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To realize a super-leanburn SI engine with a very-high compression ratio, it is required to design a new fuel which could have low ignitability at a low temperature for antiknocking, but high ignitability at a high temperature for stable combustion. Ethane shows a long ignition delay time at a low temperature close to that of methane, but a short ignition delay time at a high temperature close to that of gasoline. In the present study, the antiknocking effect of adding methane with the RON of 120, ethane with the RON of 108, or propane with the RON of 112 to a regular gasoline surrogate fuel with the RON of 90.8 has been investigated. Adding each gaseous fuel by less than 0.4 in heat fraction advances knocking limit in the descending order of SI timing advance of ethane, methane, and propane, and in the descending order of CA 50 advance of ethane, propane, and methane. Adding methane extends combustion duration slightly, but adding ethane or propane shortens it considerably.

In the context of energy conservation and emission reduction, high power density(HPD) and low fuel consumption are the consistent pursuit of diesel engine development. Among the small-bore diesel, the limited space in the cylinder poses higher challenges and requirements for the arrangement of sprays.The high injection pressure results in a greater impulse when the spray impinges chamber, which allows the combustibles to develop along the chamber wall. Based on these characteristics of small-bore HPD diesel, a reasonable injection scheme is proposed to help flame diffusion surface increasing and thermal efficiency enhancing. This work proposes an optimization path to increase the flame diffusion surface, then improve thermal efficiency. It can be achieved with matching between the injector extension length and the spray spray angle.

The combustion of hydrogen (H2) as a fuel is attractive due to its clean combustion or combustion-enhancing properties when used as a supplement to other fuels. However, the challenge of using H2 as a fuel for transportation applications is the difficulty of onboard storage. Cracking onboard stored ammonia (NH3) into H2 can also improve combustion performance and emissions in mobile applications fuelled with zero and carbon-neutral fuels. However, the reforming process is not always 100 % efficient which can lead to the presence of NH3 in the combustion process. The presence of NH3 can influence engine performance, combustion and emissions. Therefore, this experimental study reports the effect of H2 and H2/NH3/N2 fuel blends added to gasoline in a dual-fuel operation under both stoichiometric (λ=1.0) and lean-burn (λ>1.0) operating conditions in a spark ignition (SI) engine.

The Advanced Fuel Ignition Delay Analyzer (AFIDA) apparatus can measure the ignition delay times with high repeatability within very short time. The device also requires small quantities of fuel samples. During AFIDA experiments, liquid fuel is injected into a hot and constant-volume chamber at high pressure. This way the ignition of the spray combines the effects of realistic influences like liquid evaporation and combustion chemistry. The present work investigates the effects of blending ethanol and 2,5-dimethylfuran with primary reference fuels (i.e., mixtures of iso-octane and n-heptane). The primary motivation of this study is to show the differences in ignition delay times of different gasoline-ethanol and gasoline-2,5-dimethylfuran blends where both physical mixing and chemical kinetics have considerable influences. The primary reference fuel is considered as the gasoline surrogate in this work. The study has been conducted at a range of temperatures and pressures.

Hydrogen engines are currently considered as a viable solution to preserve the internal combustion engine (ICE) as a power unit for vehicle propulsion. In particular, lean-burn gasoline Spark-Ignition (SI) engines have been a major subject of investigation, due to their reduced emission levels and high thermodynamic efficiency. Lean charge is suitable for passenger car applications, where the demand of mid/low power output does not require an excessive amount of air to be delivered by the turbocharging unit, but can difficulty be tailored in the field of high-performance engine, where the air mass delivered would require oversized turbocharging systems or more complex charging solutions. For this reason, the range of feeding conditions near the stochiometric is explored in the field of high-performance engines (20 BMEP), leading to the consequent issue of abatement of pollutant emissions.

The global push to minimize carbon emissions and the imposition of more rigorous regulations on emissions are driving an increased exploration of cleaner powertrains for transportation. Hydrogen fuel applications in internal combustion engines are gaining prominence due to their zero carbon emissions and favorable combustion characteristics, particularly in terms of thermal efficiency. However, conventional Spark-Ignition (SI) engines are facing challenges in meeting performance expectations while complying with strict pollutant-emission regulations. These challenges arise from the engine's difficulty in handling advanced combustion strategies, such as lean mixtures, attributed to factors like low ignition energy and abnormal combustion events. To address these issues, the Barrier Discharge Igniter (BDI) stands out for its capability to generate non-equilibrium Low-Temperature Plasma (LTP), a strong promoter of ignition through kinetic, thermal, and transport effects.

In a context of growing concern for vehicle-related CO2 and pollutant emissions, non-conventional fuels like methanol (CH3OH) represent a valid alternative to fossil fuels to decarbonize the transport sector in a reasonable time. This is mainly due to its lower carbon content than conventional gasoline and diesel. Moreover, methanol can be obtained either from biomass or CO2 capture from the atmosphere, which makes the latter a renewable fuel. Given the possibility of being stored in liquid phase at standard temperature and pressure (STP), methanol is very suitable for Light Duty Vehicles (LDVs), in which the need to contain fuel tank dimensions is relevant. Regarding the deployment of methanol as a fuel, it is not very challenging, as it can be adopted in current production Internal Combustion Engines (ICEs) either in pure form or in blend with other fuels without any significant modifications.

The research for sustainable alternative fuels for combustion engines was driven by the urgency to meet future emission regulation norms and mitigate climate change and dependency on fossil fuels. In this context, methanol emerges as a promising candidate due to its potential for greenhouse gas-neutral production methods and its advantageous characteristics for employment in SI engines. Adverse effects, such as elevated emissions due to incomplete combustion along with liner impingement and oil dilution as a consequence of the high injected fuel mass and the large enthalpy of vaporization, can be improved by a dual injection concept. The tests were conducted on a single-cylinder research engine derived from a common passenger vehicle engine. The exhaust gas composition was measured with an FTIR-analyzer employing a methanol-specific evaluation method, standard exhaust gas analyzers, and a solid particle counter system with 10 and 23 μm cut-off sizes.

Hydrogen-powered mobility is believed to be crucial in the future, as hydrogen constitutes a promising solution to make up for the non-programmable character of the renewable energy sources. In this context, the hydrogen-fueled internal combustion engine represents one of the suitable technical solution for the future sustainable mobility. In a short-term perspective, the development of the green hydrogen production capability and distribution infrastructure do not allow a substantial penetration of pure hydrogen IC engines. For this reason, natural gas – hydrogen blends can represent a first significant step towards decarbonization, also determining a trigger effect on the hydrogen market development. The present paper is focused on the analysis of the combustion and performance characteristics of a production PFI natural gas engine, run on blends with 15% in volume of hydrogen (HCNG).

Brake caliper commonly utilizes rubber or spring components to maintain specific clearance range for sliding characteristics, rendering them susceptible to rattle noise. The Electro-Mechanical Brake (EMB) caliper has attracted attention for its advantageous features such as reduced brake drag, optimized vehicle layout, and precise brake control. However, the inclusion of additional components related to the dry-type pressurizing system results in increased caliper weight and susceptibility to rattle noise. This study thoroughly examines rattle noise characteristics in our prototype EMB caliper, identifying primary noise sources on the piston and guide-pin sides. Implementing piston seals and guide-pin boots tightening force proves the effectiveness in improving rattle noise characteristics. Collisions between the piston and ball-screw head can be mitigated by piston inner seal, significantly reducing rattle noise.

Vibrations in IC engines have a widespread effect on the operations of consumer and commercial vehicles, which not only affect the life and efficiency of the vehicle but also affect user comfort and nervous system of human body. This paper focuses on the comparative analysis of vibration and acoustic characteristics while utilizing fuels such as petrol and CNG. ADXL 335 3-axis accelerometer was employed to measure acceleration vs time data, which was then processed using MATLAB to obtain FFT and PSD plots. These plots thus obtained gave insights on dominating frequency as well as frequencies with maximum energy. Six different cases with different engine speeds and loading conditions are studied with analysis of all the different parameters such as sound pressure levels and mean and max cylinder pressure.

The fast acceleration of GHG (CO2 in particular) emitted by human activities into the atmosphere is accelerating the average temperature increase of our globe causing heavy climate change. This phenomenon has triggered a strong pressure on GHG emission reduction in all the human activities including the transportation sector which contributes for the 29% to the total emissions in EU [1]. A mitigation to this tendency can come from synthetic fuels: when produced by using clean energy, they can be considered CO2 neutral. H2 is the building block of synthetic fuels and can be used in spark ignited engines where releases the energy accumulated during its production. This solution is particularly attractive for HD applications thanks to the high energy density. H2 can be burned in a quite wide range of λ, but staying on 2,2 the amount of engine out NOx will be low enough for the use on a 13L engine with a relatively simple aftertreatment system.

Nowadays, green hydrogen can play a crucial role in a successful clean energy transition, thus reaching net zero emissions in the transport sector. Moreover, hydrogen exploitation in internal combustion engines is favored by its suitable combustion properties and quasi-zero pollutant emissions. High flame speeds enable a lean combustion approach, which provides high efficiency and reduces NOx emissions. However, high airflow rates are required to achieve the load levels typical of heavy-duty applications. In this framework, the present study aims at investigating the required boosting system of a 6-cylinder, 13-litre heavy-duty spark ignition engine through 1D numerical simulation. A comparison among various architectures of the turbocharging system and the size of each component is presented, thus highlighting the limitations and potentialities of each architecture and providing important insights for the selection of the best turbocharging system.

Due to its physical and chemical properties, hydrogen is an attractive fuel for internal combustion engines, providing grounds for studies on hydrogen engines. It is common practice to use a mathematical model for basic engine design and an essential part of this is the simulation of the combustion cycle, which is the subject of the work presented here. One of the most widely used models for describing combustion in gasoline and diesel engines is the Wiebe model. However, for cases of hydrogen combustion in DI engines, which are characterized by mixture stratification and in some cases significant incomplete combustion, practically no data can be found in the literature on the application of the Wiebe model. Based on Wiebe’s formulas, a mathematical model of hydrogen combustion has been developed. The model allows making computations for both DI and PFI hydrogen engines. The parameters of the Wiebe model were assessed for three different engines in a total of 26 operating modes.

Combustion characteristics of a hydrogen (H2) direct-injected (DI) pre-chamber (PC)-assisted opposed piston two-stroke (OP2S) engine are investigated by 3D computational fluid dynamics (CFD) simulations. The architecture of the OP2S engine has potential features for reducing wall heat losses, as the DI H2 jets are not directed towards the piston face. To overcome the high resistance to autoignition of H2, a PC technology was implemented in order to enhance the ignition of the mixture by the multiple hot reactive jets. To further investigate the interaction between the H2 plume and the chamber walls, three different piston bowl designs were evaluated and ranked based on a merit function. For the cases under study, the flat piston design was found to be most favorable (compared to the narrow and wide pistons) due to its reduced surface area for lower wall heat losses.

Heavy duty engines for long-haul trucks are quite difficult to electrify, due to the large amount of energy that should be stored on-board to achieve a range comparable to that of conventional fuels. In particular, this paper considers a stock engine with a displacement of 12.9 L, developed by the manufacturer in two different versions. As a standard diesel, the engine is able to deliver about 420 kW at 1800 rpm, whereas in the compressed natural gas configuration the maximum power output is 330 kW, at the same speed. Three possible alternatives to these fossil fuels are considered in this study: biodiesel (HVOlution by Eni), bio-methane and green hydrogen. While the replacement of diesel and compressed natura gas with biofuels does not need significant hardware modifications, the implementation of a hydrogen spark ignition combustion system requires a deep revision of the engine concept.

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.

Hydrogen engines are currently considered as a viable solution to preserve the internal combustion engine (ICE) as a power unit for vehicle propulsion. In particular, lean-burn gasoline Spark-Ignition (SI) engines have been a major subject of investigations, due to their reduced emission levels and high thermodynamic efficiency. Lean charge is suitable for the purpose of passenger car applications, where the demand of mid/low power output does not require an excessive amount of air to be delivered by the turbocharging unit, but can difficulty be tailored in the field of high performance engine, where the air mass delivered would require oversized turbocharging systems or more complex charging solutions. For this reason, the range of feeding conditions near the stochiometric value is explored in the field of high performance engines, leading to the consequent issue of abatement of pollutant emissions.

This work aims at investigating the optimal configuration of an internal combustion engine fueled with bio-ethanol for improving its brake power and efficiency as well as for reducing the NOx emissions, in stationary applications. A turbocharged spark ignition engine characterized by a single-point injection was preliminarily considered; subsequently, a direct injection configuration was investigated. For both cases, a 1-D numerical model was developed to compare the injection configurations under stoichiometric conditions and different spark timings. The analysis shows that the direct injection guarantees: a limited improvement of brake power and efficiency when the same spark timing is adopted, while NOx emissions increases by 20%; an increase of 6% in brake power and 2 percentage points in brake thermal efficiency by adopting the knock limited spark advance, but an almost double NOx emissions increase.

This study explores the feasibility of using a sustainable lignin-based fuel, consisting of 44 % lignin, 50 % ethanol, and 6 % water, in conventional compression ignition (CI) marine engines. Through experimental evaluations on a modified small-bore CI engine, we identified the primary challenges associated with lignin-based fuel, including engine startup and shutdown issues due to solvent evaporation and lignin solidification inside the fuel system, and deposit formation on cylinder walls leading to piston ring seizure. To address these issues, we developed a fuel switching system transitioning from lignin-based fuel to cleaning fuel with 85 vol% of acetone, 10 vol% of water and 5 vol% of ignition improving additive, effectively preventing system clogs.