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This work describes an updated cold start system for ethanol fuelled engines using an electronic gasoline injector. The new system is a substitute to the conventional cold start system that employs a calibrated hole for gasoline introduction in the intake pipe. The new system is constituted by a gasoline reservoir, electrical fuel pump, fuel injector, fuel filter, and solenoid valve frequency controller. Experiments have been carried out in a production 1.0-liter, four-cylinder, ethanol-fuelled engine, submitted to transient emissions tests after cold start. The results show that the updated system reduces the cold start period by 31% in comparison to the conventional system. Acceleration after cold start was also improved, with gasoline consumption reduction of 67%.

The intake valves of a 1.0 liter, 16-valve production engine has been phase shifted to increase the intake air charge, aiming at improved performance. The engine has been tested in a dynamometer bench to verify the performance attained with the modification and its influence on raw exhaust emissions. Total hydrocarbons, carbon monoxide, nitric oxide and oxides of nitrogen emissions were analyzed for varying load and engine speed. The results have shown that shifting the valves of a dual intake valves engine can provide increased performance, while keeping emissions at acceptable levels.

The piston and intake valves alternate movements produce pressure waves that propagate throughout the intake conduit. Such waves can adequately increase the intake air mass charge to the engine cylinders. In the present work an experimental study on the engine intake valves phase shift was carried out with the objective to analyze its influence on the intake air mass charge. A production 1.0-liter, 16-valve engine was used, with two intake valves per cylinder. Preliminary tests were conducted in a flow bench, simulating the engine intake air flow conditions, and, then, the engine was tested in a dynamometer bench. The results in the flow bench showed that the intake air mass charge is increased up to a phase shift angle of about 30 degrees. From the tests conducted in the dynamometer tests, results are shown for a phase shift angle of 7.5 degrees, with one of the intake valves opening late with respect to the original opening angle.

This work presents an optimized model that calculates the rate of formation of oxides of nitrogen in spark-ignited internal combustion engines. Model optimization was done by establishment of a correlation between the fuel-air mixture equivalence ratio and the first rate reaction constant of the Zeldovich's mechanism, which describes the kinetics of formation of nitric oxide. The calculated values by the model were compared to experimental data available from a single-cylinder engine, featuring a disc type combustion chamber, for variations of fuel-air mixture equivalence ratio. When the mixture equivalence ratio was varied, the optimized model produced calculated values much closer to the experimental results than the previous model, especially in the lean mixture region and in the peak region near to stoichiometry.

This work has as an objective the development of a numerical model to calculate the kinetic formation rate of carbon monoxide in spark-ignited internal combustion engines. The model is added to a computer program that simulates the cycle of spark ignition engines, to calculate the exhaust concentration of carbon monoxide emissions. The model is validated through experimental data from a single-cylinder research engine. Comparisons with calculated equilibrium concentration of carbon monoxide confirm that this pollutant should be modeled according to the theory of kinetic formation, for a better approach to exhaust measured values.

Four samples of three different types of gasoline found in Brazil were tested to verify their aging effects on engine performance and exhaust emissions: two samples of regular gasoline, one sample of regular gasoline plus additives, and one sample of premium gasoline. The regular gasoline is the most commonly used automotive fuel in Brazil; regular plus additives contains an improved detergent capacity; and premium is a gasoline of higher octane number. All these types of gasoline are, in fact, a blend of approximately 75% gasoline and 25% ethanol, with the ethanol having an anti-knocking function. The gasoline samples were tested in a total period of six months, using a production 1.3-liter, four-cylinder, sixteen-valve engine mounted on a bench test dynamometer. Performance parameters and exhaust emissions levels were obtained for engine speeds of 1000 to 6000 rev/min. The general test results point to an increase in HC and CO emissions and in fuel consumption with fuel aging.

The gasoline injection system used as an auxiliary during cold start of ethanol-fuelled engines has been improved to reduce exhaust emissions levels. In substitution to the conventional system, which introduces gasoline in the throttle body through a calibrated pipe in a hole, an electronic fuel injector and other peripheral components have been used to inject gasoline. Experiments were carried out in an ethanol-fuelled vehicle powered by a 1.0 liter engine to measure regulated exhaust pollutant gases concentrations, to compare the modified system to the conventional one. The tests were according to FTP-75 test cycle, which simulates a typical urban travel including cold start and acceleration during warm-up. The results showed that the concentrations of aldehyde, hydrocarbon, carbon monoxide and oxides of nitrogen emissions were simultaneously reduced when the modified system was used.

Experiments were carried out in an ethanol-fuelled vehicle powered by a 1.0 liter engine to measure exhaust aldehyde and other pollutant gases, hydrocarbons, carbon monoxide, oxides of nitrogen and carbon dioxide, as a function of some engine geometric parameters. The varied parameters were intake and exhaust valve timing, compression ratio and spark plug gap. The tests were developed according to a standard test cycle of 5.8 km, simulating a typical urban travel with an already warmed engine. The results showed the that higher compression ratios can simultaneously reduce aldehyde, carbon monoxide and hydrocarbon emissions, while keeping the level of oxides of nitrogen emissions.

Ethanol has been adopted as an alternative fuel to gasoline, especially in the Brazilian automotive market. The chemical properties of this fuel imposes difficulties for cold start and operation during the warm up period. To minimize this problem, up to the present ethanol–fuelled vehicles are equipped with a reservoir of gasoline, which is injected in small percentages in the cylinder at the start–up of the engine. This solution is not seen as a definitive one, because of the extra cost of the gasoline system, and because the results obtained are not entirely convincing. In this work MTBE (Methyl–t–butyl–ether) has been tested as an additive to ethanol to improve its cold start characteristics. Results have shown immediate start of the engine at temperatures as low as –6 degrees centigrade. Emissions levels for exhaust hydrocarbons, oxides of nitrogen and aldehydes were reduced, while carbon monoxide showed an increase for the ethanol–MTBE blend, when compared to pure ethanol.