STUDY ON THE INFLUENCE OF BIOFUELS ON THE CHARACTERISTICS OF THE GASOLINE DIRECT INJECTION

Abstract

In order to reduce the amount of greenhouse gases emitted by vehicles, more and more mineral fuels are replaced by biofuels. However, the physical and chemical properties of biofuels are usually significantly different from traditional fuels, which affects the performance of vehicle engines and fuel emissions. Engine performance is partly determinate by the preparation of the combustible mixture. This is especially important for engines with direct gasoline injection, which use is increasing in cars rapidly.

The aim of the work was to study the influence of biofuels on the characteristics of the gasoline direct injection system. Tests were performed by injecting three different fuels: gasoline, a mixture of 85% bioethanol and 15% gasoline (E85), a mixture of 85% biobutanol and 15% gasoline. Injection characteristics were recorded using the Bosch method. The fuel was injected at pressures of 10,0 MPa, 17,5 MPa and 25 MPa, with the injector control pulse duration varying from 0,25 to 1,2 ms.

Research has shown that when fuel flow rate for E85 is 5,07 % lower than when gasoline is injected. When B85 fuel was injected at the same pressure, the flow rate was 13,7% higher. When the injection pressure was increased to 17,5 MPa, the flow rate was 6,1% higher for E85 fuel injection and 11,3% higher for B85 fuel injection than for gasoline injection. When fuel pressure was increased to 25 MPa, E85 and B85 fuel flow rate was 19,03% higher than gasoline injection. In all cases the actual injection duration was longer than the injector control pulse duration.