Research on Spray, Combustion and Emission Characteristics for DI Diesel Engine

To improve the combustion chamber shape that can decrease the directed injection （DI） diesel emission, the theories of DI diesel spray, combustion and pollutant formation model are analysed and implemented based on the CFD code FIRE. Results show that the chamber with contracting orifice can get stronger squish swirl intensity. The results of the verification studies show a good accordance with the measurements and reveal that the individual processes of spray, evolution, combustion and pollutant formation are well captured in FIRE. Finally, based on the analyzing and comparing of the calculation results of different chambers, a combustion chamber of contracting orifice geometry with lower emission is proposed.

Research on the Impact of CeO2 -based Solid Solution Metal Oxide on Combustion Performance of Diesel Engine and Emissions

当引擎使用与纳米大小的添加剂 Ce0.9Cu0.1O2 和 Ce0.9Zr0.1O2 混合的重油时，这篇论文主要在高速度的柴油机引擎和排放减小的表演上学习。在测试期间， Indiset 620 燃烧分析器由 AVL 做了，被用来在柱体压力上做即时调查，燃料点火时刻，并且在柱体和曲柄角度建立在温度的变化趋势之间的一种关系。为烧与添加剂混合的重油和重油的引擎，燃烧分析软件 Indicom 和协奏曲被用来分析它的燃烧进程和排放条件。试验性的调查证明缩放 nano 的复杂氧化物能改进与重油，和还原剂造成的柴油机引擎的表演象 NOx 和公司一样的污染物质的排放，把它与纯重油作比较。根据这个实验的后果，添加剂在重油的使用改进全面表演。

Numerical Investigation of the Effects of Rate-Shaped Main Injection on Combustion and Emission in an OPOC Two-Stroke Diesel Engine

The effects of various split injection strategies on the opposed-piston opposed-cylinder(OPOC)diesel engine combustion and emission characteristics have been studied numerically using AVL-Fire CFD tools.The five rate-shaped main injections were used in split injection strategies.The results show that ignition delay from a rectangular injection rate is the shortest.Maximum pressure of the trapezoid injection rate is the largest.And the NOx emission of the rectangular injection rate is the largest.Meanwhile,the soot emission of the trapezoid injection rate is the least among the five injection rates.

Complete Modeling for Systems of a Marine Diesel Engine

这份报纸基于物理、半物理、数学、热力学的方程论述一台海洋的柴油机引擎的一个模拟器模型，它允许快预兆的模拟。整个引擎系统被划分成几功能的块：冷却，润滑油，空气，注射，燃烧和排出物。亚模型和单个块的动态特征根据在参考书 6M26SRP1 下面为 SIMB 同伴从一张海洋的柴油机引擎测试凳子收集的引擎工作原则方程和试验性的数据被建立。全面引擎系统动力学用 Matlab/Simulink 的亚块和 S 功能被表示为一套同时的代数学、微分的方程。这个模型的模拟，在 Matlab/Simulink 上实现了被验证了并且能被用来获得引擎性能，压力，温度，效率，热版本，曲柄角度，燃料率，在不同亚块的排出物。模拟器将被使用，在未来工作，到学习处于有缺点的条件的引擎性能，和罐头被用来象设计者一样在差错诊断和评价( FDI )帮助海洋的工程师预言冷却系统的行为，润滑油系统，注射系统，燃烧，排出物，以便优化不同部件的尺寸。这个程序是为差错模拟器的一个平台，到在为差错参数改变值例如的亚块引擎输出上调查影响：有缺点的燃料注射者，漏的柱体，穿的燃料泵，破活塞戒指，脏 turbocharger，脏空气过滤器，脏空气冷却器，空气漏，水漏，油漏和污染，热 exchanger 犯规，泵穿，注射者的失败(并且许多其它) 。

Study on Effects of Oxydal on Diesel Engine Combustion

Based on the analysis of the high temperature decomposition of oxydal(H2O2)and the combustion of diesel engine,the effects of H2O2 on the improvement of diesel combustion were studied.An oxydal spray system was designed to inject H2O2/water mixture into the manifold.The experiment was carried out on a 1135 diesel engine bench.The results show that H2O2 injection can make the curve of heat release rate move forward and decrease its peak value.The specific fuel consumption is decreased a little,while both NOx and PM emission are obviously reduced.

Experimental Study on the Performance and Emission of Chinese Small Agricultural Diesel Engine Fuelled with Methanol/Biodiesel/DTBP

Diesel engine alternative fuels, such as methanol and biodiesel, are beneficial to reduce diesel engine emission. In order to study the influence of methanol and biodiesel on the performance, economy and emission of small agricultural diesel engine, the physical-chemical properties(cetane number, lower heat value(LHV), viscosity, etc.) of methanol and biodiesel were analyzed. The methanol and biodiesel showed good complementary property to some extent. When a large proportion of methanol was added into biodiesel, the cetane number of the methanol/biodiesel blend will be greatly reduced. Since the cetane number of the blend fuel has great influence on the combustion process of diesel engine, after testing for blending ratio of methanol/biodiesel, the blend was prepared with 5%(BM5), 10%(BM10) and 15%(BM15) methanol, respectively. Di-Tert-Butyl Peroxide(DTBP) was chosen as a cetane number improver to be added into methanol/biodiesel blend. 0.25%, 0.50% and 0.75% of DTBP was added into BM15. The bench test was carried out on a 186 FA diesel engine to study the effect of methanol and DTBP on the engine performance and emissions. The results show that, at rated condition, compared with biodiesel, the NO;concentration of BM5, BM10 and BM15 is reduced by 5.02%, 33.85% and 21.24%, and smoke is reduced by 5.56%, 22.22% and 55.56%. However, the engine power is also reduced by 5.77%, 14.23% and 25.41%, and the brake specific energy consumption is increased by 3.31%, 7.78% and 6.37%. The addition of DTBP in methanol/biodiesel could recover the engine power to the level of diesel. DTBP shows good effect on the reduction of the brake specific energy consumption and NO_(x), CO, HC concentration, but a little increase of exhaust smoke.

Combustion Characteristics and Emission of a Two-Stroke Compression Ignition Engine with Two-Stage Injection

In order to study the effect of two-stage injection on two-stroke diesel engines, a well characterized research engine equipped with electronically controlled common rail system and scavenging system was constructed. Through analysis of combustion and emissions, two-stage injection shows its advantages. Compared with the standard injection, it produces less emissions, while compared with single early injection, it expands engine operation range. Further experiments were carried out to study the influence of several injection control parameters on two-stage injection. The fuel in the first injection is used for forming homogeneous mixture. The fuel in the second injection keeps combustion, and it is the main source of smoke emissions. NO_x is formed in both combustion process caused by these two injections, and there is an optimum fuel allocation ration to produce minimum NO_x. The cylinder pressure decreases, and the combustion is depressed with the increasing of scavenging pressure. By optimizing the injection control parameters of two-stage injection, NO_x and smoke can be reduced beyond 30% simultaneously.

Improving Designs of CA6DF2 Series Diesel Combustion System

The technical improvements are made based on the former CA6110 diesel engine to meet the requirements of Euro Ⅱ emission standards. The performance and emission for CA6DF1 and CA6DF2 are all met the demand of design by improving the fuel, combustion and supercharging systems. The injection system adopts high-pressure pump-pipe-injector injection system. To enhance the injection pressure, the methods of augmenting plunger diameter, decreasing the nozzle hole diameter and reducing the inner diameter of the high-pressure fuel pipe are adopted. The design of combustion chamber and the match of inner fuel distributions with air motion are based on a great deal of experimental database and some simple computer-aided methods, which ensure the optimization of performance and provide the guide for experimental development.

Diagnosis of Valve-Slap of Diesel Engine with EEMD-EMD-AGST Approach

A hybrid of ensemble empirical mode decomposition and empirical mode decomposition (EEMD-EMD) is introduced to diagnose the valve-slap vibration signal,which is relative to the dominant combustion knock vibration signal given out by a diesel engine around the top dead center (TDC).The time-frequency representations of intrinsic mode functions (IMFs) decomposed by EEMD-EMD are obtained by adaptive generalized S transform (AGST).A type 493 diesel engine was used for the experiment,and the result indicates that the valve-slap of the diesel engine is serious,and the vibration frequencies are higher than the combustion knock.With EEMD-EMD-AGST approach,the valve-slap can be identified by the vibration analysis of the diesel engine.

甲醇喷射正时对柴油/甲醇双燃料HCCI发动机燃烧及排放特性的影响研究

文章利用CFD仿真软件Converge研究了甲醇喷射正时对柴油/甲醇双燃料HCCI发动机燃烧和排放特性的影响。研究结果表明:随着甲醇喷射正时提前,缸内混合气质量提高,缸压峰值和压力升高率均升高,缸内温度分布更加均匀;当甲醇喷射正时提前角度较小时,缸内混合气存在明显的浓度梯度,使得燃烧始点前移;随着甲醇喷射正时提前,SOOT,HC和CO的排放量显著减少,当甲醇喷射正时为150℃A BTDC时,HC排放量最低;甲醇喷射正时的提前也减弱了甲醇汽化潜热对缸内温度的影响,导致NOx排放量升高。

Characteristics of Diesel/N-Butanol Blend on a Common Rail Diesel Engine with Exhaust Gas Recirculation

20%n-butanol is blended in diesel by volume(noted as D80B20)and experiment has been carried out to study the effect on the combustion and emission characteristics based on a common rail diesel engine with exhaust gas recirculation(EGR)system.The results reveal thatD80B20 has longer ignition delay,shorter combustion duration and higher maximumin-cylinder temperature than pure diesel(noted as D100).Further,the number concentration and volume concentration of ultrafine particles decrease significantly while NO_(X) emissions increase a little with the addition of n-butanol.When the exhaust gas is induced into cylinder,NO_(X) emissions significantly decrease and ultrafine particles emissions increase.The number geometric mean diameters and volume geometricmean diameters of ultrafine particles increase withEGR ratio.Compared toD100 without EGR,D80B20 with 20%EGR ratio can reduce both NO_(X) and ultrafine particles emissions at 0.14MPa BMEP and 0.56MPa BMEP.

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.

MULINBUMP-HCCI复合燃烧放热特征及其对排放和热效率的影响

提出了基于多脉冲喷射和BUMP燃烧室的MULINBUMP HCCI复合燃烧技术。发动机试验和CFD数值模拟研究表明,多脉冲喷射参数,特别是多脉冲喷射定时可以控制预混合气的形成,从而控制燃烧放热率。具有分布式放热率的工作过程的热效率与直喷式柴油机相当,但同时改善了NOx和碳烟排放。在不采用废气再循环的条件下,NOx排放在较低负荷时只有11×10-6,高负荷时也不超过250×10-6。碳烟排放始终小于0 5BSU。

HCCI甲醇发动机的燃烧与排放特性

在Ricardo Hydra单缸四冲程发动机上利用内部废气再循环策略实现了甲醇燃料的HCCI燃烧.通过调整HCCI发动机的过量空气系数和转速,研究了HCCI甲醇发动机的燃烧和排放特性.结果表明,甲醇燃料的HCCI燃烧不同于普通汽油,其着火更早、燃烧更快,但在低转速时,平均指示压力相对较低.甲醇燃料可以在更稀的混合气条件下实现HCCI燃烧.在相同的转速和过量空气系数下,甲醇燃料的NOx和HC排放低于汽油.

不同引燃方式下氨掺氢燃烧对发动机的性能影响

氨被认为是最有前景的零碳燃料之一,但掺氨量过大时氨逃逸现象严重,故将氨中掺混一定比例氢气,促进缸内燃烧反应进行,并将引燃柴油替换成氢气实现零碳燃烧。本文使用CONVERGE软件进行仿真,模拟了柴油引燃与氢气引燃时,氨掺氢对发动机燃烧和排放性能的影响。研究发现在柴油引燃时,当掺氢比为30%时与0时相比,缸内爆压、功率升高,燃油消耗率下降,氨逃逸占比下降,NO_(x)排放升高,CO_(2)零增长,soot、HC等排放改善;在氢气引燃时,当掺氢比为30%时与0时相比,缸内爆压、功率升高,燃油消耗率下降,氨逃逸占比下降,NO_(x)排放升高4倍,燃烧前后CO_(2)零增长,掺氢燃烧后改善了发动机整体性能,柴油引燃模式缸内直喷氨气掺混30%氢是实现净零碳排放较优方案。研究结果为氨燃料的实用性提供了依据,并可用于指导试验研究。

不同EGR方法对柴油燃料HCCI燃烧影响的探讨

研究了内部EGR和外部EGR模式对柴油燃料HCCI燃烧的影响.随着内部EGR率的增大,HCCI燃烧的着火始点提前,在相对较小的负荷下,-40℃A气门重叠期的着火始点比-20℃A气门重叠期的着火始点提前5～7℃A,内部EGR的加热作用大于其对混合气的稀释作用;内部EGR增大有利于均质混合气的形成,使柴油燃料HCCI燃烧的烟度排放减小,但使低NOx排放的负荷范围减小;外部EGR起到了推迟着火始点的作用,是一种有效的扩展运行范围负荷上限的方法.

DME／柴油混合燃料HCCI燃烧与排放特性的试验研究

在单缸柴油机上采用轴针式喷嘴进气道燃油喷射方式，开展了二甲醚（DME）／柴油混合燃料预混均质压燃（HCCI）燃烧及其排放特性的试验研究，探讨了喷油嘴启喷压力、进气温度以及进气掺混不同比例CO2对混合气制备率和发动机性能的影响。结果表明：低沸点液相DME在进气道喷射过程中所具有的闪急沸腾效应，可有效强化柴油／DME混合燃料的雾化与蒸发，减少燃油撞击壁面而出现的进气歧管壁湿现象，从而改善柴油HCCI发动机均质混合气的形成与燃烧，拓宽发动机的运行工况范围。进气掺混0～30％的CO2能使HCCI发动机的正常工作范围从0．32MPa提高到0．5MPa，实现高负荷工况下同时降低NOx和碳烟的排放，但CO和未燃HC排放有所增加。

掺烧不同比例的异戊醇对船舶柴油机性能的影响

为了研究不同比例的异戊醇/柴油混合燃料在4190Z L C-2型船用中速柴油机中的燃烧和排放特性,运用AVL_FIRE仿真软件建立柴油机燃烧室模型,并通过台架实验验证其仿真模型的准确性。在仿真软件中通过调整异戊醇在柴油中的掺混比来研究混合燃料对柴油机燃烧和排放性能的影响。结果表明:掺混异戊醇有助于改变NO的生成规律,使NO在速燃期的生成量上升,在缓燃期与后燃期的生成量减少,并且总体生成的NO质量分数降低;随着异戊醇掺混比的上升,CO最终生成质量分数下降,Soot最终生成质量分数上升,同时生成的Soot质量分数峰值降低,在缓燃期的氧化速率增快,并因为较快的耗氧量使得最终生成的Soot质量分数比纯柴油的高。

在汽油机上实施HCCI的技术策略

均质混合气压燃(HCCI)燃烧方式,是一种克服常规柴油机和汽油机缺点、集常规汽油机和柴油机优点于一体的新概念燃烧。本文分析了汽油机实施HCCI的可行性,介绍了HCCI发动机实用化所面临的问题,提出了双工作模式的折衷方案:在中低负荷工况实施HC CI,而在大负荷工况和冷起动工况恢复常规发动机工作方式。推荐可变压缩比(VCR)方案、可变废气再循环率(EGR)方案、可变排气门关闭时刻方案,以及废气再循环滚流分层充气方案等。为尽快在汽油机上实施HCCI燃烧方式指出了技术方向。

喷射参数对柴油HCCI复合燃烧过程燃烧效率及散热损失影响的研究

在复合燃烧模式下研究了喷射参数对燃烧效率、散热损失和热效率的影响。试验结果表明,改变多脉冲喷射定时可控制预混燃烧放热幅度,影响NOx与HC和CO排放的折中关系。多脉冲喷射定时提前,NOx排放减少,但HC和CO增加,导致燃烧效率降低。在平均指示压力0 78MPa下,当采用复合燃烧模式,随主喷射后推,主喷射定时为3°CAATDC时,可获得最高燃烧效率,同时NOx排放仅为280×10-6,烟度为0 4BSU,相对此主喷定时,提前或拖后喷射都会使HC和CO排放增加,从而造成燃烧效率降低。