Direct Injection of Variable Gasoline/Methanol Mixtures: A Future Potential of SI Engines

The balance of the exchange between internal combustion engines and the environment regarding both consumption and emissions depends principally on the type of working substance, respectively on their management during the process within the engine. Regarding the process management, the internal mixture formation by direct injection has a better potential for reduction of both consumption and pollutant emission than external mixture formation, by carburetor or manifold injection. This fact results from the possibilities of control extended up to the start of combustion and is well demonstrated by recent developments. On the other hand, the limited availability of fossil resources, as well as the stringent requirement of a partial CO₂ re-circulation in the atmosphere imposes an increased use of alternative fuels.

The paper presents the performances obtained with a direct injection system with high pressure modulation when using different gasoline/methanol ratios. Both the numerical simulation and the experimental data confirm that the system performances are practically not influenced by the mixture ratio. This is a good base for the volume adaptation to the methanol content for same air-to-fuel ratios. The atomization and vaporization are better with increased methanol content.