缸内直喷型汽油车起动工况颗粒组分排放特性

Effects of Start Conditions on the Composition of Particle Emissions from a Gasoline Direct Injection Vehicle

摘要:

以一辆国V 排放均质燃烧模式缸内直喷型（GDI）汽油车为研究对象，分析了该GDI汽油车25 ℃冷机起动、25 ℃热机起动、5 ℃冷机起动等不同起动条件下GB18352.52013Ⅰ型试验的颗粒质量、数量排放及组分特性.结果表明：该车产生的颗粒物质量、数量排放受起动条件的影响较大，5 ℃冷机起动的颗粒物质量、数量较高；颗粒排放的碳质组分中有机碳约为总碳排放的81%，25 ℃热机起动有机碳与元素碳比例变化不大，5 ℃冷机起动有机碳比例降低15%；颗粒可溶性有机物(SOF)组分主要以脂肪酸和烷烃为主，25 ℃热机起动SOF组分变化不大，5 ℃冷机起动多环芳烃（PAHs）比例增大24倍；脂肪酸主要是C16:0和C18，受冷、热机起动和环境温度变化影响较小；烷烃主要是C24H50、C25H52、C26H54和C27H56，受冷、热机起动影响不大，受环境温度变化影响较大；PAHs主要是中环和高环芳烃，受冷、热机起动和环境温度变化的影响均较大.

关键词:缸内直喷型汽油车; 起动工况; 颗粒物; 有机碳; 元素碳; 可溶性有机物(SOF)

Abstract:

Based on a stoichiometric gasoline direct injection (GDI) vehicle certified to China V emission standards, the particulate mass, particulate number, and the composition of particle emissions during New European driving cycle (NEDC) with different start conditions (cold start at 25 ℃, hot start at 25 ℃ and cold start at 5 ℃) was investigated. The results show that particulate mass，number and copositions are significantly affected by start conditions i.e. the GDI vehicle bring higher particulate mass and number emission when cold start at 5 ℃, 81 percent of total carbon (TC) is organic carbon (OC) when cold start at 25 ℃, OC percentage changes little when hot start, but decreases 15 percent at 5 ℃. Soluble organic fractions (SOF) are mainly composed of fatty acids and alkanes, SOF components change little when hot start, but PAHs fractions increase 24 times at 5 ℃; Fatty acids are mainly composed of C16:0 and C18, start conditions and ambient temperature have little effect on fatty acids components; Alkane are mainly composed of C24H50、C25H52、C26H54 and C27H56, alkane components change little when hot start, but change greatly at 5 ℃; PAHs are mainly composed of middlering PAHs and highring PAHs, and these fractions changed greatly when hot start at 25 ℃ and cold start at 5 ℃.

Key words:gasoline direct injection vehicles; start conditions; particle; organic carbon; elemental carbon; soluble organic fractions(SOF)