Hydrogen Engine Research Articles

Investigations on particle emissions of large-bore engines powered by natural gas and hydrogen

This research provides the first insights into the particle emissions of large-bore engines powered by natural gas and hydrogen, identifying an increased lubricating oil influence in hydrogen engines.

Green ammonia synthesis from stationary NOx emission sources on a catalytic lean NOx trap

The NOCCRA (NOx capture and catalytic reduction to ammonia) process enables local ammonia/fertiliser production out of NOx in the flue gas of stationary engines. The two-phase process adsorbs NOx on a lean NOx trap, followed by reduction to NH3 by H2.

Effect of Hydrogen Injection Flow Rate on the Performance of In-Cylinder Direct Injection Hydrogen Engines

Effect of Hydrogen Injection Flow Rate on the Performance of In-Cylinder Direct Injection Hydrogen Engines

Development of thermoelectric exhaust energy recovery system of a hydrogen internal combustion engine in a city bus using a Three-Dimensional multiphysics model

In this study, individual thermoelectric generator (TEG) module was developed and validated through comprehensive analyses and experiments. A model of the TEG module was constructed and subsequently verified through a coherent alignment with experimental results, ensuring its viability and accuracy within the application of interest. A thermoelectric exhaust energy recovery (TEER) system designed with a robust rectangular structure was also developed for an urban mass transit bus, which operates using a hydrogen internal combustion engine. By accommodating 40 TEG modules, each complemented with cooling fins, and placing cooling channels at the top and bottom of the exhaust channel, it was demonstrated that a proportionality between the power output and load resistance of the TEER system through a dimensionless analysis. The system’s three-dimensional multiphysics model constructed concurrently with the actual system facilitated both optimization and validation, predicting an energy recovery of 1.0–1.1% from the hydrogen engine exhaust and an optimal load resistance of 3.2 Ω under various operating conditions.

Failure analysis and design improvement of high-pressure seal cone head for vehicle hydrogen engine

As hydrogen energy vehicle technology advances, the performance requirements of vehicle hydrogen engine components become increasingly stringent. The high-pressure sealing cone head is a vital connection of the vehicle's hydrogen engine, however, it is easily fractured during the loading test. To address this issue, this research combines finite element modeling and material characterization methodologies to perform failure analysis and re-optimization design of the sealing cone head. First, the parameters for the CL toughness fracture criteria and the Johnson-Cook constitutive model were obtained by the inversion technique and the tensile test, respectively. On the cold heading formation process of the cone head, finite element analysis and microstructure analysis were performed. The results show that machining defects on the outer surface are the root cause of failure. Fatigue cracking is the main failure mechanism, and the crack gradually expands under the effect of alternating loads, which eventually causes a fracture of the cone head. At the same time, there are bending-type folding defects caused by the instability of the cone head under pressure. Second, the critical structural and process factors that impact the mechanical behavior of the components are investigated, and the orthogonal experiment optimization method is utilized to find the optimal process parameters, using the damage value as the evaluation index. According to the findings, the die angle has a major impact on the damage value, but the eligible die angle that is too small would negatively affect the force of the cone head and nut. Finally, a multi-station cold heading procedure for the high-pressure seal cone head was innovatively presented, and its mechanism of action was unveiled. The aforementioned defects were effectively addressed by the optimized process, and as compared to the pre-optimization, the maximum principal stress of the optimized component in the C-region was reduced by 27%, which did not exceed the tensile strength. At the same time, the spindle load was decreased by 25% and the maximum damage value was decreased by 48%, reaching the safe range. The optimized process effectively improves the performance of the part and increases the quality stability.

Sources and Destinations of Oil Leakage through TPOCR Based on 2D-LIF Observation and Modeling Analysis

The Three-Piece Oil Control Ring (TPOCR) is becoming a viable option for heavy duty gas and hydrogen engines due to the low particle concentration in these engines. Although direct oil leakage from the gap is not likely to happen with the misalignment of the upper and lower rail gaps, there exist other less-apparent oil leaking mechanisms through the TPOCR. This work is targeted at understanding the oil leakage’s source and destination through the rail and liner interfaces across the whole cycle. The 2D Laser Induced Fluorescence technique was applied on an optical engine to study the oil transport behavior. Combined with a TPOCR model for dynamics and lubrication, the mechanisms that cause rail twist and oil scraping by the upper rail were analyzed. It was found that the symmetrical rail can scrape the oil up in the up-strokes. The scraped oil first accumulates in the clearance between the upper rail and groove, as well as at the upper corner of the rail Outer Diameter before being transferred to both the third land and liner when the piston changes direction at Top Dead Center. Rails with an asymmetrical profile can reduce or enhance these effects depending the orientation of the rails. This study provides findings that could help design the engine to better control Lubricate Oil Consumption and properly lubricate the Top Dead Center’s dry region at the same time.

Can lubricant oil promote undesired self-ignition of the charge in hydrogen engines?

Hydrogen utilization in internal combustion engines is deemed a viable solution for promoting a rapid transition towards a carbon-free mobility, especially for those hard-to-electrify applications. However, critical aspects still poorly understood remain and need to be investigated in order to accelerate the development of such a promising technology. Some of these might originate from the undesired but unavoidable participation of lubricant oil to the combustion process. The present work aims at ascertaining if the lubricant oil chemical characteristics can be at the basis of the onset of certain uncontrolled self-ignition modes of the charge. Considering a lubricant oil droplet suspended in a H2/air environment, an analytical model was developed to derive essential information about mixture composition and thermodynamic conditions that might establish where oil contamination occurs. The results were used to initialize zero-dimensional numerical simulations performed in the OpenSMOKE++ framework with the aim of highlighting charge reactivity variations induced by the presence of oil vapour in the vicinity of an oil droplet. A reduced chemical model, developed for this very purpose in a previous recent work, was employed in the simulations for emulating the reactivity properties of the H2/oil/air mixture.

The use of hydrogen as a fuel in road transport on the Polish path to climate neutrality - a literature review

Abstract Hydrogen is expected to be one of the most important fuels meeting stringent emission standards shortly. Using hydrogen as a fuel in an internal combustion engine (ICE) is an alternative application to replace hydrocarbon fuels that, when burned, produce harmful gases such as carbon monoxide and hydrocarbons, particulate matter, and greenhouse gases. This work provides an overview of the latest research results and future challenges and opportunities related to the use of hydrogen to power ICEs. The article presents the work of various research centres describing the technical use of hydrogen as a fuel in motor vehicles with combustion engines. Specific chemical and physical properties of hydrogen used in combustion engines were presented. The article presents modern research on a hydrogen-powered ICE. First, the basics of hydrogen engines are described, examining the engine-specific properties of hydrogen, followed by a review of the existing literature. Attention was paid to the fundamental importance of optimising the air composition from the point of view of combustion quality, NOx emissions, engine efficiency, and performance. Another issue under consideration is cleaning exhaust gases to meet future emissions regulations for hydrogen-fuelled combustion engines.

Revolutionizing Transportation: A Comprehensive Review of Hydrogen-Powered Engines

Abstract: Hydrogen as an alternative fuel source has gained significant attention due to its potential to mitigate greenhouse gas emissions and address energy sustainability concerns. This paper presents a comprehensive analysis of hydrogen engines, exploring their advancements, challenges, and prospects. The study encompasses a thorough review of the current state of hydrogen engine technology, including various combustion mechanisms, fuel delivery systems, and emissions characteristics. The paper delves into the key advancements achieved in hydrogen engine design, addressing efficiency improvements, power output optimization, and enhanced durability. It highlights the importance of advanced ignition and combustion strategies, such as lean burn and stratified charge combustion, in maximizing engine performance while minimizing emissions. Additionally, the integration of hydrogen engines with hybrid and electric systems is discussed as a means of further enhancing their efficiency and overall environmental impact.

Influence of water‐methanol injection and turbocharging on the performance of a hydrogen‐fueled spark ignition engine

AbstractThis article presents a study that compares the performance and emission characteristics of a four‐stroke, four‐cylinder spark ignition (SI) engine fueled by gasoline and neat hydrogen. The engine was equipped with turbocharging to optimize ignition timing for power boosting and vaporized water–methanol injection to reduce emissions. Engine tests were conducted at speeds ranging from 2000 to 6000 rpm, with a fixed intake pressure and varying quantities of hydrogen and spark advance timings. The study compared the results of non‐turbocharged and turbocharged engines with water–methanol injection in terms of combustion, performance, and emissions. The findings showed that the turbocharged water–methanol hydrogen operation had a higher brake thermal efficiency (BTE) than its counterpart, while the brake power of the hydrogen engine operation increased with turbocharging but slightly decreased with water–methanol injection. Additionally, volumetric efficiency improved by 7% for turbocharged and 4% for water‐injected hydrogen engine operation compared to the counterpart. The cylinder pressure for turbocharging with water–methanol operation yielded 16.32% higher compared with counterpart gasoline engine operation. Finally, nitrogen oxides (NOx) emissions were reduced with turbocharging and water–methanol injection compared to the counterpart non‐turbocharged hydrogen engine operation.

Numerical assessment of water injection for improved thermal efficiency and emissions control in a medium-duty hydrogen engine for transportation applications

The existing political environment and the growing worries about climate change have resulted in the imposition of stringent regulations on traditional propulsion systems reliant on fossil fuels. While new technologies are being investigated to substitute internal combustion engines, their current technological advancement necessitates further development and refinement in order to emerge as a viable alternative to the conventional internal combustion engine. The utilization of hydrogen-powered internal combustion engines has showcased their capacity to rapidly achieve complete decarbonization in the transportation industry. However, these engines continue to encounter limitations regarding their operational range that need to be addressed. The utilization of EGR for controlling combustion instabilities and mitigating NOx formation still has significant limitations in operating at high engine loads, mainly affecting the boost requirements for reaching high power densities. The present work evaluates the potential of substituting the EGR dilution with a water injection system for reaching full load operation on a conventional diesel engine, assuming the minimum modifications required for it to work under H2 combustion. The study is carried out assuming a multi-cylinder engine representing the medium- to high-duty transport sector. The evaluation includes a comparison of the engine performance and emissions obtained when using EGR and water injection at full load, comparing the requirements of the boost system for both strategies to reach power densities of 24 bar of BMEP equivalent to modern diesel applications. The results show that WI allows for significantly reduced boost pressure requirements lowering intake pressure by up to 1 bar, while achieving very similar engine efficiency and a reduction of NOx emissions around 80%, resulting a similar effectiveness compared with EGR. Additionally, WI provides additional prevention against undesired autoignition.

Life cycle assessment of ammonia/hydrogen-driven marine propulsion

Marine fuels are the main sources of pollution from shipping industry. Hydrogen and ammonia have been suggested to be alternative fuels for shipping as these two fuels do not emit carbon dioxides in the combustion process. This study employed life cycle assessment method to compare the environmental performance of propulsion systems using hydrogen and ammonia as marine fuels to fossil fuels. 2-stroke and 4-stroke engines of tankers using fossil fuels were chosen as base case scenarios. Alternative scenarios using ‘green’ and ‘blue’ hydrogen and ammonia with the support of pilot fuel were then compared to the base case scenarios. While the performance of the coming combustion concepts for hydrogen and ammonia engines are still unknown, preliminary estimations were used in this study. The results showed that hydrogen and ammonia could substantially reduce the global warming potential, compared with the fossil fuel scenarios. Hydrogen and ammonia are also expected to be highly effective in cutting down the particulate matter and the emission of black carbon.

Evaluation of a pressure sensing glow plug in terms of its application possibility to control the combustion process of a hydrogen-powered spark-ignition engine

The article contains the results of an analysis of the suitability of a pressure sensing glow plug for use in a hydrogen engine control system. Due to the properties of hydrogen, the process of its combustion in spark-ignition engines is significantly different from the classic fuels. It is planned to use the pressure sensor signal to control the combustion process to obtain high power and efficiency, with the lowest possible emission of nitrogen oxides, which is the main harmful component of hydrogen engines. After an initial assessment of suitability, it was decided to use a pressure sensing glow plug. This choice is dictated by the low price, good availability and high durability of these sensors. The preliminary tests were carried out using a low-power single-cylinder SI engine coupled with a 48V generator. The tests were carried out for several values of engine speed and load of the generator and for classic gasoline with a research octane number (RON) of 95. In order to obtain an increased pressure rise rate in the cylinder, as for hydrogen fueling, the engine operation was also tested with unmodified light gasoline used as solvent, which is characterized by a significantly lower RON value. The use of a reference pressure sensor in the cylinder made it possible to determine the behavior of the PSG in various operating conditions. The tests revealed that the differences in the pressure waveforms registered with both sensors can be systematized depending on the engine speed and its load.

Reliability and Wear Evaluation of Hydrogen Engines in Long-term Operation in Vehicles

Reliability and Wear Evaluation of Hydrogen Engines in Long-term Operation in Vehicles

Experimental investigation of the working boundary limited by abnormal combustion and the combustion characteristics of a turbocharged direct injection hydrogen engine

In the process of hydrogen energy conversion and utilization, the direct-injection hydrogen internal combustion engine has been proven to produce zero carbon emissions with high thermal efficiency. However, the risk of abnormal combustion and high requirements of turbocharging limits the improvement of engine performance. This paper focuses on exploring the performance boundary of a 2.0 L turbocharged direct injection hydrogen engine with bench test under all working conditions. Applied variable geometry turbocharger can provide high intake pressure of 270 kPa with proper exhaust back pressure under all engine speed working conditions by changing the turbo opening angle. Delayed injection timing can enhance the performance, while improper injection timing may cause severe pre-ignition and afterburning. The burn duration ranges from 11 °CA to 29 °CA is significantly impacted by the engine speed and the excess air fuel ratio, whereas the load exerts less influence. Furthermore, the boundary of the minimum excess air fuel ratio limited by knock with different intake pressure, compression ratio and ignition timing are investigated and optimized. The minimum excess air fuel ratio limited by knock reaches 1.80 with a maximum torque of 325 Nm at the engine speed of 2500 rpm due to the limitation of the pre-ignition and super -knock. A high brake thermal efficiency of 43.02 % and a maximum power of 125 kW are achieved with the minimum excess air fuel ratio limited by knock of 2.05 and 1.4 respectively.

Advanced development of hydrogen engines for diverse transportation

The hazard of conventional fossil fuels that transportation relies on nowadays has urged the scientific community to speed up the process of diminishing the pollutants caused by daily transportation and finding an opulent energy source for its superstition. Renewable resources and hydrogen are deemed as the next generation resource. However, hydrogen is the ultimate choice for transportation for its excellent performance both in the fields of environmental protection and energy. In this article, a study on the global production of hydrogen is performed, delving into the present conditions of the hydrogen industry. The principles referred to when choosing hydrogen to be an energy source for various transportation are discussed, and a comparison between conventional fuel engines and hydrogen fuel engines is made. The existing technical problems concerning the application of hydrogen engines or hydrogen fuel cells are reviewed. Combined with the usage of technologies on hydrogen, an envisage of future clean transportation is demonstrated.

Effect of direct injection of small amounts of ethanol on port-injected hydrogen internal combustion engines

Hydrogen is a renewable fuel with excellent combustion characteristics. However, the direct use of hydrogen in existing engines faces obstacles such as abnormal combustion and high NOx emissions. This study proposes a strategy for controlling the combustion and emissions performance of a port-injection (PI) hydrogen internal combustion engine using ethanol direct injection (DI). The test conditions are 1000 rpm, 1500 rpm, and 2000 rpm respectively, the excess air coefficient is 1, 1.5, and 2, and 3%, 6%, and 9% ethanol is added. The results showed that the addition of ethanol can significantly reduce the pressure rise rate of the hydrogen engine and prolong CA0-10 and CA10-90. The addition of ethanol can promote the BMEP and BTE of the hydrogen engine. The addition of ethanol can reduce NOx emissions under lean burn conditions by 18%. The disadvantage is that the addition of ethanol increases the hydrocarbon emissions of hydrogen engines by about 50%, but the total amount is less. After the addition of ethanol, the flashback phenomenon of the hydrogen engine was significantly improved.

Exhaust gas aftertreatment to minimize NOX emissions from hydrogen-fueled internal combustion engines

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.

FLAME PROPAGATION IN A NARROW GAP BETWEEN THE PISTON AND CYLINDER OF A HYDROGEN ENGINE

The processes of flame penetration and propagation in a narrow annular gap between the piston and cylinder of a hydrogen piston engine are investigated by the method of 3D mathematical modeling. The model is verified by comparing the changes in pressure and heat release rate in the cylinder obtained from an experimental hydrogen engine, considering the data collected during numerical experiments. The movement of the flame front into the gap is analyzed by changes in the instantaneous local values of the hydrogen fractions in the mixture and the local temperatures of the cold gas (unburned mixture) and combustion products. A comparative analysis of the spread of gasoline and hydrogen flames is carried out. The phenomenon of increasing heat losses in the combustion chamber of a hydrogen engine compared to a gasoline engine, previously confirmed experimentally by different authors and not yet having an acceptable theoretical interpretation, is explained by neglecting the role of heat transfer in the indicated gap.

Unerroric of vibration diagnostics of a hydrogen engine

Unerroric of vibration diagnostics of a hydrogen engine