High-pressure exhaust gas recirculation line condensation model of an internal combustion diesel engine operating at cold conditions

Abstract

To fulfill the future NOx emission regulations, the use of exhaust gas recirculation could be necessary for the engine starting at cold conditions. In this context, condensation inside the exhaust gas recirculation line could appear, affecting in several ways the engine components and their life span. In this article, a mathematical model is developed with the aim of predicting the conditions that produce the condensation phenomenon to appear inside the exhaust gas recirculation circuits of an internal combustion engine working at low ambient temperatures (−7 °C). In particular, the humidity ratio and the internal engine conditions that characterize the appearance of this phenomenon are estimated by the model. The model is validated by experimentally visualizing the condensation behavior along a representative driving cycle by means of cameras fitted on the exhaust gas recirculation rail. This validation process shows that the predictions made by the model are in good agreement with the results obtained from the experimental tests.