Effects of intake manifold water injection on combustion and emissions of diesel engine

Intake manifold water injection (IMWI) is an effective way to control combustion temperature and NOx emission for diesel engines. The various effects of IMWI on diesel combustion and emissions reflect on the dilution effect, thermal effect and chemical effect. However, researchers have paid little attention to investigate the three effects. In this study, the dilution, thermal and chemical effects of IMWI on the combustion and emissions characteristics of a four-stroke, direct injection as well as turbocharged diesel engine are investigated by CFD simulation. The results indicate that IMWI reduces the in-cylinder mean pressure and temperature, and the ignition delay becomes longer. IMWI leads to a remarkable decrease of NOx and Soot emissions. Comparing to the thermal effect and chemical effect, the dilution effect of IMWI on engine combustion and emissions plays a dominant role.