Parametric analysis for performance and emissions of gasoline direct injection engine using mathematical modelling

Abstract

The study aims to estimate the performance and emissions of a gasoline direct injection (GDI) engine by analyzing parameters such as engine speed between 2000 and 6000 rpm, compression ratio (CR) between 9 and 13, and the start of ignition between 140 and 180 deg. A thermodynamic mathematical model was developed using MATLAB to simulate the two-zone combustion process of a four-cylinder, four-stroke direct injection engine operating on gasoline at specified parameters. The results showed that parameter variations greatly affect the performance and emissions of the GDI engine. The highest values of in-cylinder pressure, burned and unburned temperature, cumulative engine power, Carbon monoxide CO and Nitrogen oxide NO emissions were found at low engine speeds, while heat transfer increased as engine speed increased,  and it's been noticed that the maximum power per cycle at speed (2000 rpm), fuel injection pressure (40 MPa), and S.O. ignition angle (165). Increasing the compression ratio between 9 and 13 increased cylinder pressure, but it is observed that a compression ratio has a minimal effect on the temperature in both the burned and unburned areas. Cumulative engine power and heat transfer decreased when the compression ratio rose, and the percentage mole fraction of CO and NO emissions decreased with increasing CR. The engine observed maximum power per cycle at a compression ratio of 10, an engine speed of 2000 rpm, and a cylinder bore/stroke ratio of 100%. Advancing the spark timing increased in-cylinder pressure and burned and unburned temperatures while delaying the ignition timing increased heat transfer. It is also noticed that in cylinder pressure, burned, and unburned temperatures increase when spark timing is advanced. As the ignition timing was delayed, heat transfer increased. In contrast, the minimum cumulative engine power at the advanced spark timing and the peak power values at the ignition angle were 170 deg. The peak values of the percentage mole fraction of CO and NO emissions at early spark timing. Also, maximum power per cycle at ignition angle (170 deg.), engine speed (1500 rpm), and engine load (75%).

Keywords

• gasoline direct injection engine engine speed
• compression ratio s.o. ignition angle mathematical model performance emissions