HEAT TRANSFER IN PARTIALLY MISCIBLE TERNARY SYSTEMS

In the study of mass transfer between partially miscible liquids, temperature perturbations have been found to have an important effect in the generation of interfacial activity. Micro- and macro-generated interfacial convection usually occurs in combination with one another even in fairly simple heat or mass transfer events. These combinations are responsible for the enhancement of mass transfer rates. In an effort to acquire a better understanding of the heat transfer effects in ternary liquid-liquid systems, temperature difference profiles were measured when contacting two partially miscible phases. A vertical and a rotational transfer cell were designed to contact the partially miscible phases without inducing external disturbances. Five thermocouples were immersed in the bottom liquid phase at predetermined positions below the interface. In order to understand the influence of the convection generated, the vertical cell was designed to hinder convection in one phase, while the rotational cell permits convection in both phases. The experimental results showed larger temperature differences in the rotational cell after the contact of the phases. Also, systems which were initially unsaturated presented larger heat effects than those in which the partially miscible solvents were initially saturated. Several parameters indicating the importance of heat effects in the ternary systems studied are reported.     

工艺参数对PP挤出发泡泡孔结构的影响

研究了螺杆转速、机头口模形状以及机头温度对挤出发泡聚丙烯(PP)泡孔结构的影响。结果表明：在挤出发泡过程中，一定配方、机头形状和温度下，螺杆转速存在最佳值；机头形状越有利于建立高压，制得的泡沫的泡孔越细密均匀且发泡倍率越高；机头口模温度在保证顺利挤出情况下．越低越有利于制得高发泡倍率的泡沫。     

注塑模温度场的计算机模拟

本文运用有限元法，采用二次等参单元，对注塑模二维非稳态温度场进行了数值分析，推导了有限元数值求解方程并研制了有限元求解程序软件。实例所得温度场等温线与实验所得结果基本相符，验证了计算机求解的可靠性。通过计算机模拟分析，可了解各瞬时模具温度场的分布状态，观察模具体能否使塑件均匀冷却，如不合理，可通过改变冷却管道参数，达到温度场均匀一致，从而提高塑件质量。通过程序运转，根据塑件的热定型温度，可以预知最短冷却时间，从而缩短冷却周期，提高塑件生产率     

成形压力对氧化铝瓷球性能的影响

本文以不同的压力等静压成形瓷球，研究了成形压力对瓷球烧结温度、密度及耐磨性的影响。结果表明：在本研究系统内随着压力的增加瓷球的烧结温度下降，烧成温度范围拓宽。采用150MPa成形的瓷球密度最大且耐磨性最好。     

自控系统在加氢反应工艺中的应用

通过对化工生产中加氢反应的危险性简要介绍,并以某药厂对加氢反应工艺自控系统改造时从自控方案选择到自控参量、主要自控设施确定及安装、校验和系统调试等主要过程实施为例,说明此种危险可行性,为药厂类加氢工艺自控系统的技术改造提供相应的参考。     

污泥中总磷测定方法的探讨

污泥样品与氢氧化钠熔融,使污泥中含磷有机化合物全部转化为可溶性的正磷酸盐,然后测定污泥中的总磷含量.此方法方便易行,平行性好,准确度高,可作为测定污泥中总磷的标准方法.     

催化剂烧炭再生模拟和分析

催化剂烧炭再生是非定态过程。本文建立了绝热反应器内催化剂烧炭模型,利用移动边界正交配置法求解。以结炭的BO2催化剂再生为工作反应,模拟预测与实验值吻合良好。模拟计算表明,用递升进口温度序列烧炭,使再生时间明显缩短。     

A kinetic model for polystyrene (PS) pyrolysis reaction

A mathematical model for the pyrolysis reaction of polystyrene (PS) in a semi-batch reactor has been presented. The thermal degradation of PS was flexibly modeled by a combination of random and specific chain-end scissions. Numerical simulation was used to investigate the effect of operating conditions on the PS products spectrum, the results of which were validated by the experimental data. It was found that as the reaction temperature increased (decreased), the monomer fraction in the products became lower (higher) while the trimer higher (lower). No significant variation in the product composition was, however, observed while constant temperature was maintained. These results indicate the reaction temperature is an effective manipulated variable for the control of products composition of PS pyrolysis. The calculation of the optimum temperature trajectories through the optimization study can thus be of interest for achieving productivity enhancement in plastics pyrolysis processes. This paper is dedicated to Professor Dong Sup Doh on the occasion of his retirement from Korea University.     

Pt-V2O5-WO3/TiO2 catalysts supported on SiC filter for NO reduction at low temperature

The catalytic filter, V₂O₅-WO₃-TiO₂ supported on a ceramic filter, is known as a promising material for treating particulates and NO _x simultaneously at optimum temperatures around 320°C. In order to improve its catalytic activity at low temperatures, the effect of Pt addition on the catalytic filter has been investigated. Catalytic filters, Pt-V₂O₅-WO₃-TiO₂/SiC, were prepared by co-impregnation of Pt, V, and W precursors on TiO₂ coated-SiC filter by vacuum aided-dip coating. The Pt-added catalytic filter shifted the optimum working temperature from 280–330°C (for the non Pt-impregnated filter) to 180–230°C, providing N _x slip concentration less than 20 ppm for the treatment of 700 ppm NO at a face velocity of 2 cm/s with the same value over the non Pt-added catalytic filters. The promotional effect following the addition of Pt is believed to result from electrical modification of the catalyst maintaining a high electron transfer state. Ammonia oxidation was also observed to be dominant above the optimal temperature for SCR.