深圳市混合动力巴士污染物排放特性的实验研究

利用高精度的车载排放测试仪,对使用同种发动机的普通柴油巴士和混合动力巴士进行城市典型道路工况下的排放测试,对比2种车型的污染物排放特征。通过对2种车型基于不同车速及比功率下的排放特性分析,发现混合动力巴士有效减少了CO和颗粒物(PM)的排放,CO、PM的排放量分别为普通柴油巴士的42.4%、28.7%;然而由于混合动力巴士的匹配控制系统相对复杂,车身总质量较大,导致其NO_x、碳氢化合物(HC)排放明显高于普通柴油巴士,NO_x、HC排放量分别为普通巴士的167.5%、931.4%。     

混合燃料中含氧量对柴油机有害物质排放量的影响

通过柴油机试验,研究了混合燃料中含氧量对柴油机有害物质排放量的影响.试验结果显示,在混合燃料中含氧量低于10.4%(质量分数,下同)时,CO和HC排放量随含氧量增加而减少;但随着混合燃料中乙醇所占比例增加,当混合燃料中含氧量达25.3%时,CO和HC排放量均增加到含氧量为10.4%时的2.5倍左右;当混合燃料中含氧量低于10.4%时,NOx排放量随其增加而少量增加.但当混合燃料中含氧量达25.3%时,NOx排放量较燃用柴油时减少50%以上;碳烟排放量则随着混合燃料中含氧量增加而不断减少.     

燃尽风位置高度对NO_x生成的影响

针对山东某电厂200 MW四角切圆燃烧锅炉NO_x排放量过高的问题,采用多空气分级低氮燃烧技术对其进行改造,基于FLUENT软件平台,对改造前后炉内燃烧过程进行模拟计算,与工业性实验结果进行对比分析;并在额定工况下,对5种不同燃尽风位置高度的改造方案进行模拟计算,综合分析炉内燃烧及氮氧化物生成排放的情况,确定燃尽风位置的最佳高度。计算结果表明:改造后,炉内NO_x排放量较改造前降幅40%左右,同时,合理地增加燃尽风位置高度,可进一步降低NO_x的排放量,综合炉内各参数变化的比较得出:燃料从主燃区至燃尽区的最佳运行时间约为0.66 s。     

西安市机动车污染控制策略实施效益评估

为研究未来西安市机动车污染控制策略的实施效果,基于情景分析法,以MOVES模型为平台,预测2020年西安市机动车PM_(2.5)、PM_(10)、NO_x、总碳氢化合物(THC)、CO、SO_2排放量分别为1 531.41、1 596.33、44 159.48、14 029.62、383 200.08、5 164.63t。设置5类不同控制措施情景,分析其对机动车的减排效果。结果显示:单一措施中,淘汰"黄标车"和老旧车对污染减排效果最明显,6种污染物均有较大幅度减排;调控轻型客车保有量可明显削减THC、CO的排放,减排比例分别为13.49%、18.59%;提升燃油质量可使各车型SO_2的减排比例均达到90%以上;使用替代燃料情景的污染物减排比例相对较低,但也是一种有效的控制策略;综合控制措施的减排效果最为显著,与基准情景相比,2020年PM_(2.5)、PM_(10)、NO_x、THC、CO和SO_2减排比例分别为78.50%、78.37%、71.77%、72.47%、76.94%、98.30%。     

以甲醇为燃料的汽车在日本已经应用

为解决大城市内的汽车公害问题,日本运输省已开发研究出一种利用甲醇燃料的汽车,并且已经开始在东京都内应用。与柴油发动机汽车相比,其含氮氧化物的排放量可减少一半;碳氢化合物排放量可下降约三分之一;一氧化碳排放量可降低五分之一。基本上不排放黑烟,低公害性能已得到实践的证明。甲醇燃料价格与柴油大致相等。     

郑州市环境空气中挥发性卤代烃污染特征与健康风险评价

用苏玛罐采样、气相色谱/质谱法分析,研究郑州市环境空气中挥发性卤代烃(VHCs)的污染特征并对其健康风险进行评价。结果显示,郑州市环境空气中共定性检出43种VHCs,其中卤代烷烃28种,卤代烯烃9种,卤代芳香烃6种,卤代烷烃、卤代烯烃、卤代芳香烃的年均质量浓度分别为67.40、34.70、20.30μg/m~3,郑州市各功能区环境空气中VHCs化合物种类稍有差异,背景点VHCs浓度与其他功能区并无显著差异,说明VHCs污染呈现区域性特征;垂直方向上,卤代烷烃浓度随高度呈先降后升趋势,卤代烯烃和卤代芳香烃浓度随高度呈先升后降趋势。健康风险评价结果显示,VHCs单体化合物对人体的非致癌风险均在安全范围内,而总风险超出了安全范围,氯乙烯、三氯乙烯、四氯化碳、氯仿、1,2-二溴乙烷、1,2-二氯乙烷和1,1,2-三氯乙烷的致癌风险超出美国环境保护署规定的可接受值;致癌风险合计为5.32×10~(-4),说明长期暴露于环境空气中对人群健康具有一定危害。     

我国氮氧化物排放因子的修正和排放量计算:2000年

根据我国城市的发展状况 ,采用城市分类的方法 ,将我国 2 6 1个地级市按照人口数量分为 5个类别。每类城市选取一个典型城市进行实地调查 ,对我国燃烧锅炉和机动车的NOx 的排放因子进行了修正 ,提出了适合我国目前排放水平的各类城市的固定源和移动源的排放因子。并依据 2 0 0 0年中国大陆地区的电站锅炉、工业锅炉和民用炉具的燃料消耗量和机动车保有量 ,以地级市为基本单位 ,估算了 2 0 0 0年我国各地区的NOx 排放量 ,分析了分地区、分行业、分燃料类型的NOx 排放特征。 2 0 0 0年我国NOx 排放总量为 11.12Mt,其中固定源占 6 0 .8% ;移动源占 39.2 %。NOx 排放在地域、行业和燃料类型上分布均不平衡。NOx 的排放主要集中在华东和华北地区 ,其排放量占全国排放量的一半以上。燃煤为最重要的NOx 排放源 ,其排放量占燃料型NOx 排放量的 72 .3%左右。     

基于COPERT 4模型的杭州市机动车排气污染特征研究

以2015年为基准年,利用COPERT 4模型计算了杭州市分车型分排放标准下的机动车排气污染物(CO、碳氢化合物(HC)、NO_x、PM_(2.5))的排放因子,并估算了各污染物排放量及分车型分排放标准下的各污染物分担率。结果表明,随着排放标准的提升,机动车排气污染物排放因子总体呈现下降的趋势。汽油车的CO和HC排放因子高于柴油车,而柴油车的NO_x和PM_(2.5)排放因子高于汽油车;天然气车的各污染物排放因子基本接近汽油车,而汽油电混动车的各污染物排放因子则明显低于其他动力车;各污染物排放因子随车型的增大(重)而增大。2015年杭州市机动车排气污染物CO、NO_x、HC和PM_(2.5)排放量分别为48 923.0、44 713.7、7 014.7、837.9t,其中汽油车CO和HC分担率较高主要是因为小型汽油客车CO和HC分担率高,并且其保有量占比也高,应重点控制小型汽油客车的保有量;柴油车NOx和PM_(2.5)分担率较高主要是因为重型柴油货车NO_x和PM_(2.5)分担率高,但其保有量占比不高,应重点控制重型柴油货车的排放因子。     

机动车尾气VOCs排放特征及减排措施研究

分析了机动车尾气挥发性有机物(VOCs)的排放特征,发现尾气VOCs排放具有明显的日变化和季节变化特征。不同区域不同车型机动车尾气VOCs成分谱略有差异,轻型汽油车尾气VOCs中芳香烃和烷烃含量较高,柴油车烷烃含量较高。尾气排放受机动车保有量、行驶里程、维护保养水平、行驶速度和燃油标准、排放标准等因素影响。从优先控制汽油车、加快机动车更新、采取本地化减排措施、加强多元管理措施、提高科研水平等方面提出了针对性的减排措施。     

高效垂直流人工湿地+多级生态塘深度处理污水厂尾水

采用高效垂直流人工湿地+多级生态塘组合工艺对污水厂尾水进行深度处理。研究发现,组合工艺进水流量为900 m3·d-1时为最优工况;在最优运行工况下组合工艺对污水处理厂尾水有显著的净化效果,对COD、NH3-N、TN和TP的去除效果可高达59.22%、81.06%、93.11%和55.81%,出水达到《地表水环境质量标准》(GB 3838-2002)Ⅳ类标准;生态塘能强化NH3-N和TN去除效果,可进一步除磷,降低富营养化风险;运行一年至少减少COD排放量9.85 t·a-1,NH3-N排放量1.73 t·a-1,TN排放量4.96 t·a-1,TP排放量0.16 t·a-1,具有良好的环境效益和经济效益。     

Effect of fuel aromatic content on PAH emission from a heavy-duty diesel engine

Polycyclic aromatic hydrocarbons (PAHs) emission tests for a heavy-duty diesel engine fueled with blend base diesel fuel by adding batch fractions of poly-aromatic and mono-aromatic hydrocarbons, Fluorene and Toluene, respectively, were simulated to five steady-state modes by a DC-current dynamometer with fully automatic control system. The main objective of this study is to investigate the effect of total aromatic content and poly-aromatic content in diesel fuels on PAH emission from the HDD engine exhaust under these steady-state modes. The results of this study revealed that adding 3% and 5% (fuel vol%) Fluorene in the diesel fuel increases the amount of total-PAH emission by 2.6 and 5.7 times, respectively and increases the amount of Fluorene emission by 52.9 and 152 times, respectively, than no additives. However, there was no significant variation of PAH emission by adding 10% (vol%) of Toluene. To regulate the content of poly-aromatic content in diesel fuel, in contrast to the total aromatic content, will be more suitable for the management of PAH emission.     

Characterization of polycyclic aromatic hydrocarbons from the diesel engine by adding light cycle oil to premium diesel fuel

Diesel fuels governed by U.S. regulations are based on the index of the total aromatic contents. Three diesel fuels, containing various fractions of light cycle oil (LCO) and various sulfur, total polyaromatic, and total aromatic contents, were used in a heavy-duty diesel engine (HDDE) under transient cycle test to assess the feasibility of using current indices in managing the emissions of polycyclic aromatic hydrocarbons (PAHs) from HDDE. The mean sulfur content in LCO is 20.8 times as much as that of premium diesel fuel (PDF). The mean total polyaromatic content in LCO is 28.7 times as much as that of PDF, and the mean total aromatic content in LCO is 2.53 times as much as that of PDF. The total polyaromatic hydrocarbon emission factors in the exhaust from the diesel engine, as determined using PDF L3.5 (3.5% LCO and 96.5% PDF), L7.5 (7.5% LCO and 92.5% PDF), and L15 (15% LCO and 85% PDF) were 14.3, 25.8, 44, and 101 mg L(-1), respectively. The total benzo(a)pyrene equivalent (BaPeq) emission factors in the exhaust from PDF, L3.5, L7.5, and L15 were 0.0402, 0.121, 0.219, and 0.548 mg L(-1), respectively. Results indicated that using L3.5 instead of PDF will result in an 80.4% and a 201% increase of emission for total PAHs and total BaPeq, respectively. The relationships between the total polyaromatic hydrocarbon emission factor and the two emission control indices, including fuel polyaromatic content and fuel aromatic content, suggest that both indices could be used feasibly to regulate total PAH emissions. These results strongly suggest that LCO used in the traveling diesel vehicles significantly influences PAH emissions.     

Polycyclic aromatic hydrocarbon exhaust emissions from different reformulated diesel fuels and engine operating conditions

The study of light-duty diesel engine exhaust emissions is important due to their impact on atmospheric chemistry and air pollution. In this study, both the gas and the particulate phase of fuel exhaust were analyzed to investigate the effects of diesel reformulation and engine operating parameters. The research was focused on polycyclic aromatic hydrocarbon (PAH) compounds on particulate phase due to their high toxicity. These were analyzed using a gas chromatography–mass spectrometry (GC–MS) methodology.Although PAH profiles changed for diesel fuels with low-sulfur content and different percentages of aromatic hydrocarbons (5–25%), no significant differences for total PAH concentrations were detected. However, rape oil methyl ester biodiesel showed a greater number of PAH compounds, but in lower concentrations (close to 50%) than the reformulated diesel fuels. In addition, four engine operating conditions were evaluated, and the results showed that, during cold start, higher concentrations were observed for high molecular weight PAHs than during idling cycle and that the acceleration cycles provided higher concentrations than the steady-state conditions. Correlations between particulate PAHs and gas phase products were also observed.The emission of PAH compounds from the incomplete combustion of diesel fuel depended greatly on the source of the fuel and the driving patterns.     

Hydrocarbon emissions speciation in diesel and biodiesel exhausts

Diesel engine emissions are composed of a long list of organic compounds, ranging from C₂ to C₁₂₊, and coming from the hydrocarbons partially oxidized in combustion or produced by pyrolisis. Many of these are considered as ozone precursors in the atmosphere, since they can interact with nitrogen oxides to produce ozone under atmospheric conditions in the presence of sunlight. In addition to problematic ozone production, Brookes, P., and Duncan, M. [1971. Carcinogenic hydrocarbons and human cells in culture. Nature.] and Heywood, J. [1988. Internal Combustion Engine Fundamentals.Mc Graw-Hill, ISBN 0-07-1000499-8.] determined that the polycyclic aromatic hydrocarbons present in exhaust gases are dangerous to human health, being highly carcinogenic.The aim of this study was to identify by means of gas chromatography the amount of each hydrocarbon species present in the exhaust gases of diesel engines operating with different biodiesel blends. The levels of reactive and non-reactive hydrocarbons present in diesel engine exhaust gases powered by different biodiesel fuel blends were also analyzed.Detailed speciation revealed a drastic change in the nature and quantity of semi-volatile compounds when biodiesel fuels are employed, the most affected being the aromatic compounds. Both aromatic and oxygenated aromatic compounds were found in biodiesel exhaust. Finally, the conservation of species for off-side analysis and the possible influence of engine operating conditions on the chemical characterization of the semi-volatile compound phase are discussed.The use of oxygenated fuel blends shows a reduction in the Engine-Out emissions of total hydrocarbons. But the potential of the hydrocarbon emissions is more dependent on the compositions of these hydrocarbons in the Engine-Out, to the quantity; a large percent of hydrocarbons existing in the exhaust, when biodiesel blends are used, are partially burned hydrocarbons, and are interesting as they have the maximum reactivity, but with the use of pure biodiesel and diesel, the most hydrocarbons are from unburned fuel and they have a less reactivity. The best composition in the fuel, for the control of the hydrocarbon emissions reactivity, needs to be a fuel with high-saturated fatty acid content.     

Characterization of Polycyclic Aromatic Hydrocarbons from the

Abstract

Diesel fuels governed by U.S. regulations are based on the index of the total aromatic contents. Three diesel fuels, containing various fractions of light cycle oil (LCO) and various sulfur, total polyaromatic, and total aromatic contents, were used in a heavy-duty diesel engine (HDDE) under transient cycle test to assess the feasibility of using current indices in managing the emissions of polycyclic aromatic hydrocarbons (PAHs) from HDDE. The mean sulfur content in LCO is 20.8 times as much as that of premium diesel fuel (PDF). The mean total polyaromatic content in LCO is 28.7 times as much as that of PDF, and the mean total aromatic content in LCO is 2.53 times as much as that of PDF. The total polyaromatic hydrocarbon emission factors in the exhaust from the diesel engine, as determined using PDF L3.5 (3.5% LCO and 96.5% PDF), L7.5 (7.5% LCO and 92.5% PDF), and L15 (15% LCO and 85% PDF) were 14.3, 25.8, 44, and 101 mg L^?1, respectively. The total benzo(a)pyrene equivalent (BaP_eq) emission factors in the exhaust from PDF, L3.5, L7.5, and L15 were 0.0402, 0.121, 0.219, and 0.548 mg L^?1, respectively. Results indicated that using L3.5 instead of PDF will result in an 80.4% and a 201% increase of emission for total PAHs and total BaP_eq, respectively. The relationships between the total polyaromatic hydrocarbon emission factor and the two emission control indices, including fuel polyaromatic content and fuel aromatic content, suggest that both indices could be used feasibly to regulate total PAH emissions. These results strongly suggest that LCO used in the traveling diesel vehicles significantly influences PAH emissions.     

Effects of Fuel Type,Driving Cycle,and Emission Status on In-Use Vehicle Exhaust Reactivity

ABSTRACT

The introduction of reformulated gasolines significantly reduced exhaust hydrocarbon (HC) mass emissions, but few data are available concerning how these new fuels affect exhaust reactivity. Similarly, while it is well established that high-emitting vehicles contribute a significant portion of total mobile source HC mass emissions, it is also important to evaluate the exhaust reactivity from these vehicles. The objective of this study was to evaluate the relative influence on in-use vehicle exhaust reactivity of three critical factors: fuel, driving cycle, and vehicle emission status. Nineteen in-use vehicles were tested with seven randomly assigned fuel types and two driving cycles: the Federal Test Procedure (FTP) and the Unified Cycle (UC). Total exhaust reactivity was not statistically different between the FTP and UC cycles but was significantly affected by fuel type. On average, the exhaust reactivity for California Phase 2 fuel was the lowest (16 % below the highest fuel type) among the seven fuels tested for cold start emissions. The average exhaust reactivity for high-emitting vehicles was significantly higher for hot stabilized (11%) and hot start (15%) emissions than for low-emitting vehicles. The exhaust reactivities for the FTP and UC cycles for light-end HCs and carbonyls were significantly different for the hot stabilized mode. There was a significant fuel effect on the mean specific reactivity (SR) for the mid-range HCs, but not for light-end HCs or carbonyls, while vehicle emission status affected the mean SR for all three HC compound classes.     

Formaldehyde,Melhanol and Hydrocarbon Emissions from Methanol-fueled Cars

Exhaust and evaporative emissions tests were conducted on several methanol- and gasoline-fueled vehicles. Separate samples for chromatographlc analysis of formaldehyde, methanol, and Individual hydrocarbons were collected in each of the three phases of the driving cycle and in each of the two portions of the evaporative emissions test. One vehicle, equipped with an experimental variable-fuel engine, was tested using methanol/gasoline fuel mixtures of 100, 85, 50,15, and 0 percent methanol. Combustion-generated hydrocarbons were lowest using methanol fuel, and increased several-fold as the gasoline fraction was increased. Gasoline components In the exhaust Increased from zero as the gasoline fraction of the fuel was Increased. On the other hand, formaldehyde emissions were several times higher using methanol fuel than they were using gasoline. A dedicated methanol car and the variable-fuel car gave similar emissions patterns when they both were tested using methanol fuel. The organic-carbon composition of the exhaust was 85-90 percent methanol, 5-7 percent formaldehyde, and 3-9 percent hydrocarbons. Several cars that were tested using gasoline emitted similar distributions of hydrocarbons, even through the vehicles represented a broad range of current and developmental engine families and emissions control systems. These vehicles continue the trend of the past twenty years toward less photochemically reactive exhaust, with higher percentages of methane and total alkanes, and correspondingly lower percentages of oleflns and aromatlcs.     

Hazardous air pollutants from mobile sources in the Metropolitan Area of Mexico City

Environmental agencies are currently in the process of implementing a new air management program, which includes the improvement of fuel quality. In this work, exhaust emissions data and estimated relative risk for various fuels testing in-use vehicles, equipped with three different exhaust emission control technologies, are presented. Aromatics, sulfur, and olefins contents; type of oxygenated compound; and Reid vapor pressure were varied. The aim also includes calculating the ozone (O3) forming potential and a relative cancer risk of emissions from current and formulated gasoline blends in Mexico. The proposed gasoline decreases carbon monoxide, total hydrocarbons (THC), and nitrogen oxides emissions by 18 and 14%, respectively, when compared with gasoline sold in the rest of the country and within ozone nonattainment metropolitan areas in Mexico, respectively.     

Comparison of vehicle exhaust emissions from modified diesel fuels

Three diesel fuels, one oil sand-derived (OSD) diesel serving as base fuel, one cetane-enhanced base fuel, and one oxygenate [diethylene glycol dimethyl ether (DEDM)]-blended base fuel, were tested for their emission characterizations in vehicle exhaust on a light-duty diesel truck that reflects the engine technology of the 1994 North American standard. Both the cetane-enhanced and the oxygenate-blended fuels were able to reduce regulated [CO, particulate matter (PM), total hydrocarbon (THC)] and nonregulated [polyaromatic hydrocarbons (PAHs), carbonyls, and other volatile organic chemicals] emissions, except for nitrogen oxides (NO(x)), compared with the base fuel. Although burning a fuel that contains oxygen could conceivably yield more oxygenated compounds in emissions, the oxygenate-blended diesel fuel resulted in reduced emissions of formaldehyde along with hydrocarbons such as benzene, 1,3-butadiene, and PAHs. Reductions in nitro-PAH emissions have been observed in both the cetane-enhanced and oxygenated fuels. This further demonstrates the benefits of using a cetane enhancer and the oxygenated fuel component.