Effect of SO2 in recirculated exhaust gas on wear in diesel engine (effect of SO2 added to intake air on wear)

In both spark ignition engines and diesel engines, the exhaust gas recirculation (EGR) system is well known as an effective technique to reduce nitrogen oxides emissions. However, wear of piston rings and cylinder liners is sharply increased by EGR. It is widely considered that sulfur dioxide contained in exhaust gas is strongly related to wear. In order to clarify the sole effect of sulfur dioxide in recirculated exhaust gas on wear of piston rings and cylinder liners, we performed an experiment where sulfur dioxide was added to the intake air. Furthermore, we compared the amount of wear, which was measured experimentally, with the amount of sulfur dioxide absorbed by a lubricating oil film, which was estimated by a numerical model. Consequently, sulfur dioxide absorbed by a lubricating oil film plays an important role on wear of piston rings and cylinder liners.