Impacts of ambient temperature, DPF regeneration, and traffic congestion on NOx emissions from a Euro 6-compliant diesel vehicle equipped with an LNT under real-world driving conditions

Jinyoung Ko, Cha Lee Myung, Simsoo Park

Research output: Contribution to journalArticle

13 Citations (Scopus)


A real driving emissions test procedure was introduced as a supplement to the chassis dynamometer test to diminish the discrepancy between on-road emissions and type approval certification emissions. In this study, on-road NOx emissions from a 2.2 L diesel vehicle equipped with a lean NOx trap were measured not by a portable emissions measurement system but by NOx sensors and an exhaust flow meter. This method provides a strategy for analyzing on-road NOx emissions with a measurement system that is relatively cheap, light and simple. The effects of ambient temperature, diesel particulate filter regeneration, traffic congestion, NOx conversion efficiency and uphill/downhill sections on NOx emissions were evaluated by comparing the NOx emissions characteristics using engine-out and lean NOx trap-out NOx sensors. NOx emissions in congested traffic conditions were 29% higher than those in smooth traffic conditions. NOx emissions at 33 °C were 55% higher than those at 27 °C. Additionally, NOx emissions under specific conditions with diesel particulate filter regeneration were 30% higher than those under normal conditions. The average on-road NOx emission factor for all test cases was 7.35, but this value decreased to 5.7 when an ambient temperature corrective factor (1.6) was applied for extended test conditions.

Original languageEnglish
Pages (from-to)1-14
Number of pages14
JournalAtmospheric Environment
Publication statusPublished - 2019 Mar 1



  • Ambient temperature
  • Diesel particulate filter (DPF) regeneration
  • Lean NO trap (LNT)
  • NO emission
  • Real driving emissions (RDE)
  • Traffic congestion

ASJC Scopus subject areas

  • Environmental Science(all)
  • Atmospheric Science

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