柴油机燃用柴油-二甲醚混合燃料对其性能及排放的影响

二甲醚是一种适用于压燃直喷式柴油机的很具潜力蹬代用燃料，除了无碳烟排放的重要特点以外，和柴油相比二甲醚还具有较好的燃烧性能，较低的自然温度和较好的雾化特性，但二甲醚较差的润滑性会带来一些问题，例如磨损和泄漏，这是一个很难处理的问题。文中对直喷式柴油机燃用二甲醚柴油混合燃料进行了实验研究，对二甲醚重量比分别为0％（纯柴油），10％和20％的混合燃料进行了评测，并测量了发动机的性能和排放，结果表明，与纯二甲醚相比，柴油－二甲醚混合燃料具有较高的润滑性能，及和纯柴油相比，具有较好的喷射雾化性能，同时发现发动机在燃用柴油时的工作特性和燃用柴油－二甲醚混合燃料时的工作特性是可以比较的，当混合燃料中的二甲醚的比例为20％，NOx，碳烟和CO的排放量分别降低了11％，42％和29％，和燃用柴油相比，HC排放量在轻载时较高，在重载时较低。     

Comparison of coal-based dimethyl ether and diesel as vehicle fuels from well to wheel in China

With life cycle assessment (LCA) methodology, a life cycle model of coal-based vehicle fuels (CBVFs) including coal-based dimethyl ether (CBDME) and coal-based diesel (CBD) is established. Their primary energy consumption (PEC) and global warming potential (GWP) from well to wheel including feedstock extraction, fuel production, fuel consumption in vehicle and energy transportation are calculated and compared. Results show that the life cycle PEC and GWP of CBD pathway are 1.17 and 1.34 times as CBDME pathway. Based on the above results, CBDME will become a choice with great potential to replace conventional petroleum-based diesel (CPBD) in China.     

煤合成柴油(F-T柴油)在柴油机上的试验研究

试验研究了单缸柴油机燃用F-T柴油和0号柴油的燃烧特性和排放特性。与发动机燃用0号柴油相比，燃用F-T柴油时燃油消耗率降低，有效热效率升高，有害排放降低，结果表明，F—T柴油是一种高品质的柴油机代用燃料。     

电喷汽油机燃用甲醇-汽油混合燃料的性能

为了研究不同体积分数的甲醇-汽油混合燃料对多点电喷汽油机性能和排放的影响,通过发动机台架试验,对比分析了发动机的动力性、经济性及排放特性,并用气相色谱分析仪测量了目前法规尚未限制的甲醇和甲醛排放,探讨其排放特性及生成机理。实验结果表明:在外特性工况运行时,甲醇-汽油混合燃料发动机的输出功率在高转速时略高于汽油机,有效燃料消耗率比汽油机低,有效热效率比汽油机高;在负荷特性工况运行时,混合燃料发动机的有效燃料消耗率和有效热效率与汽油机基本相当;随着混合燃料中甲醇体积分数的增加,CO排放有所降低,NOx排放几乎保持不变,THC排放在大负荷时略有升高;混合燃料发动机的甲醛排放明显高于汽油机,并且随甲醇体积分数的增加而增大,而甲醇排放低于汽油机。     

舰用高压共轨柴油机燃烧与排放的仿真计算

利用高速闪光摄影技术，对高压喷射喷雾体空间发展规律进行了试验分析，提出了一个计算高压喷射喷雾体发展的数学公式．在正确描述高压燃油喷雾的基础上，建立了一个能预测高压共轨柴油机性能和排放的准维燃烧模型．此模型改进了燃油喷射模型以及碳烟的生成与氧化模型，考虑了燃烧区的区间传热和缸内工质的对流辐射传热，由此对一台高压共轨柴油机进行了仿真计算，计算与试验结果对比分析表明，改进后的燃烧与排放模型能够较好地反映缸内各区的燃烧与排放情况．     

基于最大熵原理的喷雾液滴尺寸和速度联合分布函数

应用最大熵原理和动量守恒定律,从理论上建立了喷雾液滴尺寸和速度联合分布函数。应用该方程编制数值计算程序,对纯柴油与质量掺混比为30%(L30)的柴油/液化石油气(LPG)混合燃料的喷雾液滴尺寸和速度联合分布进行了数值计算,比较了两种燃料的雾化特性。比较结果表明:由于L30闪急沸腾效应的影响,其液滴尺寸分布曲线的峰值明显高于柴油的分布曲线峰值,且峰值和曲线整体趋势都向小颗粒方向偏移,说明喷射L30产生的液滴颗粒比柴油颗粒小;L30的速度分布曲线峰值较高,且位于小速度范围,说明小速度液滴所占的比例更大。液滴尺寸与速度(D-u)等高线图表明:液滴颗粒越小,其速度分布范围越广;液滴速度越小,其尺寸分布范围越大。L30液滴尺寸与速度联合分布的收敛速度较快,说明L30喷雾所产生的小颗粒和小速度液滴更加密集,雾化质量更佳。     

Fuel Property Effects on Liquid and Vapor Penetrations of Evaporating Sprays

The purpose of this study is to investigate the effect of fuel properties on liquid and vapor penetrations in evaporating spray systems. A recently developed model, which can simultaneously account for the finite thermal conductivity, finite mass diffusivity and turbulence effects within atomizing multi-component liquid fuel sprays, is utilized for the numerical predictions. Two different multi-component fuels with different boiling temperatures, densities and other thermal properties are implemented in the KIVA-3V computational fluid dynamics (CFD) code to study the evaporation behaviors. A six-component surrogate fuel is used to emulate the relevant volatility property of the real diesel fuel, and a second bi-component fuel is chosen to represent a low boiling-temperature fuel. The numerical results are compared with the experimental data, and the representative results are obtained. For a lower density and lower boiling temperature fuel, the liquid penetration length is shorter. However, the vapor penetration lengths are not affected by the fuel type in terms of fuel volatility. Available experimental data are used for validation and appraisal of the multi-component evaporation model.     

Spray Characteristics with High-Speed Tomographic Particle Image Velocimetry Under Non-Flash and Flash Boiling Conditions

Compared with port fuel injection engines, direct injection(DI) gasoline engine is becoming the mainstream of gasoline engines because of its higher fuel economy and excellent transient response. It has been proven that fuel spray characteristics in DI engines are crucial to the performance and emission quality of the engine. Flash boiling spray has great potential to achieve high fuel economy and low emission by dramatically improving the fuel atomization and vaporization and it has different spray-air interaction behavior as compared with non-flash boiling one, while its mechanism is more complex as compared with subcooled spray. We investigate the time-resolved spatial velocity field of the spray using 2-camera high-speed 3 D3 C(3-dimension 3-component)tomographic particle image velocimetry(PIV) diagnostic technique. A 10 mm thick laser sheet is used to illuminate the fuel spray. Characteristics of both non-flash and flash boiling sprays are studied. A single-hole injector is mounted within a heat exchanger so that different fuel temperature can be accessed. In the experiment, n-pentane is used as the fuel. For the non-flash boiling spray, the velocity field of the liquid spray is mostly consistent to the injection direction. With the increase of the degree of superheat(Do S), the overall velocity scale decreases especially at the spray tip. Meanwhile, larger swirls occur at the lower part of the flash boiling spray, which means stronger spray-air interaction occurs at a higher Do S.     

四孔喷油器流量分布对燃油喷雾及柴油机性能的影响

探讨了四孔喷油器流量分布对燃油喷雾和柴油机性能的影响。结果表明,不正常的流量分布可改变喷雾的形状及各孔油束的射程,导致燃油在燃烧室中分布情况的恶化,从而使柴油机性能,特别是在低速大负荷工况下的性能下降。     

柴油与LPG/柴油双燃料喷雾特性的对比

采用高分辨率数码照相机对柴油与LPG／柴油混合喷雾特性进行了对比研究。结果表明，随着LPG掺混比的增大，喷雾油滴的平均直径减小，油滴尺寸数目分布曲线向小颗粒方向偏移，小颗粒油滴数目增多，雾化质量提高，使发动机碳烟排放大幅度降低；大颗粒油滴尺寸变化不大，小颗粒油滴尺寸变小，相对尺寸范围和发散边界扩大。随着喷雾贯穿距离的增大，柴油油滴的粒度增大；混合燃料的油滴尺寸的数目分布向小颗粒偏移，累积容积油滴直径则增大；相对尺寸范围和发散边界呈减小趋势，油滴容积分布在较大油滴的范围内渐趋均匀；喷射距离较长，油束射程总是等于油束到达燃烧室壁面的最大距离。     

Experimental study on flow structure of a swirling non-premixed syngas flame

The development of integrated gasification combined cycle（IGCC） systems provides cost-effective and environmentally sound options for meeting the future coal-utilizing power generation needs in the world.The combustion of gasified coal fuel significantly influences overall performance of IGCC power generation.Experiments are performed to investigate the characteristics of syngas swirling flame using the particle image velocimetry （PIV） in this paper.With the increase of CO/H₂ molar ratio,the distance between the nozzle and the fuel vortex in flame increases at first,and then reduces slowly;maximum of the axial mean velocity increases continuously, but the axial mean velocity peaks on the side of centerline change little.The experiment indicates that with the increase of fuel to air velocity ratio,the fuel vortex grows up at first,and then becomes thinner;the distance from the fuel vortex to the nozzle reduces at first,and then increases;inner boundary of the recirculating zone increases. Furthermore,difference between the methane swirling flow field and the syngas swirling one is analyzed in this paper.It can establish the benchmarks for the development and validation of combustion numerical simulation by the data from this experiment.     

柴油溶气喷射雾化粒径特性分析与计算

运用激光粒度分析仪(LDSA)和瞬间高速摄影等装置,就喷射压力对溶解有二氧化碳气体的柴油喷射雾化特性的影响进行研究. 研究结果表明将CO2气体溶解于柴油只能在特定的喷射压力范围内改善喷射雾化. 同时,依据柴油喷射雾化粒径的实验数据,采用曲线拟合的方法建立了计算不同溶气量的柴油在不同喷射压力下喷雾液滴的索特直径(SMD)的经验公式.     

Multi-Component Model of Diesel Sprays Under High Injection Pressure

The combustion efficiency of a diesel engine depends not only on spray characteristics but also on fuel-air mixing characteristics. Based on the original spray model, a new spray model is established in this paper to accurately predict the diesel spray, and then a multi-component evaporation model is added into it. The model takes the influence of component concentration gradient and species on its evaporation rate in the liquid phase into account. This paper studies the spray characteristics (spray penetration, spray angle and spray morphology) and fuel-air mixing characteristics (spray area, spray volume and air entrainment mass) using the spray model, and the results are compared with the experimental results. The comparison shows that the simulated spray penetration and spray angle are close to the experimental results with the average deviations less than 3%. Moreover, this paper studies the spray area, spray volume and air entrainment using empirical formula under different conditions. And the maximum deviations of the spray volume, spray area and air entrainment mass are less than 5% as compared with the test values. Overall, this spray model can predict the diesel spray characteristics and fuel-air mixing characteristics under high injection pressure accurately.     

喷雾特性对生物柴油燃烧和排放特性的影响

在手压泵试验台上进行了生物柴油与柴油的喷雾对比试验,在一台单缸直喷柴油机上进行了生物柴油与柴油燃烧和排放性能对比试验.分析了燃料喷雾特性的液滴粒径尺寸分布和特征参数,研究了燃用生物柴油与柴油燃烧和排放规律的差异及其本质原因.研究结果表明:与柴油相比,生物柴油喷雾锥角小,粒子总数少,小直径粒子比例低,最大粒子直径大;在转速为1 500 r*min-1与平均有效压力为0.531 MPa时,生物柴油最大燃烧压力、最大压力升高率以及最大燃烧放热率分别降低了1.91%、30.10%和29.32%,生物柴油燃烧持续期长于柴油;在转速为1 500 r*min-1时,燃用生物柴油HC、CO和烟度排放平均分别降低17.17%、26.73%和37.85%,NOX排放平均增加21.93%.     

以沥青为燃料的沥青拌合设备加热装置的研究

阐明了石油沥青是一种燃烧不产生致癌物质、能燃尽的特殊液体燃料,替代柴油作燃料经济效益明显,且管理方便。深入讨论了双重内击式雾化喷咀的特点和设计中的问题及特种燃料沥青使用中的一些工程问题。     

喷射压力对生物柴油掺混燃料喷雾特性的影响

基于自行设计的定容弹和高压共轨喷油试验台,通过高速相机对不同掺混比的柴油‐生物柴油混合燃料的喷雾过程进行瞬时拍摄,并运用图像后处理技术量化分析喷射压力对掺混燃料的喷雾锥角和喷雾贯穿距离等宏观喷雾特性的参数影响。结果表明：喷射压力从75 M Pa提高到135 M Pa时,喷射压力对喷雾锥角的影响在4°～5°左右;喷雾锥角和喷雾贯穿距离均逐渐增大,混合燃料的雾化质量有所改善。     

柴油溶气对稳定喷射雾化影响的研究

本文进一步研究了溶气对稳定喷射的雾化特征的影响。着重研究了不同溶气方法、不同被溶气体对溶气浓度及浓度梯度的影响;喷嘴喷孔形状和溶气量对喷雾质量、结构的影响.     

Z6170ZLC型LNG-柴油双燃料船用增压发动机性能仿真分析

LNG-柴油双燃料发动机同时存在预混合燃烧和缸内压缩点火燃烧,其性能与原型柴油机有较大的差别.文中基于AVL-Boost发动机性能仿真软件,采用等热值当量处理不同比例的混合燃料,考虑了不同工况预混合LNG燃料对充气效率的影响,采用双韦伯函数燃烧放热率模拟不同比例混合燃料的预混合燃烧和缸内压缩点火燃烧,对比分析了LNG-柴油双燃料增压发动机和原型柴油机的动力性和经济性.研究表明：（1）预混合LNG燃料对充气效率的影响不会导致单点预混合LNG-柴油双燃料增压发动机的动力性下降;（2）相比较原型柴油机,各负荷工况双燃料发动机的燃油经济性均有下降,低负荷工况燃油经济性下降更为严重;（3）高负荷工况掺烧过高比例的LNG燃料将导致气缸压力急剧增加.     

电控柴油机燃油喷射技术

柴油机电控燃油喷射系统在满足排放法规的条件下,能大大提高柴油机的燃油经济性和动力性。柴油机电控燃油喷射系统是在传统燃油喷射系统基础上发展起来的,由位置控制和时间控制两种主要形式构成。柴油机高压燃油共轨技术被公认为20世纪3大突破之一,将成为21世纪柴油机燃油系统的主流。分析柴油机电控燃油喷射系统的优点、类型及应用,着重介绍柴油机电控燃油喷射系统的控制原理。     

燃用生物柴油增压柴油机的性能和排放

为了在柴油发动机上优化生物柴油的应用,利用发动机台架试验,对比分析了不同掺混比生物柴油对增压直喷柴油机排放、燃料经济性和动力性的影响,在不同转速和负荷下,研究了发动机的碳烟、NOx、CO与HC排放及有效能量消耗率和功率。试验结果表明:与柴油相比,燃用B10、B20、B30、B50、B80和B100生物柴油的发动机碳烟排放平均降低了34.69%,NOx排放平均增加了25.01%,HC排放平均降低了33.05%,CO排放在满负荷下平均增加了11.13%;虽然有效燃料消耗率有所增大,但有效能量消耗率平均降低了2.18%;功率平均增加了5.34%;生物柴油碳烟排放降低的百分比较NOx排放增加的百分比分别提高了7.01%、15.37%、14.17%、10.45%、6.73%和4.39%,因此,B20掺混比最佳。