Cost Effective Pathways Toward Highly Efficient and Ultra-Clean Diesel Engines, Part II: Air-handling and Exhaust Aftertreatment

Following global trends of increasingly stringent greenhouse gas (GHG) and criteria pollutant regulations, India will likely introduce within the next decade equivalent Bharat Stage (BS) regulations for Diesel engines requiring simultaneous reduction in CO2 emissions and up to 90% reduction in NOx emission from current BS-VI levels. Consequently, automakers are likely to face tremendous challenges in meeting such emission reduction requirements while maintaining performance and vehicle total cost of ownership (TCO), especially in the Indian market which has experienced significant tightening of emission regulation during the past decade. Therefore, it is conceivable that cost effective approaches for improving existing diesel engines platforms for future regulations would be of high strategic importance for automakers. In this second of a two-part article, several component levels advancements are discussed including both engine and the aftertreatment system (ATS). For engine, role of efficient air-handling system (AHS) including turbochargers and EGR configurations to reduce engine out NOx emissions, were reviewed. For thermal efficiency improvements, potential of millerization and implications on AHS requirements were presented. For efficient ATS performance during engine cold-start warmup period, critical to meet the criteria emissions compliance, thermal management strategies including valve variability were reviewed. For comparison, potential of an electric heater system (EHS) during cold operations was also discussed. Finally, market relevant HD engine system recipes with minimal TCO implications were highlighted, for consideration.