低温等离子体降低生物柴油发动机有害排放的研究

根据介质阻挡放电理论,设计出低温等离子体发生器.利用气相色谱/质谱联用仪对生物柴油样品进行了测定,确定了生物柴油的主要成分.通过台架试验研究了低温等离子体对生物柴油和0号柴油发动机有害排放的作用规律,运用扫描电镜和X射线能谱仪对柴油机排气中收集的颗粒物样品进行检测和分析.研究结果表明:低温等离子体技术可以有效降低柴油机颗粒物排放,NO<,x>排放总量变化较小;生物柴油属于富氧燃料,可使发动机燃烧室碳燃料充分燃烧,颗粒物样品中碳烟成分较少,颗粒粒径也较小.元素分析结果表明,低温等离子体技术受燃料中硫的影响较小,是一项有前途的柴油机排气后处理技术.     

低温等离子体降低生物柴油发动机有害排放的研究

根据介质阻挡放电理论,设计出低温等离子体发生器。利用气相色谱/质谱联用仪对生物柴油样品进行了测定,确定了生物柴油的主要成分。通过台架试验研究了低温等离子体对生物柴油和0号柴油发动机有害排放的作用规律,运用扫描电镜和X射线能谱仪对柴油机排气中收集的颗粒物样品进行检测和分析。研究结果表明：低温等离子体技术可以有效降低柴油机颗粒物排放,NO_x排放总量变化较小;生物柴油属于富氧燃料,可使发动机燃烧室碳燃料充分燃烧,颗粒物样品中碳烟成分较少,颗粒粒径也较小。元素分析结果表明,低温等离子体技术受燃料中硫的影响较小,是一项有前途的柴油机排气后处理技术。     

低温等离子体技术在降低柴油机排放中的应用

研究了低温等离子体技术基本原理,提出了利用低温等离子体降低柴油机有害排放物方案,设计了适用于柴油机后处理的等离子体发生器,研究了发生器特性,通过实验验证了该研究方案对柴油机有害排放物的总体转化效果。结果表明,采用低温等离子体技术可有效降低柴油机HC、颗粒和NO排放,而NOx总量基本不变。     

排气背压对柴油机燃油经济性影响研究

当前大气污染问题严重,颗粒物捕集器(DPF)是处理柴油机尾气中所含颗粒物的主要方法。但随着颗粒物捕集器应用时间增长,颗粒物不断堆积,排气阻力不断增加。当排气阻力达到一定值时,柴油机性能会明显受到影响。本文基于GT-Power研究了柴油机排气阻力对柴油机燃油经济性的影响,为颗粒物捕集器的再生时机提供了依据。     

DPF载体结构对非道路柴油机再生性能影响的试验研究

非道路柴油机对加装壁流式颗粒物捕集器(DPF)降低发动机排气污染物中的颗粒物和粒子数量做出了明确要求。DPF对降低柴油机颗粒物排放起到决定性的作用,同时其不同材料载体和孔壁厚度又对发动机排气阻力、油耗、再生性能、DTI超温风险以及可靠性产生影响。因此,DPF必须尽可能降低排气阻力,提高再生性能与捕集效率,以利于发动机油耗和排放降低。本文就DPF载体结构对柴油机的影响进行深入分析研究。     

柴油机排气颗粒物电晕放电下荷电特性的研究

柴油机排气颗粒物粒径小,不易沉降,严重危害人体健康。这里设计并制造了一种电收集柴油机颗粒物的预荷电系统,并通过试验论证了该系统的有效性。对柴油机尾气分流采样,样气中的颗粒物通过线-筒式的负高压电晕放电装置荷电。尾气颗粒物在自制的法拉第杯中被收集,通过与之相连的数字电荷仪测量出收集颗粒物带电量,并用微克天平测量收集到的颗粒物的质量,从而计算得到柴油机尾气颗粒物的荷质比。试验探究了柴油机尾气颗粒物荷电效果与尾气流速之间的关系,验证了柴油机颗粒物可以用带电的方法收集。为柴油机颗粒物通过电晕放电收集提供了理论依据,该技术及产品未来有望用于柴油车尾气后处理系统之中。     

柴油机车载诊断系统新型颗粒物传感器的研究

随着柴油机颗粒物排放法规的不断严格,颗粒物捕集器被广泛使用以去除尾气中的颗粒物。为了精确地监测尾气中的颗粒物排放,就需要采用新型的颗粒物传感器。该传感器需要有足够的耐热性和承受力,并且能够忍受恶劣的排气环境。文中介绍了几种国内外新型颗粒物传感器的工作原理及其研究方法,其中通过流场模拟对电阻传感器进行了研究,分析了电容传感器电场强制收集方法的碳烟收集效率,对电化学传感器电极加入离聚物后的变化进行了对比分析,并引入了有应用前景的颗粒物传感器。     

合肥工大成功研制全国首台治理柴油机尾气装置

近日,合肥工业大学成功研制治理柴油机尾气装置-柴油机颗粒物捕集系统DPF,可清除柴油机尾气排放中的颗粒物(PM2.5)成效显著,攻克了城市柴油车辆尾气排放污染难题。该项目使用主动再生技术DPF系统,通过对柴油机排气系统进行改造,以特定材料制成壁流式的过滤通道载体,过滤捕集尾气的颗粒物,当捕集器中的颗粒物充满到设定程度后,通过特殊设计的再生设备,将捕集到的颗粒物氧化,生成二氧化碳排出。捕集器可以一直循环使用。采用该技术装置后,柴油机尾气黑烟消失,噪音降低。     

颗粒捕集器捕集效率及对柴油机性能影响的研究

柴油机颗粒捕集技术是降低柴油机颗粒物排放的最有效的手段之一。但是,加装颗粒捕集器后也会对柴油机的性能产生一定影响。对一款满足国Ⅲ排放的高压共轨柴油机加装颗粒捕集器(DPF),通过台架试验研究了颗粒捕集器的捕集效率以及对柴油机排气背压、燃油经济性以及排放特性的影响。试验结果表明发动机加装颗粒捕集器后颗粒物排放降低90%以上,燃油消耗率增加5%左右,排气背压增加约10kPa,这可以为颗粒捕集器的正确开发及再生策略的制定提供依据。     

柴油机DPF系统研究现状综述

随着全球内燃机技术的不断提升,柴油机的排放法规日趋严格,而柴油机颗粒物捕集器(DPF)可以减少排气中85-95%的颗粒物排放,成为了汽车达到国六法规要求必备的一个关键部件。本文主要介绍了柴油机DPF系统的国内外研究现状,通过对近年来DPF关键技术的总结,展望了DPF的发展趋势,为其后续的优化设计提供参考,以期促进今后该技术的发展。     

Non-thermal plasma for exhaust gases treatment

This article describes a study on a non-thermal plasma device to treat exhaust gases in an internal combustion engine. Several tests using a plasma device to treat exhaust gases are conducted on a Honda GX200-196 cm³ engine at different rotational speeds. A plasma reactor could be efficient in degrading nitrogen oxides and particulate matter. Monoxide and carbon dioxide treatment is minimal. However, achieving 1%–3% degradation may be interesting to reduce the emission of greenhouse gases.     

微粒捕集器对柴油机性能影响的研究

柴油机排气微粒捕集技术是实现柴油机微粒排放控制的一个非常有效的技术，然而，微粒捕集器也会对柴油机的性能产生一定的影响。通过大量的柴油机台架试验，研究了微粒捕集器对ＹＣ６１０８柴油机的动力性、燃油经济性以及排放性能的影响，研究结果可以为微粒捕集器的正确使用及再生控制策略的确定提供依据。     

基于等压差水膜的柴油机尾气净化装置研究

开发设计了一款新型尾气颗粒物过滤净化装置,该装置利用颗粒物惯性作用和水膜吸附效应实现颗粒物与柴油机尾气的分离。通过分析计算得到形成湿润壁面连续水膜的条件。选择合适的波形板面,搭建柴油机尾气颗粒物检测系统。试验结果表明,设计的柴油机尾气颗粒净化装置可以起到很好地净化颗粒物的作用,尤其是在柴油机刚刚启动低速运转的情况下净化效率高。     

发动机燃用生物柴油的颗粒可溶有机组分及多环芳烃排放

以一台车用柴油机为样机,研究发动机燃用生物柴油的常规排放,重点探讨其颗粒(Particulate matter,PM)、可溶有机组分(Soluble organic fraction,SOF)及多环芳烃(Polycyclic aromatic hydrocarbons,PAHs)的排放特性。所用燃油分别为柴油、生物柴油掺混配比为10%的B10燃油。结果表明,与柴油相比,该车用柴油机燃用B10燃油后颗粒、SOF和PAHs的质量排放均有所降低;NOx排放略有增加,HC和CO排放有所下降。B10燃油燃烧的颗粒SOF中醇类、酮类、醚类质量分数下降;脂类、酸类、醛类质量分数上升。在检测到的12种PAHs中,B10燃油有10种质量排放减少,尤其是苯并(a)芘等高环数致癌性的PAHs降幅明显,这表明发动机燃用生物柴油后,排气颗粒的化学成分毒性有所降低。     

NO2和O3氧化柴油机微粒的对比试验研究

柴油机微粒物质（PM）后处理最有效的措施是微粒捕集器（DPF）技术,而DPF技术的关键点在于其再生。为了降低DPF的再生温度,首先采用玻璃纤维无胶滤筒捕集PM,然后在管式反应器内加入氧化性气体氧化PM,并通过试验对比研究了NO2和O3对PM的氧化效果。研究结果表明,NO,氧化PM的起燃温度为250℃,而O3在155cc时开始明显氧化PM,适宜温度为200℃～240oC;提高了臭氧或NO2气体浓度,明显加快了氧化速度;O3可以在低温下快速氧化PM,且不需任何催化剂。     

Relation between particulate emissions and exhaust smoke level in premixed charge compression ignition engine

For simplicity in measurement, the smoke level or opacity of the exhaust gas is often measured in diesel engine tests for the purpose of estimating the level of particulate emissions in the belief that smoke level is proportional to the particulate emissions. Existence of the correlation between these two has been well established in conventional diesel engines, but it is not clear yet whether the linear relationship stays in PCCI engines, which are known to emit significantly less NOx but more hydrocarbons than the conventional diesel engines. The objective of this study was to investigate the existence of the correlation between the smoke level and particulate mass in a directly fuel-injected PCCI engine with a DOC in the exhaust system. The smoke and PM are simultaneously measured before and after the DOC, while the single-cylinder diesel engine is operated in either diesel or PCCI combustion mode under various operation conditions. The study reveals that many more hydrocarbons and particulates are emitted in PCCI combustion than in the diesel combustion, and the strong correlation between the engine-out smoke level and particulate emissions in the diesel combustion does not exist in PCCI combustion. The correlation, however, comes back in the post-DOC measurements where most of SOF contained in PM is removed by the DOC.     

The influence of engine oil on diesel exhaust emissions

Increasingly stringent emission legislation, together with the requirements for improved diesel engine performance, such as fuel economy, friction reduction, and extended drain intervals, have led to attention being focused on engine oil quality. The use of low‐friction engine oils can improve engine fuel efficiency and lead to a significant reduction of gaseous emissions. Therefore, engine oil is of importance when considering engine design parameters. This paper describes a study of the contribution of engine oil to diesel exhaust emissions. The investigations have shown that diesel engine particulate emissions as well as hydrocarbons and NO_X emissions depend on the lubricant oil properties, in particular on the sulphur content, volatility, and metal content.     

Characterization of engine oil additive packages on diesel particulate emissions

This study investigated the impact of engine oil formulation on particulate matter (PM) characteristics from a light-duty diesel engine. The test engine was a 1.6 L Euro-5 diesel engine operated from low- to high-speed and high-load conditions. Specially formulated nonadditive containing base oil and genuine oil were evaluated. For diesel PM characterization, physicochemical analytic procedures were conducted on engine oil formulation, oil flushing, PMs sampling, morphology, and particle constituent determination. Size-resolved particle number (PN) concentration at the engine-out position was evaluated by differential mobility spectrometer (DMS). Nucleation mode particles originating from engine oil consumption during the expansion stroke had a higher concentration from genuine oil than those from base oil. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to analyze the morphology patterns and atomic compositions with engine oil packages. From the SEM analysis, spherical PM of nucleation and accumulation mode particles were agglomerated on a quartz filter. In the XPS spectrum, more engine oil additive fractions of Ca, P, and Zn were found in the PM sample from genuine oil. In conclusion, the variation of physicochemical engine oil properties and additive amounts had strong contributions to engine oil derived PN emissions, morphology, and additive metal compositions in the exhaust gas stream.

     

A study of the fouling characteristics of EGR coolers in diesel engines

Diesel emission regulations have recently become more severe. An important goal in diesel engine research is the development of methods to reduce the emissions of NOx and PM (particulate matter). Cooled EGR (exhaust gas recirculation) system has been widely used to reduce the NOx and PM emissions of light-duty diesel engines. In this study, numerical analyses, rig tests and engine tests were performed to assess how changes in internal shape characteristics can improve the heat exchange efficiencies of EGR coolers. The heat exchange efficiencies of EGR coolers have been numerically and experimentally measured during a fouling process. The results show that the second type of oval EGR cooler tested (oval #2) exhibited better heat exchange efficiency than either the first type of oval EGR cooler was tested (oval #1) or the shell and tube cooler examined. The turbulence generated in exhaust gas flows by the wavy-finned design of the oval EGR coolers facilitated PM desorption that allows these coolers to self-purify. With respect to the two similar oval EGR coolers, the cooler with fin pitch 4 mm has better efficiency than the cooler with fin pitch 6 mm due to differences in the heat transfer areas of these coolers. Both CFD analyses involving extreme conditions of engine operation and engine fouling tests involving conditions experienced during vehicular operation indicate that the two oval coolers differed by less than 4% with respect to both initial heat transfer efficiency and heat transfer efficiency after a 78-hour fouling test.