DocumentCode :
1938926
Title :
Fuel puddle model and AFR compensator for gasoline-ethanol blends in flex-fuel engines
Author :
Ahn, Kyung-ho ; Stefanopoulou, Anna G. ; Jankovic, Mrdjan
Author_Institution :
Univ. of Michigan, Ann Arbor, MI, USA
fYear :
2009
fDate :
7-10 Sept. 2009
Firstpage :
1148
Lastpage :
1155
Abstract :
Ethanol is being increasingly used as an alternative fuel to petroleum-based gasoline and diesel derivatives. Currently available flexible fuel vehicles (FFVs) can operate on a blend of gasoline and ethanol in any concentration of up to 85% ethanol (93% in Brazil) with minimum hardware modifications. This flexibility if partly achieved through the closed-loop air-to-fuel ratio (AFR) control which maintains automatically operation around the stoichiometric ratio. Precise transient AFR control depends however on a feedforward compensator that reduces the transient effects of fuel puddle dynamics. An accurate and tunable model of the fuel puddle dynamics for gasoline-ethanol blends is, thus, necessary for the purpose of air-to-fuel ratio control. In this paper, we propose a physics-based fuel puddle model that may be used for control purposes in FFVs. In particular, the gasoline-ethanol blend is modeled using several chemical compounds and is parameterized by ethanol content. The model consists of a droplet evaporation model and a single-puddle vaporization model. The droplet evaporation model is simulated off-line to generate port wall-impacting factors of injected fuel to be used in a single-puddle vaporization model. The single-puddle vaporization model is a cycle-based model that may be simulated on-line to characterize fuel puddle dynamics in port fuel injected engines. To verify the validity of the model, simulation results are compared with limited experimental data. A transient fuel compensator based on the proposed model is also formulated.
Keywords :
biofuel; closed loop systems; internal combustion engines; AFR compensator; closed-loop air-to-fuel ratio control; droplet evaporation model; feedforward compensator; flex-fuel engine; flexible fuel vehicle; fuel puddle dynamics; fuel puddle model; gasoline-ethanol blend; port fuel injected engine; port wall-impacting factor; single-puddle vaporization model; stoichiometric ratio; transient fuel compensator; Automatic control; Calibration; Delay estimation; Diesel engines; Engine cylinders; Ethanol; Fuels; Petroleum; Vehicle dynamics; Vehicles; Fuel dynamics; air-to-fuel ratio control; evaporation; flex-fuel vehicles; gasoline-ethanol blend; multi-component fuel;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Vehicle Power and Propulsion Conference, 2009. VPPC '09. IEEE
Conference_Location :
Dearborn, MI
Print_ISBN :
978-1-4244-2600-3
Electronic_ISBN :
978-1-4244-2601-0
Type :
conf
DOI :
10.1109/VPPC.2009.5289721
Filename :
5289721
Link To Document :
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