Abstract
KEYWORDS – Cold start, Multi-component fuel, Evaporation, GDI engine
ABSTRACT
CFD simulation of cold start under extremely low ambient temperature in the internal combustion engine is very challenging due to both low evaporation and complicated evaporation processes of fuel. The objective of this study was to develop a computational tool to model evaporation processes of a wide range of multi-component fuels in the gasoline engines realistically and accurately. Particular interest was in GDI engine start operation under extremely cold conditions. For CFD simulation surrogate models for ten different gasoline fuels with different evaporation characteristics used for engine test were developed with a ten-component fuel data base. Reasonably good agreement of distillation curves were obtained between the measurements and the predictions. Validation of these surrogate models were performed by simulating gasoline spray injections into a GDI engine, as well as a constant volume chamber at the engine start conditions of -30℃. In the paper evaporated fuel mass fraction and spatial distribution of ten surrogate fuels were compared. The results show that the multi-component fuel model performs well, capturing the evaporation behavior of multi-component gasoline fuels under start conditions of -30℃. Gasoline fuels which have more light components vaporize faster and their vapor penetrate longer than gasoline fuels which have more heavy components. The more light fuels show higher fuel vapor mass fraction around spark plug as well as injector in the engine combustion chamber. It’s expected that this tool aids in understanding the mixture formation and in better development of cold startability for different type fuels under extremely cold condition.