The Effect of Back Pressure Change on Exhaust Emissions According to the Confluence Geometry of a Dual Exhaust System in Idling

In this study, a pressure transducer was installed in an exhaust system to analyze the effect of the change in back pressure according to the change of the confluence geometry of an exhaust pipe system on an exhaust emission. In addition, to perform exhaust gas measurement, the system was warmed up for about 40 s on the chassis dynamometer, and exhaust gas and back pressure measurements were performed simultaneously. In the back pressure measurement results, it was possible to confirm the difference in back pressure according to the change in the confluence shape. In addition, it was also confirmed that there was a clear difference in the exhaust emission measurement result. In particular, the H-type exhaust pipe system showed the highest pressure in the exhaust pipe due to the influence of the confluence geometry. Due to this influence, THC showed the highest measured value in the exhaust emission result. However, the X-type exhaust pipe system showed the lowest pressure due to the influence of the confluence geometry. Due to this influence, the THC showed the lowest measured value in the exhaust emission result. Therefore, through the conclusion of this study, an optimal exhaust system to reduce THC was proposed, and the importance of back pressure in exhaust system design was confirmed.