Two-dimensional Simulation for Hydrogen/Air Combustion in a Monolith Reactor

Recent studies on hydrogen combustion were reviewed briefly. The laminar flow and combustion of premixed hydrogen/air mixture in a cylindrical channel of a monolith reactor with and without catalytic wall was numerically modeled by solving two-dimensional (2-D) Navier Stokes (N S) equations, energy equation, and species equations. Eight gas species and twenty reversible gas reactions were considered. The control volume technique and the SIMPLE algorithm were used to solve the partial differential equations. The streamlines of the flow field, temperature contours, the entrance length, and the concentration fields were computed. It is found that the entrance zone plays an important role on flow and temperature as well as species distribution. Therefore, the flow cannot be assumed either as fully developed or as plug flow. There is a small but strong thermal expansion zone between the wall and the entrance. Both diffusion and convection affect the heat and mass transfer processes in the expansion zone. Thus the equations of momentum, energy and species conservations should be used to describe hydrogen/air combustion in the monolith reactor. The hot-spot location and concentration field of the homogeneous combustion is strongly influenced by the inlet velocity and temperature, and the equivalence ratio. The catalytic combustion of premixed hydrogen/air mixture over platinum catalyst-coated wall in a cylindrical channel was also simulated.     

炭黑的分散性对抗静电涂层导电性能的影响

通过高速砂磨法制备了以丙烯酸树脂为基底、炭黑为导电填料的导电涂料.分别用X射线衍射和热重分析-差热扫描考察了炭黑/丙烯酸树脂复合涂层的结晶度和热力学性能.重点研究了炭黑添加量、偶联剂、分散程度等因素对涂层导电率的影响.结果表明,炭黑添加量在3％时,以异丙基三(十二烷基苯磺酰基)钛酸酯作为偶联剂,机械研磨时间160min,得到的导电涂层电阻率达到最低值,为533 Ω·cm.     

纳米二氧化硅填充PVDF聚合物微孔膜的研究

以丙酮及N,N-二甲基甲酰胺为混合溶剂、聚偏氟乙烯为成膜物质、纳米二氧化硅为填料,通过溶液共混法制备了聚偏氟乙烯/二氧化硅(PVDF/SiO2)复合微孔薄膜。研究发现,溶剂组分质量比对薄膜力学性能有重要影响,当m(丙酮)∶m(N,N-二甲基甲酰胺)=19∶1时,薄膜力学性能最佳,其拉伸强度为3.26 MPa;经纳米SiO2改性后,复合薄膜力学性能随SiO2质量分数的增大先提高后降低,在w(SiO2)=20%时,薄膜拉伸强度达最大值6.36 MPa;复合薄膜孔隙率随SiO2质量分数的升高而增大,当w(SiO2)=40%时,孔隙率达最大值113.9%。     

RGO/BaTiO_3复合材料的制备与性能研究

采用改进的Hummer法制备氧化石墨烯(GO),以乙二醇为还原剂将GO还原得到RGO(Reduced graphene oxide),并通过物理共混法制备RGO/BaTiO3复合材料。采用扫描电镜、X射线衍射、傅里叶红外、介电性能测试仪等对其表面形貌、微观结构、介电性能进行了表征。结果表明,乙二醇为还原剂成功实现了GO的还原,且还原后的RGO有效提高了RGO/BaTiO3复合材料的介电性能。当RGO质量分数为0. 5%～0. 8%时,复合材料的介电常数高达140以上,比纯BaTiO3材料提高约1. 75倍,且介电损耗控制在0. 2～0. 45之间。     

高稳定性导热油基磁性流体的制备

以氨水为沉淀剂、油酸为表面改性剂制备了高稳定性导热油基磁性流体.研究了所制备的Fe3O4粒子和磁性流体的各项性能.结果表明,制备的Fe3O4粒子晶型完整、粒径均一,具有很高的饱和磁化强度.通过表面改性油酸成功地包覆到Fe3O4粒子表面.所制备的导热油基磁性流体具有强磁性和高稳定性.     

碳纳米管承载纳米Fe_3O_4颗粒的制备(英文)

采用一种简单又经济的方法将Fe3O4纳米颗粒填充到碳纳米管中。透射电镜(TEM)、扫描电镜(SEM)及其能谱附件(EDX)和X射线多晶衍射(XRD)测试结果表明:Fe3O4纳米颗粒成功地填充到碳纳米管中。材料的磁性能测试结果表明:碳纳米管中填充Fe3O4纳米颗粒后,在常温下具有超顺磁性,其饱和磁化强度由0.35emu/g增大到了13.15emu/g。Fe3O4纳米颗粒填充的碳纳米管可望应用于工程和医学领域。     

等离子体法制备导电炭黑的过程与装备研究进展

综述了热等离子体工艺与低温等离子体工艺制备炭黑的发展历程,认为热等离子体裂解甲烷制备导电炭黑具有转化率高、产物结构好等优势,但高温导致的设备负担,及电极损耗问题亟待解决;而低温等离子体制备导电炭黑亦有反应体系温度低,能耗下降等优势,但缺陷是转化率不高,积碳现象严重。这两种工艺虽有待完善,但各方面均胜于燃烧式工艺。等离子体法裂解甲烷不仅可以制备多种碳纳米材料,还能得到氢气、乙炔等珍贵的化工原料。我国天然气资源丰富,该工艺潜力巨大,有待大力发展。     

流化床数学模型进展

本文回顾了近代流化床反应器数学模型的发展状况，比较了三类主要模型的优缺点，提出了不同模型的应用范围及以后的发展方向。     

径向流固定床数学模型研究进展

简要阐述了径向流固定床反应器在化学工程中的重要性及研究该类流动问题的迫切性，回顾了文献中描述该反应器中流体流动的六类数学模型，提出了设计准则及均布措施，指出了存在的问题及解决的途径．