直喷式柴油机燃烧过程模拟与分析(一)

利用KIVA-Ⅱ程序模拟计算直喷式柴油机燃用柴油时缸内的燃烧过程，如混合气形成过程、缸内温度场、主要有害物质NOx的生成浓度分布等。通过对直喷式柴油机燃用柴油时燃烧过程的模拟计算与分析，对模拟燃用绿色能源-二甲醚的燃烧过程提出了一些建议。     

直喷式柴油机燃烧低十六烷值柴油的研究

通过实测直喷式柴油机燃烧不同十六烷值柴油时的缸内压力示功图,以此计算出相应的燃烧放热规律。通过分析影响放热规律的有关参数,确定了对几项因子通过试验匹配来进行直喷式柴油机燃用低十六烷值柴油机的初步研究。以试验研究为基础,利用神经网络的非线性映射性能得出了燃用低十六烷值柴油机时几个参数的调整方案。     

柴油和碳酸二甲脂混合燃料对柴油机性能的影响

碳酸二甲酯(DMC)具有含氧量高、沸点低、与柴油互溶性好等特点,适合作为柴油机的燃料添加剂。在轻型直喷式柴油机上对柴油机燃用柴油和碳酸二甲脂混合燃料后,柴油机的燃烧特性、传热特性、排放特性进行了研究。结果表明:燃用柴油和碳酸二甲酯混合燃料后,柴油机的碳烟排放大幅度下降,缸内辐射传热量减少,热效率提高。     

柴油/丙烷混合燃料发动机燃烧和排放特性研究

比较了柴油和丙烷的主要理化性能;在一台单缸直喷式柴油机上开展了燃用柴油和柴油/丙烷混合燃料时的发动机燃烧和排放特性研究.研究结果表明：在相同工况下,与燃用柴油相比,燃用柴油/丙烷混合燃料时的有效热效率增加,柴油/丙烷混合燃料的有效热效率随丙烷比例的增加而稍有增加,混合燃料的滞燃期和燃烧持续期随丙烷比例的增加而缩短;缸内最大压力,最大燃烧放热率,最高平均燃烧温度随丙烷比例的增加而增加.燃用丙烷柴油混合燃料可同时降低CO、HC和碳烟排放,但NOx排放有所增加.     

490Q柴油发动机掺烧LPG的试验研究

对490Q直喷式柴油机进行了LPG/柴油双燃料的技术改造。在分别燃用纯柴油和柴油/LPG双燃料的情况下,研究了相应工况下发动机的动力性、经济性以及排放特性等性能。试验结果表明,加入一定比例的LPG可改变缸内燃烧过程,大幅度降低排气烟度,在一定程度上提高了燃油经济性。     

柴油机燃用二甲醚的燃烧特性

对直喷式柴油机燃用二甲醚的燃烧特性进行了研究,测量了示功图和油器针阀升程,计算了燃烧特性并与燃用柴油进行对比。结果表明,与柴油相比,发动机燃用二甲醚时的喷油延迟期延长,滞燃期缩短,最高爆发压力和最大压力升高率均低于柴油机。研究表明发动机燃用二甲醚具有良好燃烧特性。     

二甲基醚（DME）燃烧特性研究

作者在定容燃烧弹上用火焰直接成像法研究二甲基醚 (DME)燃烧过程 ,研究了 DME的滞燃期和火焰传播特性以及不同环境温度和压力对燃烧过程的影响。研究结果表明 ,DME的滞燃期比柴油短 ,燃烧室内的温度和压力升高时 ,滞燃期缩短 ;DME的着火位置靠近喷嘴一侧 ,柴油与 DME的体积相同时 ,DME的燃烧持续期比柴油短 ;DME的燃烧火焰亮度比柴油小 ,表明 DME的燃烧温度比柴油低。燃烧后期 ,燃用 DME时 ,喷嘴有明显的泄漏现象。此外 ,作者在单缸直喷式柴油机上进行了燃用 DME的燃烧特性试验研究 ,研究结果表明 ,DME的预混合燃烧放热率比柴油低 ,缸内最大爆发压力和最大压力升高率比柴油低。由于喷油持续期延长 ,DME的燃烧持续期比柴油长 ,在上止点后 80° CA出现一个较大的放热峰值。     

直喷式柴油机缸内过程的能量可用性分析

本文以柴油机工作过程的热力学第一定律数值模拟为基础，应用热力第二定律分析一台直喷式柴油要的缸内过程的能量可用性。通过各过程的能量可用性平衡分析，定量地计算了能量作功能力和不可逆损失，并且与势和不第一定律的能量平衡进行了比较；分析计算了直喷式柴油机的循环喷油量、燃烧开始角、燃烧持续期、燃烧品质指标及气缸绝热对缸内能量可用性和热力学第一定律、第二定律热效率的影响。     

生物柴油发动机燃烧与排放数值模拟及试验研究

对燃用生物柴油的一台增压中冷直喷式柴油机,利用CFD分析软件FIRE建立了喷雾和燃烧计算模型并进行模拟计算,在理论和试验上对模型进行了研究和验证。结果表明,燃料的十六烷值和粘度对放热率影响较大,模拟计算得出的曲线与实测结果吻合较好。并对柴油机喷油参数改变后燃用生物柴油发动机NO和颗粒物排放进行了性能预测。     

基于FIRE的柴油机燃烧过程的CFD研究

应用三维CFD仿真软件AVL FIRE对CY4102直喷式柴油机的燃烧过程进行了数值模拟计算,再现了缸内流体的运动过程、湍流参数的变化、燃油粒子的空间分布、燃烧过程的进展状况、传热过程以及缸内温度场的分布等,结果表明:随着喷油提前角的增大,滞燃期变长,最高平均温度、压力和放热率峰值均增大,且其对应的曲轴转角均有前移趋势...     

Flavin mononucleotide (FMN)-ethylenediaminetetraacetic acid (EDTA) photogalvanic cell

The photovoltages and photocurrent in a photogalvanic cell containing flavin mononucleotide (FMN) and a reducing agent, ethylenediaminetetraacetic acid (EDTA) have been determined and found to be appreciable. The efficiency of the cell has been estimated to be ～ 0-048 percent. The electrochemical behaviour of FMN in the presence of EDTA has been examined by cyclic voltametry.     

Optimized supply-air temperature (SAT) in variable-air-volume (VAV) systems

A criterion, based on optimization principles, for determining the SAT setpoint in VAV systems is presented. It is generally accepted that conventional SAT reset controls (SATRC), bounded by either space humidity or ductwork size, will save cooling and/or heating energy. How-ever, the ventilation consequences and penalty resulting from increased fan power have generally been overlooked. Ventilation is impacted since changes in the SAT setpoint change the primary airflow rate and the operation of economizer cycles, i.e. the distribution of fresh outdoor air (OA). These changes may result in extra energy demand and ventilation inefficiency if the reset criterion is not appropriate. This optimization concept simultaneously reduces energy consumption and meets ventilation requirements. Simulation results illustrate that the use of the optimized SATRC saves more energy than a conventional one.     

Decreasing the thermal dehydrogenation temperature of methylamine borane (MeAB) by mixing with poly(methyl acrylate) (PMA)

This paper reports on a hydrogen storage material of poly(methyl acrylate) and methylamine borane (PMA/MeAB) composite, which is synthesized by a simple solution-blending process at room temperature. The thermal decomposition process of the as-prepared composite is investigated by temperature programmed desorption/mass spectrometer (TPD/MS), thermogravimetry (TG) measurements and water displacement method. It is found that PMA/MeAB100 (100 mg PMA with 100 mg MeAB) starts to release H₂ at the temperature of 90.5 °C with the dehydrogenation peak centered at 120.7 °C. This is about 20 °C lower than that of neat MeAB. Meanwhile, the evaporation of MeAB and the volatile byproducts from the dehydrogenation stage of PMA/MeAB100 are also suppressed. The present result shows that the dehydrogenation property of MeAB is enhanced by using PMA/MeAB composite.     

Investigation of molybdenum-(resorcinol-formaldehyde) (Mo-RF) electrode for alkaline electrolyser operation

The use of zero-gap cell geometry and development of low cost electrodes are some of several attempts on reducing cost and increasing efficiency of electrolytic hydrogen production. This study involves the synthesis of an electrode consisting of resorcinol-formaldehyde (RF) carbon aerogels of high surface area (>700 m²/g) and nano-pore sizes (4 nm) thermally deposited on molybdenum metal. The hydrogen evolution reaction (HER) characteristics of the Mo-RF electrode involving an intermediate ‘spectator metal-oxo’ compound and its Volmer-Heyrovsky electro-catalyst property are described. The physical and morphological structure of the Mo-RF has been shown through SEM images thus confirming the effectiveness of the synthesis method. Polarisation measurement of the Mo-RF electrode in 30% (by vol) KOH solution at 298 K indicates its potential applications in alkaline electrolysers. It is anticipated that the use of Mo-RF electrode offers economic benefit of reduced capital cost investment compared with other electrodes such as Pt-C previously used in electrolysers.     

双燃料发动机（一）

介绍了双燃料发动机的工作特点，燃料供给系的组成、工作原理、以及如何对其进行正确使用及保养。     

Lithium-iodine batteries based on metal dibenzo(b,i)-1,4,8,11)Tetraaza(14)annulene-iodine charge transfer complexes

Metal dibenzo(b,i)(1,4,8,11)tetraaza(14)annulene-iodine charge transfer complexes show high electrical conductivity even in the presence of a large excess of molecular iodine. Investigations of the behaviour of these materials as cathodes in lithium-iodine batteries is reported. The ease of preparation and handling as well as the discharge characteristics make it a potential alternative to the P2VP poly(2-vinylpyridine)-iodine system.     

Solvatochromic effect studies on the absorption spectra of 4-((2-ethylphenyl)diazenyl)benzene-1,3-diol and 2-((2-ethylphenyl)diazenyl)benzene-1,3,5-triol molecules

The electronic absorption spectra of 4-((2-ethylphenyl)diazenyl)benzene-1,3-diol and 2-((2-ethylphenyl)diazenyl)benzene-1,3,5-triol molecules in the nine different solvent variable electronic characters have been recorded. The solvent dependent maximum absorption band (π–π* transitions) shifts, ν_max, were analyzed using a wide range of parameters such as refractive index, dielectric constant and Kamlet–Taft parameters [hydrogen bond donating ability (α) and hydrogen bond accepting ability (β)]. The electronic transitions are assigned and the solvent-induced spectral shifts have been analyzed in relation to the different solute–solvent interaction mechanism using computational chemistry. The intermolecular interaction types in the azobenzene derivatives solutions have been established on the basis of a multiple linear regression analysis. The fitting coefficients obtained from this analysis allowed us to estimate the contribution of each type of interactions to the total spectral shifts in the studied solutions.     

双燃料发动机 (三)

介绍了双燃料发动机的工作特点 ,燃料供给系的组成、工作原理 ,以及如何对其进行正确使用及保养。