Injection System Control for a Multi-Fuel SI Engine

In this paper, the dependency on fuel blends of a four-stroke, four-cylinder SI engine equipped with a low-pressure, common-rail-type injection system is analyzed. With reference to an operating condition using E21 (21% ethanol, 79% gasoline) as a fuel, the experimental performance of the engine are firstly introduced, and the brake power, the specific fuel consumption, the total efficiency, the heating combustion power and the injected mass per stroke dependency on shaft speed are introduced.Then, the multi-fuel injection system actual behavior is predicted by means of a properly tailored lumped and distributed numerical model, whose general reliability is defined mainly in terms of injected mass per stroke. Afterward, the engine performance variation with the fuel mixture is determined, and the adaptation of the PWM control applied to injectors is proposed to compensate the engine operating characteristics.Finally, with reference to the engine performance using E100 (100% ethanol, 0% gasoline) as a fuel, the influence of the engine rotational speed on the injected mass per stroke, on the heat of combustion power, on the specific fuel consumption and on the brake power are introduced, and the numerical prediction reliability is assessed with respect to the engine experimental behavior.