Effect of direct water injection on emission of pollutants in a diesel engine using CFD and water/fuel mass ratio based parametric analysis

One of the current major challenges in the industry is to considerably reduce polluting emissions from internal combustion engines to comply with increasingly strict anti-pollution standards and to remain competitive in the face of the rapid spread of green technologies. The work carried out in this paper focused on a study of the effect of direct water injection on the emission of pollutants in a diesel engine. The strategy of injecting water into the combustion chamber allows better control of the combustion phase and improves engine performance due to the temperature drop during combustion. This work aims to develop a CFD model of a diesel engine with direct water injection in the combustion chamber and to analyze the effects of water/fuel ratio on combustion, particularly on pollutant emissions. The novelty of this work is the realization of a parametric CFD study based on the water/fuel mass ratio, which is a powerful indicator that can effectively generalize the results obtained to engines of different architecture and consumption. For it, data were taken from the work done at Sandia National Laboratories by Stephen Bush and his team from a light unicycle optical diesel engine. These data made possible to design and validate a CFD model. After that we associate a model of direct injection of water, which has also been validated. Finally, we analyze the effects of water/fuel mass ratio on combustion and particularly on pollutant emissions. This work shows that the injection of water into the combustion chamber of the engine effectively reduces the emission levels of pollutants in nature. Thus, depending on the value of the water/fuel ratio, there is a reduction of 2% − 30% of NOx, 5% − 70% of soot, 5% − 40% for CO and 3% − 30% for HC.