Control strategy for UREA-SCR system in single step load transition

Ryota Nakayama*, Tazuki Watanabe, Keishi Takada, Matsuo Odaka, Jin Kusaka, Yasuhiro Daisho

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

2 Citations (Scopus)


Urea-SCR system has a high NOx reduction potential in the steady-state diesel engine operation. In complicated transient operations, however, there are certain problems with the urea-SCR system in that NOx reduction performance degrades and adsorbed NH3 would be emitted. Here, optimum urea injection methods and exhaust bypass control to overcome these problems are studied. This exhaust bypass control enables NO/NOx ratio at the inlet of SCR catalyst to be decreased widely, which prevents over production of NO 2 at the pre-oxidation catalyst. Steady-state and simple transient engine tests were conducted to clarify NOx reduction characteristics when optimum urea injection pattern and exhaust bypass control were applied. In simple transient test, only the engine load was rapidly changed for obtaining the fundamental knowledge concerning the effect of those techniques. Transient test results shows that cutting urea injection and supplying the exact required amount of urea calculated from inlet NOx concentration reduce NH3 slip and NOx as much as possible. In addition, exhaust bypass control also reduced NOx more quickly for the period when NO2 was excessively formed at pre-DOC.

Original languageEnglish
JournalSAE Technical Papers
Publication statusPublished - 2006 Jan 1
EventPowertrain and Fluid Systems Conference and Exhibition - Toronto, ON, Canada
Duration: 2006 Oct 162006 Oct 19

ASJC Scopus subject areas

  • Automotive Engineering
  • Safety, Risk, Reliability and Quality
  • Pollution
  • Industrial and Manufacturing Engineering


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