Cost Effective Pathways toward Highly Efficient and Ultra-Clean Compression-Ignition Engines, Part II: Air-Handling and Exhaust Aftertreatment

Currently, on-road transport contributes nearly 12% of India's total energy related carbon dioxide (CO) emissions that are expected to be doubled by 2040. Following the global trends of increasingly stringent greenhouse gas emissions (GHG) and criteria emissions, India will likely impose equivalent Bharat Stage (BS) regulations mandating simultaneous reduction in CO emissions and nearly 90% lower nitrogen oxides (NOx) from the current BS-VI levels. Consequently, Indian automakers would likely face tremendous challenges in meeting such emission reduction requirements while balancing performance and the total cost of ownership (TCO) trade-offs. Therefore, it is conceivable that cost-effective system improvements for the existing internal combustion engine (ICE) powertrains would be of high strategic importance for the automakers. In this second part of a two-part article, several component-level advancements are discussed, including both the engine and the aftertreatment system (ATS) for heavy-duty (HD) diesel engine based powertrains. For engine system level, the role of efficient air-handling systems (AHS), including turbochargers and EGR configurations to reduce engine out NOx emissions, was reviewed. For thermal efficiency improvements, potential of millerization and its implications on the AHS performance were presented. For an efficient ATS performance during the engine cold-start warm-up period, critical to meeting criteria emissions compliance, thermal management strategies, including valve variability, were reviewed. Finally, market-relevant HD engine system recipes with a minimal TCO implications were highlighted.