Optimising the Aftertreatment Configuration for NOx Regeneration on a Lean-NOx Trap 1999-01-3499
This paper describes a series of vehicle emission tests on a port-fuel injected lean-burn engine, to determine the preferred aftertreatment configuration yielding the most efficient regeneration of a lean-NOx trap (LNT). Three configurations were tested: (A) single starter three-way catalyst (TWC) upstream of an underfloor LNT; (B) bifurcated system with short downpipes comprising parallel TWCs upstream of a single underfloor LNT (Y-pipe configuration); and (C) bifurcated system with extended downpipes. System ‘A’ exhibits satisfactory LNT regeneration behaviour, and is within the European Stage III limits after accelerated aging. Results for system ‘B’, with identical TWC and LNT formulations as the single system, show that this LNT cannot be adequately regenerated under standard purge conditions; even with a fresh trap. In this non-optimized bifurcated system, the AFR profile entering the LNT during the rich purge deviates markedly from that requested by the calibration. A change in TWC formulation to one with different oxygen storage characteristics demonstrates that this system can perform satisfactory in the bifurcated configuration. Further tests on system ‘C’ with: (1) uncoated TWC substrates; and (2) the original TWC formulation, indicate that LNT regeneration efficiency in a bifurcated system is dependent upon the TWC formulation in conjunction with oscillatory flow in the Y-pipe. Implications of these results are discussed in terms of future direct injection gasoline engine programs.
Citation: Marshall, R., Gregory, D., Eves, B., Peirce, G. et al., "Optimising the Aftertreatment Configuration for NOx Regeneration on a Lean-NOx Trap," SAE Technical Paper 1999-01-3499, 1999, https://doi.org/10.4271/1999-01-3499. Download Citation
Author(s):
R. A. Marshall, D. Gregory, B. Eves, G. Peirce, T. Taylor, S. Cornish, M. Dearth, J. Hepburn
Affiliated:
Dunton Engineering Centre, Ford Motor Company Ltd., Ford Research Laboratory, Ford Motor Company.
Pages: 13
Event:
International Fuels & Lubricants Meeting & Exposition
ISSN:
0148-7191
e-ISSN:
2688-3627
Also in:
Gasoline Direct Injection and Diesel Aftertreatment-SP-1476, SAE 1999 Transactions - Journal of Fuels and Lubricants-V108-4
Related Topics:
Three-way catalysts
Environmental testing
Emissions certification
Air / fuel ratio
Lean burn engines
Nitrogen oxides
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