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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.

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.

Over the last few years, a growth of the Brazilian light duty vehicle fleet converted to Natural Gas (NG) has been observed. This is mainly due to license tax reductions on NG vehicles; the increase of the NG distribution around the country and attractive price difference between NG and other fuels. The Brazilian CNG (Compressed Natural Gas) light-duty vehicle fleet has currently reached more than 1,4 million units, being the 2nd largest in the World. ANP (Brazilian National Petroleum Agency) published in 2002 Resolution no104, which defines the NG specification for automotive application. The IBAMA (Brazilian Institute for Environment and Natural Renewable Resources) published in 2002 Resolution no 291, which defines ways for the environmental certification of the NG conversion kits.

On-board measurement is a powerful method to assess vehicular exhaust gas emission, since it enables the acquisition of instantaneous raw emission values in real-world conditions. While the vehicle emissions are subject to traffic and environment fluctuations, on-board measurement is a fast and economical way to generate data for fleet emission inventories, for instance. It is part of the mandatory testing for heavy-duty vehicles in the USA, as regulated by the USEPA. In 2004, Petrobras (Brazilian Oil Company) first experienced on-board emission measurements while participating in an international joint project, whose objective was to obtain information regarding the light-duty vehicular gas emission contribution to pollutant levels in some of the major Latin-American cities.

In the 80's, due to the oil crisis, natural gas (NG) began to be regarded as a fuel with great potential for replacing diesel in heavy duty vehicles. At that time, Petrobras, together with other companies, developed conversion kit technology for heavy duty diesel engines to run burning simultaneously diesel and NG, known as diesel gas. For several reasons, the trials were interrupted. In the late 90's and beginning of the 2000's, factors such as NG availability, expansion of NG distribution network; increase of NG converted light duty vehicle fleet, government interest in increasing NG's energy matrix share, all together made a scenario which stimulated new developments in diesel gas technology. The scenario changed in the last couple of years, with Brazilian NG demand reaching its offering, mainly due to thermoelectricity generation guarantee of supply. This makes the diesel gas technology more attractable than the NG dedicated technologies.

In last few years, Petrobras has been working to make feasible the vehicular usage of the natural gas (NG) produced in Brazilian north region. This gas is produced in the Urucu field located at the Amazon forest. Due to its low methane and high nitrogen contents that could promote, respectively, performance losses and higher NOx emissions, Urucu's gas does not meet ANP specification for vehicular natural gas. Previous studies performed at Petrobras Research Center (CENPES) indicated the possibility of vehicular application for Urucu's NG, attending the Brazilian emission legislation (PROCONVE). However, with new PROCONVE's phases, recent vehicles have more advanced technological levels of fuel injection and catalyst systems, which require that kits for natural gas follow this evolution, including interfacing with flexible fuel engines.

Due to worldwide concern regarding greenhouse gases emission, mainly CO₂, automakers are developing new technologies to reduce vehicles' fuel consumption. One of the most promising technologies, growing fast in USA, Japan and Europe is the Hybrid Electric Vehicles (HEVs). In the Brazilian Market, HEVs availability is still absent, which causes uncertainties about possible impacts caused by the introduction of this new vehicle technology in the big cities. However, as requirements of non-pollutant technologies arise, HEVs are expected to be available in Brazilian Market in the next years. Within this scenario, in 2002, aiming to evaluate the adequacy of Brazilian Gasolines blended with up to 25% v/v of Ethanol in HEV technology, Petrobras Research and Development Center (CENPES) purchased from USA a 2002 Toyota Prius and a 2002 Honda Insight. Since then, both HEVs are being tested at CENPES's Vehicle Test Laboratory (LEV).

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.

The automobile industry has developed and marketed hybrid electric vehicles (HEV) internationally for over 10 years. The presence of batteries in these vehicles poses difficulties for their approval in laboratory trials. The difference between the initial and final battery state of charge changes the energy balance measured in the tests, affecting the emissions and fuel economy levels. Two proposals have emerged to address this problem. One is described in ISO 23274, which consists in determining and applying a correction factor to the emissions and fuel economy results. This factor is based on the difference between the initial and final battery state of charge after the test. The other is described by SAE J1711 which consists in conditioning the battery, in order to equal the state of charge level at the end and start of the test, avoiding the factor recalculation.

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.

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.

Natural gas (NG) produced in the Urucu area (Amazon Forest) has low methane and high nitrogen and therefore does not meet current NG specifications for vehicular use, as established by standard number 104 of ANP (National Petroleum Agency). This paper reports the steps for these NG conversion kit adjustments and also the results and comparisons of vehicle performance, emissions and fuel economy tests on a chassis dynamometer. The vehicles were tested with different fuels like regular NG, Amazon Forest NG, gasoline and ethanol. The results were presented to ANP that authorized in the beginning of 2005 the experimental use of the Urucu natural gas for 30 months. Also reported on this paper is an overview of the Brazilian NG fleet, present and future emission legislation, fuel specification, new trends on NGV (Natural Gas Vehicle) market and conversion kit technologies. Updated information is included regarding the experimental project of Urucu natural gas that is running on Manaus city.

Due to the worldwide trends to develop new automotive technologies for vehicle emissions and fuel consumption reduction, and because PETROBRAS (Brazilian Oil Company) decided to act as an energy company, CENPES (PETROBRAS Research Centre) imported two hybrid electric vehicles (HEV) to study this technology. The main objective was to verify if Brazilian gasoline (which is blended with 25% ethanol) was adequate to use with hybrid electric vehicles. Preliminary emissions tests with both vehicles, following the FTP-75 cycle, indicated a significant variation in the results, motivating further research to study the problem. It was verified that one of the main causes for this poor repeatability was the battery charge level of the hybrid system at the beginning of the emission tests. Based on this conclusion, CENPES studied ways to develop procedures that could guarantee the same initial conditions for the battery in emissions tests and also how battery charging system works.

Natural gas (NG) produced in the north of Brazil (Amazon Forest) has low methane and high nitrogen and therefore does not meet current NG specifications for vehicular use, as established by ANP (National Petroleum Agency). This paper reports the steps for NG conversion kit adjustments and also the results and comparisons of vehicle performance, emissions and fuel economy tests on a chassis dynamometer. The vehicles were tested with different fuels like regular NG, Amazon Forest NG, gasoline and ethanol. Also reported on this paper is an overview of the Brazilian NG fleet, present and future emission legislation, fuel specification, new trends on NGV (Natural Gas Vehicle) market and conversion kit technologies.

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.

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.

In Brazil, the introduction of high biodiesel blends has been defined by standard CNPE no 16 of 2018, which stablished the latest chronogram for compulsory biodiesel incorporation to all diesel fuel commercialized nationally, from 11% v/v in 2019 to 15% v/v in 2023, and up to B20 in case of captive fleets. Nevertheless, with the adoption of more stringent emission standards in Brazil, concerns arise from the unrestricted use of higher biodiesel blends, especially regarding the assurance of Heavy-Duty Diesel (HDD) emissions aftertreatment systems correct operation and of fulfillment of national emissions requirements defined by PROCONVE. Considering the current emission standards (PROCONVE P7, equivalent to EURO V), such concerns already take place and become critical with the perspective of PROCONVE P8 (EURO VI) implementation, in 2022 for new models and 2023 for all commercialized vehicles, as defined by CONAMA Resolution no 490/2018.

Hydrogen is considered one of the cleanest solutions for sustainable mobility. This paper presents an overview of some of these applications, such as internal combustion engines, fuel cell application and also blends of hydrogen and natural gas. This paper addresses questions regarding hydrogen properties such as net heating value, flame speed, power density, range of flammability and ignition energy. Also, the paper will draw a comparison between H2 and fossil and biofuels, such as ethanol. Questions regarding storage conditions, emissions levels, Internal Combustion Engine (ICE) air/fuel ratio among others are expected to be covered as well.