测试系统和尿素品质对柴油车PN排放的影响

潘晓¹，孙运中²，田浩宇¹，江宏昊¹，贾建成³，于振东¹，谭峰¹，梁傲然³，

蔡树峰^4*，车金涛⁴，杨梓华⁴

1.潍柴动力股份有限公司，山东 潍坊  261061；2.潍柴重机股份有限公司，山东 潍坊  261108；

3.中国重型汽车集团有限公司，山东 济南250100；4.中汽研汽车检验中心（广州）有限公司，广东 广州  511340

摘要：为明确测试系统和尿素溶液品质对粒子数量（particle number，PN）排放二次污染的影响机制，以某国六重型柴油车为试验对象，使用便携式排放测试系统（portable emissions measurement system，PEMS）、全流稀释采样（constant volume sampling，CVS）系统和5种尿素溶液，在底盘测功机平台上试验研究测试系统及尿素溶液品质对PN排放的影响，并对比分析粒径不小于23 nm的粒子数量（记为PN₂₃）排放和粒径不小于10 nm的粒子数量（记为PN₁₀）排放的测量结果。结果表明：由于颗粒计数原理及采样策略的差异，不同排放测试系统测量的PN₂₃排放差异显著；不同尿素溶液品质显著影响PN₂₃排放；PEMS中，所有污染组（添加氯化钙、甲醛、磷酸盐和缩二脲）的尿素溶液均导致PN₂₃排放显著升高，其中添加甲醛的尿素溶液的PN₂₃排放峰值远高于CVS系统；Ca²⁺对电泳颗粒计数法（electrophoretic particle counting，EPC）存在干扰效应，导致添加氯化钙的尿素溶液的PN₂₃排放显著升高；CVS系统中，仅添加氯化钙和甲醛的尿素溶液的PN₂₃排放显著增加，这可能与固态颗粒物生成及团聚效应有关；不同试验组中PN₁₀排放增幅均高于PN₂₃，表明尿素喷射主要增加粒径为10~23 nm的细颗粒物数量，其中缩二脲对该粒径范围颗粒物生成的促进作用最显著。

关键词：重型柴油车；排放测试系统；尿素溶液品质；PN；EPC

The impact of test systems and urea quality on PN emissions of diesel vehicles

PAN Xiao¹, SUN Yunzhong², TIAN Haoyu¹, JIANG Honghao¹, JIA Jiancheng³,

YU Zhendong¹, TAN Feng¹, LIANG Aoran³, CAI Shufeng^4*, CHE Jintao⁴, YANG Zihua⁴

1. Weichai Power Co., Ltd., Weifang 261061, China;

2. Weichai Heavy Machinery Co., Ltd., Weifang 261108, China;

3. China National Heavy Duty Truck Group Co., Ltd., Jinan 250100, China;

4. CATARC Automotive Test Center (Guangzhou) Co., Ltd., Guangzhou 511340, China

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 vehicle; emission test system; urea solution quality; PN; EPC