Computational Investigation of Ethanol and Bi-fuel Applied in GDI Engine

Computational simulation is used to investigate the feasibility of ethanol and gasoline-ethanol mixtures as a fuel in a Direct Injection (GDI) engine. A dynamic mesh of the varying compression ratio models is built to simulate flow physics, fuel injection, and combustion in the engine. Ethanol delivery from the stock fuel injector model is investigated and compared with gasoline models. Additionally, a dual-injection gasoline ethanol operation mode is investigated using the high compression ratio model 13: 1. A comparison between gasoline and ethanol performance at cruising speed shows that gasoline produced 1.7Mpa more cylinder pressure (18.7% increase) and 314K more cylinder temperature (14.9% increase) under operation at the same equivalency. The bi-fuel injection timing study shows that the gasoline first injection was consistently the lowest cylinder pressure and temperature, with both standard and ethanol first offering higher pressure and temperature. The bi-fuel ignition timing study shows that cylinder pressure depends strongly on spark timing. A cylinder pressure increases 27.5% was found when comparing all the ignition timing. The bi-fuel ignition timing study shows that the cylinder pressure is maximized for E80, however, E50 and E30 have almost the same peak cylinder pressure.