Method for Reducing Engine Cold Start Emissions from Transient Fueling in an Alternative Fueled Engine
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Publisher:The Ohio State University
Series/Report no.:The Ohio State University. Department of Mechanical and Aerospace Engineering Honors Theses; 2013
EcoCAR 2 is a three year competition among 15 North American Universities dedicated to reduce the negative environmental impact of a 2013 Chevy Malibu while maintaining standard vehicle operation. The planned E85 (85% ethanol and 15% gasoline) internal combustion engine for the vehicle produces harmful emissions during its cold startup. Previous research has shown that the majority of unwanted emissions from modern vehicles occur during engine cold starts. The inability to control the stoichiometric air fuel ratio from transient fuel dynamics as the engine warms is a major cause of these emissions. The purpose of this study was to create an engine control algorithm that compensates for the transient fuel dynamics during a cold start. The algorithm will be developed by determining fuel dynamic parameters describing the fuel evaporation time constant (τ) and fraction of liquid fuel entering the engine intake manifold (X). The fuel dynamic parameters are determined from comparing the exhaust air fuel ratio traces with step input perturbations of injected fuel. Because the fueling dynamics depend on temperature, engine speed, and manifold air pressure, the data from perturbation testing was collected over several engine speeds and manifold pressures during the engine’s cold start. Lookup tables of τ and X parameters for different engine operating conditions were created and will be implemented into the engine control unit (ECU) to compensate the transient fueling. The research will help achieve the goals of the EcoCAR 2 competition to reduce the vehicle’s environmental impact while maintaining standard operation. The procedure to create the algorithm can be implemented to control emissions of production E85 vehicles.
Related Item:Academic Major: Mechanical Engineering
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