Real-world operation conditions and on-road emissions of Beijing diesel buses measured by using portable emission measurement system and electric low-pressure impactor

Zhihua Liu, Yunshan Ge*, Kent C. Johnson, Asad Naeem Shah, Jianwei Tan, Chu Wang, Linxiao Yu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

93 Citations (Scopus)

Abstract

On-road measurement is an effective method to investigate real-world emissions generated from vehicles and estimate the difference between engine certification cycles and real-world operating conditions. This study presents the results of on-road measurements collected from urban buses which propelled by diesel engine in Beijing city. Two widely used Euro III emission level buses and two Euro IV emission level buses were chosen to perform on-road emission measurements using portable emission measurement system (PEMS) for gaseous pollutant and Electric Low Pressure Impactor (ELPI) for particulate matter (PM) number emissions. The results indicate that considerable discrepancies of engine operating conditions between real-world driving cycles and engine certification cycles have been observed. Under real-world operating conditions, carbon monoxide (CO) and hydrocarbon (HC) emissions can easily meet their respective regulations limits, while brake specification nitrogen oxide (bsNOx) emissions present a significant deviation from its corresponding limit. Compared with standard limits, the real-world bsNOx emission of the two Euro III emission level buses approximately increased by 60% and 120% respectively, and bsNOx of two Euro IV buses nearly twice standard limits because Selective Catalytic Reduction (SCR) system not active under low exhaust temperature. Particle mass were estimated via particle size distribution with the assumption that particle density and diameter is liner. The results demonstrate that nanometer size particulate matter make significant contribution to total particle number but play a minor role to total particle mass. It is suggested that specific certified cycle should be developed to regulate bus engines emissions on the test bench or use PEMS to control the bus emissions under real-world operating conditions.

Original languageEnglish
Pages (from-to)1476-1480
Number of pages5
JournalScience of the Total Environment
Volume409
Issue number8
DOIs
Publication statusPublished - 15 Mar 2011

Keywords

  • ELPI
  • Heavy-duty diesel buses
  • On-road measurement
  • Operating condition
  • PEMS
  • Real-world
  • Regulatory emissions

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