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To attend the new tendencies of the automotive market, new technologies must be used throughout the engine conception. One way of improving the project is to use computational numerical simulation, predicting engine behavior in a wide range of situations. This paper presents a methodology to estimate the engine characteristic parameters necessary to numerical simulation. Morse test was used to determine friction power, mean effective pressure friction and friction torque, considering the engine behavior during cylinder ignition cut-off. In this test all the results were compatible with manufacturer data, which validates the methodology. To define the moment of inertia, it's also proposed a fuel cut methodology, associated with the Morse test, because the torque values measured by dynamometer after the fuel cut did not correspond to the real value. Thus, plausible values of engine moment of inertia, very close to values obtained by software, were obtained.

Combustion images are not simple to be obtained in conventional engines. Therefore, some experimental apparatus, such as a rapid compression machine (RCM), are useful to conduct this kind of study. Imaging techniques allow flame front propagation analysis, which is a very important parameter to understand engine performance, using different fuels and also to generate data to improve fuel modeling in engine simulation softwares. A RCM was adapted to operate in a spark ignition engine mode. It was used to obtain cylinder pressure measurements of gasoline-ethanol combustion synchronized with high-speed photos of flame propagation. Contour plots of the flame front profiles, assumed to be spherical, were used in successive frames to calculate the propagation speeds toward the cylinder walls. So, it was possible to correlate images, pressure curves and flame speeds of gasoline-ethanol blends.

An experimental investigation was performed on an engine dynamometer to study in cylinder pressure curve and combustion parameters variability with ethanol addition. It was used a Flex-Fuel engine, 1.4 L, 4 cylinders, with a programmable engine control unit to optimize the calibration for different blends of Brazilian gasoline and hydrous ethanol. Engine was calibrated for maximum break torque limited by knocking. In-cylinder pressure was measured by using a pressure sensor installed on the spark plug and analyzed by a combustion data system. Combustion duration, mass fraction burned, indicated mean effective pressure (IMEP) and others were calculated based on in-cylinder pressure curve data. The combustion variability was analyzed from 300 recorded engine cycle for each operating condition. Results for some operating conditions indicated that ethanol addition can reduce combustion variability on a non linear pattern.

Rapid Compression Machine (RCM) is an experimental tool developed to study engine combustion parameters. The RCM used is a pneumatically and hydraulically driven device which reproduces a single combustion shot, considering a compression and a partial expansion stroke. This paper describes RCM adaptations made in order to run Otto cycle tests using Brazilian regular gasoline (E25) [1]. These adaptations enable pre-vaporized air-fuel mixture combustion tests, representative of port fuel injection engines, by using a gasoline direct injection (GDI) injector. It is also presented RCM piston displacement and cylinder pressure comparisons to a real engine and RCM comparative results for different spark timings and compression ratios. These results show that RCM reproduced satisfactorily piston displacement and pressure curves during the combustion shots, when compared to real engine curves.

In Brazilian market, Flex-Fuel vehicles represented over 85% of new light-duty vehicles sold in 2010. These vehicles can use gasoline blended with anhydrous ethanol (18 to 25% v/v), 100% of hydrous ethanol (contains from 6,2 to 7,4% w/w of water) or any blend of these fuels. Some studies regarding Flex-Fuel technology are being made in Brazil, but there are not many published information about fuel properties of different ethanol-gasoline blends. Also, it is important to better understand emissions of aldehydes, unburned ethanol and total hydrocarbons of different ethanol blends on gasoline. A Flex-Fuel engine, 1.4 l, 4 cylinders was tested on a dynamometer. A FTIR (Fourier Transform Infrared analyzer) bench measured aldehydes, unburned ethanol and total hydrocarbons. It was used Gasoline with 25% of anhydrous ethanol was used as a reference fuel (E25). E25 was blended with different hydrous ethanol contents such as 30% (H30), 50% (H50), 80% (H80) and 100% (H100).

In Brazilian market, Flex-Fuel vehicles represented over 90% of new light-duty vehicles sold in 2009. These vehicles can use gasoline blended with anhydrous ethanol (20 to 25% v/v), 100% of hydrous ethanol (contains from 6,2 to 7,4% w/w of water) or any blend of these fuels. An experimental investigation was done to study fuel consumption, emissions and in-cylinder pressure data of a Flex-Fuel Otto engine, 1.4 L, 4 cylinders. It used gasoline with 22% of anhydrous ethanol as a reference fuel (E22). E22 was blended with different hydrous ethanol contents such as 50% (H50) and 80% (H80), also a 100% hydrous ethanol H100) was used. The main fuel properties were analyzed as part of this work. To control the engine operation, a programmable ECU (Engine Control Unit) was used, allowing spark timing calibration either for maximum break torque (MBT) or to keep the engine below the knocking limit.

Brazil is known for its long experience on using alternative fuels, mainly ethanol for light duty vehicles. In 2002, it was released the Flexible fuel car that can run with gasohol (gasoline with 22% of ethanol), hydrated ethanol or any blend of these fuels. By the end of 2006, national production of these vehicles represented around 80% of the total. Brazil is also the second world fleet of Natural Gas Vehicles (NGV), with more than 1,4 million light duty converted vehicles. This paper describes the development of a computational thermodynamic model of compression, combustion and expansion processes of gasohol, ethanol and Natural Gas (NG) for the cylinder pressure curve prediction of a Flexible Fuel engine, working with a NG kit installed. The combustion process is modeled using a Wiebe function, which establishes the mass fraction of burned fuel. Convective heat transfer to cylinder walls is estimated with an empirical correlation for heat transfer coefficient determination.

This paper describes the development of a computational thermodynamic model of compression, combustion and expansion processes of gasohol, ethanol and Natural Gas (NG) for the cylinder pressure curve prediction of a Flexible Fuel engine, working with a NG kit installed. The combustion process is modeled using a Wiebe function. Equations for specific heat at constant pressure (Cp) were developed for each fuel for temperatures up to 4000 K. The model output generates the cylinder gas pressure and temperature, work output and heat release profiles as functions of crank angle, allowing studies of engine performance parameters in different working conditions for each fuel. The differences between the experimental and simulation results were lower than 4% for the maximum cylinder pressure value.