THE OPTIMUM PLATE-SPACING FOR THE BEST PERFORMANCE IN FLAT-PLATE THERMAL DIFFUSION COLUMNS OF THE FRAZIER SCHEME

The effect of plate spacing on the degree of separation and production rate in flat-plate thermal diffusion columns of the Frazier scheme with fixed operating expense, has been investigated. The equations for estimating optimum plate-spacing for maximum separation and for maximum production rate have been developed. Considerable improvement in performance is obtainable when the thermal diffusion columns with optimum plate-spacing are employed for operation.     

THE OPTIMUM PLATE-SPACING FOR THE BEST PERFORMANCE IN A FLAT-PLATE THERMAL DIFFUSION COLUMN WITH TRANSVERSE SAMPLING STREAMS

The equations for estimating optimum plate-spacing for maximum separation and for maximum production rate in a flat-plate thermal diffusion column with transverse sampling stream and with fixed operating expense, have been derived. Considerable improvement in performance is obtainable if the optimum plate-spacing is selected so that the convective strength can be properly reduced and controlled, resulting in suppressing the undesirable remixing effect while still preserving the desirable cascading effect and thereby leading to improved performance.     

OPTIMAL PLATE ASPECT RATIO FOR THE BEST PERFORMANCE OF THE ENRICHMENT OF HEAVY WATER IN THERMAL-DIFFUSION COLUMNS OF A COUNTERCURRENT-FLOW FRAZIER SCHEME

The effect of plate aspect ratio on the performance of enrichment of heavy water in thermal-diffusion columns of a countercurrent-flow Frazier scheme was investigated. The equation for the optimal plate aspect ratios and the corresponding best performance were derived. Considerable improvement in performance is obtained when thermal-diffusion columns are operated at the optimal plate aspect ratio. Further improvement can be achieved if the scheme is connected and operated in countercurrent flow, instead of concurrent flow.     

OPTIMAL PLATE ASPECT RATIO FOR THE BEST PERFORMANCE OF THE ENRICHMENT OF HEAVY WATER IN THERMAL-DIFFUSION COLUMNS OF A COUNTERCURRENT-FLOW FRAZIER SCHEME

The effect of plate aspect ratio on the performance of enrichment of heavy water in thermal-diffusion columns of a countercurrent-flow Frazier scheme was investigated. The equation for the optimal plate aspect ratios and the corresponding best performance were derived. Considerable improvement in performance is obtained when thermal-diffusion columns are operated at the optimal plate aspect ratio. Further improvement can be achieved if the scheme is connected and operated in countercurrent flow, instead of concurrent flow.     

微孔曝气/斜板沉淀工艺处理含铬含砷废水

攀钢钛白粉厂一车间含铬含砷废水处理工程采用微孔曝气与高效絮凝斜板沉淀相结合为主体的处理工艺。整套处理装置运行稳定,出水TCr、Cr6+、As平均去除率分别达到72.22%、86.18%、47.46%,符合污水综合排放标准(GB 8978-1996)第一类污染物最高允许排放浓度标准。     

MASS TRANSFER IN LAMINAR FLOW IN CONCENTRIC-TUBE THERMAL-DIFFUSION COLUMNS FOR HEAVY WATER ENRICHMENT UNDER THE EFFECTS OF FLOW-RATE FRACTIONS AND RECYCLES

An orthogonal expansion technique for solving separation problems in laminar countercurrent concentric circular thermal-diffusion columns under flow-rate fraction variations is developed analytically and applied to heavy water enrichment. Experimental work for the H₂O–HDO–D₂O system has been also conducted. The present theoretical predictions are based on Sturmian theory, and positive and negative eigenvalues are needed for enriching and stripping sections, respectively, during the calculation procedure. The results show that the theoretical predictions are in better agreement with the experimental results than those predicted in previous works by using the transport equation.     

线性酚醛对计算机直接制版版材灵敏度的影响

线性酚醛树脂是热交联型计算机直接制版版材的成膜树脂之一,它的性质对版材的灵敏度有很大影响。利用热交联型版材的红外和紫外两用性,研究了影响版材灵敏度的线性酚醛树脂的指标,实验表明其分子质量在5000左右合适。并在版材中优化了成膜树脂的比例,提高了版材的灵敏度。     

横向剪应变对正交异性板弯扭耦合效应影响的数值分析

本文给出了层合板位移增量型的平衡微分方程。定量地估计了横发变形对四边铰支的正交异性板弯扭耦合效应的影响。结果表明：四边铰支的正交异性层合板，当其长厚比小于３０时，横发变形对其位移和应力的影响是不容忽略。     

铺层方向角偏差对复合材料层板阶梯挖补的拉伸强度影响研究

针对复合材料损伤结构维修中容易出现的铺层角度偏差,根据实际维修情况建立复合材料层板阶梯挖补结构的有限元计算模型,并通过试验验证了该模型的准确性。基于该有限元分析模型并考虑真实维修过程中可能出现的铺叠误差与基准偏差,分别进行了维修结构的单层与整体铺层方向角偏移的拉伸强度性能分析。结果表明,补片出现小角度方向角偏移时,补片中面层以下的铺层角偏移对于拉伸强度的影响可以忽略,中面层以上的铺层随着偏移角度的增大与越靠近表层的位置,结构整体极限应力逐渐增大,当最表层铺层出现偏移时,对于修补结构拉伸强度的影响较大;附加层在修补结构中受载严重,通用的0°附加层铺设角度不一定适用于所有的修补工况,该分析结论也为实际工程维修提供了很好的指导意义。     

孔板波纹填料的结构参数对其性能的影响

在内径Φ30 0mm的填料塔中研究了孔板波纹填料的结构参数对液相轴向混合特性、流体力学和传质性能的影响 .研究结果表明 ,轴向返混参数随开孔率、倾角的增加及盘高的减小而增加 ,填料层压降随开孔率、盘高的增加及倾角的减小而降低 ,传质单元高度随倾角的增加、盘高的减小而降低 ,开孔率对传质单元高度的影响有一个适宜值 .通过对实验数据的回归分析得出了轴向返混参数、填料层压降及传质单元高度的关联式 .该研究结果对孔板波纹填料的开发与设计具有参考价值     

倾斜管内热进口段自然强制复合对流传热

用数值分析方法研究了倾斜管内热进口段自然强制同向复合对流传热 ,分析了浮力、倾斜角及轴向导热对流动和传热特性的影响 ,得到了速度、温度、壁面剪切应力、局部及平均Nusselt数的分布和变化 研究结果显示Pe=71时平均Nusselt数的最大值位于 2 5°～ 45°之间 ,Pe=2 5时则在 90°处出现 .     

塔板沟流及其影响

介绍了塔板上一种特殊的流动不均现象．首次给出了用热膜流速仪在φ1200冷模高弹性浮阀塔板上测定的沟流量数据．并进行了塔板沟流量对塔板效率影响的模拟研究,在计算中采用了新的分区法──将塔板分为传质鼓泡区和沟流区,得出了不同参数条件下塔板沟流量与塔板效率的变化关系曲线。     

INFLUENCE OF SOLUTE TEMPERATURE AND CONCENTRATION ON THE COMBINED OSMOTIC AND AIR DRYING

ABSTRACT

The effect of solute concentration (15–45 % sugars) and temperature (10–40 °C) on the osmotic dehydration of apple was investigated. Cylindrical samples of apple were immersed in glucose or sucrose solutions and the water loss, the volume of solids and the porosity were measured as a function of time. Water loss was proportional to the square root of time, while the volume of solids decreased and the porosity increased with time. Sugar gain and water loss decreased the compression stress of the apple samples. Osmotic pre-treatment reduced the shrinkage and the porosity of apple solids during air-drying, compared to the no-treated samples. The results of this investigation are useful in the design of efficient osmotic dehydration processes, and in the evaluation of texture of dehydration of products.     

PSF/SPSF相容性对合金膜结构和性能的影响

通过混合焓法预测并用相差显微镜表征了PSF/SPSF合金体系的相容性，表明二者为部分相容体系，合金膜中聚合物的组成和铸膜液中溶剂的性能影响PSF/SPSF间的相容性，进而影响合金膜的结构和性能。随合金体系相容性下降，膜的平均孔径显著增加，水通量增大而相应的截留率下降，研究表明，改变PSF/SPSF间的相容性是调节膜结构，提高膜性能的有效方法。     

INFLUENCE OF SOLUTE TEMPERATURE AND CONCENTRATION ON THE COMBINED OSMOTIC AND AIR DRYING

The effect of solute concentration (15-45 % sugars) and temperature (10-40 °C) on the osmotic dehydration of apple was investigated. Cylindrical samples of apple were immersed in glucose or sucrose solutions and the water loss, the volume of solids and the porosity were measured as a function of time. Water loss was proportional to the square root of time, while the volume of solids decreased and the porosity increased with time. Sugar gain and water loss decreased the compression stress of the apple samples. Osmotic pre-treatment reduced the shrinkage and the porosity of apple solids during air-drying, compared to the no-treated samples. The results of this investigation are useful in the design of efficient osmotic dehydration processes, and in the evaluation of texture of dehydration of products.     

THERMAL-DIFFUSION AND DIFFUSION-THERMO EFFECTS ON NATURAL CONVECTION ALONG AN INCLINED STRETCHING SURFACE IN A POROUS MEDIUM WITH CHEMICAL REACTION

The steady natural convection along an inclined stretching surface in the presence of chemical reaction under thermal-diffusion and diffusion-thermo effects is studied. The governing equations for continuity, momentum, energy, and concentration are transformed by similarity transformation and then solved numerically using the Runge-Kutta integration with shooting scheme. Comparisons between the present data with previously published work are performed and found to be in very good agreement with each other. The obtained results show that the flow, thermal, and diffusion fields are influenced appreciably by the effects of endothermic or exothermic chemical reaction, angle of inclination, thermal radiation, magnetic field, and Soret and Dufour numbers. The physical phenomenon can be realized from the graphical profiles and in tabular form to depict special features of the solutions.     

锌系脱硫剂脱硫反应中的联合扩散效应

从描述气固非催化反应动力学行为的粒子模型出发，探讨了国产Ｔ３０２、Ｔ３０５脱硫剂脱除Ｈ_２Ｓ反应过程中联合扩散行为的影响，分析了影响联合扩散系数的因素。实验结果和理论研究表明，采用联合扩散系数，可以非常有效且方便地用粒子模型描述该反应体系的动力学行为。     

THE EFFECT OF DISTRIBUTORS ON TWO-PHASE AND THREE-PHASE FLOWS IN VERTICAL COLUMNS

Two-phase air-water and three-phase air-water-solids flows have been investigated in a 0.152 m internal diameter vertical column. Pressure drop across the distributor and average phase hold-up were measured for two-phase and three-phase flows over flow ranges of superficial gas velocity from 0 to 259 m/s and superficial liquid velocity from 0 to 0.0346 m/s. Gas hold-up/pressure-drop ratios were obtained as a function of superficial gas velocity and liquid flow rate. It was found that the bubble cap was better at gas distribution than that of the Koch static mixer in two-phase and three-phase vertical flows. Drift flux to gas hold-up and drift flux to gas flow rate correlations were obtained for two-phase and three-phase vertical flows. Three flow patterns, churn-turbulent, transition and ideal bubble flows, were observed for vertical upflow.     

PVC/PSf共混相容性及其对膜结构和性能的影响

本文通过混合焓法预测并用差示扫描量热法表征了PVC／PSf共混体系的相容性,表明二者为部分相容体系。以Flory-Huggins的高分子溶液理论为基础,通过Wood方程,计算出了不同共混比的PVC／PSf共混体系两相中二组分的表观体积分率,进而计算出体系的聚合物-聚合物相互作用参数X1.2对PVC／PSf共混体系的相容性进行了校验。通过对不同共混比的膜结构和性能的考察,结果表明：共混膜中聚合物的共混比影响PVC／PSf的相容性,进而影响共混膜的结构和性能;当聚合物浓度为17%,PVC／PSf共混比为4：1时,所制得的PVC／PSf共混中空纤维膜具有较高的水通量和截留率。     

INFLUENCE OF THE DISTRIBUTOR PLATE AND OPERATING CONDITIONS ON THE FLUIDIZATION QUALITY OF A GAS FLUIDIZED BED

Experiments were carried out to examine the influence of both the type and the pressure drop of distributor plates on the fluidization quality of an atmospheric fluidized bed. Three different distributor types were used, perforated Perspex, metallic mesh, and porous ceramic, with pressure drops ranging from 0.05 to 350 kPa and superficial air velocities ranging from 0.1 to 2.3 m/s. Three sizes of silica Ballotini beads, 355–425, 600–710, and 850–1000 µm, were used as bed material. The static bed height was set to 300 mm and was divided into six horizontal 50 mm high slices. For each slice, pressure drop values were recorded for U₀/U_mf ratios from 20 to 1. In order to produce a reference for the pressure drop evolution, a modification of the two-phase theory was introduced, taking into consideration the increase in the average global porosity as well as the change in the ratio of flow through the bubbles versus the flow through the dense phase. This allowed assessment of the influence of the different operating conditions and setups on the quality of fluidization, Q?.