| Numerical simulations have been performed to compare the vaporization and combustion of gasoline and ethanol in a direct injection spark ignition engine. The widely used, open source, computational fluid dynamics KIVA - 3V code has been used for this purpose. A multidimensional look up table of ignition delays has been formulated from a detailed mechanism for ethanol oxidation using CHEMKIN(TM) and has been used to modify the ignition delays predicted by the global one step mechanism used to simulate combustion. The "cold start" phenomenon in ethanol operated engines has been observed in the simulations and various strategies to enhance ethanol vaporization and combustion have been tested. Simulation results indicate that some of the strategies used for emission control and downsizing of gasoline engines may be employed for "improving" combustion in ethanol operated engines. |
