| Recent years, electronic control based on model in the gasoline engine becomes hot topic in the domestic and international researches. In order to improve AFR control performance during transient conditions, fuel compensator based on fuel film model has to be applied in port fuel injected (PFI) engines.X-τmodel by Aquino is the simple alternative to describe the fuel film dynamics. Impact factor X and fuel film evaporating time constantτare the important parameters in X-τmodel, which need to be calculated by EKF algorithm using data of AFR signals produced by injection vibration. The model structure of the wall-wetting temperature model, X andτare built on the basis of the phenomenon of physics known as heat-transfer principle and mass-transfer with phase change. After fitting the coefficients in the models, the analysis of the effects of various operation conditions on film dynamic characteristics is carried out.Furthermore, by analyzing volatility of the ethanol-gasoline blends, its effects on fuel film dynamic characteristics in the intake port can be achieved. Film dynamic parameters of the different ethanol content blends are calibrated to valid the conclusion. Here are the results of the study:ethanol tends to volatilize much more easily than pure gasoline does.τturns to be smaller.
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