柴油引燃甲醇双燃料发动机排放性能试验分析

介绍了柴油引燃甲醇双燃料燃烧对柴油机CH、NOx和碳烟排放的影响。采用柴油引燃甲醇双燃料在一台单缸、直喷、中冷柴油机上进行。随着甲醇质量分数的增加,HC排放迅速增加,NOx排放减少,发动机碳烟排放大幅度降低。     

车用柴油-LPG双燃料发动机工作状态的控制及性能研究

采用单片机控制进气道预混合混合器供气方式,对490Q直喷型柴油机进行了柴油-LPG双燃料技术改造。在分别燃用全柴油和柴油-LPG双燃料的情况下,得到了相应工况下动力性、经济性以及排放噪声等性能指标的对比试验结果。结果表明,然用柴油-LPG混合燃料,发动机的动力性有所提高;经济性在低负荷时优于全柴油,高负荷时较差;排放方面,烟度大幅降低,NOx也有所降低。     

柴油/CNG双燃料汽车发动机的性能研究

以某柴油/CNG双燃料发动机为对象,研究了它的结构特点和工作原理,并进行了发动机性能试验.结果表明,柴油机在改为柴油/CNG双燃料发动机后功率和扭矩均有所下降,最大值达到了9%左右,但经济性变好了,最多可以节省24%,排放性也明显得到了改善.通过采用一定的措施,可以使柴油/CNG的动力性恢复,从而弥补CNG带来的不足,使得柴油/CNG发动机具有了动力性、经济性、排放性较好的特点.     

甲醇柴油对发动机摩擦磨损以及清净性影响的实验研究

在发动机结构和参数未做改动的条件下,用4D160柴油机使用市售-10号柴油和甲醇柴油(添加甲醇体积比为20%的-10号柴油)分别进行100 h试验研究,研究甲醇柴油对发动机的动力性和经济性,摩擦磨损性能和清净性,以及发动机润滑油黏度、润滑油中金属元素含量变化的影响。试验结果表明:使用甲醇柴油燃料的发动机动力性、燃油经济性下降,在大负荷时燃油经济性下降更加明显;甲醇燃料燃烧时产生更多的酸性物质,使润滑油酸值增加较快,从而导致发动机磨损量增加,其中缸套部位的磨损量最大;在100 h实验中,不论是使用柴油还是甲醇柴油,润滑油的100℃运动黏度都呈下降的趋势,且使用甲醇柴油时润滑油黏度的下降幅度更大;使用甲醇柴油时发动机沉积物总质量比使用柴油的小,且发动机清净性评分略高。     

国内外双燃料发动机发展现状

介绍了国内外主流厂家的柴油/天然气双燃料发动机,并从动力性、经济性、燃油替代率、NOX排放及甲烷逃逸量等方面对各机型进行比较。结果表明:国外双燃料发动机性能更加突出,热效率均在45%左右,NOX排放均满足IMO TierⅢ,且均实现微引燃。国内双燃料发动机多数还停留在混烧阶段,性能有待提高。结论:为提高双燃料发动机动力、经济及排放性能,建议采用进气歧管多点喷射和缸内直喷进气,开发"微引燃"双燃料发动机。     

低压双燃料船用发动机天然气液压驱动管泄漏检测技术攻关

针对瓦锡兰的最新产品,也即低压双燃料低速船舶发动机使用燃气的特点,为保障发动机运行过程天然气进气阀高压驱动油的密封性,尤其是燃气使用时的安全性,必须在发动机台架试验前进行液压管的泄漏检测。低压双燃料船舶发动机是世界首例双燃料系统且采用低压天然气模式运行,首次使用天然气运行模式系统时,新增天然气管路、引燃油喷油器系统、以及天然气进气阀系统等技术,进一步优化了柴油机的经济性、动力性和排放指标;由于新设计的低压双燃料系列机依旧不成熟,发动机在试车过程中可能会出现了天然气进气阀高压驱动管严重泄漏问题,严重的影响了发动机性能的测试、发动机耗油量的计算以及发动机运行的经济性,针对此问题,为保障发动机性能正常运行,发动机外观质量,尤其是发动机运行的经济性。因此,进行液压驱动管泄漏技术攻关,研究、设计并实施相应方案解决此技术难题,确保发动机正常台架试验以及发动机运行的经济性。     

不同甲醇预混合气引燃燃烧模式燃烧特性分析

针对甲醇、生物柴油和聚甲氧基二甲醚PODE的优势,为了改善经济性,在一台CY25柴油机上分析不同引燃燃料对甲醇预混合气引燃燃烧模式燃烧特性的影响。试验结果表明:PODE引燃模式的排放特性较差,CO浓度相较生物柴油模式可高达2-3倍。在大甲醇质量比下HC排放浓度可高达生物柴油的5倍。甲醇质量比较小时促进了NO_X生成,增大质量比可以降低NO_X浓度。生物柴油引燃模式的排放特性随甲醇质量比变化较平稳,PODE引燃模式则随甲醇质量比变化增长较快。     

高压直喷天然气发动机技术简介

缸内高压直喷(HPDI)天然气发动机是一款缸内喷入少量柴油、引燃直喷入缸内的天然气的1A型双燃料发动机。HPDI发动机可以保持同排量柴油机原有的性能;与传统点燃式天然气发动机相比,主要优势表现为动力强劲,燃气消耗低,可靠性高,排温低,响应快;与进气道喷射双燃料发动机相比,替代率高,经济优势明显,市场前景光明。     

大负荷下柴油-天然气双燃料发动机燃烧特性数值模拟

为提升柴油-天然气双燃料发动机在大负荷工况下的动力性、经济性和排放性等多种性能,利用某商用软件建立发动机三维气缸模型,探究了二次喷油策略下柴油的喷射时刻对发动机燃烧与排放的影响。研究表明,一定范围内较早的主、预喷时刻可以提高发动机的缸温、缸压、IMEP、燃烧效率等参数,使燃料燃烧更加充分,缸内温度分布更加均匀,并能实现较高的热效率和较低的排放。但是过早的主、预喷时刻会导致燃烧不充分,燃烧效率降低、发动机的性能减弱并产生大量废气等负面影响,由此可见,大负荷下适当提前引燃柴油的喷射时刻可优化燃烧,降低大负荷工况下的爆燃倾向,提高发动机的动力性和经济性,稳定燃烧过程。     

甲醇柴油燃料的试验研究

云内4100QBZL柴油机分别采用MD20、MD10、MD5甲醇柴油与0#柴油时,对其动力性、经济性、排放性等方面进行了研究。试验表明,随着掺烧甲醇添加量的增加,动力性略有下降;采用甲醇柴油在经济性上要优于柴油;尾气中的CO、HC排放都下降明显;在甲醇添加量超过20%时,出现增加甚至超过柴油工况的情况,而随着甲醇添加量的增加,NOx呈现先增加后减小的趋势。     

MECHANISM ON DISTRIBUTION OF PILOT FUEL SPRAY AND COMPRESSING IGNITION IN PREMIXED NATURAL GAS ENGINE IGNITED BY PILOT DIESEL

Numerical simulations of pilot fuel spray and compressing ignition for pre-mixed natural gas ignited by pilot diesel are described. By means of these modeling, the dual fuel and diesel fuel ignition mechanism of some phenomena investigated on an optional engine by technology of high-speed CCD is analyzed. It is demonstrated that the longer delay of ignition in dual fuel engine is not mainly caused by change of the mixture thermodynamics parameters. The analysis results illustrate that the ignition of pre-mixed natural gas ignited by pilot diesel taking place in dual fuel engine is a process of homogenous charge compression ignition.     

文丘里管废气再循环系统对涡轮增压柴油机性能影响的研究

加装文丘里管的高压废气再循环(Exhaust gas re-circulation,EGR)进气系统,在兼顾柴油机经济性、动力性的前提下,研究该进气系统对NO_x排放的影响。根据一款柴油机的基本结构建立柴油机一维仿真计算模型和燃烧室的三维仿真计算模型。在对模型进行标定和对柴油机原机性能仿真计算的基础上,为进气系统引入文丘里管装置并对其结构参数进行优化设计。应用所建立的一维和三维柴油机模型,对文丘里管EGR系统柴油机的经济性、NO_x和Soot排放特性进行仿真计算研究,并对计算结果进行试验验证。研究结果表明,优化设计的文丘里管EGR系统可使柴油机在欧洲稳态循环(European steady state cycle,ESC)各工况下实现较为理想的EGR率,并在不明显影响柴油机燃油经济性的前提下,使NO_x排放量下降了约28.4%。文丘里管进气系统可以实现较为理想的高压EGR循环,在柴油机ESC工况下(怠速除外)能够达到较为理想的EGR率。     

Excavator energy-saving efficiency based on diesel engine cylinder deactivation technology

The hydraulic excavator energy-saving research mainly embodies the following three measures: to improve the performance of diesel engine and hydraulic component, to improve the hydraulic system, and to improve the power matching of diesel-hydraulic system-actuator. Although the above measures have certain energy-saving effect, but because the hydraulic excavator load changes frequently and fluctuates dramatically, so the diesel engine often works in high-speed and light load condition, and the fuel consumption is higher. Therefore, in order to improve the economy of diesel engine in light load, and reduce the fuel consumption of hydraulic excavator, energy management concept is proposed based on diesel engine cylinder deactivation technology. By comparing the universal characteristic under diesel normal and deactivated cylinder condition, the mechanism that fuel consumption can be reduced significantly by adopting cylinder deactivation technology under part of loads condition can be clarified. The simulation models for hydraulic system and diesel engine are established by using AMESim software, and fuel combustion consumption by using cylinder-deactivation-technology is studied through digital simulation approach. In this way, the zone of cylinder deactivation is specified. The testing system for the excavator with this technology is set up based on simulated results, and the results show that the diesel engine can still work at high efficiency with part of loads after adopting this technology; fuel consumption is dropped down to 11% and 13% under economic and heavy-load mode respectively under the condition of driving requirements. The research provides references to the energy-saving study of the hydraulic excavators.     

Demonstrating Improved Fuel Economy Using Subsystem Specific Lubricants on a Modified Diesel Engine

Fuel economy performance in modern internal combustion engines is of increasing importance to lubricant formulators due to regulations targeting global greenhouse gas emissions. Engines typically employ a single lubricant, with a common sump, to service all components. As a result, base oil and additive selection for fuel economy performance is a compromise among competing demands for different engine subsystems. Opportunities for significant fuel economy improvement through targeted formulation of lubricants for specific engine subsystems are presented, with specific emphasis on segregating the lubricant supplies for the valve train and the power cylinder subsystems. A working prototype was developed in a lab environment by modifying a commercially available twin-cylinder diesel engine. Motored valve train and whole-engine fired test results were obtained and compared to model data. Fuel economy benefits were demonstrated using market representative heavy-duty diesel lubricants, including mineral oil and polyalphaolefin (PAO) blends. The fuel economy benefits of a dual-loop lubricant system are demonstrated through significant viscosity reduction in the power cylinder subsystem, achieving overall engine friction reductions of up to 8% for the investigated operating condition. Results suggest that additional gains may be realized through targeted base oil and additive formulation. Implications for incorporation in larger diesel engines are also considered.     

Lubricant viscosity and viscosity improver additive effects on diesel fuel economy

This work verifies the impact of lubricant viscosity and viscosity improver additives on diesel fuel economy. Eight lubricants were tested in a single-cylinder, four-stroke, direct injection diesel engine mounted on a dynamometer, under different load and speed conditions. Engine friction power was also investigated through Willans’ line. The results demonstrate that fuel economy obtained from multigrade viscosity oils is higher than that obtained from monograde viscosity oils. A linear relationship was obtained between the high temperature high shear viscosity and specific fuel consumption. The lubricant which provided lower fuel consumption also required lower friction power.     

LJ276发动机电喷化改造设计

应用GT-Power软件搭建原机模型,并进行仿真计算,计算结果与试验结果基本吻合,验证了仿真模型的准确性。针对原机化油器的不足,建立了LJ276电喷化仿真模型,模拟性能有所提高。依次对进气系统结构进行了一系列的优化设计。结果表明,改进后的汽油机的动力性、燃油经济性均得到一定的改善。制作样机进行台架试验,与原机相比,电喷发动机扭矩最大提高9．2％,功率最大提高9．2％,燃油消耗率最大降低15．4％。     

低黏度柴油发动机润滑油性能研究

根据国六排放法规对柴油发动机的发展和润滑油的性能要求开发了低黏度柴油发动机润滑油。选用10W40和5W30柴机油进行发动机台架试验,并通过发动机台架试验和整车道路试验重点考察了5W30对发动机节能和整车耐久性的影响。试验结果表明:采用低黏度柴油发动机润滑油可以提高柴油发动机的燃油经济性。     

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.