Technical Paper
Assessment of Tier 4 Final Aftertreatment Strategies
2012-09-24
2012-01-1953
Non-road machineries cover a large variety of platforms requiring aftertreatment strategies which are different from those utilized in on-road platforms. The right choice of an aftertreatment strategy is complex due to the consideration of engine power rating, duty cycle, durability and regulatory requirements as well as fuel economy concerns and total operating costs. Some powertrain systems utilize merely a DOC-SCR aftertreatment system, with or without EGR, depending upon engine-out versus targeted tailpipe NOx emission. This strategy necessitates integrating a urea (DEF/AdBlue®) injection system. When combined with moderate EGR, the requirements on NOx conversion efficiency can be reduced below 90%. Without EGR, a conversion efficiency about 95% is required. Some other platforms intend to use a DOC-DPF system, along with a "high PM" approach on the NOx/PM trade-off.
