The impact of test systems and urea quality on PN emissions of diesel vehicles
PAN Xiao
SUN Yunzhong
TIAN Haoyu
JIANG Honghao
JIA Jiancheng
YU Zhendong
TAN Feng
LIANG Aoran
CAI Shufeng
CHE Jintao
YANG Zihua
Abstract：To elucidate the impact mechanisms of testing systems and urea solution quality on secondary particle number(PN)emissions,a China Ⅵ heavy-duty diesel vehicle is tested using two measurement systems,a portable emissions measurement system(PEMS)and a constant volume sampling(CVS)system,along with five types of urea solutions.The experiments are conducted on a chassis dynamometer to investigate the influence of the testing systems and urea solution quality on PN emissions,with comparative analysis performs between the number of particles with a particle size not less than 23 nm(referred to as PN23)and the number of particles with a particle size not less than 10 nm(referred to as PN10)measurements.The results demonstrate that due to differences in particle counting principles and sampling strategies,the PN23 emission measured by different testing systems varies significantly;urea solution quality notably affects PN23 emission.For the PEMS,all contaminated urea solutions(containing calcium chloride,formaldehyde,phosphate,and biuret)lead to a marked increase in PN23 emission,with the peak PN23 emission level from the formaldehyde-added solution being substantially higher than that measured by the CVS system;Ca2+interferes with the electrophoretic particle counting(EPC)method,resulting in significantly elevated PN23 emission from the calcium chloride-added urea solution.Under the CVS system,only urea solutions with added calcium chloride and formaldehyde cause a significant rise in PN23 emission,which may be attributed to the formation and agglomeration of solid particles.Across all test groups,the increase in PN10 emission is more pronounced than that of PN23,which indicates that urea injection primarily augmentes the number of fine particles in the 10～23 nm size range,with biuret exhibiting the most significant promoting effect on particle generation within this diameter range.
Keywords：heavy-duty diesel vehicleemission test systemurea solution qualityPNEPC
Publication Date：2025-09-30
Online Publishing Date：2026-05-22(First online date of this platform, not the publication date of the document)
Pages：7( 12-18 )