A SIMULATION OF THE COMBUSTION OF N-HEPTANE FUELED HCCI ENGINES USING A 3-D MODEL WITH DETAILED CHEMICAL KINETICS

摘要

A CFD multi-dimensional computational approach has been developed through a combination of a modified KIVA3 code together with a detailed chemical kinetics scheme for the oxidation of n-heptane in air while considering the effects of turbulence. The effects of adding different quantities of hydrogen, methane and carbon monoxide to the heptane on the combustion characteristics of the HCCI engine under different conditions were investigated both experimentally and numerically. The effects of changes in the combustion chamber wall surface temperature on the combustion characteristics of the HCCI engine were examined. It was found that the presence with n-heptane of some hydrogen, methane or carbon monoxide could delay to various extents the autoignition, while changes in the values of the combustion chamber wall temperature influence the autoignition timing and its initial location. It is suggested that the supplementing of the liquid fuel with gaseous fuels and /or application of a suitable glow-plug surface of optimum size and location fitted with temperature control may aid in controlling the combustion process of an HCCI engine while obtaining higher power output without producing knock.