Combustion and emissions of RP-3 jet fuel and diesel fuel in a single-cylinder diesel engine

The combustion characteristics and emission behaviors of RP-3 jet fuel were studied and compared to commercial diesel fuel in a single-cylinder compression ignition(CI)engine.Engine operational parameters,including engine load(0.6,0.7,and 0.8 MPa indicating the mean effective pressure(IMEP)),the exhaust gas recirculation(EGR)rate(0%,10%,20%,and 30%),and the fuel injection timing(–20,–15,–10,and–5°crank angle(CA)after top dead center(ATDC))were adjusted to evaluate the engine performances of RP-3 jet fuel under changed operation conditions.In comparison to diesel fuel,RP-3 jet fuel shows a retarded heat release and lagged combustion phase,which is more obvious under heavy EGR rate conditions.In addition,the higher premixed combustion fraction of RP-3 jet fuel leads to a higher first-stage heat release peak than diesel fuel under all testing conditions.As a result,RP-3 jet fuel features a longer ignition delay(ID)time,a shorter combustion duration(CD),and an earlier CA50 than diesel fuel.The experimental results manifest that RP-3 jet fuel has a slightly lower indicated thermal efficiency(ITE)compared to diesel fuel,but the ITE difference becomes less noticeable under large EGR rate conditions.Compared with diesel fuel,the nitrogen oxides(NOx)emissions of RP-3 jet fuel are higher while its soot emissions are lower.The NOx emissions of RP-3 can be effectively reduced with the increased EGR rate and delayed injection timing.

Performance, emission and combustion characteristics of DI diesel engine running on blends of honne oil/diesel fuel/kerosene/DMC

Honne oil(tamanu)(H),a non-edible vegetable oil is native for northwards of Northern Marianas islands and the Ryukyu Islands in southern Japan and westward throughout Polynesia.It has remained as an untapped new possible source of alternative fuel that can be used as diesel engine fuel.Literature pertaining to use of vegetable oil in diesel engine with kerosene and dimethyl carbonate(DMC)is scarce.The present research is aimed to investigate experimentally the performance,exhaust emission and combustion characteristics of a direct injection(DI)diesel engine,typically used in agricultural sector,over the entire load range,when fuelled with neat diesel(ND)and blends of diesel fuel(D)/DMC/H/kerosene(K).DMC/D/H/K blends have a potential to improve the performance and emissions and to be an alternative to ND.Experiments have been conducted when fuelled with H20(20%H+80%D),HK(20%H+40%K+40%D)and HKD5(20%H+40%K+35D+5%DMC)to HKD15 in steps of 5%DMC keeping H and K percentages constant.The emissions(CO,HC and smoke density(SD))of fuel blend HKD15 are found to be lowest,with SD dropping significantly.The NOx level is slightly higher with HKD5 to HKD15 as compared to ND.The brake thermal efficiency of HKD5 to HKD15 is same and it is higher than that of ND.There is a good trade off between NOx and SD.Peak cylinder pressure and premixed combustion phase increases as DMC content increase.

Investigation to meet China Ⅱ emission legislation for marine diesel engine with diesel methanol compound combustion technology

In order to reduce the pollutant emission and alleviate the pressure of petroleum resources shortage and greenhouse gas emission at the same time,the use of clean and renewable alternative fuel for marine engines is a promising option.In this study,a marine diesel engine,which was modified to run in diesel methanol compound combustion (DMCC) mode,was investigated.After the diesel injection parameters were calibrated,and combined with a sample after-treatment device DOC (diesel oxidation catalyst),the engine could meet the requirements of China II legislation.The overall MSP (methanol substitute percent) reached 54.1%.The value of each pollutant emission was much lower than that in China II emission legislation,and there was almost no methanol and formaldehyde emissions.When methanol was injected into the inlet manifold,the intake air temperature decreased a lot,as well as the exhaust gas temperature,which were beneficial to increase engine thermal efficiency and improve engine room environment.Compared with the engine running in pure diesel mode,when the engine ran in diesel/methanol dual fuel mode,the combustion phase was advanced,and the combustion duration became shorter.Therefore,the engine thermal efficiency increased,and fuel consumption decreased significantly.

Preparation and emission characteristics of ethanol-diesel fuel blends

The preparation of ethanol-diesel fuel blends and their emission characteristics were investigated. Results showed the absolute ethanol can dissolve in diesel fuel at an arbitrary ratio and a small quantity of water(0.2%) addition can lead to the phase separation of blends. An organic additive was synthesized and it can develop the ability of resistance to water and maintain the stability of ethanol-diesel-trace amounts of water system. The emission characteristics of 10%, 20%, and 30% ethanol-diesel fuel blends, with or without additives, were compared with those of diesel fuel in a direct injection(DI) diesel engine. The experimental results indicated that the blend of ethanol with diesel fuel significantly reduced the concentrations of smoke, hydrocarbon(HC), and carbon monoxide(CO) in exhaust gas. Using 20% ethanol-diesel fuel blend with the additive of 2% of the total volume, the optimum mixing ratio was achieved, at which the bench diesel engine testing showed a significant decrease in exhaust gas. Bosch smoke number was reduced by 55%, HC emission by 70%, and CO emission by 45%, at 13 kW/1540 r/min. However, ethanol-diesel fuel blends produced a few ppm acetaldehydes and more ethanol in exhaust gas.

多点分布式导向台燃烧室结构优化模拟研究

为了改善柴油机燃烧室内燃油喷雾撞壁和混合气形成情况,提出一种直喷式柴油机多点分布式导向台燃烧室。将这种新燃烧室结构参数化,对7个设计变量进行多参数协同优化。以一台230 mm缸径的中速船用柴油机为基础模拟缸内工作过程,采用拉丁超立方取样的方法从设计空间得到600个样本点,根据模拟结果分析各设计参数对发动机性能的影响,根据不同的优化目标得到3种新燃烧室结构。仿真结果表明:在75%负荷工况下与原机ω型燃烧室相比,Ⅰ型燃烧室的指示油耗率(indicated specific fuel consumption,ISFC)降低1.83%,烟粒(soot)排放量降低86.83%;Ⅱ型燃烧室的ISFC降低0.97%,NO_(x)排放量降低7.44%,soot排放量降低68.26%;Ⅲ型燃烧室的INO_(x)和soot排放量分别降低10.52%和58.08%,ISFC基本不变。

氨替代率对柴油发动机的燃烧及排放性能的仿真

内燃机引入氨燃料,有利于减少汽车污染物排放。该文研究了掺氨后的柴油发动机的燃烧品质以及污染物排放性能。针对某商用车柴油发动机,采用发动机缸内Converge仿真分析软件,建立三维仿真模型,分析掺氨能量比为0%~40%的5组燃料的燃烧及排放性能。结果表明:随着氨替代率的提高,发动机滞燃期有延长趋势,燃烧持续期先缩短后延长,缸内平均温度、缸压下降;CO、NO和碳烟排放显著降低,氨替代率为40%时,CO排放量降低了41.6%,NO排放量降低了68.7%,碳烟排放量降低了17.2%。因而,柴油发动机掺氨燃烧可有效降低排放水平,但需要控制氨能量比例在合理范围以防止燃烧恶化。

改变喷油压力对柴油机掺烧水/生物柴油性能的影响

基于某常规增压柴油机,研究了掺烧代用燃料生物柴油对柴油机性能的影响。但是,相比柴油,生物柴油黏性较大,含氧量高,对柴油机影响较大。因此对掺烧水/生物柴油做进一步研究,通过提高喷油压力进行优化。在柴油机75%中高负荷下,选择以下工况进行研究:生物柴油掺混比为40%,掺水率为2%~8%,喷油压力为31 MPa~61 MPa。结果表明:随着掺水率增加,缸内爆压下降幅度较小,NO排放降幅较大,能有效缓解生物柴油富氧性带来的NO废气增加问题;随着喷油压力升高,燃油雾化效果变好,最高爆发压力也有所提高,CO与碳烟排放得到优化,这改善了掺烧生物柴油带来的燃油雾化效果变差的不利影响。最终选择生物柴油掺混比为40%,掺水率为8%,组合喷油压力为41 MPa为最佳组合,该组合下的NO排放及缸内爆压与原机相当,CO和碳烟的排放优于原机。仿真结果可为生物柴油的实际应用提供解决措施。

Research on the Physical Property of Diesel-Gasoline Blend Fuel

In this paper, physical property parameters including density, viscosity and surface tension of different contents of diesel-gasoline blend fuel were measured and analyzed. The experiments were performed on the diesel gasoline blend fuels with 4 different volume fractions of diesel(20%, 40%, 60% and 80%) at temperature from 5℃ to 65℃. The influence of temperature and diesel content on the blends' properties was summarized based on experimental data, formulas about the material parameters were established, and the accuracy of these formulas was verified. Besides, saturated vapor pressure, freezing point and flash point of the blend fuel have also been measured and analyzed, and a database of the material parameters of the blends was also established.

低转速工况下喷油量对柴油机缸内压力振荡和排放特性的影响

缸内压力高频振荡现象对发动机低速、低负荷起动过程的燃烧稳定性、运行可靠性和排放物水平有着重要影响。为探明在柴油机低转速工况下喷油量对缸内压力振荡和排放特性的影响规律,基于单缸柴油机试验平台获取了低转速工况(800 r/min)下,喷油压力为40 MPa,喷油脉宽为3500~6000μs时的缸内燃烧压力、放热率、平均指示压力以及NO_(x)和Soot排放量。试验结果表明:在低转速工况下,随着喷油量的增大,缸内压力峰值逐渐增大;压力高频振荡的幅值呈现先增大后减小的非单调变化规律,当喷油脉宽为5000μs时,缸内压力高频振荡幅值达到最大值0.84 MPa。缸内燃烧放热各指标如压力升高率、放热率、滞燃期和平均指示压力与缸压振荡的变化规律呈现高度一致性,缸内压力振荡最大值大致对应上述指标的最佳值。适当强度的缸压振荡有利于缸内燃烧效率的提高。此外,随着喷油量的增大,Soot的排放量呈现两阶段非线性增加的变化规律,NO_(x)的排放量呈现先增大后减小的非单调变化规律,增加喷油量与缸内压力振荡导致的缸内当量比浓度转变造成了上述变化。

氨柴双燃料高压缩比发动机柴油喷射策略优化

为了提高氨柴发动机的燃烧效率与热效率,研究了柴油喷射策略对燃烧与排放特性的影响。在一台6缸、压缩比21的氨柴发动机上,采用了进气道喷射氨并缸内2次喷射柴油的控制方法。用柴油第1次喷射来活化缸内热氛围,用第2次喷射来控制燃烧相位。结果表明:提前柴油第1次喷射时刻,可使氨柴模式的氮氧化物(NOx)排放减少30%;增加第1次喷射量有助于提高氨燃烧效率,并能减少85%的N2O和50%的CO排放。随第1次喷射量的增加,有效热效率先升高后降低。相比同压缩比下纯柴油模式,优化的氨柴双燃料模式的柴油喷射策略下,最高有效热效率提高1.2个百分点。因此,该文的优化柴油直喷策略,可节能和降低重型车辆的碳排放。

掺烧不同比例乙醚对船用柴油机燃烧和排放性能的影响

为研究掺烧不同比例的乙醚对柴油机燃烧及排放特性的影响,以4190Z L C-2型船用中速机为研究对象,利用AVL_FIRE仿真软件构建燃烧室高压循环模型,在全负荷工况下对比实测与仿真缸压和放热率曲线,验证模型的准确性。在全负荷工况下,通过仿真模拟实验,在柴油中分别掺混体积分数为0%、5%、10%、15%的4种比例的乙醚,研究其对柴油机燃烧和排放特性的影响。结果表明:与燃烧纯柴油相比,使用柴油-乙醚混合燃料,缸内最大爆发压力和缸内最高温度均有所下降,对应的曲轴转角也稍有延后。增加乙醚的掺混比例,CO和NO的排放量均呈现降低趋势,碳烟排放略有增加。在反应过程中,乙醚加入延长了混合燃料的滞燃期,油气混合更加充分,放热过程稳定,提升柴油机的稳定性。当乙醚掺混体积分数为15%时,NO排放量较原机降低12.7%,CO排放量降低7.8%,碳烟排放量增大10.7%。

喷油策略对甲醇/PODEn双燃料压燃燃烧特性的影响

为提高直喷柴油发动机的缸内燃烧效率,降低污染物的排放,研究了不同喷油策略下的甲醇/PODEn混合燃料燃烧、排放特性。基于计算流体动力学(CFD)和仿真分析软件Converge,对某款预混压燃燃烧(PCCI)的直喷柴油发动机进行三维建模;在发动机转速为1200 r/min,在进气压力100kPa、进气温度340.6 K的低负荷初始工况下,进行了仿真计算。结果表明:采用单次喷油时,提前喷油能够大幅提升缸压峰值和比放热峰值,使燃油利用率增加,且主要污染物显著减少;但过早喷油,反应速率加快,污染排放增多。采用2次喷油时,随着预喷时刻的提前,预喷、主喷的正时间隔变长,缸压曲线变化不大;比放热曲线出现2个峰值,峰值略微降低,且喷射时刻(曲轴转角,CA)提前;与各自的质量排放峰值比较,碳烟(Soot)、氮氧化物(NOx)、一氧化碳(CO)的质量排放,分别降低了6.89%、5.41%、23.31%;优化后的预喷、主喷的CA为-27°、-22°。

柴油/天然气双燃料发动机油气耦合分层燃烧

针对柴油/天然气反应活性控制压缩点火发动机低负荷热效率低、未燃CH_(4)和CO排放高等问题,本文提出了一种发动机双进气道双阀燃气独立喷射方法,通过三维CFD仿真,对比研究了双阀燃气喷射比例对缸内油气耦合分层、燃烧以及排放特性的影响规律。结果表明:双阀燃气喷射比例对缸内混合气形成和燃烧过程有重要影响,通过微量柴油分段喷射和调整双阀燃气喷射比例,缸内能够形成高低反应活性燃料的耦合分层,缸压和放热率峰值增加,峰值相位提前,燃烧持续期缩短,未燃CH_(4)和CO排放总体呈现下降趋势。当双阀中直管燃气喷射比例为80%时,不仅能够提高发动机热效率,并且可以在NO排放不增加的情况下实现CH_(4)和CO排放的同时降低。

机车柴油机开发流程研究及技术趋势展望

介绍了柴油机在内燃机车中的总体应用情况,阐述了机车柴油机的总体开发流程,并概述了国产机车柴油机的类型及发展情况。同时,重点对机车柴油机设计研制的发展过程及其所面临的技术问题进行了研究,并给出了解决上述问题的有效措施。最后,对机车柴油机的未来发展趋势进行了展望。

柴油机燃用菜籽油-柴油混合燃料的试验研究

文章在一台双缸直喷柴油机上开展了燃用菜籽油-柴油混合燃料时的发动机性能、燃烧和排放特性研究,并与燃用柴油时相比较。研究结果表明:当菜籽油的掺混比(体积分数)不大于20%时,混合燃料的运动粘度和密度接近于柴油;在低负荷工况下,燃用混合燃料时的燃烧开始时间与柴油几乎相同,但缸内压力峰值和放热率相对较高;在高负荷工况下,燃用混合燃料时的燃烧开始时间略早于柴油,特别是VD50;在低负荷工况下,燃用VD50时的燃油消耗率最高,有效热效率最低;随着发动机负荷的逐渐增加,燃用混合燃料与柴油时的燃油油耗率差异逐渐减小,有效热效率也不断提高;在低负荷工况下,燃用混合燃料时的碳烟排放量较高,高负荷时则与之相反;在低负荷工况下,燃用混合燃料时的NOx排放量略低于柴油,高负荷时则几乎相同;在整个负荷范围内,燃用混合燃料时的CO和HC排放量均较高。

甲醇燃料低速机性能仿真研究

基于某型低速柴油机,利用CONVERGE仿真软件建立了柴油模式缸内燃烧模型,并根据试验数据进行了燃烧模型标定。在标定的柴油模式缸内燃烧模型的基础上,将3个甲醇喷射器和3个引燃柴油喷射器安装在缸盖上,每个甲醇喷射器与引燃柴油喷射器成30°夹角安装,开展了柴油引燃甲醇燃烧模式缸内燃烧模拟,在100%负荷下研究了甲醇喷射器喷孔大小、引燃柴油喷射正时对发动机着火及燃烧过程的影响及与原柴油模式的对比。研究表明:甲醇喷射持续期为25°时,可以得到与原柴油机相近的缸内峰值压力水平;甲醇喷射正时不变的情况下随着引燃油喷射正时的提前角减小,发动机整体性能呈下降趋势,但下降幅度较小。

燃烧室形状对国六柴油机性能的影响

为满足国六b排放法规要求,基于同一台国六柴油机,在相同压缩比下对3种不同形状特征的ω型燃烧室进行了对比研究。使用仿真模拟及台架测试的方法,研究了不同燃烧室特征对柴油机经济性及排放的影响。研究表明:深坑、大凹坑半径的燃烧室燃油消耗率较差,但烟度较好;浅坑、小凹坑半径的燃烧室烟度较差,但燃油消耗率较好;而凹坑深度及凹坑半径适中的燃烧室燃油消耗率及烟度均较优,按此燃烧室特征设计开发的国六柴油机具有良好的经济性及排放表现。

掺混乙醇对菜籽油/柴油混合燃料燃烧及排放特性的影响

为改善发动机燃用高比例生物质混合燃料的性能,在中等比例的菜籽油/柴油混合物(VD50)中分别添加10%、20%和30%体积比的乙醇,在助溶剂的作用下制备了菜籽油/柴油/乙醇混合燃料(VD50E10、VD50E20和VD50E30),并对其主要性能进行测试。在1 800 r/min不同负荷条件下,研究乙醇掺混比对中等比例菜籽油/柴油混合燃料燃烧和排放特性的影响,并将其与柴油进行对比。结果表明,在低负荷时,随着乙醇掺混比的增加,混合燃料的燃烧开始时间延迟,缸内峰值压力和瞬时放热率峰值逐渐减小,其中VD50E30最小;在高负荷时,混合燃料的瞬时放热率峰值增加,VD50E30的缸内峰值压力略高于其他试验燃料,柴油的缸内峰值压力最小。随着乙醇体积分数的增加,混合燃料CO和HC的排放量增加,而碳烟和NOx的排放量减小。在某些负荷工况下,VD50E30的碳烟排放量甚至低于柴油。

船用柴油机替代燃料研究现状及发展趋势

结合当前船用柴油机替代燃料现状,介绍了天然气、生物柴油、甲醇、乙醇等替代燃料的主要特点,并从替代燃料的喷雾特性、燃烧特性、排放特性三个方面对近年来的发展研究进行了综述。最后,根据当前清洁、高效、可持续发展的船舶动力推进技术发展理念,探讨了燃料电池动力、电动力、清洁能源混合动力等动力推进技术的发展趋势。

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 %～ 2 5 %乙醇柴油燃料以及柴油和乙醇的基本物理性质 ,在ZS1 1 0 0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、1 5 %乙醇柴油、1 5 %乙醇柴油加十六烷值改进剂的燃烧过程。