Eduardo CesarAt CTBE, equipment to test spark plugs and to study the burning of ethanol in enginesEduardo Cesar
Drivers who drove ethanol-fueled cars in the 1980s certainly remember the choke, a button or lever that had to be pulled to inject more fuel into the engine when turning the engine on to warm it up and make it work properly. Technological progress resulted in automatic chokes and triggered the development of the dual-fuel system in the early 2000s. In this system, gasoline and ethanol are placed together in the same engine in any combination in terms of the percentages of each. This configuration became a best-seller, though it still needs some adjustments, especially regarding ethanol consumption, which is 30% higher than that of gasoline. This drawback is now being analyzed more extensively, thanks to several partnerships between research institutes, the automotive industry and the car parts industry.
“We know very little about how ethanol burns inside the engine,” says engineer Jayr de Amorim Filho, a researcher at the National Bioethanol Science and Technology Laboratory (CTBE) in the city of Campinas, São Paulo State . “Since 2009, we have conducted basic studies on the plasma that forms between the spark ignited by the spark plug and the ethanol combustion inside the engine,” he says. “We have already proposed new techniques to enable us to better understand what goes on during the ignition when the burning of the ethanol spreads throughout the space, provoking a chemical reaction and releasing the energy to move the vehicle forward.”
The researchers were able to view what happens in the engine using an optic fiber attached to the spark plug. The optic fiber goes into the inside of the engine, “like an endoscope,” says Amorim, and it captures the light emitted by the spark. This light is analyzed to detect the gases that form before, during, and after combustion. “In our study, the spark plug emits sparks every 10 milliseconds, or 100 pulses per second; the light gives us information about the gases that form at the moment of the explosion within these intervals. Our objective is to help reduce ethanol consumption and the emissions of polluting gases, although these are lower than the emissions of gasoline-fueled engines.”
The research conducted by Amorim’s team was funded through an agreement between FAPESP and the State of Minas Gerais Research Foundation (Fapemig), as part of a project linked to the FAPESP Program for Research on Bioenergy (Bioen). The research team is comprised of researchers from the Federal University of Juiz de Fora (UFJF) and from the Physics Department at the Aeronautics Technology Institute (ITA), where the researcher from CTBE began his research work on ethanol-fueled engines. Since the start of the study, Bosch – the manufacturer of the spark plugs and automotive fuel systems, which pioneered the development of the dual-fuel system – has helped by supplying the material. Bosch is now exploring the possibility of setting up a partnership to open a research lab at CTBE for research on the burning of ethanol. Bosch has also partnered a combustion-related project with the Mahle company, a manufacturer of engine parts. Mahle’s plant is in the city of Jundiaí (São Paulo State).
A deeper understanding of engines fueled by ethanol requires a better understanding of the wearing out and attrition of the engine parts. “Even though they have evolved significantly, dual fuel engines running on ethanol wear out more, because ethanol has a lower lubricating capacity than gasoline,” says professor Amilton Sinatora, from the Polytechnic School (Poli) of the University of São Paulo (USP). “We began to focus on this issue some years ago and published academic papers. We were motivated by articles published in trade magazines, such as 4 Rodas, on wearing out problems in the engine rings and valves, for example,” says the professor. Sinatora then began organizing a project in partnership with Mahle’s technology center.
Droplets from the explosion
The project, in the pipeline since 2009, was approved by FAPESP in 2011. Other partners were brought in: Fiat, Volkswagen, Renault and Petrobras. The latter is involved in the study to develop new lubricants to deal with the effect of the simultaneous use of different lubricants on dual-fuel engines. “In the last few years, the tendency has been to manufacture smaller, lighter and less polluting engines. Now we´re focusing on engines that will undergo less wear from ethanol.” The importance of the research also lies in the fact that there are no lengthy studies on ethanol-fueled dual-fuel engines being conducted in other countries. “Research studies by other countries began three years ago,” he says. Sinatora is coordinating the project with the help of teams from companies and from two universities: the Federal University of ABC, with professor Humberto Yoshimura, and the State University of Campinas (Unicamp), with professor Francisco Marques.
Measuring the size of the spray droplets in ethanol flames by means of laser techniques is part of another project related to ethanol-fueled engines. The aim of this project is to analyze biofuel’s new combustion possibilities. “This will be a basic research project to study ethanol combustion,” says professor Guenther Carlos Krieger Filho, from Poli-USP. The project he coordinates is part of the Bioen program and is the result of a cooperation agreement for technological development between FAPESP, Vale S.A, the State of Pará Research Foundation (Fapespa) and Fapemig. This project is scheduled to be concluded in 2015.
“These studies are very important because the dual-fuel engine lies halfway between gasoline-fueled engines and engines running on ethanol in terms of adjustments,” says engineer Waldemar Christofoletti, a member of the light vehicles committee of SAE Brasil, an association of automotive and aerospace engineers. In his opinion, the dual-fuel system is very good, but is far from being an efficient ethanol-fueled engine. “I believe that the ratio could drop from 30% in terms of the difference in consumption to 15% at most. To this end, it is necessary to include software and hardware, or physical and electronic components that form the fuel injection system,” says Christofoletti.
Another factor that has aroused the interest of companies in improvements for ethanol-fueled engines is the federal government’s Program for the Fostering of Technological Innovation and Expansion of the Production Chain of Automotive Vehicles (Inovar-Auto), launched last April. The program will grant a discount on excise tax (IPI) as of January 2013. Automobile and car part manufacturers will qualify for this tax rebate if they prove that they invest in technological development and energy efficiency.
The Projects
1. Ethanol – Use of ethanol as fuel: plasma ignition of vehicle engines (nº 2008/58195-3); Modality Fapesp Program for Bioenergy Research (Bioen); Coordinator Jayr de Amorim Filho – CTBE; Investment
R$ 174,962.34 and US$ 149,501.85 (FAPESP)
2. Tribological challenges in dual-fuel engines (nº 2009/54891-8); Modality Program for the Support of Research in Partnership with Technological Innovation (Pite); Coordinator Amilton Sinatora – USP; Investment R$ 975,435.65 and US$ 690,091.30 (FAPESP)
3. Experimental and computer study of turbulent ethanol sprays for applications in internal combustion engines (nº 2010/51310-1); Modality Fapesp Program for Bioenergy Research (Bioen); Coordinator Guenther Carlos Krieger Filho – USP; Investment R$ 123,551.15 and US$ 293,241.32 (FAPESP) and R$ 285,274.15 and US$ 293,241.32 (Vale)
