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The use of green hydrogen as a fuel is a promising solution for reducing greenhouse gas emissions from our current fleet of petrol-fueled vehicles. However, achieving zero emissions remains a challenge due to the higher relative air-to-fuel ratio (lambda) required to avoid NOx formation during periods of increased load demand. On the other hand, the capability of hydrogen combustion to use a lean mixture with lower combustion variability presents a great advantage. In such cases, thermal efficiency can be improved by reducing pumping work through leaning the mixture and dethrottling to maintain the same load. This study investigates the efficiency and combustion parameters of hydrogen spark ignition operation while maintaining a constant load at several intake pressure conditions. Tests were conducted on a Ricardo Proteus spark ignition single-cylinder research engine to evaluate the impact of throttle aperture on pumping work and combustion parameters.

The increasingly strict environmental legislations require the use of strategies and technologies to achieve higher efficiencies in internal combustion engines (ICE). In Brazil, governmental programs as Rota 2030 stimulate the development of technologies to improve engine efficiency and therefore promote fleet decarbonization. Due to lower carbon footprint, the use of renewable fuels as ethanol is an effective way to reduce greenhouse gas emissions. Nowadays, direct injection (DI) and variable valve timing (VVT) technologies are also used in modern downsized engines to reach higher thermal efficiencies with advanced strategies operation. As a significant part of energy losses in a spark ignition (SI) engine is caused by pumping work due to the method used for load control, operation in lean conditions have the potential to increase engine efficiency due to less pumping work requirement.

Due to the large negative impact of combustion gas emissions on air quality and the more stringent environmental legislation, research on internal combustion engines (ICE) are being developed to reduce emissions of pollutant gases to the atmosphere. One of the research fronts is the use of lean mixtures with the pre-chamber ignition system (PCIS). This system consists of a pre-chamber (PC) connected to the main chamber by one or more interconnecting holes. A spark plug initiates combustion of the mixture present in the pre-chamber, which is propagated as gas jet into the main chamber, igniting the lean mixture present therein. The gas jets have high thermal and kinetic energy, which promote faster combustion duration, making the system less prone to knock and with lower cyclic variability of the IMEP, enabling the lean limit extension. The pre-chamber system can be assisted with a supplementary liquid or gaseous fuel injection, enabling the charge stratification.

Atmospheric pollution is the major public health issue in many cities around the world. Internal combustion engines (ICE) and industries are common sources of pollutants that aggravate this situation. Aiming to overcome this problem, increasingly restrictive legislation on combustion pollutant emissions has been formulated and new technologies are being developed to ensure compliance with such restrictions. In this scenario, the lean mixtures appear as a possible alternative, but also bring some inconveniences such as combustion instabilities. Pre-chamber ignition systems (PCIS) enable a more stable combustion process due to high kinetic, thermal and chemical energy of the gases from the pre-chamber (PC), which pass through nozzles and begin the combustion process of the air-fuel mixture contained in the main combustion chamber (MC). However, some challenges still have to be overcome in the development of these systems, one of the main ones being hydrocarbon (HC) emissions.

Environmental policies and fuel costs have driven the development of new technologies for internal combustion engines. In this sense, the use of mixtures with small portions of fuel allows lower fuel consumption and pollutants emissions, emerging as a promising strategy. Despite the advantages, lean burn requires a larger energy source to provide satisfactory flame propagation speed and consequently a stable combustion. The use of pre-chamber ignition systems (PCIS) has been used in SI engines to assist the start of combustion of lean mixtures, in which a supplementary fuel system can stratify the amount of either liquid or gaseous fuels supplied to the pre-chamber. In this context, this paper aims to evaluate combustion characteristics of a commercial engine with the use of stratified PCIS operating with impoverished mixtures of ethanol-air in main-chamber and hydrogen assistance in pre-chamber.

Extensive studies of pre-chamber ignition systems in internal combustion engines have proven its effectiveness in reduction of fuel consumption and improvement in several combustion parameters. Considering the different types of pre-chamber configurations, this paper aims to compare the combustion in a SI engine with both homogeneous and stratified pre-chamber ignition systems. To achieve this objective a system with the ability to control the hydrogen injection in the pre-chamber was built. This system was installed in a multi-cylinder Ford Sigma 1.6L engine and tested in a dynamometric room. Tests consisted in imposing a constant rotation and IMEP to test three conditions: standard spark ignition, pre-chamber ignition system without fuel injection (homogenous) and with hydrogen injection (stratified). It was possible to identify that with the use of pre-chamber ignition system there is a reduction in specific fuel consumption and in the combustion duration.

Environmental issues and energy security are critical concerns of the most countries. According researchers, excessive growth of land vehicles is one of the biggest contributors to global air pollution and oil reserves reduction. In this context, the use of lean burn technologies emerges as a promising strategy, allowing lower fuel consumption and pollutants emissions. Present work aims to analyze the behavior of a current commercial engine, gasoline fueled, varying the air-fuel ratio without the use of lean burn ignitions technologies. Analysis was performed through bench dynamometer tests, evaluating cylinder pressure, exhaust gas temperature, fuel conversion efficiency, cycle thermal efficiency, coefficient of variation in indicated mean effective pressure, apparent heat release rate, flame development angle and burn duration.

Reducing environmental pollution by the transport sector has been influenced according to the increasingly restrictions imposed by regulatory standards. For this, legislation such as Euro (at global level) and Proconve (at local level) set new limits each new phase, usually stipulating reductions in the levels of greenhouse gas emissions. Compliance with these requirements is seen with the vehicle or engine ratings working through the conditions imposed by a standard test cycle. However, standard driving conditions often do not represent the real-world driving conditions, being influenced by relief, traffic lights and other peculiarities of each city or route. This paper aims to compare real-world driving cycles of urban bus and passenger car in the city of Santa Maria, in southern Brazil, with the conditions used for light gasoline vehicles and heavy diesel vehicles approval.

In order to improve urban air quality and to meet legislation requirements, vehicular technology is constantly advancing. It focuses on techniques that reduce fuel consumption and emissions of greenhouse gases as well as harmful pollutant emissions. The technologies, however, have different impacts depending on the city, its traffic conditions and urban planning as well as other socioeconomic and cultural factors that affect the driving stile. Thus, standard drive cycles such as NEDC, FTP75 and HWFET may not represent properly the actual condition and are being progressively replaced by real-world driving cycles. This paper aims to analyze real-world driving conditions in the city of Santa Maria, in southern Brazil, in respect to emissions and fuel consumption. Computer models were used to establish a comparison between standard conditions and real conditions, acquired experimentally by a family car.

The ever increasing pressure for more efficient engines, with lower production cost and time has led to the development of advanced simulation tools. Likewise, the experimental development of combustion systems has benefited from computational tools while reducing the necessary experimental time. This paper describes the analysis of combustion performance of a Diesel engine normally used on generator sets. A detailed heat release analysis is performed through one-dimensional simulation software and experimental results, enabling a comprehensive description of combustion parameters of the engine through a simplified study. Brake and indicated values were obtained and analyzed to point out efficiency maps and show the effectiveness of the simulation tool in engine and combustion systems development.