柴油机燃用生物柴油的多环芳香烃排放试验研究

在一台直喷式增压柴油机上进行了生物柴油、柴油及其掺混油B20的排放特性试验,分别用玻璃纤维滤膜和“聚氨基甲酸乙酯泡沫（PUF）＋XAD．2”采集了尾气排放物中的颗粒相和气相多环芳香烃（PAHs）,并用色谱．质谱联用仪对PAHs进行了分析。结果表明：生物柴油的颗粒相、气相以及总PAHs的排放在大多数工况下低于柴油,其平均排放浓度均低于柴油。3种燃料的二环PAHs排放均在50％,生物柴油的三环以上PAHs所占比例均低于柴油。生物柴油PAHs排放的毒性当量与柴油相比有较大程度地下降。燃用生物柴油可以降低柴油机PAHs排放物对人体的危害。     

小球藻生物柴油详细燃烧反应动力学模型的构建

采用气相色谱质谱联用仪测定了小球藻生物柴油的组分和比例,分析了小球藻生物柴油的理化特性,在此基础上,确定了小球藻生物柴油的表征物质。应用“叠加法”构建了小球藻生物柴油的详细燃烧反应动力学模型,利用激波管试验和发动机台架试验数据对模型加以验证。研究结果表明,选取物质的量比为1∶1的癸酸甲酯和正庚烷作为小球藻生物柴油的表征物质,所构建的详细燃烧反应动力学模型包含3300种物质,10851个基元反应。温度高于1000 K时,着火延迟期的预测值与实验值的最大误差小于8.1%,温度低于1000 K时,误差介于8.1%~15.3%。所构建的模型能较好地预测内燃机缸内压力,最大相对误差为6.6%。     

生物柴油的酯类组成和理化特性对燃烧温度的影响

利用色谱-质谱联用仪测量了生物柴油的酯类组成,分析了燃料的密度、运动粘度、元素组成、弹性模量、碘值、氧化安定性等理化特性对燃烧温度的影响.结果表明:生物柴油中含有大量的不饱和脂肪酸甲酯,主要是油酸甲酯、亚油酸甲酯和棕榈酸甲酯;生物柴油较大的密度、较高的含氧量和碘值、较大的弹性模量、含有较长的碳链、较差的氧化安定性、存在双键且双键位置偏向分子中间会导致燃烧温度升高,而较大的运动粘度会使燃烧温度降低.     

生物柴油标准及质量评价

生物柴油是一种可再生清洁能源,受到世界各国青睐。许多国家纷纷成立了专门的生物柴油研究机构,投入大量人力、物力,推广生物柴油的生产和应用,全球生物柴油产业发展迅速。与此同时,生物柴油标准也在规范生物柴油生产、提高产品质量及提高企业竞争力等方面体现出越来越重要的作用。文章介绍了国内外生物柴油产业发展的现状和制定生物柴油质量标准的意义,分析了质量标准中各个评价指标对生物柴油储存稳定性以及生物柴油作为燃料时对发动机的影响。     

国外生物柴油的应用

介绍了生物柴油的主要成分和特性、生物柴油与石化柴油的品质比较、世界一些国家生物柴油的品质标准、生物柴油与菜籽油性能比较,以及国外生物柴油的开发与应用现状。     

生物柴油低温流动性研究

采用碱催化法制备生物柴油样品,通过毛细管气相色谱法分析了大豆油生物柴油、菜籽油生物柴油和棕榈油生物柴油的组分,以浊点(CP)、倾点(PP)和冷滤点(CFPP)为指标考察了不同原料生物柴油的低温流动性,对不同原料生物柴油的复配物以及生物柴油与矿物柴油的复配物进行了研究,比较了2种降凝剂的添加效果,提出了改善生物柴油低温流动性的方法.     

柴油机燃用微乳化生物柴油的性能和排放研究

微乳化生物柴油是由生物柴油、水以及表面活性剂组成的具有热力学稳定性的混合物.它能够结合生物柴油和掺水燃烧的优点,而且又稳定长期不分层.作者选用复配的表面活性剂配置了三种不同含水量的微乳化生物柴油,讨论了温度对其稳定性的影响,并且在单缸四冲程直喷柴油机上对比试验了微乳化生物柴油、0#柴油和生物柴油的排放.结果表明一定含水量的微乳化生物柴油能正常燃烧,相对于柴油和生物柴油能够明显地降低碳烟和NOx的排放,而且水含量比较低的微乳化生物柴油的油耗变化很小.     

生物柴油燃烧过程内窥镜高速摄影试验研究

采用内窥镜直接高速摄影的方法,对燃烧柴油和生物柴油发动机的燃烧过程进行了试验研究,分析了柴油、生物柴油、不同比例的生物柴油／柴油混合燃料的着火延迟期、着火点位置、燃烧温度和燃烧速度的变化规律。研究结果表明：燃油喷射过程中,柴油的喷雾锥角大于生物柴油的喷雾锥角;生物柴油在预混燃烧阶段的燃烧速度大于柴油,其最高燃烧温度小于柴油。在相同工况下,生物柴油的燃烧终点早于柴油,燃烧持续期也小于柴油。燃烧生物柴油时,高转速工况下的燃烧终点对应的曲轴转角较低转速时有所增加,燃烧持续期对应的角度有所延长。     

生物柴油氧化安定性研究的新进展

作为石化柴油的替代燃料,生物柴油在世界范围内得到广泛应用。氧化安定性是生物柴油在贮存和使用过程中面临的技术难题之一,因此氧化安定性是生物柴油研究必须关注的重要质量指标。文章对生物柴油氧化安定性的影响因素、生物柴油氧化机理、生物柴油氧化安定性的标准评价方法的最新进展等方面作了综述,并对我国生物柴油氧化安定性的标准评价方法的建立提出了建议。     

生物柴油的应用研究

简要介绍生物柴油的制取方法、生物柴油的理化特性以及国内外生物柴油技术的研究发展水平,表明生物柴油具有良好的发展前景。还在一台4102型柴油机上开展了燃用生物柴油和石化柴油发动机的性能对比试验,结果表明：与柴油相比生物柴油可以提高发动机的热效率,降低碳烟、CO和HC的排放。     

内燃机车用16V280ZJ柴油机燃油系统可靠性研究

为了满足对可靠性越来越高的要求，非常有必要对机车用16V280ZJ柴油机的针阀偶件和出油阀偶件设计结构进行研究。通过理论估算和试验测试，对改进前、后燃油系统的性能进行了分析和比较。结果表明改进的燃油系统满足了“保证柴油机性能不变的前提下，提高可靠性”这一设计要求。     

双燃料发动机的燃烧模型

针对双燃料发动机燃烧特性，建立了柴油喷雾扩散燃烧子模型和气体燃烧均质混合气火焰传播燃烧子模型，应用该模型研究了双燃料发动机燃烧机理，计算结果和实验结果相当吻合。计算表明：当引燃柴油比例较大时，双燃料发动机燃烧过程以喷雾混合控制燃烧为主，柴油喷雾扩散燃烧模型与实测较吻合；当柴油比例较小时，该过程以均质混合气火焰传播燃烧为主，均质混合气火焰传播燃烧模型与实测软吻合。计算结果表明，引燃柴油量对双燃料发动机性能影响较大，引燃柴油减少，着火滞燃期延长，缸内最大爆发压力升高。     

Development of glycerol/O2 biofuel cell

Glycerol is an attractive fuel for a fuel cell, because it is non-toxic, non-volatile, non-flammable, has high energy density, and is abundant due to the fact that it is a byproduct of biodiesel production. However, it has not been an effective fuel for low temperature, precious metal catalyzed fuel cells. In this paper, we describe the use of glycerol as a fuel in an enzymatic biofuel cell. An alcohol dehydrogenase and aldehyde dehydrogenase-based bioanode has been developed that oxidizes glycerol, a safe high energy density fuel. Glycerol/O₂ biofuel cells employing these bioanodes have yielded power densities of up to 1.21 mW cm⁻², and have the ability to operate at 98.9% fuel concentrations. Previous biofuel cells could not operate effectively at high fuel concentrations due to the nature of the solid fuel such as sugar or the solvent characteristics of fuels such as lower aliphatic alcohols. The glycerol/O₂ biofuel cell provides improved power densities compared to ethanol biofuel cells due to ability to more completely oxidize the fuel.     

日本生物柴油的发展

通过作者的观察和感受,介绍了日本国生物柴油的应用与发展,以及对中国的启示.认为生物柴油是一种清洁的可替代燃料,发展生物柴油应因地制宜,解决好"与民争口油"的问题.日本国用废煎炸油生产清洁的生物柴油燃料的做法是可取的,并且已开始了商业应用;中国是美食大国,尤应重视发展利用废煎炸油加工生产清洁的生物柴油燃料,减少其对环境污染的技术.为了使废煎炸油生产生物柴油燃料得到可持续发展,应重视推进普通老百姓对该项技术的认知和参与;并且重视副产品甘油的冉利用问题.     

煤沥青燃料的研究进展

煤沥青是焦油加工的大宗产品,其产率占焦油的50 %～60 %,随着对环保要求的日益提高,煤沥青的燃烧进一步限制了其利用.如何对煤沥青进行必要的深加工,提高沥青产品的附加值是煤焦油加工中的一个重要问题,而煤沥青浆体燃料成为解决这一问题的有效途径之一.在沥青浆体燃料的基础上,提出了煤沥青浆体燃料.阐述了煤沥青浆体燃料的制备原理,介绍了2种煤沥青浆体燃料--煤沥青乳化燃料和煤沥青水浆的研究进展.目前,关于煤沥青浆体燃料的研究报道较少,因此,非常有必要加大煤沥青浆体燃料的研究开发.     

The efficient and economic design of PEM fuel cell systems by multi-objective optimization

Since the efficiency of fuel cells is the ratio of the electrical power output and the fuel input, it is a function of power density, system pressure, and stoichiometric ratios of hydrogen and oxygen. Typically, the fuel cell efficiency decreases as its power output increases. In order for the fuel cell system to obtain highly efficient operation with the same power generation, more cells and other auxiliaries such as a high-capacity compressor system, etc. are required. In other words, fuel cell efficiency is closely related to fuel cell economics. Therefore, an optimum efficiency should exist and should result in the definition of a cost-effective fuel cell system. Using a multi-objective optimization technique, the sequential quadratic programming (SQP) method, the efficiency and cost of a fuel cell system have been optimized under various operating conditions. This paper has obtained some analytical results that provide a useful suggestion for the design of a cost-effective fuel cell system with high operation efficiency.     

New vehicle fuel economy in the UK: Impact of the recession and recent policies

Interests in vehicle fuel economy have increased in the past few years with the implementations of more stringent CAFE standard in USA and mandatory carbon emission standard in the EU. We seek to understand the effects of recent policies such as restructuring of Vehicle Excise Duties and EU standard on new vehicle fuel economy in the UK. In the past few years there have been substantial fluctuations in income and fuel prices, offering an interesting testing ground to understand their impact on the demand for fuel economy in vehicles. We use a monthly dataset to find that the emission standard is the largest driver for fuel economy improvements in recent years. Also, contrary to some recent findings in Europe and in UK, we find that income has an effect and that the recession had some role in improving the fuel economy. The effects of fuel prices were relatively small. Restructuring of the VED also improved new vehicle fuel economy in the UK, but the scrappage scheme had no significant effect. Results indicate that both supply and demand side policies are effective in improving fuel economy, although quantitatively the emission standard appears more effective due to its stringency. It is also important to consider the effects of income while devising demand side policies.     

天然气锅炉分级柔和燃烧模拟研究

燃气锅炉在我国应用广泛,随着煤改气的进行,应用越来越多, NO_x排放标准也越来越严格。降低NO_x的排放有利于减少空气污染。以小型天然气柔和燃烧炉膛为研究对象,通过数值模拟的方法研究燃料分级下的柔和燃烧特性,分析在不同当量比、不同热强度条件下轴向分级对炉膛烟气中NO_x生成的影响。结果表明,给定条件下柔和燃烧分级带来的NO_x减排收益随着二级燃料量的增加而减小,当二级燃料量在15%左右的时候可以最大程度地优化温度场分布,降低燃烧峰值温度,获得比较好的NO_x控制效果。随着当量比和热强度的提高,燃料分级带来的收益也会变大。     

Simultaneous thermal and visual imaging of liquid water of the PEM fuel cell flow channels

Water flooding and membrane dry-out are two major issues that could be very detrimental to the performance and/or durability of the proton exchange membrane (PEM) fuel cells. The above two phenomena are well-related to the distributions of and the interaction between the water saturation and temperature within the membrane electrode assembly (MEA). To obtain further insights into the relation between water saturation and temperature, the distributions of liquid water and temperature within a transparent PEM fuel cell have been imaged using high-resolution digital and thermal cameras. A parametric study, in which the air flow rate has been incrementally changed, has been conducted to explore the viability of the proposed experimental procedure to correlate the relation between the distribution of liquid water and temperature along the MEA of the fuel cell. The results have shown that, for the investigated fuel cell, more liquid water and more uniform temperature distribution along MEA at the cathode side are obtained as the air flow rate decreases. Further, the fuel cell performance was found to increase with decreasing air flow rate. All the above results have been discussed.     

探究增压直喷机型机油稀释的影响因素及解决方法

机油稀释现象是发动机常见的试验表象之一,尤其是增压缸内直喷汽油发动机,机油稀释较明显。机油发生稀释后会破坏机油使用性能,降低运动粘度,严重时还导致机油压力下降,零部件功能丧失,发动机可靠性下降。主要分析一款1.8L GDI缸内增压直喷发动机产生机油稀释的影响因素进而对机油牌号、机油温度、水温、SOI角度、曲轴箱通风系统、活塞漏气量、喷油器布置方式进行Benchmark分析及优化验证,为改善增压直喷发动机机油稀释现象提供解决方法,机油稀释包括燃油喷射稀释和机油挥发稀释,重点探究的方向是燃油喷射稀释。