Water injection for higher engine performance and lower emissions

The influence of variable water injection by mass on the performance and emission characteristics of a gasoline direct injection (GDI) engine under light load conditions has been investigated and the results are presented in this paper. The study involved the injection of water into the cylinder at an angle of 640 °CA over an injection duration of 10 °CA. Gasoline was directly injected into the cylinder with a fixed injection timing duration starting from 660 °CA to 680 °CA and determined the flow rate of fuel. The results indicated that a 15% water injection by mass used together with fuel gave the best engine performance due to the increase in the indicated mean effective pressure and efficiency resulting from the cooling of certain parts of engine. Water injection also demonstrated a decrease in the NOx emissions (ppm), as well as soot emissions.