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The hydrogen engine is one of the promising technologies that enables carbon-neutral mobility, especially in heavy-duty on- or off-road applications. In this paper, a methodological procedure for the design of the combustion system of a hydrogen-fueled, direct injection spark ignited commercial vehicle engine is described. In a preliminary step, the ability of the commercial 3D computational fluid dynamics (CFD) code AVL FIRE classic to reproduce the characteristics of the gas jet, introduced into a quiescent environment by a dedicated H2 injector, is established. This is based on two parts: Temporal and numerical discretization sensitivity analyses ensure that the spatial and temporal resolution of the simulations is adequate, and comparisons to a comprehensive set of experiments demonstrate the accuracy of the simulations. The measurements used for this purpose rely on the well-known schlieren technique and use helium as a safe substitute for H2.

For the purpose of achieving carbon-neutrality in the mobility sector by 2050, hydrogen can play a crucial role as an alternative energy carrier, not only for direct usage in fuel cell-powered vehicles, but also for fueling internal combustion engines. This paper focuses on the numerical investigation of high-pressure hydrogen injection and the mixture formation inside a high-tumble engine with a conventional liquid fuel injector for passenger cars. Since the traditional 3D-CFD approach of simulating the inner flow of an injector requires a very high spatial and temporal resolution, the enormous computational effort, especially for full engine simulations, is a big challenge for an effective virtual development of modern engines. An alternative and more pragmatic lagrangian 3D-CFD approach offers opportunities for a significant reduction in computational effort without sacrificing reliability.

Ducted Fuel Injection (DFI) engines have emerged as a promising technology in the pursuit of a clean and efficient combustion process. This article aims at elucidating the effect of piston geometry on the engine performance and emissions of a metal DFI engine. Three different types of pistons were investigated and the main piston design features including the piston bowl diameter, piston bowl slope angle, duct angle and the injection nozzle position were examined. To achieve the target, computational fluid dynamics (CFD) simulations were conducted coupled to a reduced chemical kinetics mechanism. Extensive validations were performed against the measured data from a conventional diesel engine. To calibrate the soot model, genetic algorithm and machine learning methods were utilized. The simulation results highlight the pivotal role played by piston bowl diameter and fuel injection angle in controlling soot emissions of a DFI engine.

Heavy duty truck engines are quite difficult to electrify, due to the large amount of energy required on-board, in order to achieve a range comparable to that of diesels. This paper considers a commercial 6-cylinder engine with a displacement of 12.8 L, developed in two different versions. As a standard diesel, the engine is able to deliver more than 420 kW at 1800 rpm, whereas in the CNG configuration the maximum power output is 330 kW at 1800 rpm. Maintaining the same combustion chamber design of the last version, a theoretical study is carried out in order to run the engine on Hydrogen, compressed at 700 bar. The study is based on GT-Power simulations, adopting a predictive combustion model, calibrated with experimental results. The study shows that the implementation of a combustion system running on lean mixtures of Hydrogen, permits to cancel the emissions of CO2, while maintaining the same power output of the CNG engine.

The reduction of anthropogenic greenhouse gas emissions and ever stricter regulations on pollutant emissions in the transport sector require research and development of new, climate-friendly propulsion concepts. The use of renewable hydrogen as a fuel for internal combustion engines promises to provide a good solution especially for commercial vehicles. For optimum efficiency of the combustion process, hydrogen-specific engine components are required, which need to be tested on the test bench and analysed in simulation studies. This paper deals with the simulation-based investigation and optimisation of fuel injection in a 6-cylinder PFI commercial vehicle engine, which has been modified for hydrogen operation starting from a natural gas engine concept.

Testing of ducted fuel injection (DFI) in a single-cylinder engine with production-like hardware previously showed that adding a duct structure increased soot emissions at the full load, rated speed operating point [1]. The authors hypothesized that the DFI flame, which travels faster than a conventional diesel combustion (CDC) flame, and has a shorter distance to travel, was being re-entrained into the on-going fuel injection around the lift-off length (LOL), thus reducing air entrainment into the on-going injection. The engine operating condition and the engine combustion chamber geometry were duplicated in a constant pressure vessel. The experimental setup used a 3D piston section combined with a glass fire deck allowing for a comparison between a CDC flame and a DFI flame via high-speed imaging. CH* imaging of the 3D piston profile view clearly confirmed the re-entrainment hypothesis presented in the previous engine work.

In the perspective of a reduction of emissions and a rapid decarbonisation, especially for compression ignition engines, hydrogen plays a decisive role. The dual fuel technology is perfectly suited to the use of hydrogen, a fuel characterized by great energy potential. In fact, replacing, at the same energy content, the fossil fuel with a totally carbon free one, a significant reduction of the greenhouse gases, like carbon dioxide and total hydrocarbon, as well as of the particulate matter can be obtained. The dual fuel with indirect injection of gaseous fuel in the intake manifold, involves the problem of hydrogen autoignition. In order to avoid this difficulty, the optimal conditions for the injection of the incoming mixture into the cylinder were experimentally investigated. All combustion processes are carried out on a research engine with optical access. The engine speed has is set at 1500 rpm, while the EGR valve is deactivated.

Dual-fuel engines powered by renewable fuels provide a potential solution for reducing the carbon footprint and emissions of transportation, contributing to the goal of achieving sustainable mobility. The investigation presented in the following uses a dual-fuel engine concept running on biogas (referred to as CNG in this paper) and the e-fuel polyoxymethylene dimethyl ether (OME). The current study focuses on the effects of exhaust gas rebreathing and external exhaust gas recirculation (EGR) on emissions and brake thermal efficiency (BTE). A four-cylinder heavy-duty engine converted to dual-fuel operation was used to conduct the engine tests at a load point of 1600 min-1 and 9.8 bar brake mean effective pressure (BMEP). The respective shares of high reactivity fuel (HRF, here: OME) and low reactivity fuel (LRF, here: CNG) were varied, as were the external and internal EGR rates and their combinations.

Hydrogen–diesel dual-fuel combustion processes were visualized using an optically accessible rapid compression and expansion machine (RCEM). A hydrogen-air mixture was introduced into the combustion chamber, and a pilot injection of diesel fuel was used as the ignition source. A small amount of diesel fuel was injected as the pilot fuel at injection pressures of 40, 80, and 120 MPa using a common rail injection system. The injection amounts of diesel fuel were varied as 3, 6, and 13 mm3. The amount of hydrogen was manipulated by varying the total excess air ratio (λtotal) at 3 and 4. The RCEM was operated at a constant speed of 900 rpm, and the in-cylinder pressure and temperature at the top dead center (TDC) were set as 5 MPa and 700 K, respectively. The combustion processes were visualized via direct photography and hydroxyl (OH*) chemiluminescence photography using a high-speed camera and an image intensifier.

As part of Nissan’s strategy of electrification and the shift to smart technologies, our powertrain department has two main pillars: zero emissions and ICE Evolution. As a core unit of ICE Evolution, we have developed a brand new 3.5L V6 Twin turbocharged gasoline engine for Nissan’s next generation full-size flagship SUV to deliver luxury and toughness at the highest level. This brand-new engine will be applied to vehicles in all corners of the world and must have strong performance in every corner. More specifically, it has to meet the latest emissions and fuel efficiency regulations, have strong power performance beyond expectation, and provide reliable drivability on rough roads and deserts. To achieve these requirements, the new engine is incorporating many cutting-edge technologies.

Engine knock is a major challenge that limits the achievement of higher engine efficiency by increasing the compression ratio of the engine. To address this issue, using a higher octane number fuel can be a potential solution to reduce or eliminate the propensity for knock and so obtain better engine performance. Methanol, a promising alternative fuel, can be produced from conventional and non-conventional energy resources, which can help reduce pollutant emissions. Methanol has a higher octane number than typically gasolines, which makes it a viable option for reducing knock intensity. This study compared the combustion characteristics of gasoline and methanol fuels in an optical spark-ignition engine using multiple spark plugs. The experiment was carried out on a single-cylinder four-stroke optical engine. The researchers used a customized metal liner with four circumferential spark plugs to generate multiple flame kernels inside the combustion chamber.

Both ammonia and hydrogen, as zero-carbon fuels for internal combustion engines, are received growing attention. However, ammonia faces a challenge of low flame propagation velocity. Through injecting hydrogen into active pre-chamber, its jet flame ignition can accelerate the flame propagation velocity of ammonia. The influence of different pre-chamber structures on engine combustion characteristics is significant. In this paper, numerical studies were conducted to assess the impact of various pre-chamber structures and hydrogen injection strategy on the combustion characteristics of ammonia/hydrogen engines while maintaining the equivalent ratio of 1.0. The results indicate that the jet angle significantly affects the position of jet flame and the followed main combustion. The in-cylinder combustion pressure peaks at jet angle of 150°. Meanwhile, the combustion duration of 150° is shortened by 74.3% compared with that of 60°.

To mitigate the NOx emissions from diesel engines, the adoption of exhaust gas recirculation (EGR) has gained widespread acceptance as a technology. Employing EGR has the drawback of elevating soot emissions. Using hydrogen-enriched air with EGR in a diesel engine (dual-fuel operation), offers the potential to decrease in-cylinder soot formation while simultaneously reducing NOx emissions. The present study numerically investigates the effect of hydrogen energy share and engine load on the formation and emission of soot and NOx from hydrogen-diesel dual-fuel engines. The numerical investigation uses an n-heptane/H2 reduced reaction mechanism with a two-step soot model in ANSYS FORTE. A reduced n-heptane reaction mechanism is integrated with a hydrogen reaction mechanism using CHEMKIN to enhance the accuracy of predicting dual-fuel combustion in a hydrogen dual-fuel engine.

A potential route to reduce CO2 emissions from heavy-duty trucks is to combine low-carbon fuels and a hybrid-electric powertrain to maximize overall efficiency. A hybrid electric powertrain can reduce the peak power required from the internal combustion engine, leading to opportunities to reduce the engine size but still meet vehicle performance requirements. Although engine downsizing in the light-duty sector can offer significant fuel economy savings mainly due to increased part-load efficiency, its benefits and downsides in heavy-duty engines are less clear. As there has been limited published research in this area to date, there is a lack of a standardized engine downsizing procedure.

The widely accepted best practice for spark-ignition combustion is the four-valve pent-roof chamber using a central sparkplug and incorporating tumble flow during the intake event. The bulk tumble flow readily breaks up during the compression stroke to fine-scale turbulent kinetic energy desired for rapid, robust combustion. The natural gas engines used in medium- and heavy-truck applications would benefit from a similar, high-tumble pent-roof combustion chamber. However, these engines are invariably derived from their higher-volume diesel counterparts, and the production volumes are insufficient to justify the amount of modification required to incorporate a pent-roof system. The objective of this multi-dimensional computational study was to develop a combustion chamber addressing the objectives of a pent-roof chamber while maintaining the flat firedeck and vertical valve orientation of the diesel engine.

Recently, the environmental temperature of vehicles is changing due to the electrification of vehicles and improved internal combustion engine system to reduce carbon emissions. However, mechanical properties of plastic materials change very sensitively to environmental temperature changes, and mechanical properties decrease when exposed to high temperatures. Therefore, it is important to estimate lifespan estimation of plastic parts according to temperature changes. In this paper, reliability analysis process to estimate the maximum service temperature of plastic parts was developed using aging data of material properties, environmental condition data of automotive parts, and field driving condition data. Changes in the mechanical properties of plastic materials such as glass fiber reinforced polyamide materials were tested. The environmental exposure temperature of the vehicle and parts was measured, and the general driving pattern of the vehicle was analyzed.

The design of engine intake system affects the intake uniformity of each cylinder of the engine, which in turn has an important impact on the engine performance, the uniform distribution of EGR exhaust gas and the combustion process of each cylinder. In this paper, the constant-pressure supercharged diesel engine intake pipe is used as the research model to study the intake air flow unevenness of the intake pipe of the supercharged diesel engine. The pressure boundary condition at the outlet of each intake manifold is set as the dynamic pressure change condition. The three-dimensional numerical simulation of the transient flow process in the intake manifold of diesel engine is simulated and analyzed by using numerical method, and the change of the Intake air flow field in the intake manifold under different working conditions during the intake overlapping period is discussed.

This paper is part of a broader research project aiming at studying, designing, and prototyping a hydrogen-powered internal combustion engine to achieve fast market implementation, reduced greenhouse gas emissions, and sustainable costs. The ability to provide a fast market implementation is linked to the fact that the technological solution would exploit the existing production chain of internal combustion engines. Regarding the technological point of view, the hydrogen engine will be a monofuel engine re-designed based on a diesel-powered engine. The redesign involves specific modifications to critical subsystems, including combustion systems, injection, ignition, exhaust gas recirculation, and exhaust gas aftertreatment. Notably, adaptations include the customization of the cylinder head for controlled ignition, optimization of camshaft profiles, and evaluation of the intake system.

The global imperative to develop clean energy solutions has redirected research efforts towards highly efficient combustion engines with ultra-low emissions. This has prompted investigations into alternative combustion concepts, including Low Temperature Combustion (LTC), utilizing environmentally friendly fuels. Within the scope of our research project, we are primarily focused on the development of an innovative combustion concept known as Homogeneous Reactivity-Controlled Compression Ignition (hRCCI), which employs renewable fuels such as ethanol and 1-octanol for a serial hybrid powertrain. The lack of predictive simulations for this concept presents a significant challenge in optimizing the engine's operation. Most of the 1D system simulation models use a non-predictive combustion model for combustion simulations. Due to the dependence on auto-ignition chemistry, a chemistry based hRCCI combustion model for real time computation has been proposed with this work.

Aluminum alloy has become an indispensable part of the automotive industry because of its excellent mechanical properties such as lightweight, high strength, high reliability, maintainability, and low cost. Aluminum alloy is used in automobiles, such as engine blocks, cylinder heads, intake manifolds, brake components, and fuel tanks. Fatigue and fracture are the main reasons for its engineering failure. Surface strengthening techniques, such as ultrasonic shot peening (USP), are often used to improve the fatigue resistance of aluminum alloys. This article expounds on the working principle of USP and elucidates the influence of USP process parameters on the surface characteristics of aluminum alloy. Experimental results observed the effects of USP parameters on surface properties such as surface roughness, microhardness, and surface morphology.