• Stable engine operation was achieved with 20% water-in-ethanol (v/v) and 40% residual gas fraction; • Negative valve overlap provided hot residual gas trapping and increased indicated efficiency; • Higher combustion efficiency was achieved with intermediate RGF between 25-30%; • Water dilution was more effective in reducing NOx emissions than residual gas trapping;

RESUMO O Brasil, terceiro maior produtor de biodiesel do mundo e terceiro maior produtor mundial de frango, pode incrementar, na sua matriz energética, o uso de óleo oriundo de aves como alternativa aos combustíveis fósseis e à redução INTRODUÇÃONo Brasil, os combustíveis líquidos representam quase 60% da matriz energética e, destes, 45% são consumidos na forma de óleo diesel (ANP, 2010). Desde 2005, o país fomenta a inclusão gradativa de combustíveis alternativos ao óleo diesel, com ênfase a óleos e gorduras vegetais e animais. Denomina-se biodiesel o combustível renovável e biodegradável, constituído de uma mistura de ésteres metílicos ou

Fuel consumption standards imposed in several countries for the next years have prompted the development of hybrid passenger cars with ever smaller internal combustion engines. In such powertrain, fuel consumption is as important as engine packaging and power density, so two-stroke engines may be an option due to their higher combustion frequency compared to four-stroke engines. Therefore, the present research investigates the air-fuel charging process of an overhead four-valve direct injection supercharged engine operating in the two-stroke cycle. The optimum start of fuel injection was evaluated for commercial gasoline by means of indicated and combustion efficiencies where a trade-off was found between early and late fuel injections. By advancing the injection timing, more fuel was prone to short circuit to the exhaust during the valve overlap, while late injections resulted in poor charge preparation. The gas exchange parameters, i.e. charging and trapping efficiencies, were obtained from seventy operating points running at fuel-rich conditions. The Benson-Brandham mixing-displacement scavenging model was then fit to the experimental data with a coefficient of determination better than 0.95. With such model, the air trapping and charging efficiencies could be estimated solely based on the scavenge ratio and exhaust lambda, regardless of the engine load, speed, or air/fuel ratio employed. Further twenty-five different lean-burn testing points were tested to certify the proposed methodology applied to the poppet valve two-stroke engine. The in-cylinder lambda was calculated and found different from the exhaust lambda due to mixing between burned gases and intake air during the scavenging process.

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IIPerformance of preheated crude soybean oil-diesel blends as fuel in agricultural engines RESUMO O óleo de soja é um dos óleos vegetais que têm potencial de uso como combustível para motores diesel INTRODUÇÃOA constante incógnita relacionada ao futuro dos combustíveis derivados de petróleo e a necessidade sempre presente de redução das emissões de contaminantes atmosféricos faz com que a substituição do óleo diesel convencional e da gasolina seja sempre orientada, em diferentes locais, pela busca de alternativas oriundas da biomassa. O ramo da agricultura que objetiva a produção e o aproveitamento da biomassa para fins energéticos denomina-se "agroenergética" (GONZÁLEZ, 1994). Segundo DELGADO (1994), essa é a alternativa mais viável pois o seu importante produto -a energia -é o único com demanda ilimitada. Potencializados como a melhor alternativa ao óleo diesel em motores de ignição por

RESUMO: A previsível escassez de petróleo aliada a uma consciência ecológica está levando pesquisadores a procurar novas fontes de energia e processos de combustão mais eficientes e menos poluentes. Entre os combustíveis menos poluentes está o gás natural, cujo consumo aumenta ano a ano. Os motores de combustão interna são transformadores de energia que têm baixa eficiência de conversão. Este trabalho avaliou um motor Diesel, bicombustível, movido a Diesel e gás natural. Nesse motor, a energia provém, basicamente, da combustão do gás natural. O Diesel tem a função de produzir o início da combustão do gás, que é o combustível principal. Assim, haverá uma substituição parcial de óleo Diesel por gás natural, aumentando o rendimento da combustão. Inicialmente, foi feito um ensaio-testemunha, somente com óleo Diesel e após foram feitos ensaios, com três repetições, para variadas proporções de óleo Diesel, gás natural e ângulos de avanço da injeção. O melhor desempenho foi obtido para 22% de óleo Diesel em relação ao máximo débito da bomba injetora e 13 L min -1 de gás natural com ângulo de avanço de injeção original (21º). Nesse caso, a potência média aumentou 14%, e o consumo específico (medido em valores monetários) diminuiu 46% em relação ao ensaiotestemunha.PALAVRAS-CHAVE: motor bicombustível, motor Diesel, gás natural. SUMMARY:The foresight of a petroleum shortage and an ecological conscience is moving scientists to look for new sources of energy and to develop more efficient combustion processes and reduced emissions. Natural gas is a reduced emission fuel, whose consumption increases every year. The present work evaluates a dual fuel compression ignition engine. The major portion of the fuel burned is natural gas. The Diesel fuel acts as combustion starter, which ignites under the compression heat. Diesel fuel is used only as an ignition source. The partial substitution of Diesel fuel by natural gas increases the combustion efficiency and achieves significant emission reduction, because the combustion of natural gas produces less emission than the combustion of Diesel fuel. Initially, it was made a reference test using only Diesel fuel for comparison with following tests. There were made tests with varied proportions of Diesel fuel and natural gas, and with variable injection angles. There were made three repetitions for each test, including the reference test. The best performance was obtained with 22% of Diesel fuel and 13 L min -1 of natural gas, and with the engine original injection angle (21º). In this case, the average power was 14% above the standard engine and the cost of consumption was 46% lower than the reference test.

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