EM - Escola de Minas

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Experimental analysis between performance parameters for an internal combustion engine fueled by gasoline and ethanol when submitted to engine block vibration.
(2022) Santana, Cláudio Márcio; Barros, José Eduardo Mautone; Almeida Junior, Helder Alves de
Ethanol and gasoline are widely used as fuels in Otto cycle engines. These fuels have diferent heating power and octane numbers and the engine behaves diferently depending on the type of fuel used. The objective of this study is to measure, compare and investigate the factors that afect the block vibration of an internal combustion engine, which uses ethanol or gasoline as its fuel, as a function of shaft torque and shaft power engine, main efective pressure, advanced ignition, pressure combustion engine and other parameters. The experiment consisted of instrumenting the side of the engine block with a triaxil accelerometer to measure the level of the vibration acceleration value of the engine running on a bench dynamometer, while varying the engine speed under full load conditions. The results showed that the engine vibration level was infuenced by engine speed, load, type of fuel and performance parameters of the engine. The highest level of vibration was noted in the region of maximum torque and maximum pressure combustion. The combustion process is primarily responsible for the highest level of vibration reached when using ethanol as a fuel. Under all operating conditions, the vibration level of the engine block was highest when using ethanol. On average, the longitudinal, vertical and transverse engine vibration was 3%, 31% and 56% higher in the engine running on ethanol compared to the engine run on gasoline. This study holds relevance as it correlates the longitudinal, vertical and transverse vibration level of the block of an internal combustion engine, as is found in an engine combustion process fueled by ethanol and gasoline.
Corrosion behavior of low carbon steel processed by ECAP in neutral and alkaline environment.
(2021) Braga, Jorgimara de Oliveira; Lins, Jefferson Fabricio; Castro, Gabriel Pessoa de; Almeida Junior, Helder Alves de; Santos, Igor Cuzzuol dos; Sousa, Gustavo Henrique; Criscuolo, Izabel Lima; Santana, Cláudio Márcio; Pereira, Ursula Cid
The purpose of this study was to evaluate the corrosion behavior of 1010 steel processed by Equal Channel Angular Pressing (ECAP), a technique that induces severe plastic deformation (SPD) in materials. The samples were processed by one and two passes of ECAP throught routes A and C. The corrosion behavior was evaluate using the potentiodynamic polarization and electrochemical impedance spectroscopy, using NaCl (pH= 6.5) and sodium hydroxide/sodium phosphate (pH= 10.5) solutions. The polarization tests showed better performance for the samples processed by ECAP than in the as cast samples both in alkaline and neutral solutions. The results showed that alkaline solution presented higher corrosion rate for the as cast and one ECAP pass materials. It is seen that samples processed throught routes A and C develop a film stabilization on the surface of these samples. In addition, the values of polarization resistance obtained from the electrochemical impedance spectroscopy in NaCl environment were higher for sample processed in route C.
Measuring and comparing the ignition delay time of the reference diesel, convectional diesel, additive ethanol and biodiesel from soybean oil using a shock tube.
(2020) Santana, Cláudio Márcio; Barros, José Eduardo Mautone; Almeida Junior, Helder Alves de; Braga, Jorgimara de Oliveira; Bosch Neto, Juan Canellas
The objective of this work is to correlate the ignition delay times of reference diesel, convectional diesel, ethanol and biodiesel from soybean oil measured in a shock tube with a 5% additive increase in the cetane number. The results were correlated with the cetane number of the respective fuels and compared with the ignition delay times available in the studies by oth- ers authors. The shock tube is a metal tube in which gas at low pressure and at high pressure is separated by a diaphragm. When the diaphragm breaks in predetermined conditions (high pressure in this case) produces shock waves that move from the high-pressure chamber (known driver section) to the low-pressure chamber (known driven section). The tests were per- formed under the following initial conditions: refected shock wave temperature from 903 to 1260 K, equivalence ratio of 1 and refected shock wave pressures of 24 bar. For determining and recording the ignition delay time, pressure sensors with high acquisition rate and luminosity sensors were used. With information from pressure sensors and the luminosity sensor, ignition delay times of reference diesel, convectional diesel, additive ethanol and biodiesel from soybean oil were recorded. We concluded that the ignition delay time of additive ethanol was twice as large as the ignition delay time of reference diesel. The ignition delay time of biodiesel from soybean oil was approximately three times greater than the ignition delay time of reference diesel. The ignition delay time of the reference diesel was smaller than the convectional diesel. The contribution of this work is that it shows why additive ethanol and pure biodiesel should not be used as substitutes for diesel compression ignition engines without any major changes in the engines. The ignition delay times of these fuels are at least two to three times longer than the ignition delay time of reference diesel.

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