McCarthy Jr, J., Yue, Y., Mahakul, B., Gui, X. et al., "Meeting Nonroad Final Tier 4 Emissions on a 4045 John Deere Engine Using A Fuel Reformer and LNT System with An Optional SCR Showing Transparent Vehicle Operation, Vehicle Packaging and Compliance to End-of-Life Emissions," SAE Int. J. Engines 4(3):2699-2717, 2011, https://doi.org/10.4271/2011-01-2206.
The nonroad Final Tier 4 US EPA emission standards require 88% reduction in NOx emission from the Interim Tier 4 standards. It is necessary to utilize aftertreatment technologies to achieve the required NOx reduction. The development of a fuel reformer, lean NOx trap (LNT) and optional selective catalytic reactor (SCR) on a John Deere 4045 nonroad engine is described in this paper. The paper discusses aftertreatment system performance, catalyst formulations and system controls of a fuel vaporizer, fuel reformer, LNT and SCR system designed to meet the nonroad Final Tier 4 emission standards. The 4045 John Deere engine was calibrated and integrated with the aftertreatment system. The system performance was characterized in an engine dynamometer performance test cell, durability test cell and on a vehicle. The catalyst performance was evaluated using aged catalysts and a detailed description of the LNT, DPF and SCR catalysts is provided. Test results show that the system performance met Final Tier 4 emission standards under a range of test conditions including limited vehicle operation. System performance was characterized under the nonroad transient cycle (NRTC), ramped eight-mode cycle, steady state modal points and not-to-exceed regulations. LNT regeneration, LNT desulfation and DPF regeneration were demonstrated in these test cycles while maintaining repeatable and consistent aftertreatment temperature control. The LNT system regeneration fuel consumption ranged between 1.4% to 3.1%. The system consistently demonstrated 85% NOx reduction in a performance and durability test cell, and on a vehicle. The downstream SCR catalyst can be removed as an option for tighter vehicle packages while still meeting Final Tier 4 emission standards.