Optimization of the Liquid Distributor in a Falling Film Evaporator by Means of Air‐Water Experiments

Air‐water experiments (cold‐flow experiments) were performed for the liquid distributor of an industrial falling film evaporator (FFE). The feed to the FFE is superheated and a flash evaporation occurs in the head of the FFE. The aim of the experiments was to investigate the vapor‐liquid flow in the head and the resulting liquid distribution to the evaporator tubes. Several different designs of the distributor were investigated and explanations for the performance losses of the real evaporator over time were found. Several measures were finally concluded and also implemented for the real FFE.     

基于CFD的喷射分配器结构优化研究

基于计算流体力学（CFD）对喷射分配器进行了数值模拟与结构优化研究，首先进行了模型验证，确保所选流体力学模型的可靠性，其次对喷射分配器的原始构型进行模拟，得到其压降、分布不均匀度以及分配器下方液相喷洒面积等性能参数。在此基础上，对分配器进气孔数目、开孔位置、喷嘴结构及尺寸进行优化，改进后的分配器的分布不均匀度比原始构型降低57.96%，分配器下方液相喷洒面积增大179.05%，压降增大10%，抗塔板倾斜能力提高2%。结果表明，改进的分配器综合性能优于原始构型。     

Evaluation of hydrodynamic behavior of the perforated gas distributor of industrial gas phase polymerization reactor using CFD-PBM coupled model

A 2D computational fluid dynamics (Eulerian–Eulerian) multiphase flow model coupled with a population balance model (CFD-PBM) was implemented to investigate the fluidization structure in terms of entrance region in an industrial-scale gas phase fluidized bed reactor. The simulation results were compared with the industrial data, and good agreement was observed. Two cases including perforated distributor and complete sparger were applied to examine the flow structure through the bed. The parametric sensitivity analysis of time step, number of node, drag coefficient, and specularity coefficient was carried out. It was found that the results were more sensitive to the drag model. The results showed that the entrance configuration has significant effect on the flow structure. While the dead zones are created in both corners of the distributors, the perforated distributor generates more startup bubbles, heterogeneous flow field, and better gas–solid interaction above the entrance region due to jet formation.     

Two/three-dimensional reduced graphene oxide coating for porous flow distributor in polymer electrolyte membrane fuel cell

There are drawbacks to use stainless-steel plates as a flow distributor plate in fuel cell, due to some of their properties being inferior to graphite flow distributor plates in terms of electrical conductivity and corrosion resistance. To overcome these problems, many researches have been conducted to improve the properties of stainless-steel flow distributor plates through coating of carbon materials. Herein, two-dimensional Web-like graphene (WG) and self-assembled three-dimensional graphene (STG) are coated through superheat vaporization of micro-droplet method. WG is coated in porous Ni–Cr foam and STG is constructed on the flat flow distributor plate, and they exhibit the feasibility to be applied in flow distributors. Compared to uncoated Ni–Cr foam, the performance of the PEMFC system with the graphene coated foam is enhanced remarkably. Furthermore, the flow distributor plate with the STG exhibits potential to be used directly to flow distributor.     

Computational investigation on the flow characteristics in beam dyeing process

Abstract

Ensuring uniform addition of coloring material to the fabric is an essential requirement in the textile dyeing process. Beam dyeing machine consists of a special beam, the barrel of which is evenly perforated with holes. The dye liquor is forced into the fabric material through this beam. For uniform fabric coloring, an equal distribution of the dye liquor through the porous beam has to be ensured. The present methodology employs theoretical and computational fluid dynamics aspects of beam dyeing process to obtain better performance. The analysis of a beam with a single row of branches shows that nonuniformity increases with an increase in inlet mass flow. Further beam flow distribution with and without fabric are studied for different parameters, such as branch diameter, inlet mass flow rate, operating conditions, and flow reversal. The present results provide guidelines to improve the levelness of the dye distribution in the fabric material.     

基于CFD技术优化50 L发酵罐内气体分布器

通过CFD模拟技术对50L通气搅拌发酵罐内不同气体分布器的传质混合效果进行气液双相流模拟。首先对发酵罐自带气体分布器进行流场模拟,针对模拟结果提出两种改进气体分布器。结果表明:双层环形气体分布器表现出一种较理想的混合传质效果,为此类发酵罐的优化和放大提供一种有效的技术手段。     

催化裂化管式待生剂分配器颗粒分配特性及内部流动特性的CPFD模拟

基于CPFD(Computational particle fluid dynamics)方法，对实验室前期研究的催化裂化管式分配器内的颗粒分配特性及内部流动特性进行了数值模拟，系统研究了输送风、松动风及分配器倾斜角度对颗粒分配不均匀指数的影响，并进一步考察了输送风和松动风对分配器各出口气体流量分布及内部气 固流动特性的影响。结果表明，增大输送风量、松动风量以及分配器的倾斜角度均可以降低颗粒分配不均匀指数，但改变松动风量的效果不如改变输送风量和倾斜角度显著。分配器倾斜角存在一个最优值时，颗粒分配均匀性最佳。输送风的增大会使得颗粒出料量最高的排料口的位置逐渐向分配器的末端移动，中间排料口所流出的气体流量占比增大，末端排料口排风量占比减小。引入松动风后，各出口的颗粒排料量更加接近，同时靠近末端排料口的气体流量占比明显增大。     

多缝型锥管布浆器的探索性研究

介绍了一种多缝型锥管布浆器，采用计算机流体动力学方法对该布浆器进行了数值模拟与分析，并对其结构进行了优化。初步研究发现，多缝型锥管布浆器的布浆效果优于支管型锥管布浆器，最大误差缩小了0.9%；优化后缝长为185 mm，多缝入口圆弧半径为7.5 mm，出口圆弧半径为265 mm，扩散管长度为90 mm时，各缝流量分布最大误差为1.43%；多缝型锥管布浆器从结构原理上可以实现在线调节缝宽，以进一步减小布浆流量分布误差，并减小或取消回流量。     

Cause of flow distributor on flow uniformity in open waterway stream passage velocity comparisons

In an open waterway flow passage, the inclusion of flow distributor paves a way to understand the idea of flow uniformity of the water along the upstream side and prevents non-uniform flow of water besides the passage length as a function of flow rate. The interesting idea in the flow distributor is its length and porosity. The essential conditions that should be satisfied are: there should not be any turbulence and there should be a possibility of achieving uniform circumferential flow in the flow passage. The other critical issue is the accurate measurement of low velocity of water. In this paper, a propeller-turbine-type anemometer is specially designed, fabricated and calibrated to measure the local velocity of water in the range of 0.001–0.01 m/s. This paper signifies how the flow uniformity is achieved by varying the size and porosity of the flow distributor.     

轴向柱塞泵摩擦副耐磨可靠性设计

本提出了以摩擦副的（ｐυ）应力模型和应力一强度干涉模型为基础，建立轴向柱塞泵缸体一配流盘这对关键摩擦副可靠性设计模型，并以ＸＢ４０型轴向柱塞泵为实例，作了缸体一配流盘的耐磨可靠性设计。