Impact of PGM Loading in DOC on Emission in Diesel Engine Off Road Vehicle to Meet CEVIV Norms

Experimental study was done for evaluation of different type of PGM loading in Diesel oxidation catalyst (DOC) for off road vehicle. The main purpose of DOC is to reduce the hydrocarbon and carbon monoxide from exhaust line and increasing the DOC outlet temperature, which used in soot oxidation in DPF and increased conversion efficiency of SCR. It is very challenging to meet the emission norm with minimum loading of DOC for low cost and durable approach for non-auto application. Test results highlights impact on emission with different PGM loading in DOC. This paper focused on the calibration of DOC model with different loading and observed that behaviour on THC and CO in exhaust system. Minimum Temperature constraint was come in NRTC rather than NRSC. With low, exhaust gas temperature white smoke observed, when unburned HCs was adsorbed on DOC. Data taken to understand thermal effect on DOC with different loading in aged condition. It observed that maximum DOC loading, conversion efficiency went up to 98% in THC after heating up. DOC loading is also responsible for conversion of NO to NO2, which is used in conversion of SCR efficiency. Detailed comparison and analysis was done to understand the impact of PGM loading in DOC for NO2 formation, exotherm, HC & CO light off temperature behaviour.