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This paper presents experimental results of a 10.6L, three-cylinder opposed-piston (OP) operating on diesel fuel designed for heavy duty (Class 8) operation. The paper will describe the engine configuration and calibration of both catalyst light-off and high efficiency modes. Analysis based on measured results show the engine can comply with all 2027 California Air Resourced Board (CARB) and Environmental Protection Agency (EPA) requirements for CO2 and criteria emissions. Due to the ability of the OP Engine to combine low oxides of nitrogen (NOX) flux with high exhaust enthalpy for early catalyst light off, the engine can meet all 2027 CARB and EPA NOX standards with a current, state of the art conventional underfloor aftertreatment system. No additional emissions control technology is required.

Reducing the greenhouse emissions from on-road freight vehicles to meet the climate change mitigation objectives, has become a prime focus of regulatory authorities all over the world. Besides India, the United States, the European Union, Canada, Japan, and China have already established or planned heavy-duty vehicle efficiency regulations addressing CO2 and NOX emissions. In addition, Argentina, Brazil, Mexico, and South Korea are all in various stages of developing policies to improve the efficiency of their commercial vehicle fleets. For CO2 emissions reduction standards, the U.S. mandates 27% reduction by 2027, EU is calling for 15% reduction by 2025, China for 27% by 2019 over 2012 levels, and India is mandating 10%-15% reduction by 2021 for phase 2 of the new standard. There has also been considerable focus on further reduction in NOX emissions from current levels (0.2 g/hp-hr), to the proposed ultra-low NOx standards (0.02 g/hp-hr) in the U.S. for heavy duty engines by 2024.

A 4-way Heavy-Duty Diesel (HDD) emissions control aftertreatment system typically consists of diesel oxidation catalyst (DOC), catalyzed soot filter (CSF), urea-based selective catalytic NOx reduction (SCR) and NH₃ slip control catalyst (AMOX). Incorporating the SCR functionality into the soot filter (SCRoF) has great potential to reduce system costs and package volume/weight. In this paper, we discuss some of the recent Cu-Zeolite-based SCR on filter (SCRoF) developments targeting Passive filter regeneration applications. The on-engine investigation of complete DOC+SCRoF+AMOX system focused on three major areas: 1) SCR performance of NOx conversion efficiency and NH₃ slip under both steady state and transient testing conditions; 2) SCRoF system response to sulfur exposure and subsequent sulfur removal for activity recovery; and 3) Characteristics of filter soot load, pressure drop, and passive soot oxidation in SCRoF.