单相NPC型H桥级联逆变器电容电压不均与环流相互作用机理及建模研究

针对单相NPC型H桥级联逆变器并联时环流与电容电压不均的相互关系进行研究。通过环流等效电路推导了一个开关周期内环流与电容电压不均之间的数学关系,发现电容电压不均差异是环流的激励源之一;同时环流会改善一台并联逆变器的电容电压不均,恶化另一台逆变器的电容电压不均。为建立周期稳态条件下的环流-电容电压不均数学模型,提出采用“假设—建模—求解—检验—校正”的建模思路建立了基于阻滞的环流作用模型,有效避免了多因素建模的复杂性,同时提高了模型的准确性,仿真和试验结果表明,基于阻滞的环流作用模型拟合决定系数可达0.963 8和0.945 0,证明了环流模型的准确性。     

世界铝工业的可持续发展

本文根据国际铝协的统计资料，分析了世界铝工业在土地恢复、能源消耗、水循环使用、含氟污染物排放、固体废物堆存方面的进展以及金属铝循环利用率的提高，说明了世界铝工业发展的可持续性。     

3种高电流密度离子膜电解槽的性能对比与介绍

目前离子膜电解槽的发展方向为复极、自然循环、高电流密度、低电耗，伍德诺拉公司BM2．7-Ⅲ型槽、美国西方化学公司ExL^B-65槽、日本氯工程公司BiTAC-858槽即具有这些先进性能。对这3种槽进行了介绍与对比。     

Dynamics of fluid circulation in coupled free and heterogeneous porous domains

Fluid flow in coupled free and porous domain, particularly when the porous medium is heterogeneous, is encountered in many hydro-environmental conditions, e.g., leakage from underground pipe, combined groundwater lake-subsurface interactions. One of the most difficult problems in the study of coupled flow behaviour has been the development of a universally applicable modelling scheme for combining the flow regimes. This is because the free/porous interfacial properties (e.g., shear-stress; velocity slip) that govern the coupled flow behaviour are difficult to determine experimentally under hydro-environmental conditions. On the other hand, the implications of various forms of heterogeneity in the porous media properties can be very different on the fluid-flow behaviour. Difficulties may also arise in direct coupling of the model equations that govern the fluid flow in the individual regions (e.g., Navier-Stokes for free-flow region and the Darcy's equation for the porous flow region). Consequently, models of coupled free and porous flow for hydro-environmental conditions are not very well developed at the moment. While there are some indications that fluids in coupled free and porous domains may circulate (i.e., development of flow cells), there is a lack of appropriate 3D analysis on how heterogeneities in porous media may affect such flow patterns. In this paper, we aim to analyse how porous media heterogeneity affects the dynamics of flow circulation in the porous side of a coupled free and porous domain. For this purpose, we analyse flow patterns in several model domains made up of two porous layers with differing permeabilities. The governing model equations are discretised and solved using the standard finite volume method on a staggered cell-centred mesh. The temporal discretisation is done using the explicit method. An in-house graphical user interface (GUI) has been created specifically to aid in the visualisation of otherwise complex flow patterns. The GUI contains many post-processing options and provides a comprehensive tool for the analysis of hydrodynamics and contaminant motion (not discussed in this paper) in coupled free and porous flow domains. This GUI is described in this paper briefly. The effects of altering the aspect ratio (i.e., multi-scale) of the domain on the coupled flow pattern have also been discussed.     

化工生产过程控制中气动薄膜调节阀的选择

本文就气动薄膜调节阀类型、作用方式、流量特性和口径大小的选择，结合化工生产的特点作了较详细地阐述。     

内循环流化床固体循环速率的研究

研究一种加料不独立的垂直气力输送装置，并以流化床作为料仓和混合区，两者构成固体循环系统。由于系统特性，加料喷嘴的插入高度与加料结构将会直接影响操作的稳定性，从力的平衡出发导出临界结构为ｈｅ／Ｄｅ＜ｆＨＬ／Ｒ，其中ｆ是颗粒特性的函数。     

共聚型聚醋酸乙烯酯乳液胶粘剂的研制

利用醋酸乙烯酯与两种烯类单体共聚,研制出防冻性、耐水性较好的环保型聚醋酸乙烯乳液胶粘剂,并通过研究发现聚醋酸乙烯乳液组成(聚乙烯醇、共聚单体以及乳化剂等)均对乳液性能产生影响。     

磷酸铵生产中高温冷凝水密闭循环回收与应用

针对目前磷酸铵生产排出的高温冷凝水的热能未得到充分利用及由此产生的热污染，介绍了一种把排出的高温冷凝水密闭循环回收利用技术，可使蒸汽热力系统的运行效率提高10％以上。分析了该技术的特点和运行状况，认为采用该技术对蒸汽能力系统进行改造，投资少、见效快，投资回收期短、经济效益好，又消除了热污染现象，在磷酸铵生产中有推广价值。     

Particle velocity and solids circulation rate in a jet-spouted bed

Radial distribution of particle velocities, solids circulation rate and radial variation in bed voidage in a jet-spouted bed were investigated in a 0.2 m diameter conical-cylindrical column. The upward particle velocity is strongly dependent on gas velocity and its radial profile is the Gaussian. The solids circulation rates are of the same order of magnitude as those in a conventional spouted bed and are proportional to the gas velocity. Estimation of the variation in bed voidage in the radial direction revealed that the annulus voidage of about 0.90 was greater than the spout voidage of around 0.70. This tendency is contrary to that in a conventional spouted bed.     

工业循环冷却水用BC－653杀生剂的抗菌性能测定

本文对ＢＣ－６５３杀生剂进行了室内抗菌实验，着重阐述了投药量对杀菌率的影响。结果显示该杀生剂与国外同类产品杀菌力基本一致。