非牛顿流体薄膜流中质量传递的实验研究

本文通过实验,研究非牛顿流体层流降膜流中质量传递过程.实验系采用温壁塔测定二氧化碳在高分子水溶液中吸收速率.这些溶液符合幂律模型.实验证明非牛顿幂律流体降膜流中考虑速度分布的微分方程精确解是正确的;对拟塑性流体,用无因次长度Z<0.1作为渗透论适用范围的判据是合适的,而精确解则不受此范围的限制.     

二乙醇胺溶液吸收CO2过程

运用双膜理论对气液两相传质进行分析,针对二乙醇胺溶液吸收CO2建立数学模型,该模型精确描述CO2传质速率对溶液pH值依赖程度及速率强化因子随化学反应进行的变化情况. 从每种含碳离子(包括CO32-, HCO3-与RNHCOO-)在不同反应阶段的浓度分布角度分析了各自对总传质速率的影响规律,实验中分别控制溶液浓度、进气流量和复合溶液配比等工艺参数. 结果表明,CO2传质速率主要受CO32-与HCO3-控制,而RNHCOO-的作用有限. 吸收液浓度提高促进传质,但当pH值降至8.2后其作用减弱;传质速率随进气流量升高而加快,70 mL/min后趋于稳定;复配溶液较单一溶液对CO2吸收速率和吸收量均有促进作用,但复配比例变化对离子贡献率影响微弱.     

伴有二级不可逆反应的非牛顿幂律流体薄膜流中化学吸收的研究

本文对伴有二级不可逆反应的非牛顿幂律流体降膜流中的吸收过程进行了研究,提出扩散反应方程和它的解,并得到实验验证.     

三角形螺旋填料旋转床全回流精馏性能研究

为了寻找强化气液传质过程的有效途径,自制了1套小型旋转填料床,床内填充了φ2mm×2mm三角形螺旋填料,以乙醇-水为实验物系,进行全回流精馏实验研究.实验结果表明:三角形螺旋填料旋转床存在一最佳转速nopt=1050r/min,当转速nnopt时,理论板数随液体流量和气体流量的增大而减小,且减小的很快.在nopt=1050r/min、液体流量L=14.7L/h、气体流量V=7.4m3/h时传质效果最好,每米填料相当于88块理论板,在适宜的转速范围内每米填料相当于62～88块理论板.三角形螺旋填料旋转床使传质过程得到极大强化,其传质效果比重力场三角形螺旋填料塔提高1倍左右.     

碱溶性羟乙基纤维素在复合溶剂体系中的流变性能

使用平行板流变仪,以氢氧化钠/硫脲/尿素/水溶液作为碱溶性羟乙基纤维素(HEC)的复合溶剂,研究了HEC在该溶剂体系中的流变性能,并考察了剪切速率、温度及溶液浓度对溶液的非牛顿指数、结构黏度指数及黏流活化能的影响。结果表明:溶液属于切力变稀型假塑性流体,随溶液温度下降及浓度增加,溶液的表观黏度和结构黏度指数增大,非牛顿性增强;该溶液的黏流活化能随着剪切速率的增加而下降。     

鼓泡反应器中幂律型流体流动与传质特性

很多废水处理装置涉及非牛顿型流体中的多相流动和传质问题,研究其中的气液传质过程有助于实现装置的优化设计和高效节能运行。以鼓泡反应器内清水和不同质量分数的羧甲基纤维素钠（CMC）水溶液为实验对象,分别研究气相表观气速和液相流变特性对气泡尺寸分布、全局气含率和体积氧传质系数的影响。实验结果表明,液相的流变特性对其传质特性参数均有较大影响。与清水相比,CMC水溶液中气泡平均直径和分布范围更大;清水和CMC水溶液的全局气含率均随表观气速的增加而增大;CMC水溶液的体积氧传质系数随CMC水溶液质量分数的增加而减小。基于实验研究,得出修正的体积氧传质系数公式和适用于幂律型非牛顿流体流动体系氧传递过程的无量纲关联式,可很好地实现非牛顿流体流动的废水处理装置中气液传质参数的计算。     

鼓泡反应器中幂律型流体流动与传质特性

很多废水处理装置涉及非牛顿型流体中的多相流动和传质问题,研究其中的气液传质过程有助于实现装置的优化设计和高效节能运行。以鼓泡反应器内清水和不同质量分数的羧甲基纤维素钠(CMC)水溶液为实验对象,分别研究气相表观气速和液相流变特性对气泡尺寸分布、全局气含率和体积氧传质系数的影响。实验结果表明,液相的流变特性对其传质特性参数均有较大影响。与清水相比,CMC水溶液中气泡平均直径和分布范围更大;清水和CMC水溶液的全局气含率均随表观气速的增加而增大;CMC水溶液的体积氧传质系数随CMC水溶液质量分数的增加而减小。基于实验研究,得出修正的体积氧传质系数公式和适用于幂律型非牛顿流体流动体系氧传递过程的无量纲关联式,可很好地实现非牛顿流体流动的废水处理装置中气液传质参数的计算。     

PB/nano-SiO2复合材料的流变性能

采用熔融共混法制备了聚丁烯(PB)/nano-SiO2复合材料,并用毛细管流变仪研究了PB及其复合材料在较宽剪切速率(1×102～6×103s-1)的流变行为.讨论了nano-SiO2含量、剪切应力、剪切速率及温度对熔体流变性、非牛顿指数和黏流活化能的影响.结果表明:PB及其复合材料的非牛顿指数均小于1,但PB/nano-SiO2的非牛顿指数大于PB的;随nano-SiO2含量增加,PB/nano-SiO2复合材料非牛顿指数上升;PB/nano-SiO2复合材料的熔融流动性随nano-SiO2用量的增加而下降;相同剪切速率时,PB/nano-SiO2的黏流活化能大于PB的.     

三相下喷式环流反应器的传质性能

在三相非牛顿型流体体系中，对下喷式环流反应器传质特性进行了实验研究。讨论了表观气速、能量耗散速率、导流筒直径与反应器直径比、喷嘴直径、导流筒下端距反应器底部的距离、固体装填量、羧甲基纤维素钠（ＣＭＣ）溶液浓度及其流变特性对它的影响。实验结果表明，容积传质系数随表观气速和能量耗散速率的增加有所增加，在实验条件下，发现最优的导流筒直径与反应器直径比在０．４～０．４５这一范围、固体装填量大约为３％（体积百分比）、导流筒下端距反应器底部的距离为０．０８ｍ左右。同时提出了容积传质系数的经验关联式。     

聚酰胺酸溶液的流变性能研究

采用锥板粘度计研究了聚酰胺酸溶液的流变性能及其粘度的影响因素。结果表明:聚酰胺酸溶液属于非牛顿假塑性流体,还具有负触变性流体的特征。聚酰胺酸溶液的粘度随剪切速率的增加而减小,随浓度的增加而增大,随温度的升高而降低,随存放时间的延长而下降;质量分数为15％的聚酰胺酸溶液的粘流活化能为20．83 kJ／mol。     

MASS TRANSFER IN DRIPPING PLATE COLUMN FOR NON-NEWTONIAN FLUIDS

In this paper, the mass transfer for non-Newtonian liquid has been studied in a dripping plate column fitted with perforated trays. The rate of evaporation of polymer solution in the column was measured and correlated. It was found that temperature, presure, mass flow rate and the non-Newtonian behavior of the solution are the significant factors having effects on mass transfer.     

一串上升气泡周围流体的湍动特性(英文)

The turbulence behavior of gas-liquid two-phase flow plays an important role in heat transfer and mass transfer in many chemical processes. In this work, a 2D particle image velocimetry (PIV) was used to investigate the turbulent characteristic of fluid induced by a chain of bubbles rising in Newtonian and non-Newtonian fluids. The instantaneous flow field, turbulent kinetic energy (TKE) and TKE dissipation rate were measured. The results demonstrated that the TKE profiles were almost symmetrical along the column center and showed higher values in the central region of the column. The TKE was enhanced with the increase of gas flow and decrease of liquid viscosity. The maximum TKE dissipation rate appeared on both sides of the bubble chain, and increased with the increase of gas flow rate or liquid viscosity. These results provide an understanding for gas-liquid mass transfer in non-Newtonian fluids.     

ILAR中醇及电解质对非牛顿流体中气-液传质的影响

在-气升式内环流反应器中试验考察了非牛顿流体羧甲基纤维素钠(CMC)中的气泡聚并现象以及表面活性物质对液相体积传质系数的影响。结果表明,非牛顿流体中气-液传质效率随黏度的增加而降低,其原因是黏度增加使Taylor泡的尾流趋于稳定,降低了液相扰动,气泡间易聚并,从而气-液传质效率低。向非牛顿流体中添加醇类物质会影响气-液传质行为,对于聚合物含量低的流体,添加微量醇可以促进气-液传质,聚合物含量高的非牛顿流体,微量醇的加入反而不利于气-液间传质过程。非牛顿流体在ILAR上升管中的气含率随着黏度的增加变化不大,而下降管中的气含率有所提高。     

Salt dissolution in drilling muds — a generalized correlation for mass transfer in non-newtonian fluids

The rate of dissolution of rock salt in drilling mud was measured as a function of flow rate and temperature under conditions simulating those in a well. A water based drilling mud, containing about 10% solids and additives was used, as well as a polymer “mud” composed of a Xanthan gum polymer solution and 5% salt, but no solids. The non-Newtonian muds were pumped through a “slit” flow cell, with a slab of rock salt flush with one side of the cell wall. The data (including water over the same range of conditions) were described by a mass transfer coefficient, and were correlated in dimensionless form based on the theoretical solution of the analogous heat transfer problem, adapted to non-Newtonian fluids. The non-Newtonian properties were described by an effective viscosity, which is consistent with either the power law or Bingham plastic viscosity model.     

Mold-filling simulations for the injection molding of continuous fiber-reinforced polymer

Injection molding can be used to fabricate fiber-reinforced polymer composites by impregnating a continuous fabric mat preplaced in a mold cavity with a polymer resin. The mold-filling time is dependent on the flow and heat transfer behavior in the mold. A model is proposed that considers the non-Newtonian How through the porous fabric mat and the heat transfer between mold, fabric mat, and flowing fluid. The model was simulated for the mold filling of a carbon fiber mat with a pseudoplastic polymer solution. The results from the simulation provide Information for optimizing mold-filling parameters through proper selection of inlet fluid pressure, heat source temperature, and type of polymer-solvent system.     

The flow resistance and aeration in modified spray tower

The paper contains the results of experimental study of air-water and air-polymer aqueous solutions atomization process in modified spray tower. The experiments on hydrodynamic characteristics in the spray column with geometrically modified confusors for water and high-molecular polymer aqueous solutions as well as on mass transfer in aeration process, have been carried out. The major running cost derived from the operation of various mass exchangers is pressure drop. It has been shown that for geometrically modified confusors with profiled inside surfaces and double profiled inside surfaces the pressure drop is smaller than in the case of classical construction. Aeration process was studied for water flow in the co-current spray column with closed circulation liquid flow. It has been shown that independently from the applied geometry of modified confusor at given gas and liquid volume rates the aeration degrees were comparable. Taking into account the considerable decrease of flow resistance in comparison with classical construction it is reasonable to recommend the modified solution for realization the aeration process.     

鼓泡床反应器内流动与传质行为的研究进展

总结了有关浆态鼓泡床反应器内流动、混合用气液传质特性的研究成果,详细地介绍了鼓泡床反应器内气含率、液速、液体轴向扩散系数、传质系数的测量方法,阐述了鼓泡床反应器性能的主要影响因素,如系统压力、温度、气体表观气速、液体性质及固含率等对流动、液相混合和传质特性的影响,并对鼓泡床反应器的应用前景进行了详述.     

Mass Transfer in a Flat Gas/Liquid Interface using non‐Newtonian Media

Gas/liquid mass transfer has been investigated using a stirred vessel gas/liquid contactor using non‐Newtonian media and carbon dioxide as absorbent and gas phase, respectively. The volumetric mass transfer coefficients at different operational variables have been determined. Non‐Newtonian media (liquid phase) were prepared as aqueous solutions of sodium carboxymethyl cellulose salt. The influence of the rheological properties, polymer concentration, stirring rate, and gas flow rate on mass transfer was studied for these liquid phases. Kinematic viscosity and density experimental data were used to calculate the average molecular weight corresponding to the polymer employed. The Ostwald model has been used to fit the rheological behavior of aqueous solutions of the polymer employed as absorbent phase. Reasonably good agreement was found between the predictions of the proposed models and the experimental data of mass transfer coefficients.