乙醇-柴油-汽油混合燃料的燃烧与排放特性

以汽油为助溶剂配制出均匀稳定的乙醇-柴油-汽油混合燃料,对比分析了单缸四气门135柴油机燃用不同配比混合燃料时的燃烧与排放特性,同时研究了燃用混合燃料时供油提前角变化和使用HL伞喷油嘴对柴油机性能的影响.结果表明:柴油机燃用适当配比的乙醇-柴油-汽油混合燃料,动力性、经济性基本保持不变,碳烟和NO2排放显著降低;着火滞燃期延长,缸内平均温度下降,燃烧速率加快,燃烧持续期缩短;当使用HL伞喷油嘴燃用E20G15燃料时,着火滞燃期进一步延长,油气混合速率和混合气均匀度明显提高,在整个工况范围内,气缸压力和缸内平均温度均较低,碳烟和NO2排放同时降低,其燃烧过程具有明显的热预混合燃烧特征.     

柴油机燃用乙醇柴油燃料的燃烧与排放特性

对燃用多种比例乙醇柴油的柴油机燃烧与排放特性进行了试验研究。测试了5％～25％乙醇柴油燃料以及柴油和乙醇的基本物理性质，在ZS1100柴油机上对各种比例的乙醇柴油测试了发动机在主要工况下的性能与排放特性，并用光学可视化方法研究了柴油、15％乙醇柴油、15％乙醇柴油加十六烷值改进剂的燃烧过程。对试验进行了分析。     

高原环境下油品对柴油机燃烧特性的影响研究

在模拟高原条件下,针对3种不同品质的柴油(十六烷值和馏分)对某增压柴油机的燃烧特性的影响规律进行了研究分析,并据此简要分析在高原运行时出现活塞烧蚀故障与所用油品的关系。结果显示:目前在用柴油由于其十六烷值低,柴油不易被压燃着火,滞燃期长,且初馏温度低,柴油容易蒸发,预混合燃烧期内积累的热量多,造成缸内压力的升高速率增大,燃烧过程粗暴;海拔升高,空气密度下降,柴油的着火时间延长,燃烧速度加快,最大压力升高率增大,由此产生强烈的热负荷和机械负荷冲击,容易造成活塞烧蚀。     

直喷式柴油机燃用柴油——LPG双燃料燃烧与排放特性的试验研究

对在单缸直喷式柴油机上进行的柴油——LPG双燃料发动机燃烧和排放特性研究表明，双燃料发动机动力性没有出现功率损失的现象，热效率在高负荷时有一定的改善；着火滞燃期比纯柴油长，燃烧持续期缩短。排放试验表明，双燃料发动机为降低NOx和微粒排放提供一种有效途径。     

添加乙醇对柴油-生物柴油混合燃料性能的影响

在一台小型直喷式柴油机上进行柴油-生物柴油(柴油70%,生物柴油30%)与柴油-生物柴油-乙醇(柴油70%,生物柴油20%,乙醇10%)两种混合燃料的燃烧、油耗和排放性能对比试验.分析了乙醇的加入对柴油-生物柴油混合燃料的发动机燃烧压力、滞燃期、放热规律、比油耗等的影响.     

LPG／柴油双燃料发动机燃烧特性研究

利用燃烧分析仪测录示功图并进行放热规律分析，结果表明ＬＰＧ／柴油双燃料与纯柴油相比，小负荷时的最高燃烧压力及最高压力上升率较小，大负荷时的最高燃烧压力及最高压力上升率较大；滞燃期略长，最大放热率高，燃烧持续期短，依据这些特征正确地调整使用参数和组织燃烧过程，将柴油机进行简单改造后改燃ＬＰＧ／柴油双燃料可望得良好的效果。     

电控汽油发动机数据流点火提前角分析

正一、混合汽的燃烧过程混合汽的燃烧包含着火落后期、明显燃烧期、补燃期(后燃期)三个过程。1.着火落后期从火花塞跳火开始到形成火焰中心为止这段时间称为着火落后期。火花塞跳火后,并不能立刻形成火焰中心,因为混合汽氧化反应需要一定时间。火花能量使局部温度迅速升高,(火花放     

发动机燃用水乳化柴油的研究进展

综述了柴油机燃用水乳化柴油的燃烧与喷雾特性、动力性与经济性及排放特性,对比分析了发动机燃用水乳化柴油与普通柴油在性能上的差异及其原因,总结了水乳化柴油在柴油机上的应用优化方法。结果表明:与柴油相比,乳化柴油着火滞燃期延迟,燃烧持续期缩短,喷雾贯穿距变长或相差不大,火焰升起高度增加;燃用乳化柴油时动力性下降,但有效热效率较柴油升高;乳化柴油可以明显降低NOx和炭烟排放,但多数工况下HC和CO排放有所升高,低转速和中低负荷工况下尤为明显;燃用乳化柴油时颗粒物数量浓度增加,体积浓度减小,且对于醛类和噪声排放并没有改善作用;添加合适添加剂或结合发动机技术协同作用,可以针对性地改善乳化柴油的燃烧过程,进一步起到节能减排的效果。基于燃料稳定性与燃料理化特性综合优化目标的燃料设计,以及适用于乳化柴油的高压共轨柴油机燃烧组织参数优化是未来的研究方向。     

二甲醚发动机的燃烧与排放研究

在一台2135直喷柴油机上，对燃油供给系统进行了适当的改造，测试了燃用二甲醚发动机的燃料喷射时刻、气缸压力和有害排放，计算分析了放热规律及滞燃期变化规律。研究结果表明，在供油提前角相同的情况下，二甲醚的喷射延迟比柴油长而滞燃期比柴油短，着火时刻落后于柴油；二甲醚的最大放热速率小，而燃烧持续期短；二甲醚发动机接近无烟排放，N0x排放浓度显著低于柴油机。     

燃油品质对柴油机燃烧循环变动特性及性能的影响

燃用3种柴油进行了柴油机性能试验,研究了不同转速和负荷下柴油对燃烧循环变动特性及柴油机性能指标的影响。研究表明:在全负荷速度特性下,随着转速的升高,最高燃烧压力和最大压力升高率的循环变动率逐渐减小;相同转速下,负荷越小,最高燃烧压力和最大压力升高率的循环变动率越大;燃油的十六烷值越小,其自燃性越差,着火滞燃期越长;初馏温度较低时,轻馏分含量较高,参加预混合燃烧的份额大,容易造成燃烧速度加快,压力升高速度快,导致最高燃烧压力和最大压力升高率的循环变动率变大,对应燃烧过程变粗暴,由此实现的动力性能和经济性能变差。     

柴油-酒精混合燃料发动机的性能研究

在分析柴油—酒精混合燃料物理化学特性的基础上，研究了不同混合比例的柴油—酒精混合燃料发动机的性能。研究表明：柴油醇燃料发动机的有效燃油消耗率较柴油机的升高，而有效能耗率有一定程度的降低；发动机的碳烟排放明显降低，在保持同样排温的前提下，其功率有一定程度的升高，尾气排放明显降低；柴油机使用混合燃料后，滞燃期延长，燃烧持续期缩短。在采用推迟供油的条件下，柴油—酒精混合燃料发动机的尾气排放性能可以得到较大幅度的提高。     

Combustion characteristics of hydrotreated vegetable oil – diesel blend under EGR and supercharged conditions

This paper investigates the effects of Hydrotreated vegetable oil-diesel blend to combustion characteristics under various ambient oxygen concentrations and ambient pressure. Combustion characteristics were investigated using heat release rate analysis, two color method, soot concentration measurement and NOx concentration measurement. The experiments were carried out on a rapid compression expansion machine to simulate the ambient condition of a CI engine at TDC. Synthetic gas with oxygen concentrations of 21 %, 15 % and 10 % were used to simulate EGR conditions. A single hole injector was used with five different fuels: commercial diesel, HVO-commercial diesel blends and HVO. The results showed that increasing HVO blending percentages decreased ignition delay, flame temperature, soot concentration and NOx concentration. Heat release at oxygen concentration of 10 % dramatically dropped due to a shortened ignition delay, which resulted in less combustion. A decreased oxygen concentration from applied EGR conditions not only increased ignition delay, heat release, flame temperature and NO_x concentration, but also increased soot concentration. A combination of EGR and supercharged conditions by increasing ambient pressure and decreasing oxygen concentrations resulted in increased heat release, decreased flame temperature, ignition delay and soot concentration, compared to EGR conditions.     

Instantaneous 2-D visualization of spray combustion and flame luminosity of GTL and GTL-biodiesel fuel blend under quiescent ambient conditions

An experimental study has been performed on spray combustion and two-dimensional soot concentration in diesel (ULSD), GTL and GTL-biodiesel fuel jets under high-pressure, high-temperature quiescent conditions. Instantaneous images of the fuel jets were obtained with a high-speed camera. It was confirmed that by blending GTL with 20% rapeseed biodiesel, certain fuel properties such as kinematic viscosity, density, surface tension, volatility, lower heating value and others may be designed and improved to be more like those of conventional diesel fuel but with considerable decrease in the amount of sulfur, PAH, cold filter plugging point, etc. The results showed that the spray tip penetration increased and the spray cone angle decreased when 20% biodiesel fuel was added to GTL fuel. Autoignition of the GTL-biodiesel blend occurred slightly earlier than that of diesel fuel. Experiments under high-pressure, high-temperature conditions showed that higher injection pressure induced a lower soot formation rate. The integrated flame luminosity, which serves as an indicator of soot concentration in the fuel jet, was slightly higher for the GTL-biodiesel blend than for pure GTL fuel due to the slightly higher sulfur content of pure biodiesel fuel.     

新型含氧混合燃料对柴油机燃烧和排放的影响

进行了丙二醇单丙醚(PGPE)/乙二醇二甲醚(EGDE)混合物用作柴油机含氧燃料的研究,对比了柴油机燃用柴油、PGPE/EGDE体积分数分别为15%和25%的混合燃料时的燃烧和排放特性。试验表明PGPE/EGDE混合燃料的燃烧特性与0号柴油相比,滞燃期、燃烧持续期和热效率等差异较小,最高燃烧压力小幅下降;显著降低柴油机中高负荷时的碳烟和CO排放,降幅分别可达73.9%和37.5%,NOx排放无显著变化,但HC排放增加。     

新型复合含氧添加剂对柴油机燃烧特性的影响

分析了自行研制的新型复合含氧添加剂(记为FHYJ)的理化特性,在车用BJ493Q柴油机上进行了燃用FHYJ掺烧比例为9%的FHYJ—柴油混合燃料的试验,测量了缸内压力、压力升高率和放热率。比较和分析了燃用柴油和FHYJ—柴油混合燃料的燃烧特性,探讨了添加剂和混合燃料对柴油机滞燃期、预混合燃烧期、扩散燃烧期以及燃烧持续期等参数的影响。结果表明,在柴油机不作任何改动的前提下,掺烧FHYJ清洁燃料复合含氧添加剂,缸内压力、压力升高率和放热率在低负荷下均与原机基本相当,在中、高负荷有所下降,滞燃期、预混燃烧期均较原机延长,扩散燃烧期和燃烧持续期均较原机缩短,且其变化程度均随负荷的增大而增大。     

发动机燃用生物柴油对NO_x排放影响的试验研究

在一台涡轮增压直喷式柴油机上分别燃用生物柴油、掺混油和石化柴油进行试验,对滞燃期、燃烧始点、燃烧压力、燃烧温度、预混燃烧放热规律和扩散燃烧放热规律等燃烧参数对NOx排放的影响进行了研究。结果表明,随着燃料中生物柴油含量的增加,发动机滞燃期缩短,燃烧始点提前,最高燃烧压力增加,最高燃烧温度上升,预混燃烧累积放热率减小,扩散燃烧累积放热率增大;燃烧参数的变化是造成NOx排放升高的主要原因。     

Influence of injection parameters on the transition from PCCI combustion to diffusion combustion in a small-bore HSDI diesel engine

In this paper, the influence of injection parameters on the transition from Premixed Charge Combustion Ignition (PCCI) combustion to conventional diesel combustion was investigated in an optically accessible High-Speed Direct-Injection (HSDI) diesel engine using multiple injection strategies. The heat release characteristics were analyzed using incylinder pressure for different operating conditions. The whole cycle combustion process was visualized with a high-speed video camera by simultaneously capturing the natural flame luminosity from both the bottom of the optical piston and the side window, showing the three dimensional combustion structure within the combustion chamber. Eight operating conditions were selected to address the influences of injection pressure, injection timing, and fuel quantity of the first injection on the development of second injection combustion. For some cases with early first injection timing and a small fuel quantity, no liquid fuel is found when luminous flame points appear, which shows that premixed combustion occurs for these cases. However, with the increase of first injection fuel quantity and retardation of the first injection timing, the combustion mode transitions from PCCI combustion to diffusion flame combustion, with liquid fuel being injected into the hot flame. The observed combustion phenomena are mainly determined by the ambient temperature and pressure at the start of the second injection event. The start-of-injection ambient conditions are greatly influenced by the first injection timing, fuel quantity, and injection pressure. Small fuel quantity and early injection timing of the first injection event and high injection pressure are preferable for low sooting combustion.     

Study of diesel spray combustion and ignition using high-pressure fuel injection and a micro-hole nozzle with a rapid compression machine: improvement of combustion using low cetane number fuel

This study aimed to reduce NO_x and soot by creating a more homogeneous lean fuel distribution in a diesel spray using high-pressure fuel injection and a micro-hole nozzle. This injection system shortened the ignition delay, but a homogeneous lean fuel distribution in the diesel spray was not achieved. Using a lower cetane number fuel, the resulting longer ignition delay made a uniform, lean fuel distribution in the diesel spray possible with this injection system. Ignition and combustion were analyzed by the combustion chamber pressure history, and flame temperatures and KL values were analyzed by the two-color method.     

Predicting auto-ignition characteristics of RCCI combustion using a multi-zone model

The objective of new combustion concepts is to meet emission standards by improving fuel air mixing prior to ignition. Since there is no overlap between injection and ignition, combustion is governed mainly by chemical kinetics and it is challenging to control the phasing of ignition. Reactivity Controlled Compression Ignition (RCCI) combustion aims to control combustion phasing by altering the fuel ratios of the high- and low octane fuel and injection timings. In this study the dual fuel blend is prepared with gasoline and diesel fuels. The applied injection timings of the diesel are very early (90 to 60° CA bTDC). In the detailed reaction mechanism, n-heptane and iso-octane represent diesel and gasoline fuel, respectively. A multi-zone model approach is implemented to perform RCCI combustion simulation. Ignition characteristics are analyzed by using CA50 as the main parameter. In the experiments for the early direct injection (DI) timing advancing the injection time results in a later ignition. Qualitatively, the trend effect of the diesel injection timing and the effect of the ratio gasoline/diesel are captured accurately by the multi-zone model.