption of NO on the platinum catalyst. The concentration and exposure time of NO in the cathode gas stream are varied at selected constant current densities and load ramps to assess the effects throughout the fuel cell system operating range. The results show the cell voltage loss in the presence of NO and reveal a near-catalyst saturation with increased injected NO mass. Additionally, several voltage recovery and mitigation strategies are introduced and discussed by presenting conclusions about the general effect of NO on a fuel cell system in operation. The most promising recovery strategy for fuel cell systems is identified, and the overall system degradation is discussed. All experiments are performed in a test bed environment on a 25 kW low-temperature fuel cell system via controlled injection of NO into the cathode gas stream.

The aim of the study is to investigate the most effective approach to reduce the emissions of a SI-engine while using a limited amount of renewable fuel. In this study, the renewable fuels ethanol, methanol, 2-ethoxy-2-methylpropane (ETBE), acetone, and dimethylformamide (DMF) were investigated with various fixed admixture rates and with a fully variable on-board fuel mixture (Smart-Fuel concept). One result of the study is that for a Smart-Fuel concept using methanol a reduction in CO 2 emissions of approx. 12.5% and a reduction in particulate emissions of approx. 60% can be achieved, when considering an entire car fleet. In terms of engine efficiency, as well as particulate emissions, the pure substances, except DMF, achieved significant improvements compared to standard gasoline. Compared with the pure substances, the Smart-Fuel concept achieved lower advantages; however, it used significantly less scarcely available renewable fuel in the process. Based on the limited availability of renewable fuels within the first stages of a circular economy, the Smart-Fuel concept proves to be a very efficient transition technology to achieve the CO 2 reduction targets. The Smart-Fuel concept only uses renewable fuel when it is worthwhile in terms of efficiency or emissions. Predefined fuel blends in a mono-fuel concept offer much less reduction potential in terms of emissions than the Smart-Fuel concept. However, with respect to particulate raw emissions, especially for moderate mixing rates significantly increased particle emissions are sometimes observed, despite the overall very good performance of the pure substances.