Numerical study on laminar burning velocity of ammonia flame with methanol addition

The combustion characteristics of ammonia/methanol mixtures were investigated numerically in this study. Methanol has a dramatic promotive effect on the laminar burning velocity (LBV) of ammonia. Three mechanisms from literature and another four self-developed mechanisms constructed in this study were evaluated using the measured laminar burning velocities of ammonia/methanol mixtures from Wang et al. (Combust.Flame. 2021). Generally, none of the selected mechanisms can precisely predict the measured laminar burning velocities at all conditions. Aiming to develop a simplified and reliable mechanism for ammonia/methanol mixtures, the constructed mechanism utilized NUI Galway mechanism (Combust.Flame. 2016) as methanol sub-mechanism and the Otomo mechanism (Int. J. Hydrogen. Energy. 2018) as ammonia sub-mechanism was optimized and reduced. The reduced mechanism entitled ‘DNO-NH3’, can accurately reproduce the measured laminar burning velocities of ammonia/methanol mixtures under all conditions. A reaction path analysis of the ammonia/methanol mixtures based on the DNO-NH3 mechanism shows that methanol is not directly involved in ammonia oxidation, instead, the produced methyl radicals from methanol oxidization contribute to the dehydrogenation of ammonia. Besides, NO_x emission analysis demonstrates that 60% methanol addition results in the highest NO_x emissions. The most important reactions dominating the NO_x consumption and production are identified in this study.     

不同级配对微表处混和料性能的影响

微表处技术是一种性能优良的路面养护技术。首先检验了微表处用原材料的技术指标,在满足规范的要求下选择了三种不同级配,并对三种不同级配的微表处混和料的使用性能进行了比较。     

乙烯齐聚催化剂研究进展

乙烯齐聚是合成直链低碳α-烯烃最先进的方法，直链低碳α-烯烃可用于生产低密度聚乙烯和高密度聚乙烯等多种精细化学品。本文综述了乙烯齐聚催化体系的研究进展，重点介绍了镍、锆、钛催化剂的组成以及反应时间、反应温度、溶剂、助催化剂等因素对乙烯齐聚活性和选择性的影响，并讨论了典型镍的催化机理。     

用晶种技术解决低品位石灰石配料中存在的问题

采用晶种技术，能有效地改善熟料的煅烧过程和熟料的质量。晶种和复合矿化剂的作用机理不同，在某些方面具有互补性。     

风扇磨煤机ZGMn13冲击板的失效分析

ZGMn13冲击板的失效方式为不同角度的粒子撞击和冲刷，其表面可以分为三个典型的磨损区域：低角度撞击区、高角度撞击区和冲刷区。详细分析了该三个磨损区域的磨损机理。次表面分析的结果表明，在低负度撞击和冲刷条件下，高锰钢未能充分加工硬化，耐磨性提高有限。     

几种典型凸轮裹包执行机构的从动系统运动规律的理论分析

详细分析了裹包执行机构的正弦型和正切型从动系统的运动规律，用数学方法对运动规律进行了详尽的理论分析。     

多元羧酸防皱机理的探讨

多元羧酸的防皱机理是近期织物防皱整理研究讨论的热点。其中，催化剂在体系中所起的作用现有多种说法，如催化成酐，催化成酯，以及既催化成酐又催化成酯和其他一些观点。本文就多元羧酸的防皱机理作一分析和归纳，并提出一些看法。     

A framework of virtual prototyping environment for the design and analysis of mechanical mechanism with clearance

Mechanical mechanisms with clearance abound in technological fields such as robotics, machine and steam turbine industry. The dynamic performance of these mechanisms in working condition can be achieved provided that the effects of the different on the mechanisms (such as mechanism dynamics, technological effects and thermal behaviour) are thoroughly understood. Virtual prototyping provides an integration of multi-domain dynamic simulation for the design and analysis process. In the current paper, a framework of virtual prototyping environment for the design and analysis of mechanical mechanism with clearance is presented. A case study with such a simulation strategy is studied for the optimum design and analysis of the technological parameter.     

Ozonation Impact on Degradation and Toxicity of Non-Ionic Surfactants

Aqueous solutions of five selected non-ionic surfactants: Triton (i-octylphenolethoxylates), Tergitol (2,6,8-trimethyl-4-nonanoloxethylates), Symperonic (n-nonylphenol-oxethylates) and Brij (fatty alcohol ethoxylates) were investigated in this study. Using the bioluminescent bacteria Vibrio fischeri the toxicity of the surfactants solutions were determined. An attempt was made to relate rather low biodegradability of nonionic surfactant solutions measured by the BOD₅/COD ratio (ranging from 1 to 17%) to their toxicity. The ozonation process was carried out in a 1.5 dm³ stirred cell reactor equipped with two ozone detectors. The following parameters were analyzed: pH, COD, BOD₅, DOC, TOC, polarography as well as UV spectrum. The positive effect of ozonation, represented by decay of UV absorption, was visible in almost complete destruction of the surfactants, with exception of Triton X-705 (only 65% degradation after absorption of 2000 mgO₃/dm³). The most striking results were obtained in toxicity tests for ozonated solutions of the non-ionic surfactants – an increase of the bacterial growth inhibition (1.5 to 4 times increase in toxicity due to ozonation). The obtained results were discussed taking into account the literature and our own experimental data on mechanisms of ozonation and biodegradation of non-ionic surfactants of the Triton-type and similar chemical structures.     

Influence of a lipid phase on steam jet agglomeration of maltodextrin powders

The contribution of an oil phase to the agglomeration mechanisms of food powders was evaluated. Maltodextrin (DE 10), palm oil stearin and two palm oil oleins (up to 25% dry mass) were used as food models. Granulation runs were carried out in a pilot plant steam jet agglomerator. The powders containing oleins were more cohesive than those with stearin and the presence of oil changed the agglomeration mechanisms. The size increase mechanism of pure maltodextrin powder was controlled by surface plasticization and agglomerates with suitable instant properties were obtained. Small amount of oil degenerated drastically the rate of dispersion in water of the powders and their agglomerates but the average size and the mechanical resistance of the agglomerates increased when the oil content of the powders increased. SEM micrographs of agglomerates indicated that higher lipid content in the powders produced compact granules, favoring sinkability but hindering their disintegration. Agglomeration enhanced considerably the flowability of the particles containing oil. The dispersion behavior of the powders with higher lipid content could be correlated with the Hausner Number. A pre-agglomeration step favored the blend of the more cohesive powders producing larger and more resistant agglomerates.