天然气后喷对高压直喷天然气船机燃烧和排放的影响研究

利用流体动力学软件CONVERGE建立了高压直喷天然气船机的三维仿真模型,基于该模型研究了后喷策略对高压直喷天然气船机燃烧和排放的影响。结果表明:随后喷比例增大,最高燃烧压力略升高,燃烧持续期增长;随着喷射间隔的增大,最高燃烧压力不变,但后喷燃烧相位推迟,燃烧持续期增长。与无后喷算例相比,后喷比例增大到10%和20%时,碳烟排放分别降低了7.7%～13.5%和1.5%～11.5%,NOx排放分别升高了12.0%～15.0%和5.0%～7.0%,指示燃油消耗率分别增大了约0.1%和1.0%;而后喷比例为30%时,碳烟排放升高了2.0%～8.0%,NOx排放降低了5.0%～7.7%,指示燃油消耗率增大了约2.3%。     

Preparation of oil-water separation network based on the novel strategies of SiO2 ceramic micro-nano structure and PDMS modification

In this study, we adopted the novel strategies of the soot template method to construct SiO₂ ceramic micro-nano structure surface and polydimethylsiloxane (PDMS) modification to reduce the surface energy. We fabricated a superhydrophobic/superoleophilic NS-PDMS oil–water separation screen by depositing coarse nano-SiO₂ ceramic on the surface of 100-mesh stainless-steel screen used as a substrate under the soot template method, which reduced the surface energy with PDMS. The fabricated NS-PDMS screen exhibited excellent superhydrophobic and self-cleaning properties. In particular, the superhydrophobic properties were stably maintained under various harsh conditions. Overall, the screen manifested self-cleaning ability for various water-containing stains, for example, coffee, milk, beer, and soy sauce. The mechanically damaged screen surface still retained its high roughness, and re-modification with PDMS could recover the superhydrophobic surface and oil–water separation performance. This suggests the re-use potential of the damaged NS-PDMS screen, which is vital for cost reduction and resource recycling. We believe that our study makes a significant contribution to the literature, because the fabricated NS-PDMS screen is superhydrophobic, superoleophilic, resistant toward several water-based solutions, chemically and mechanically stable under certain conditions, and can be reused with modification and repair after damage. Therefore, this screen can be broadly used as an oil–water separator.     

Nanostructured manganese oxide on fullerene soot for water oxidation under neutral conditions

The sluggish kinetics of oxygen-evolution reaction (OER) through water-oxidation reaction results in high overpotentials for water splitting. Among different compounds, carbon-based material/Mn oxide composites were reported as OER catalysts. Fullerene soot (FS), which contains a mixture of fullerenes and carbon blacks, is low-cost compared to fullerenes and is commercially available. Herein, the Mn oxide/fullerene soot (MnO_x/FS) composite was investigated as an OER catalyst under neutral conditions. The composite was prepared through the reaction of KMnO₄ and FS as a facile, easy, and low-cost procedure. In this method, amorphous Mn oxide is formed directly on FS. The material was characterized by a number of methods. Then, the OER catalytic activity of MnO_x/FS was studied in a LiClO₄ solution (pH ≈ 6.3). Compared to pristine FS, the OER activity of MnO_x/FS is 2.5 times higher at 2.25 V vs. RHE. The Tafel slopes for OER are 450 and 240 mV per decade for FS and the reported composite, respectively.     

混合分组矩量投影法应用于详细碳烟模型求解

提出一种新型的可有效求解碳烟颗粒群体平衡模型的数值算法：混合分组矩量投影法。该方法结合传统分组法及矩方法的技术，通过在每个分组区间内引入权重粒子来拟合原始的颗粒群尺寸分布函数，解决群体平衡模型中方程的封闭性问题。该方法具有结构简单、计算量小、精确度高等优点。分别在层流预混火焰及柴油机模拟中进行试验验证，结果表明，该算法可高效地应用于不同燃烧条件下碳烟颗粒群体平衡模型的求解，模拟结果能较好复现测量结果，并为深入研究不同的碳烟反应机制提供便利。     

声波除灰与蒸汽吹灰的能量传播特性比较

蒸汽吹灰与声波除灰是目前锅炉运行中使用较多的两类除灰方式，本文重点讨论了两类除灰器的能量传播特性，并进行比较得出声波除灰在能量传输方面优于蒸汽吹灰的结论。     

Soot–additive interactions in engine oils

Soot is known to cause engine wear. In this work, we focus on how engine oil formulation affects soot‐related wear, and how the lubricant‐derived anti‐wear film changes when soot is present. Friction and wear experiments of fully and partially formulated diesel engine oils (containing basestock, dispersants and viscosity modifiers) are conducted with a ball‐on‐disk rig in the presence of carbon black (CB) as a soot surrogate. The friction coefficient was largely unaffected by CB dispersed in the oils, but electrically insulating film formation, an indication of the formation of anti‐wear films, was decreased. Wear on the disk was found to either remain the same or decrease when CB was present, depending on the oil formulation. An examination of the lubricant‐derived films using Raman and Auger electron spectroscopies found that the presence of more abundant amorphous carbon and lesser amounts of anti‐wear film components on the surface was associated with higher wear. Copyright © 2009 John Wiley & Sons, Ltd.     

炭黑与NO还原反应的研究综述

1引言利用含碳材料(活性炭、煤焦、石墨等)去除燃烧系统产生的NO是一种有效的方法,越来越受到人们的重视。例如,近年来一些研究者对煤焦还原去除NO的机理进行了大量的研究,这为开发有效煤粉再燃技术提供了保证。炭黑也是一种在燃烧过程中生成的典型含碳颗粒,利用它来去除NO是很