磁化燃油对柴油机燃烧性能影响的实验研究

通过搭建具有工况控制和功率测量功能的柴油机实验台架,从柴油机燃烧前处理技术中燃油磁化的角度进行节能减排研究,测试燃油磁化对柴油机燃烧性能的影响。试验结果表明,磁化燃油在不同磁场大小和不同负荷下对柴油机燃烧性能的影响各异。燃油磁化后,在低负荷工况下,油耗反而增大,烟度也变大,但NO排放量减少(最多减少5.85%);中负荷工况下则节油比较明显,最大节油率达到4.17%,但烟度值和CO2、O2、NO变化不明显;高负荷工况下,磁化燃油对油耗、烟度和CO2、O2、NO等影响均都不明显。可根据这一规律在不同的工况下选择是否对燃油进行磁化。     

应用温控系统汽车发动机各工况最佳温度分析

发动机在适宜的温度下工作,才能充分发挥其效率且提高动力性和燃油经济性。对发动机温度控制单元ECU模块分析的基础上,对发动机输出模型尤其是各工况的燃油消耗进行分析,并对温度控制系统进行研究,建立温度控制系统模型;搭建发动机性能测控系统试验台,根据温度控制系统模型设置参数采集点,对怠速工况和部分负荷工况下,发动机的最佳工作温度进行测试;通过调整油门开度、发动机转速等,获取5个不同温度工况点的油耗、扭矩及排放参数等,最终对比确定不同目标工况的最佳工作温度点。分析结果可知：怠速工况,工作温度为92℃时,平均油耗量为最低值0.633kg/h,此时,温度对尾气平均排放量的影响不大;部分载荷工况下,目标性能工况不同,最佳温度点也不完全相同;发动机燃油经济性最佳的工作温度为93℃,而输出动力最佳的工作温度为91℃。选择不同的工作模式时,可将发动机的工作温度控制在相应的范围内,实现最佳燃油经济性或输出动力性。发动机最佳工作温度的分析内容和结果为此类设计提供参考。     

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。     

吸附-热解吸法与气相色谱-质谱法联用测定蚊香烟雾中的有机化合物

利用吸附-热解吸法与气相色谱-质谱法联用,对两种固体蚊香烟气中的有机成分进行定性和半定量分析。在两种固体蚊香烟气中共检测出52种挥发性成分,包括酚类、醇类、醛类以及脂肪烃和芳香烃等多种化合物,其中的部分化合物对人体有毒害作用。蚊香A烟气中含量较多的成分为右旋烯丙菊酯(30.06%)、1,6-脱水-β-D-吡喃葡萄糖(19.4%)和甘菊环(13.9%)等;蚊香B烟气中含量较多的成分为1,6-脱水-β-D-吡喃葡萄糖(24.4%)、甘菊环(14.4%)和正十四烷(5.91%)等。     

调合生物柴油燃烧及颗粒物组分的试验研究

为深入研究不同比例调合生物柴油对发动机燃烧特性及颗粒物组分的影响,在一台单缸四冲程发动机上进行了调合生物柴油燃烧及颗粒物排放的试验研究。利用燃烧分析仪研究调合生物柴油对发动机燃烧过程的影响,利用热重分析仪(TGA)、气相色谱/质谱联用仪(GC-MS)研究调合生物柴油对颗粒物热重特性、挥发性有机物(VOCs)质量分数及有机可溶成分(SOF)和多环芳香烃(PAHs)组分的影响规律。研究表明:随着生物柴油掺混比的增加,发动机最高爆发压力及压力升高率峰值增加,压力曲线前移,预混放热率峰值随生物柴油掺混比增加而减小。与B0相比,燃用B20调合生物柴油,最高爆发压力增加了5.59%,对应的曲轴转角提前了3°CA。燃用调合生物柴油后VOCs及SOF组分略有增加,燃用B0、B5、B10及B20后颗粒物中VOCs组分的质量分数分别为12.28%、15.09%、23.06%和26.94%,SOF组分的质量分数分别为29.32%、32.08%、34.26%和35.67%,燃用B20后排放颗粒物中总PAHs降低了10.26%。     

电喷汽油机使用乙醇汽油的试验研究

在电喷汽油机参数耒作任何调整的情况下,试验研究了燃用乙醇汽油对发动机动力性和经济性的影响.研究表明:电喷汽油机改燃乙醇汽油后,全负荷时汽油机动力输出不变;但部分负荷时,动力输出稍微有所下降;与普通汽油相比,乙醇汽油的燃油消耗率有所增加;在怠速工况下.汽油机的CO、HC等废气排放有显著降低.     

柴油机空气燃油控制器

<正>柴油机在两种状态下排烟度最高,一是启动工况,二是加速工况。启动时燃油供给量是依靠怠速螺钉位置控制的,这是预先设置的一个定值。加速时供油量随着油门开度的加大急剧增加,但由于增压器的惯性作     

汽油添加剂含量对其节油和排气净化效果的影响

简述了汽油添加剂的种类和基本工作原理,在汽油机试验台架上,进行了一系列汽油中含有不同含量的MAZ添加剂在等同工况下的热车怠速、常用转速为2 800 r/m in的负荷特性和外特性对比试验,探讨新型多效燃油添加剂MAZ加到国产90#汽油中的体积分数对其节油和排气净化效果的影响。检测结果表明,汽油中含MAZ添加剂的体积分数为0.1%时,能有效改善发动机的燃油经济性和排放特性,而发动机的动力性则基本不变,其综合使用效果较佳。     

生物催化剂对柴油发动机经济性影响研究

通过将一种生物质催化剂加入昆明市通用的0#柴油中进行柴油发动机台架试验,对比加入催化剂后柴油发动机和原柴油机的燃油经济性,为后期催化剂的发展及研究做出相应贡献。试验结果表明,在现有昆明市典型环境中,柴油发动机在外特性及低、中、高转速的各负荷特性下,加入催化剂后的各工况燃油消耗均有一定改善,在外特性工况下低转速低负荷工况下表现最为突出,最高节油率可达12.1%,高转速催化剂节油率影响不明显。     

SI/HCCI双模发动机的研究现状和发展趋势

SI/HCCI双模发动机在起动和高负荷工况下采用SI模式,在中、低负荷下采用HCCI模式,从而将HCCI发动机扩展到了全工况负荷。本文介绍了SI/HCCI切换实现的方式,并从燃烧、排放、油耗、切换瞬态过程等方面介绍了SI/HCCI双模发动机的研究现状,并指出了其产业化面临的问题及以后的发展趋势。     

Study of performance and emission characteristics of IC engines by using diesel–water emulsion

Due to the shortage of petroleum products and its increasing cost, efforts are on to develop alternate fuels, especially diesel oil, for partial or full replacement. Also, internal combustion engines generate undesirable emissions during combustion process. The emissions exhausted in to the surroundings pollute the atmosphere and causes several problems. The emissions of concern are: unburnt hydrocarbons, oxides of carbon, and oxides of nitrogen (NO_X). Advanced diesel fuel formulations offer significant emission reductions to new and older in-use engines every time the fuel tank is filled. The addition of water to diesel fuel lowers particulate emissions by serving as diluents to the key combustion intermediates that lead to particulate formation. The incorporation of water also reduces NO_X emissions by lowering the peak combustion temperatures through high heat of vaporization. When using water blend diesel, the engine fuel system recognizes the liquid as diesel fuel because the water droplet is encapsulated within a diesel fuel. In this experiment, we have used single cylinder four-stroke engine and the water-blend diesel emulsion is used and the diesel emission test, emulsion emission test, and various gases has been analyzed; smoke meter test is also conducted for various rate of loads. The test results from the engine fuelled with water-blend diesel showed reduction in emissions as compared to that of engine fuelled with conventional diesel. The better emissions in the CI engine using water-blend diesel is due to the incorporation of water which reduces NO_X emissions by lowering the peak combustion temperatures. Water-blend fuel enhances fuel atomization by micro-explosion. The addition of water to diesel fuel lowers particulate emissions by serving as diluents to the key combustion intermediates that lead to particulate formation     

Performance and emission studies on an agriculture engine on neat Jatropha oil

Diesel engines have proven their utility in the transportation, agriculture, and power sectors in India. They are also potential sources of decentralized energy generation for rural electrification. Concerns on the long-term availability of petroleum diesel and the stringent environmental norms have mandated the search for a renewable alternative to diesel fuel to address these problems. Vegetable oils have been considered good alternatives to diesel in the past couple of years. However, there are many issues related to the use of vegetable oils in diesel engine. Jatropha curcas has been promoted in India as a sustainable substitute to diesel fuel. This study aims to develop a dual fuel engine test rig for evaluating the potential suitability of Jatropha oil as diesel fuel and for determining the performance and emission characteristics of an engine with Jatropha oil. The experimental results suggest that engine performance using Jatropha oil is slightly inferior to that of diesel fuel. The thermal efficiency of the engine was lower, while the brake-specific fuel consumption was higher with Jatropha oil compared with diesel fuel. The levels of nitrogen oxides (NOx) from Jatropha oil during the entire duration of the experiment were lower than those of diesel fuel. The reduction of NOx was found to be an important characteristic of Jatropha oil as NOx emission is the most harmful gaseous emission from engines; as such, its reduction is always the goal of engine researchers and makers. During the entire experiment, carbon monoxide (CO), hydrocarbon (HC), and carbon dioxide (CO₂) emissions in the case of using Jatropha oil were higher than when diesel fuel was used. The higher density and viscosity of Jatropha oil causes lower thermal efficiency and higher brakespecific fuel consumption. The performance and emission characteristics found in this study are significant for the study of replacing diesel fuel from fossils with Jatropha oil in rural India, where the availability of diesel has always been a problem.     

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.     

纳米WS2车用机油添加剂在柴油发动机中的应用效果研究

通过柴油发动机台架实验和行车实验,分析了不同工况下自制纳米WS2车用机油添加剂在柴油发动机中的应用效果。结果表明,在FC2000柴油发动机台架上应用时,纳米WS2车用机油添加剂在不同转速和不同负载下均能在一定程度上降低发动机油耗率,减少发动机尾气中NOx含量和颗粒物含量,并且当发动机转速为1 700r/min,负载为70N.m时,节油率最高为9.95%,颗粒物减排率最高为49.3%,而当发动机处于低速、高速、低载和高载等工况时,NOx减排率较高,最高达到36%;在柴油机大客车上应用时,纳米WS2车用机油添加剂使其耗油量下降约14.4%,并能在一定程度上降低发动机的运行噪声,使发动机的有害气体(NOx)排放减少34.8%～51%。综合表明纳米WS2车用机油添加剂具有良好的节能减排效果。     

Piston crevice hydrocarbon oxidation during expansion process in an SI engine

Combustion chamber crevices in SI engines are identified as the largest contributors to the engine-out hydrocarbon emissions. The largest crevice is the piston ring-pack crevice. A numerical simulation method was developed, which would allow to predict and understand the oxidation process of piston crevice hydrocarbons. A computational mesh with a moving grid to represent the piston motion was built and a 4-step oxidation model involving seven species was used. The sixteen coefficients in the rate expressions of 4-step oxidation model are optimized based on the results from a study on the detailed chemical kinetic mechanism of oxidation in the engine combustion chamber. Propane was used as the fuel in order to eliminate oil layer absorption and the liquid fuel effect. Initial conditions of the burned gas temperature and in-cylinder pressure were obtained from the 2-zone cycle simulation model. And the simulation was carried out from the end of combustion to the exhaust valve opening for various engine speeds, loads, equivalence ratios and crevice volumes. The total hydrocarbon (THC) oxidation in the crevice during the expansion stroke was 54.9% at 1500 rpm and 0.4 bar (warmed-up condition). The oxidation rate increased at high loads, high swirl ratios, and near stoichiometric conditions. As the crevice volume increased, the amount of unburned HC left at EVO (Exhaust Valve Opening) increased slightly.     

An investigation of the effect of the lubricant on the soluble organic fraction of particulate emissions from a DI diesel engine

This paper looks at the effect of the lubricant on emissions of paniculate matter. A short literature review is presented, together with experimental results for an engine operating with a synthetic lubricant and a defined fuel. The influence of engine operating parameters such as engine load and speed on particulate matter (PM) emissions is discussed, based on measurement of the composition of the aliphatic fraction of the soluble organic fraction (SOF) of the PM. Based on the results from the experiments, which include some comparative data for a mineral-based lubricant, it is concluded that the method that is generally used to estimate fuel and lubricant contribution to the SOF of the PM has to be reconsidered.     

AutoCAD二次开发实用机械设计系统的探讨

二甲醚(DME)是一种重要的超清洁能源产品,文中分析了二甲醚的理化特性,并在D1110柴油机上掺烧D90(二甲醚柴油质量分数比9:1),结果表明:功率和转矩略低于原柴油机,PM排放大幅度下降,NOx在整个负荷范围内得到控制.结果体现了柴油机燃用二甲醚柴油混合燃料在降低排放方面的优越性能.     

甲醇裂解气-柴油混合燃料对柴油机排放的影响

为研究甲醇裂解气-柴油混合燃料对柴油机排放的影响,设计了一种集成式尾气裂解甲醇反应器和进气共轨系统,将YC6A220型柴油机改装成燃烧由甲醇裂解而成的氢富气与柴油混合燃料的柴油机。实验研究表明,改装后的柴油机在中、高负荷运行时可以使NOx、HC和碳烟大幅度降低,且随着甲醇裂解气掺烧量的增加,各排放物质的减少量增加。     

Size distributions and number concentrations of particles from the DOC and CDPF

Particulate matters (PM) from diesel combustion comprise the major portion of harmful components of air in urban areas. In this study, the effects of DOC and/or CDPF on the size distributions and catalytic reactions of these nano-sized particles were investigated to clarify the exhaust mechanism and to minimize the emission of the nano-sized PM. Parameters of interest in the investigation included sulfur content of the fuels used, air-fuel equivalence ratio, fuel injection pressure, and the engine speed. The number concentration of the particles in diluted exhaust gas was measured by a SMPS in the diametric range of 10–385 nm. The number of nanometer-sized particles increased when the engine was operated at high equivalence ratio with diesel fuel that contained 500 ppm of sulfur. As the sulfur concentration in the fuel increased, the number of the particles smaller than 30 nm increased upon passing DOC and CDPF in the exhaust system of the common-rail diesel engine.