The synergistic effect of fuel aromatic components refinement and ignition timing on GDI engine performance and emissions

Abstract

In this study, a four-cylinder, four-stroke GDI engine was used to study the effects of refined aromatic components combined with advanced ignition timing on engine combustion and emission performance at 1800 rpm, 80% load rate. It was found that the different types of aromatics in the fuel have a considerable impact on the combustion and emission performance of the engine. The aromatic components of fuel Me and fuel Tr are toluene and trimethyl-benzene, respectively. They have shorter combustion durations and ignition delays, which mean better combustion effect, compared with fuel B, whose aromatic component is mixed with toluene, xylene and trimethyl-benzene. Fuel Xy whose aromatic component is xylene has a longer combustion duration, lower indicates mean effective pressure (IMEP), and increased fuel consumption. When ignition timing is −3.75°CA ATDC, fuel Xy has the shortest ignition delay and combustion duration, which shows that fuel Xy has the best combustion effect at this ignition time. On the premise that the combustion stability does not deteriorate, when the aromatic component of the fuel is mainly toluene and the ignition timing is advanced to −5.25°CA ATDC, the IMEP of fuel Me increased by 3.16%, the brake specific fuel consumption (BSFC) decreased by 5.06%, and the THC content remained almost unchanged, but NOx emissions increased by 31.35%, compared with that of fuel B. Refining the type of aromatics in the fuel, combined with the adjustment of ignition timing, can optimize the combustion process to a certain extent, increase engine power output and reduce BSFC, but it will increase NOx emissions.