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Technical Paper

Computer Simulation of a Flex-Fuel Engine Running on Different Gasoline-Hydrous Ethanol Blends

2012-10-02
2012-36-0487
Nowadays computer simulation is an important tool to support new internal combustion engine projects, but still further studies are necessary for its use in fuel development. In order to study the influence of fuel properties on engine combustion and emission performance, a computer model was designed based on a Flex-Fuel engine geometric data. Model was validated with experimental tests done on an engine dynamometer. A simulation software was used to simulate the experimental conditions, by using Wiebe two zone combustion and Woschni heat transfer models. In-cylinder maximum pressure, IMEP and emission data were calculated for different gasoline-hydrous ethanol blends at 3875 rpm, 60 Nm and 105 Nm. Total hydrocarbons concentration was simulated comparing the experimental data of hydrocarbons added with unburned ethanol emission measured with a FTIR analyzer.
Technical Paper

Diesel Cetane Number Versus Noise Emission

2005-05-11
2005-01-2150
The 2005 Brazilian vehicle noise emission limits, together with the Euro III engine technology necessary to attend these limits, set the scene for this paper. In this context, it is important to evaluate the influence of Diesel cetane number on noise emission from Euro III technology vehicles. The vehicle noise emission tests were performed abroad and also in Brazil according to Brazilian norms NBR 8433/1995 (accelerating noise test) and NBR 9714/2000, (stationary noise test) using Euro III engine technology vehicles. The fuels evaluated were representative of Brazilian production and had cetane numbers varying from 42 to 52. The paper shows that there was no significantly correlation between vehicle noise emission and Diesel cetane number, with the vehicles and fuels used.
Technical Paper

Different Hydrous Ethanol-Gasoline Blends - FTIR Emissions of a Flex-Fuel Engine and Chemical Properties of the Fuels

2011-10-04
2011-36-0080
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).
Technical Paper

Experimental Investigation of Different Hydrous Ethanol-Gasoline Blends on a Flex-Fuel Engine

2010-10-06
2010-36-0469
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.
Technical Paper

Flex Fuel Engine - Influence of Fuel Composition on the CA50 at Maximum Brake Torque Condition

2015-09-22
2015-36-0215
The automotive industry usually adopts the crankshaft angle between 8° and 10° after piston top dead center for the CA50 (crank angle of 50% of mass fraction burned) in order to set the maximum break torque spark timing calibration in Otto cycle engines. There are few studies of the influence of fuel composition, such as the ethanol content, on the CA50 at the maximum torque operating condition. The subject is relevant to the extent that the fuels used in the Brazilian domestic market are different from those usually adopted abroad. The Brazilian gasoline must contain, by law, a volumetric percentage between 18% and 27% of anhydrous ethanol in its composition and, currently, this level is set at 27%. The introduction of flex fuel vehicles in the domestic market in 2003, which now represent most of the new vehicles production in the Country, allowed the use of any blend of national gasoline and hydrous ethanol. This significantly expanded the range of fuel properties variation.
Technical Paper

In Cylinder Pressure Curve Simulation On Multifuel Engines - A Comparison Between A Polytrophic And General Thermodynamic Model For Gasoline, Ethanol And Natural Gas

2007-11-28
2007-01-2820
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.
Technical Paper

In Cylinder Pressure Curve and Combustion Parameters Variability with Ethanol Addition

2012-10-02
2012-36-0486
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.
Technical Paper

Multifuel Engine Performance, Emissions and Combustion Using Anhydrous and Hydrous Ethanol

2012-10-02
2012-36-0475
The increasing ethanol participation in Brazilian fuel market and its supply and price oscillations, motivate studies on multifuel engines behavior with the two specified types of ethanol in Brazil, the anhydrous and the hydrous fuels. The present work includes a comparative engine test bed performance study of a multi-fuel engine equipped with a programmable electronic central unit (ECU), fueled with anhydrous and hydrous ethanol. Fuel properties, engine performance, emissions and combustion parameters are reported using these two fuels for maximum power operating point. The programmable ECU was installed in order to make possible the setting of some parameters that are not accessible in engines operating with commercial ECU. This way, torque was optimized regarding spark timing and air fuel ratio, for all selected fuels and engine conditions tested. Test results presented the effects of anhydrous and hydrous ethanol on a multi-fuel engine performance, emissions and combustion.
Technical Paper

PANORAMA OF NATURAL GAS USAGE IN HEAVY DUTY VEHICLES IN BRAZIL

2005-05-11
2005-01-2192
In the 80s, due to the oil crisis, natural gas (NG) appeared as a fuel with great potential for replacing diesel in heavy duty vehicles. At that time, Petrobras, together with other companies, had developed partial conversion kit technology for diesel to diesel plus NG, known as “dual fuel” technology. Engine dynamometer and vehicle bus tests have been developed to verify the technical and economic viability of the “dual fuel” kit. For several reasons, the dual fuel program did not advance and the trials were interrupted. At the same time, other trials, using NG Otto cycle bus engines, manufactured in Brazil, were being conducted, mainly in São Paulo, although unsuccessfully.
Technical Paper

Prediction of Gasolines Performance in Internal Combustion Engines Using Kriging Metamodels

2015-09-22
2015-36-0189
Accurate simulation of fuel properties influence in internal combustion engines performance is a very complex approach and combines many physical and chemical concepts such as combustion phenomena, chemical kinetics, fluid dynamics, turbulence and thermodynamics. The right modelling of that is still a challenge and currently available software packages for engines simulation usually consider standard or surrogate fuels. The objective of this paper is the prediction of gasolines performance in internal combustion engines as an auxiliary tool in researches and developments of new fuels, reducing experimental timing and costs. It is proposed the use of kriging metamodels based on bench test results of a flexible fuel engine running with distinct blends of iso-octane, n-heptane, toluene and ethanol, to predict performance, energetic efficiency and pollutant emissions in function of fuel properties and operating conditions.
Technical Paper

SI Engine Performance and Emissions using Surrogate Fuel for Oxygenated Gasoline

2016-10-25
2016-36-0240
Gasoline is a complex mixture, composed of hundreds of different hydrocarbons. Surrogate fuels decrease the complexity of gasoline and are being used to improve the understanding of internal combustion engines (ICEs) fundamental processes. Computational tools are largely used in ICE development and performance optimization using simple fuels, because it is still not possible to completely model a commercial gasoline. The kinetics and interactions among all the chemical constituents are not yet fully understood, and the computational cost is also prohibitive. There is a need to find suitable surrogate fuels, which can reproduce commercial fuels performance and emissions behavior, in order to develop improved models for fuel combustion in practical devices, such as homogeneous charge compression ignition (HCCI) and spark ignition (SI) engines. Representative surrogate fuels can also be used in fuel development processes.
Technical Paper

Thermodynamic Modeling of Compression, Combustion and Expansion Processes of Gasoline, Ethanol and Natural Gas with Experimental Validation on a Flexible Fuel Engine

2007-09-16
2007-24-0035
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.
Technical Paper

Using Fractal Modeling to Predict Flex-Fuel Engine Combustion Process with Different Gasoline-Ethanol Blends

2014-09-30
2014-36-0162
Combustion Modeling of Internal combustion engines is still a complex matter, requiring further developments to better simulate the performance and emissions of different fuels. In order to study the influence of gasoline-ethanol blends on a Flex-Fuel engine, a computer model was designed to simulate the experimental conditions using Fractal combustion and Woschni based heat transfer models. The simulations were validated with engine dynamometer experimental tests. In-cylinder maximum pressure, IMEP and emissions data were calculated for different gasoline-hydrous ethanol blends at different engine conditions. The computer model presented a predictive behavior and a good agreement with experimental data for in-cylinder maximum pressure and IMEP. Regarding emissions, the simulations of some pollutants could not match precisely the experimental data, showing the need for additional combustion modeling improvements.
Technical Paper

Vehicle Efficiency on Chassis Dynamometer Tests

2014-09-30
2014-36-0263
Nowadays, due to the global warming questions related to CO2 emissions, many countries legislation lead automotive and fuel industries to search for higher efficiencies in their products. Therefore, new engine technologies and cleaner fuels are being developed and launched in the market. This paper presents a study of efficiencies on chassis dynamometer tests, in order to evaluate vehicle and fuel contributions. Tests were performed using one Brazilian flex fuel vehicle in full load condition at constant speeds to evaluate the losses of each part of the system, such as, wheel, air resistance and powertrain. The vehicle energy parcels were determined. So, it was possible to assess vehicles mechanical losses, aerodynamic losses and also the engine efficiencies.
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