重型国六在用柴油车劣化排放特性研究

基于车载排放测试(PEMS)和加载减速法(Lugdown)测试对一辆采用废气再循环(EGR)结合选择性催化还原(SCR)+催化氧化器(DOC)+颗粒捕集器(DPF)技术路线的国六在用柴油车进行部件劣化模拟排放研究。结果表明：EGR或SCR劣化后氮氧化物(NO_x)排放均明显恶化,DPF劣化后粒子数量(PN)排放明显升高,任一部件的劣化都无法达到国六排放水平。PEMS对劣化后排放最敏感,总通过率仅为28.6%,Lugdown测试的总通过率高达100.0%,而车载诊断系统(OBD)检查只有在载体泄露时未能有效识别并报出故障,总通过率为42.9%。可见,Lugdown测试已难以对重型国六在用柴油车进行有效的排放监督。     

在用汽油车简易测试工况排放特性研究

通过实验方法对在用汽油车在稳态ASM测试工况、IG195瞬态测试工况下的排放特性进行了研究,并与双怠速、怠速测试工况下的排放测试结果进行了比较。分析了车龄与排放的关系、发动机燃油供给方式与排放及与排放测试方法的关系,研究了排放因子与车龄的关系。     

深圳市在用柴油公交车排放研究

以公交车为例,利用OBS-2200和ELPI(electrical low pressure impactor)对深圳市重型柴油车(high-duty diesel vehicles,HDDVs)进行了3次在实际道路上的车载排放测试.根据测试数据计算了NOx和PM排放因子及百公里油耗,并分析了不同道路、不同工况对NOx...     

欧盟工业废水污染物排放限值的制定

目前欧盟废水污染物排放限值的制定,主要依据欧盟委员会公布的污染综合防治指令和水政策行动框架指令的原则来进行。限值的制定方法主要有两种：一是以技术先进、经济合理为基础的最佳可行技术法;二是通过水环境质量标准、水体稀释能力以及污水处理系统削减能力来计算的反演法。中国可借鉴欧盟的先进方法进行环境标准体系的建设和完善。     

负载对实际道路重型柴油车排放的影响研究

利用车载测试系统对重型柴油货车空载、50％负载和100％负载不同负载情况下在实际道路的排放进行测试,基于测试数据分析负载对重型柴油货车排放CO、HC、NOx和微小颗粒物(PM)等4种污染物的影响.不同速度区间和行驶模式下负载对排放的影响分析表明,在有负载时,大多数工况下4种污染物排放呈现增加趋势,但各速度区间和行驶模式下的增幅不尽相同,部分工况出现下降.空载时测试柴油车基于新欧洲行驶循环测试(NEDC)工况的标准化CO、HC、NOx和PM排放因子分别为3.38、0.39、6.27、0.39 g/km.对于柴油车重点污染物NOx和PM而言,与空载相比,50％负载时分别增加43％和59％,100％负载时分别增加62％和44％.     

基于实际道路测试的重型柴油车排放评估方法研究

为分析重型柴油车实际道路测试情况下污染物的排放评估方法,选取了4辆国六重型柴油车进行实际道路排放试验。试验结果表明,现行《重型柴油车污染物排放限值及测量方法(中国第六阶段)》(GB 17691—2018)采用的功基窗口法在计算过程中剔除了大量发动机处于低功率段时氮氧化物(NO_x)高比排放区域数据,大幅低估了重型柴油车在实际道路工况下的NO_x排放量,不能充分反映车辆实际道路排放水平,应进一步修改完善,建议后续标准修订时,去除法规中功率阈值最小10%的限制,采用全窗口的90%分位值来表征车辆的排放水平,或通过行程时间占比加权值法计算污染物比排放。     

在用车简易工况污染物排放检测法

详细论述了在用车简易工况污染物排放检测法的概念、内容和要求,针对目前世界最流行的简易工况法ASM、IM240和VMAS,比较了它们的不同标准与特点,重点介绍了VMAS检测设备的原理、组成、检测方法和特点,最后指出了简易工况法的发展趋势.     

Speciated hydrocarbon profiles and calculated reactivities of exhaust and evaporative emissions from 82 in-use light-duty Australian vehicles

Mass emissions of non-methane hydrocarbon (NMHC) from 26 pre-1986 and 56 post-1985 catalyst-equipped in-service vehicles were determined from measurements made on a chassis dynamometer using an urban drive cycle. Evaporative emissions were measured on a subset (4 pre-1986 and 8 post-1985) of these vehicles. Average ADR emissions (mg/km) of the individual HCs from the older pre-1986 vehicles were generally 4–7 times the emissions from newer catalyst-equipped vehicles. Evaporative emissions from the older vehicles are also much higher than those of newer vehicles. Exhaust from newer catalyst-equipped vehicles had lower proportions of substituted aromatics and alkenes and higher proportions of lower molecular weight alkanes. The effect of fuel type on the exhaust emissions was also investigated by refuelling 9 of the pre-1986 vehicles with both unleaded and leaded petrol. A 20–40% reduction in HC mass emissions was observed when unleaded petrol was used instead of leaded petrol. Reactivities of the emissions and the contributions from different classes of compounds are also reported. The specific reactivity of the exhaust emissions from newer vehicles was lower than that for older vehicles owing to the smaller proportions of highly reactive alkenes and substituted aromatic species. Moreover, as older vehicles have higher average mass emissions, when considered on a per-km basis, the pre-1986 vehicles have a greater ozone-forming potential than post-1985 vehicles. The specific reactivities of the NMHC (gO₃/gNMHC) of both the heat build and hot soak evaporative emissions were much lower than the exhaust emissions.     

Real-world emissions of in-use off-road vehicles in Mexico

Off-road vehicles used in construction and agricultural activities can contribute substantially to emissions of gaseous pollutants and can be a major source of submicrometer carbonaceous particles in many parts of the world. However, there have been relatively few efforts in quantifying the emission factors (EFs) and for estimating the potential emission reduction benefits using emission control technologies for these vehicles. This study characterized the black carbon (BC) component of particulate matter and NOx, CO, and CO₂ EFs of selected diesel-powered off-road mobile sources in Mexico under real-world operating conditions using on-board portable emissions measurements systems (PEMS). The vehicles sampled included two backhoes, one tractor, a crane, an excavator, two front loaders, two bulldozers, an air compressor, and a power generator used in the construction and agricultural activities. For a selected number of these vehicles the emissions were further characterized with wall-flow diesel particle filters (DPFs) and partial-flow DPFs (p-DPFs) installed. Fuel-based EFs presented less variability than time-based emission rates, particularly for the BC. Average baseline EFs in working conditions for BC, NOx, and CO ranged from 0.04 to 5.7, from 12.6 to 81.8, and from 7.9 to 285.7 g/kg-fuel, respectively, and a high dependency by operation mode and by vehicle type was observed. Measurement-base frequency distributions of EFs by operation mode are proposed as an alternative method for characterizing the variability of off-road vehicles emissions under real-world conditions. Mass-based reductions for black carbon EFs were substantially large (above 99%) when DPFs were installed and the vehicles were idling, and the reductions were moderate (in the 20–60% range) for p-DPFs in working operating conditions. The observed high variability in measured EFs also indicates the need for detailed vehicle operation data for accurately estimating emissions from off-road vehicles in emissions inventories.

Implications: Measurements of off-road vehicles used in construction and agricultural activities in Mexico using on-board portable emissions measurements systems (PEMS) showed that these vehicles can be major sources of black carbon and NO_X. Emission factors varied significantly under real-world operating conditions, suggesting the need for detailed vehicle operation data for accurately estimating emissions inventories. Tests conducted in a selected number of sampled vehicles indicated that diesel particle filters (DPFs) are an effective technology for control of diesel particulate emissions and can provide potentially large emissions reduction in Mexico if widely implemented.     

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.     

Real-world emissions of carbonyl compounds from in-use heavy-duty diesel trucks and diesel Back-Up Generators (BUGs)

Emissions of carbonyl compounds such as formaldehyde, acetaldehyde, and acrolein are of interest to the scientific and regulatory communities due to their suspected or likely impacts on human health. The present work investigates emissions of carbonyl compounds from nine Class 8 heavy-duty diesel (HDD) tractors and also from nine diesel-powered backup generators (BUGs); the former were chosen because of their ubiquity as an emission source, and the latter because of their proximity to centers of human activity. The HDD tractors were operated on the ARB 4-Mode heavy heavy-duty diesel truck (HHDDT) driving cycle, while the BUGs were operated on the ISO 8178 Type D2 5-mode steady-state cycle and sampled using a mobile emissions laboratory (UCR MEL) equipped with a full-scale dilution tunnel. Samples were analyzed using the SAE930142 (Auto/Oil) method for 11 aldehydes, from formaldehyde to hexanaldehyde, and 2 ketones (acetone and methyl ethyl ketone). Although absolute carbonyl emissions varied widely by BUG, the relative contributions of the different carbonyls were similar (e.g., median: 56% for formaldehyde). A slight increasing trend with engine load was observed for relative formaldehyde contribution, but not for acetaldehyde contribution, for the BUGs. On-road per-mile carbonyl emission factors were a strong function of operating mode of the ARB HHDDT cycle, and found to decrease in the order Creep>Transient>Cruise. This order is qualitatively similar to emission factors for PAHs and n-alkanes determined for the same set of Class 8 diesel tractors in an earlier work. In general, relative carbonyl contributions for the HDD tractors were similar to those for BUGs (e.g., median: 54% for formaldehyde). These results indicate that while engine operating mode and application appear to exert a strong influence on the total absolute mass emission rate of the carbonyls measured, they do not appear to exert as strong an influence on the relative mass emission rates of individual carbonyls.     

Evaluation of particulate matter emissions from non-passenger diesel vehicles in Qatar

ABSTRACT

Road traffic is one of the main sources of particulate matter (PM) in the atmosphere. Despite its importance, there are significant challenges in the quantitative evaluation of its contribution to airborne concentrations. In order to propose effective mitigation scenarios, the proportions of PM traffic emissions, whether they are exhaust or non-exhaust emissions, should be evaluated for any given geographical location. In this work, we report on the first study to evaluate particulate matter emissions from all registered heavy duty diesel vehicles in Qatar. The study was applied to an active traffic zone in urban Doha. Dust samples were collected and characterized for their shape and size distribution. It was found that the particle size ranged from few to 600 μm with the dominance of small size fraction (less than 100 μm). In-situ elemental composition analysis was conducted for side and main roads traffic dust, and compared with non-traffic PM. The results were used for the evaluation of the enrichment factor and preliminary source apportionment. The enrichment factor of anthropogenic elements amounted to 350. The traffic source based on sulfur elemental fingerprint was almost 5 times higher in main roads compared with the samples from non-traffic locations. Moreover, PM exhaust and non-exhaust emissions (tyre wear, brake wear and road dust resuspension) were evaluated. It was found that the majority of the dust was generated from tyre wear with 33% followed by road dust resuspension (31%), brake wear (19%) and then exhaust emissions with 17%. The low contribution of exhaust PM₁₀ emissions was due to the fact that the majority of the registered vehicle models were recently made and equipped with efficient exhaust PM reduction technologies.

Implication: This study reports on the first results related to the evaluation of PM emission from all registered diesel heavy duty vehicles in Qatar. In-situ XRF elemental analysis from main, side roads as well as non-traffic dust samples was conducted. Several characterization techniques were implemented and the results show that the majority of the dust was generated from tyre wear, followed by road dust resuspension and then brake wear; whereas exhaust emissions were tremendously reduced since the majority of the registered vehicle models were recently made and equipped with efficient exhaust PM reduction technologies. This implies that policy makers should place stringent measures on old vehicle license renewals and encourage the use of metro and public transportation.     

在用轻型汽油车排放随行驶里程劣化规律分析

基于佛山市3.5万条简易稳态工况(ASM)下的尾气排放检测数据,通过分类统计和线性拟合方法分析在用轻型汽油车的污染物排放浓度随行驶里程的劣化规律。分析结果表明,该地区轻型汽油车污染物排放浓度主要分布于低值区间,超过85%的样本数据低于最低排放限值;车辆排放劣化特征随行驶里程呈规律性变化,行驶里程在0~5万km时污染物排放缓慢增长,5万~16万km时呈快速线性增长,16万km后震荡缓慢增长;行驶里程在16万km前,不同车型的排放特征存在一定差异,其中轻型货车和轻型客车的排放浓度高、劣化速度快;CO、HC、NO随行驶里程的劣化规律可用线性增长模型表示。本研究结论可为预测机动车污染变化趋势、完善在用车检查/维护制度、高排放车辆识别和淘汰等方面提供理论支持。     

Idle emissions from heavy-duty diesel vehicles: review and recent data

Heavy-duty diesel vehicle idling consumes fuel and reduces atmospheric quality, but its restriction cannot simply be proscribed, because cab heat or air-conditioning provides essential driver comfort. A comprehensive tailpipe emissions database to describe idling impacts is not yet available. This paper presents a substantial data set that incorporates results from the West Virginia University transient engine test cell, the E-55/59 Study and the Gasoline/Diesel PM Split Study. It covered 75 heavy-duty diesel engines and trucks, which were divided into two groups: vehicles with mechanical fuel injection (MFI) and vehicles with electronic fuel injection (EFI). Idle emissions of CO, hydrocarbon (HC), oxides of nitrogen (NOx), particulate matter (PM), and carbon dioxide (CO2) have been reported. Idle CO2 emissions allowed the projection of fuel consumption during idling. Test-to-test variations were observed for repeat idle tests on the same vehicle because of measurement variation, accessory loads, and ambient conditions. Vehicles fitted with EFI, on average, emitted approximately 20 g/hr of CO, 6 g/hr of HC, 86 g/hr of NOx, 1 g/hr of PM, and 4636 g/hr of CO2 during idle. MFI equipped vehicles emitted approximately 35 g/hr of CO, 23 g/hr of HC, 48 g/hr of NOx, 4 g/hr of PM, and 4484 g/hr of CO2, on average, during idle. Vehicles with EFI emitted less idle CO, HC, and PM, which could be attributed to the efficient combustion and superior fuel atomization in EFI systems. Idle NOx, however, increased with EFI, which corresponds with the advancing of timing to improve idle combustion. Fuel injection management did not have any effect on CO2 and, hence, fuel consumption. Use of air conditioning without increasing engine speed increased idle CO2, NOx, PM, HC, and fuel consumption by 25% on average. When the engine speed was elevated from 600 to 1100 revolutions per minute, CO2 and NOx emissions and fuel consumption increased by >150%, whereas PM and HC emissions increased by approximately 100% and 70%, respectively. Six Detroit Diesel Corp. (DDC) Series 60 engines in engine test cell were found to emit less CO, NOx, and PM emissions and consumed fuel at only 75% of the level found in the chassis dynamometer data. This is because fan and compressor loads were absent in the engine test cell.