Andre Valente Bueno

Effect of soybean oil ethyl ester/diesel fuel blends on engine efficiency

Variation of engine thermal efficiency in response to the addition of soybean oil ethyl ester to diesel fuel was analysed in terms of the in-cylinder phenomena and fuel properties. Blends with concentrations of up to 30% of soybean oil ethyl ester in volume were used in steady-state experiments conducted in a high speed turbocharged direct injection engine. Engine internal processes were studied by means of exergy balances based on engine indicating data, which provided information about the impact of biodiesel blending on the amount of fuel exergy exchanged through heat, work and mass transfer. The data obtained from this exergy analysis served to identify the causes of the alterations in brake thermal efficiency measured in dynamometric bench tests. Operating in full load conditions and fuelled with the B20 blend, the engine showed an average increase of 4.16% in brake thermal efficiency and a gross increase of 4.24% in indicated thermal efficiency in relation to its performance with mineral diesel fuel.

Performance impact of the application of castor oil biodiesel in diesel engines.

The use of renewable fuels, such as the biodiesel, can ease the demand of fossil fuel for the power generation and transportation fields in rural area. In this work, the performance impact of the application of castor oil biodiesel is evaluated with an automotive and a stationary diesel engine. The application of B20 and B10 biodiesel blends and pre-heated net biodiesel is considered. The viability of the employment of B10 and B20 blends to mobility and power generation was observed from dynamometric bench tests, where this blends performed similar to fossil diesel. With the pre-heated net biodiesel, however, a brake torque loss and a specific consumption increase were observed with relation to diesel fuel.

Energetic efficiency of an agricultural tractor in function of tire inflation pressure

The tire inflation pressure, among other factors, determines the efficiency in which a tractor can exert traction. It was studied the effect of using two tire inflation pressures, 110.4 kPa in the front and rear wheels, 124.2 kPa in the front wheel and 138 kPa in the rear wheels, the energetic efficiency of an agricultural tractor of 147 kW of engine power, in the displacement speed of 6.0 km.h-1, on track with firm surface, with the tractor engine speed of 2000 rpm. For each condition of the tire pressure, the tested tractor was subjected to constant forces in the drawbar of 45 kN and 50 kN, covering 30 meters. It was used a randomized complete block with a 2x2 factorial arrangement (tire pressure and drawbar power) with four replications, totaling 16 experimental units. Data were subjected to analysis of variance, using the Tukey test at 5% probability for comparison averages. The lowest hourly and specific fuel consumption, the lowest slippage of the wheelsets and the highest efficiency in the drawbar was obtained with the tire inflation pressure of 110.4 kPa in the front and rear tires of the tractor, highlighting that lower pressures improve energetic and operational performance of the tractor.

Internal Combustion Engine Indicating Measurements

In engine combustion diagnosis, the apparent heat release rate and the combustion reaction extent are the most useful quantities obtainable from engine indicating data. The apparent heat release rate is calculated by computing the amount of fuel chemical energy release necessary to obtain the experimentally observed pressure, while the combustion reaction extent is evaluated through the released fraction of the total fuel chemical energy. Heat release analysis is often complemented using optical techniques and its utilization as a diagnostic tool covers a wide range of objectives, including the development of new combustion systems, the analysis of alternative fuel burning, the validation of mathematical models for engine simulation, the investigation of combustion chamber insulation effects and the study of new injection strategies.