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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.

The new trends of the automotive market require the development of a new concept of engines using different types of fuel, mainly those resulting from alternative sources of energy. For this purpose those multi-fuel engines must function with higher energy efficiency therefore allowing for lower fuel consumption and a drastic reduction of exhaust emission. The multi-fuel engines available in the market display only one volumetric compression ratio, which leaves ample room for the development of a better level of fuel energy use. To achieve so, such an engine must count on a variable volumetric compression ratio, which, despite being technically possible, is not economically viable for a low cost product. The present project intends to create a system capable of achieving the best performance for all types of fuel through the variation of the boost pressure, viable for a low cost product, without changing its volumetric compression ratio.

Global climate change and an increasing energy demand are driving the scientific community to further advance internal combustion engine technology. Invented by Sr. Henry Ricardo in 1918 the torch ignition system was able to significantly decrease engine’s fuel consumption and emission levels. Since the late 70s, soon after the Compound Vortex Controlled Combustion (CVCC) created by Honda, the torch ignition system R&D almost ceased due to the issues encountered by very complex and costly mechanic control systems that time. This work presents a stratified torch ignition prototype endowed with a sophisticated electronic control systems and components such as electro-injectors from direct injection systems placed on the pre-combustion chamber. The torch ignition prototype was tested and its performance are presented and compared with the baseline engine, which was used as a workhorse for the prototype engine construction.

The analysis of the air motion inside the cylinders of an internal combustion engine constitutes a very important step during engines design. It is already known that its movement, normally decomposed in tumble and swirl motion, is totally related to the majority of phenomena which occur inside cylinder, like fuel evaporation, mixture formation or flame propagation. The use of mechanical devices in the intake system represents an interesting option in the attempt of optimizing the airflow and finding the best condition for maximum power and minimum specific fuel consumption. Devices like flow boxes, which control the airflow and change its main characteristics before entering the cylinder, by obstructing the air and changing its directions, are one possibility. Based on this idea, this paper presents a numerical analysis of the utilization of a flow box in the intake system of a spark ignition engine.

This paper describes a reverse engineering methodology to obtain a three-dimensional (3D) model of an internal geometry of an engine adapted with a torch ignition system. The reverse engineering methodology began with the measurement of the internal geometry from the cylinder head using silicon. Then, the obtained silicone molds were analyzed in a 3D scanner obtaining a cloud of points which was then treated in a commercial CAD software in order to generate de 3D computer model. The virtual geometry obtained was used to run CFD simulations with the torch ignition system. In order to increase the reliability of the results, a comparison between the pressures in the cylinder obtained numerically and experimentally were made. The same procedure was made in the pre-chamber, thus validating the model.

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.

In Brazil, in the last few years, there has been a tendency to the use of alternative fuels. One of them is Compressed Natural Gas (CNG) and it is used due to its low cost, low fuel consumption and available technology. An originally gasoline or alcohol fuel engine can be also fuelled by CNG with some modifications, turning it into a multi-fuel engine. Commonly, however, the original compression ratio is unchanged, not allowing to explore CNG higher resistance to knock. This work aims at obtaining and analyzing the 1.3-L 8v FIRE FLEX engine performance curves for different compression ratios. A 5th generation BRC CNG multi-point fuel injection system is used for 11:1, 12,5:1 and 15:1 compression ratios and a development engine control unit and its calibration software were used to perform the system electronic management.

In this work an analysis of the performance of a multi-fuel engine fuelled allowing for the concentration of alcohol in gasoline and the use of CNG. The engine used was a four cylinder, 1.242-L, multi-fuel engine in full load, respecting the air/fuel rate established by the manufactures in the engine original calibration. A CNG BRC 5th generation multi-point fuel injection system was installed in order to run with CNG. The calibration and adjustments were made using a development engine control unit for the different fuels. This work presents a comparison among the performance curves aiming to obtain the best relation among torque, power and specific fuel consumption for the various proposed configurations.

This work presents an analysis of the performance of a multi-fuel engine fuelled by gasoline, alcohol, a mixture of gasoline and alcohol and CNG. The tests are made using a four cylinder, 1.242-L, multi-fuel engine in full load, respecting the air/fuel rate established by the manufactures in the engine original calibration. In order to run with CNG, it was installed a BRC 5th generation multi-point fuel injection system. The calibration and adjustments were made using a development engine control unit for the different fuels. In this work, the performance curves are compared aiming to obtain the best relation among torque, power and specific fuel consumption for the various proposed configurations.

Electronic management system applied to Automotive Engineering is able to optimize the operation parameters for an Internal Combustion Engine (ICE) increasing their efficiency. The development of those systems is a multidisciplinary task that involves specialists from different areas that use, among other resources, high performance digital computers. The objective of this work is to present the implementation of a new variable control system of spark time ignition, controlled by computer, that uses a Digital Signal Processor (DSP) to optimize the spark advance curves of ICE's during the development in engine test bed. This work presents the implementation of the variable spark time ignition system and the comparative results, obtained during the development tests in dynamometer, between the implemented system and the original engine management used in the tests.

This work presents an experimental procedure to find the best operating point for a spark ignition engine controlled by a general Engine Management System. The ECU control allows changing the ignition and fuel injection timing as a function of load and rotational speed, beyond configuring the whole system according to the sensors and actuators types. The ignition dwell time and the best moment to start the injection fuel can be controlled accurately by this system. In addition, this electronic system allows adjustments in real time with engine installed onto a dynamometric test stand. This work describes the experimental apparatus, sensors characteristics used and also the methodology to accomplish the adjustments in the ECU maps, seeking to obtain the best performance. Comparison performance data for the standard engine and the proposed configuration are presented here, showing a 50% gain for a spark ignition engine of 1300 cm3, four cylinders in line, and 16 valves.

The work evaluates as the adaptation of a torch-ignition system, without charge stratification, in an Otto cycle engine alters the acting curves and also its level of emissions in relation to the motor with original ignition system. For this, based on the literature, three combustion prechamber geometries are projected, built and adapted to a engine FIAT 1581 cm3, 4 cylinders, 16 valves modified previously for operation in a cylinder end with development ECU. After accomplishment of the tests it was verified losses in performance and gain in the emissions of CO and CO2 in comparison with the engine using original ignition system.

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.

The pollutants emitted by fuel burn in an internal combustion engine are harmful to humankind health. One of undesirable pollutants are the nitrogen oxides (NOx), witch in the presence of sunlight is responsible by photochemical mist, forming products that irritates eyes, respiratory system and may damage plants. The present article aims to present the theoretical potential reduction in volumetric emissions of nitrogen oxides (NOx) in an internal combustion engine operating with the torch ignition system and homogeneous charge. Therefore, a calculation methodology based in measured pressures and determined temperatures were implemented to check the potential reduction in these pollutant emissions. The presented methodology used to estimate the NOx formation is based in NO formation model presented by [1].

The use of torch ignition systems in spark-ignition engines represents an interesting option in the efforts to reduce pollutants emission and specific fuel consumption. Based on this idea, this paper presents a 3D model of a prechamber created for a spark-ignition engine and focuses on the numerical analysis of the fluid flow inside the modified chamber. This kind of analysis is very important once it allowed evaluating aspects like turbulence parameters, pressure inside the chamber and prechamber, fluid recirculation and a possible prechamber’s geometry for the engine. The studies were done in a four valve Single Cylinder Research Engine - SCRE. For the numerical modeling and fluid flow investigation it was used STAR-CD Software. The numerical results permitted to characterize the fluid flow in the modified engine and compare it with the standard engine, which showed significant differences and an interesting potential.

Direct inject engine provides increased possibilities to work with injection strategies in order to achieve better efficiency. Some ethanol properties such as the higher octane number, the latent heat of vaporization as well as the faster laminar speed made ethanol one of the most promising biofuels. These properties help to achieve knock suppression in a SI engine and therefore allow the use of higher volumetric compression ratio, which is one of the key factors in efficiency improvement. Several studies have showed ethanol as a way to reduce soot formation in direct injection engines as the oxygen molecule reduces the locally fuel-rich region. The use of ethanol contributes significantly to the reduction of total hydrocarbon (THC) and carbon monoxide (CO).