缸内直喷汽油机排放PM_(2.5)的理化特征及影响因素

通过发动机台架实验研究了发动机的转速、负荷对缸内直喷(GDI)汽油机排放PM_(2.5)的排放水平、化学组成及颗粒物数浓度等的影响.结果表明:GDI汽油机排放PM_(2.5),OC,EC的排放因子分别为(49.8±28.2),(21.6±6.9),(11.4±10.8)mg/kg.低转速时,PM_(2.5)排放量随着负荷的增加先减少后增加,中、高转速时随着负荷的增加逐渐增加.碳质气溶胶是GDI汽油机排放的PM_(2.5)的主要组成成分,有机物(OM)和元素碳(EC)分别占PM_(2.5)的45.6%~70.6%和7.9%~42.7%.PM_(2.5)数浓度呈核态(10nmDp30nm)和积聚态(30nmDp200nm)的双峰分布,数浓度排放量比进气道喷射(PFI)汽油机高2个数量级,不同转速下积聚态颗粒数浓度随着负荷的增加而增加.     

轻型汽油车尾气PM2.5的排放特征

为研究轻型汽油车尾气PM_2.5的排放特征,利用整车测试台架和颗粒物稀释采样系统,对12辆轻型汽油车尾气的PM_2.5进行了采集,并进一步分析了PM_2.5排放因子及其碳质组分——OC(有机碳)和EC(元素碳)的排放特征;在此基础上,参考文献研究结果,计算了我国轻型汽油车分阶段PM_2.5排放因子,结合活动水平数据估算轻型汽油车PM_2.5排放量.结果表明:测试的国Ⅰ前~国Ⅳ轻型汽油车PM_2.5平均排放因子分别为(73.2±3.8)(50.5±45.4)(34.7±18.4)(22.6±10.3)和(1.0±0.2)mg/km,随排放阶段升级而显著降低.OC是轻型汽油车尾气PM_2.5中的主要碳质组分,在TC(总碳)中所占比例超过90%. 2012年我国轻型汽油车PM_2.5排放量为21 828.7 t,占机动车颗粒物排放总量的3.5%,其中仅占轻型汽油车保有量17%的国Ⅰ及以前车辆排放了约43%的PM_2.5. 研究显示,轻型汽油车尤其是国Ⅰ及国Ⅰ前车辆颗粒物排放不容忽视,在机动车颗粒物减排工作中应给予足够重视.      

缸内直喷汽油机多环芳烃排放特性的试验研究

在一台缸内直喷(GDI)汽油机上,分别用玻璃纤维滤膜和“聚氨基甲酸乙酯泡沫(PUF)+XAD-2”对尾气中的颗粒相和气相多环芳烃(PAHs)进行了采集,并用色谱-质谱联用仪(GC-MS)对PAHs进行了定性定量分析,研究了点火时刻和废气再循环(EGR)对PAHs排放的影响.结果表明:在缸内直喷汽油机尾气中,气相PAHs浓度远高于颗粒相PAHs浓度,在气相PAHs中主要是2环和3环等小环PAHs,而在颗粒相PAHs中则主要是4环及以上的大环PAHs.随着点火时刻的提前,尾气中PAHs总浓度呈现先减小后增加再减小的变化趋势,气相和颗粒相PAHs浓度也呈现相似的变化趋势.随着EGR率的增大,气相PAHs所占比例先减小后增大,颗粒相PAHs所占比例则先增大后减小,总PAHs的排放在整体上呈现逐渐减小的变化趋势.加入EGR后,GDI汽油机尾气的毒性显著增大.     

无铅汽油添加剂甲基叔丁基醚(MTBE)的环境化学行为及其分析方法

本文简要介绍了无铅汽油添加剂MTBE的物理化学性质、环境化学行为、地下水的污染状况和对动物的潜在致癌毒理 ,并对其分析方法作了综述 ,指出了我国开展MTBE有关研究的重要性。     

新型L沸石在FCC汽油加氢脱硫催化剂中的应用研究

采用等体积浸渍法,制备了一系列含有相同含量活性组分(MoO3、CoO和NiO)不同USL沸石含量的加氢脱硫催化剂。通过X-射线衍射(XRD)、氮气吸附脱附、吡啶红外(Py-FTIR)和氨气程序升温脱附(NH3-TPD)等分析方法对样品进行了表征。结果表明:与Cat.0(参比剂,仅以γ-Al2O3为载体)相比,添加USL沸石催化剂所得加氢油的烯烃含量、芳烃含量和研究法辛烷值(RON)均增加;仅当催化剂载体中USL沸石加量在0~40m%之间变化时,加氢油的异构烷烃含量呈上升趋势;而当载体中USL沸石添加量在0~20m%之间变化时,催化剂的脱硫率有所升高。综合对比,当载体中USL沸石添加量约为40m%,催化剂具有最佳的综合性能指标,脱硫率达90%,RON损失仅为1.5左右。     

缸内直喷汽油车颗粒物化学组分特征

随着缸内直喷汽油车（GDI）的大量使用,其尾气颗粒物排放问题日益凸显.研究缸内直喷汽油车尾气颗粒物构成组分是有效控制其颗粒物排放的重要前期工作之一.选取了5辆满足国六排放标准的缸内直喷汽油车进行了尾气颗粒物碳质成分、水溶性离子和多环芳烃（PAHs）组分分析.结果发现,各类碳质是测试车辆尾气颗粒物中的主要成分,平均占比约70%.颗粒物碳质中有机碳质（OC）多于核态碳质（EC）,OC/EC比值在1.03~3.43之间.测量了颗粒物中多种水溶性离子的含量,结果表明Ca²⁺和SO₄^2-是尾气颗粒物中的主要水溶性离子,主要来源均为机油添加剂.此外,结果还发现GDI车辆尾气颗粒物中高环PAHs排放占比较高,对人体健康危害大,需要重点关注.     

Assessment of using unleaded fuel in the harsh environment of the United Arab Emirates

The service life of lubricating oil produced in the United Arab Emirates (UAE) was examined using a car fueled with leaded or unleaded gasoline of the same grade in harsh local conditions. In addition, the economic impact of using leaded vs. unleaded gasoline via the effects on the useful life of engine oil was investigated. Every 500 km that the car was operated, the physical properties of the oil were examined to determine the optimum oil life before replacement. It was found that relative to unleaded gasoline, leaded gasoline resulted in a faster deterioration of lube oil properties and a reduced useful life of the oil. Many of the effects of use on the physical properties of oil became apparent from the beginning of its service, especially when leaded gasoline was used. Our findings indicate that the recommended useful life of oil when using leaded gasoline is 2500 km. With unleaded gasoline, deterioration of the physical properties of the lubricating oil became a concern after 3000 km. Thus with unleaded gasoline, it is recommended to have an oil change every 3500 km. These findings indicate that the decision of the UAE government to stop using lead compound additives to improve the octane number of gasoline will not only protect the environment from the harmful effects of lead compounds, but will also extend the useful life of oil. This extension will reduce the amount of used oil that is disposed of by up to 4678 tons/year. This reduction in oil use translates to a cost savings of about 23.4 million UAE Dirhams (=$6.37 million US Dollars) per year.     

A ban on one is a boon for the other: Strict gasoline content rules and implicit ethanol blending mandates

Ethanol and methyl-tertiary butyl ether (MTBE) were close substitutes in the gasoline additives market until MTBE was banned due to the concerns about groundwater contamination, leading to a sudden and dramatic substitution toward ethanol as an alternative oxygenate and octane-booster. We use variation in the timing of MTBE bans across states to identify their effects on gasoline prices. We find that state bans increased reformulated gasoline prices by 3–6 cents in non-Midwestern states for which the bans were binding, with larger impacts during times of high ethanol prices relative to MTBE and crude oil. We find qualitatively similar, yet smaller effects for conventional gasoline. We argue on the basis of a simple conceptual model and supporting empirical evidence that these bans functioned as implicit ethanol blending mandates in areas that were previously using MTBE to comply with strict environmental constraints. Overall, our results are consistent with the theoretical prediction that mandating a minimum market share for a more costly alternative fuel—either directly, or implicitly through a ban on the preferred conventional fuel—will inevitably increase fuel prices in a competitive market.     

车用乙醇汽油静电起电特性试验研究

为研究乙醇汽油使用过程中存在的静电风险及带电变化规律,基于自主研发的油品电荷密度表,试验研究了乙醇含量对管输汽油静电带电规律的影响,获得乙醇体积含量0~5%的管输油品静电数据;对油库内乙醇汽油装车作业及加油站加油作业乙醇汽油静电起电特性进行了试验研究。研究结果表明:随着乙醇含量的增加,油品静电呈现先增大后减小的趋势;乙醇体积含量在0.5%~1%时,油品静电起电量最高可达到-77.2 μC/m3,为此需注意乙醇汽油调配过程中可能存在的静电风险;高电导率的车用乙醇汽油在加油作业时,油品静电起电量较低。