Experimental study of inlet manifold water injection on combustion and emissions of an automotive direct injection Diesel engine

This paper describes an experimental study conducted on a modern high speed common-rail automotive Diesel engine in order to evaluate the effects on combustion and pollutant emissions of water injected as a fine mist in the inlet manifold.First, a literature survey describing the several ways to introduce water in an internal combustion engine and reporting the main results from previous studies is presented. It is followed by a short description of the engine and experimental set-up.After that, various results are presented. A special focus is made on water injection (WI) cooling effect. Then, the influence of WI on ignition delay, rate of heat release, nitrogen oxides (NOx) and particulate matter (PM) emissions and engine efficiency is analysed, for various engine operating conditions (speed and load) and various amount of water (up to 4 times the amount of fuel injected). A comparison is made with exhaust gas recirculation to evaluate the potential of inlet WI as an in-cylinder emissions reduction device for automotive application.