湍流搅拌槽中原油-水分散体系的液滴破碎

对搅拌槽内原油-水分散体系中液滴的破碎过程进行了实验和理论分析。实验测定了在不同温度和转速条件下油滴的粒径分布以及最大稳定粒径,并采用以Voigt模型为基础的理论对最大稳定粒径进行了计算。在温度较低时,原油表现出了具有触变性的流变学性质,经过计算和数量级分析,液滴破碎时间与粘度达到平衡的时间相比非常短,可认为在破碎过程中液滴的粘度始终为初始粘度。实验结果与以初始粘度计算的理论值吻合较好。     

油-水体系均匀液滴分散装置的改进研究

在借鉴油一气体系振动分散装置的基础上,改进设计了油一水体系均匀液滴分散装置。调节装置振动参数,可在油一水体系中获得分散均匀的油滴,并可对分散状态进行记录分析,可应用到悬浮聚合造粒中。     

湍流分散体系中液滴破碎频率模型的黏性修正

在分析研究分散相黏度对液滴变形和破碎影响的基础上,提出了一个改进的液滴破碎频率模型并拓展了液滴破碎判据标准.同时通过Monte Carlo模拟的随机方法,得到了湍流搅拌槽中液-液分散体系的液滴直径分布和Sauter平均直径d₃₂.通过与文献中关于d₃₂的实验结果比较发现,该模型预测的Sauter平均直径更接近实验值,对于黏性分散相改进的液滴破碎频率模型要优于Coulaloglou和Tavlarides提出的模型.计算结果表明对于黏性分散相液滴,其黏度限制了液滴变形,使得液滴破碎频率被大大减少, 液滴直径明显增加,液滴直径分布向右偏移.     

高分散沉淀白炭黑的粒径分布研究

利用激光衍射法研究高分散沉淀白炭黑的粒径分布。文中对测试原理、样品制备和测试要求作了详细的阐述。对影响试验结果的因素（超声振幅、超声时间和停放时间等）进行了深入探讨。研究了实验结果的精确度以及粒径大小对胶料物理性能的影响。结果表明,激光衍射法能快速、准确和客观地反映高分散沉淀白炭黑的分散能力和评价材料的品质。在制造绿色轮胎和轮胎半制品过程中,起着调整工艺、优化配方和提高轮胎成品质量的重要作用。     

高固含量多分散粒径分布乳液的研究2.二元种子法制备二元分散粒径分布乳液

通过在聚合过程中加入第２种子乳液,制备出了具有二元分散粒径分布的乳液,研究了第２种子乳液量对乳液粒径及粒径分布的影响。实验结果表明,通过改变第２种子乳液的量可以调节乳液搂闰径及粒径分布。当大粒子质量分数为８０％时,乳液粘度最小。通过粒径分布的多分散化,可显著降低乳液的最低成膜温度。     

高固含量多分散粒径分布乳液的研究 1.二次成核方法制备二元分散粒径分布乳液

通过在聚合过程中后加一定量的乳化剂,制备出了具有二元分散粒径分布的乳液。研究了后加乳化剂的用量及加入时机对乳液粒径及粒径分布的影响,并用粒子表面乳化剂覆盖率阐述了实验结果。实验结果表明：通过改变后加乳化剂的用量和加入时机,可调节乳液的粒径及粒径分布     

高固含量多分散粒径分布乳液的研究：1.二次成核方法制备二元分散粒径分布

通过在聚合过程中后加一定量的乳化剂,制备出了具有二元分散粒径分布的乳液。研究了后加乳化剂的用量及加入时机对乳液粒径及粒径分布的影响,并且粒子表面乳化剂覆盖率阐述了实验结果。实验结果表明：通过改变后加乳化剂的用量和加入时机,可调节乳液的粒径及粒径分布。     

液滴间相互碰撞融合与破碎的实验研究

液滴间的相互碰撞对发动机液体燃料雾化、燃烧效率及颗粒物排放的减少均有重要影响;为了探究液滴间相互碰撞后的液滴融合与破碎过程,采用高速摄影技术对液滴间相互碰撞的融合过程、融合振荡无量纲宽长比变化历程、破碎过程以及液体物性参数对碰撞破碎的影响进行了分析。结果表明,液滴间相互碰撞后主要呈现融合振荡与破碎两种运动形态;对融合振荡形态而言,两液滴间的碰撞速度及初始无量纲尺寸比越大,融合后液滴振荡的宽长比的最大值越大;对破碎形态而言,两液滴间的碰撞速度越大、初始无量纲尺寸比越小以及大液滴的表面张力越小,液滴发生破碎的时刻越小。研究结果可以为改善发动机缸内雾化,增大气/液间的接触面积,强化气/液间传热传质提供理论依据。     

水体系中颜料分散过程的研究

从理论角度讨论了颜料粒子分散过程中的三个步骤：润湿、分散、稳定。     

MgO超细颗粒水分散体系的稳定性研究

研究了影响MgO颗粒在水介质中的分散稳定性的因素,并通过降沉实验和测定颗粒的Zeta电势、颗粒粒度以及分散剂在颗粒/水界面的吸附等温线等来解释相关机理。研究发现,阴离子表面活性剂SDS和阳离子表面活性剂CTAB能够吸附在颗粒/水界面,提高颗粒表面的Zeta电势,增加颗粒间静电排斥效应,从而阻碍颗粒间发生絮凝,提高体系的分散稳定性。而阳离子高分子聚合物聚乙烯亚胺(PEI)在颗粒表面形成多点吸附,从而阻碍其它PEI分子在颗粒表面的吸附,对MgO微粒分散体系的稳定性贡献较小。     

Simulation of Turbulent Emulsification in a Sonolator Mixer: Interpretation of Drop Breakage Time

The simulation of dilute emulsions in a model ACIP2 Sonolator is investigated using computational fluid dynamics and population balance methods. Two breakage frequency models are used that differ in the expression of the drop breakage time. Drop breakage modeling based on homogenous isotropic turbulence (HIT) shows poor agreement of the Sauter mean diameter when compared to the experiments; simulations with the empirical model from Alopaeus et al. yield better agreement. By perturbing the classical HIT spectrum, it is shown that the breakage time in the empirical model corresponds to a non‐isotropic energy spectrum. Such spectra have been observed in the non‐isotropic near field in a model A Sonolator, which provides a plausible explanation of why the empirical model performs better than the HIT‐based model.     

轴流桨搅拌槽内完全湍流的研究

为研究轴流桨搅拌槽内完全湍流状况,采用相位多普勒粒子分析仪(PDPA)对MK和ZHX搅拌器进行流场测试,得到不同工况下的时均速度场分布.应用渐近不变性方法,选取适当的特征尺度,给出挡板处壁面射流的轴向速度相似剖面,确定用于评定槽内完全湍流界限的轴向速度分布曲线,建立了搅拌雷诺数与搅拌槽内完全湍流流动达到的高度之间的线性关系.结果表明,非全槽完全湍流状态下,槽上部会出现过渡流区;随雷诺数的增大,搅拌槽内完全湍流流动达到的高度增大;不同型式搅拌器的完全湍流流场所需的雷诺数不同,单层桨搅拌槽内达到全槽完全湍流需要很大的搅拌功率.     

Drop size distribution and mean drop size in a pulsed packed extraction column

Drop size distribution and mean drop size are used for calculation of interfacial area available for mass transfer. In this study, the drop size distribution and Sauter mean drop diameter (d₃₂) have been investigated using three different liquid systems in the absence of mass transfer in a pilot plant pulsed packed column. The drop size was measured at four different points along the active column height. Three operating variables have been studied including the pulse intensity (af) and flow rates of both liquid phases. The effect of liquid properties and height of the active column were also investigated. A combination of the pulse intensity and interfacial tension had the largest effect on the drop size distribution while none of the flow rates were of significance. The height of the column played an important role at the bottom of the active column, but the associated effect was reduced with increase of the height. Finally, a normal probability function of number density was proposed for prediction of the drop size distribution with an Average Absolute Relative Error (AARE) of 8.8% for their optimized constant. Furthermore, two correlations were presented involving height or flow rates of the two phases along with operating variables and physical properties of the liquids. These correlations had AARE values of about 8.5 and 7.8%, respectively.     

Determination of Breakage Parameters in Turbulent Fluid‐Fluid Breakage

Numerous sets of single‐particle breakage experiments are required in order to provide a sufficient database for improving the modeling of fluid particle breakage mechanisms. This work focuses on the interpretation of the physical breakage events captured on video. In order to extract the necessary information required for modeling the mechanisms of the fluid particle breakage events in turbulent flows, a well‐defined image analysis procedure is necessary. Two breakage event definitions are considered, namely, initial breakup and cascade breakup. The reported breakage time, the number of daughter particles created, and the daughter size distribution are significantly affected by the definition used. For each breakage event definition, an image analysis procedure is presented.     

Effect of Impeller Vertical Position on Drop Sizes in Agitated Dispersions

The effect of impeller height relative to the vessel bottom was studied by measuring the drop size distributions of kerosene dispersions in water at two positions inside a stirred tank. Measurements were taken at 1/3, 1/ 2, and 2/3 of total vessel height for rotational speeds 250, 300, 350 and 400 RPM and for hold‐up fractions 0.02 and 0.04. Results show an influence of impeller height on drop sizes ranging from a Sauter mean diameter decrease of 7.8 % to an increase of 35 % relative to the ones obtained with the impeller at the center of the vessel     

Effect of Impeller Blade Height on the Drop Size Distribution in Agitated Dispersions

A common method to achieve a contact of two liquid phases – required for many chemical engineering operations – is the dispersion of one into the other by mechanical agitation. The drop size distribution in such an agitated dispersion is a result of the dynamic equilibrium existing between the breaking and coalescing drops. A comparison has been made of drop diameters produced by four disk type impellers differing only in blade height (D_W = 1, 2, 4 and 6 cm). Measurements in situ at 200, 250, 300, 350, 400, 450 rpm and at holdup fractions 0.02, 0.05, and 0.07, showed that the Sauter mean drop diameters increased up to 140 % as the impeller blade height decreased from 6 to 1 cm. Plots of ln α₃₂ vs. ln N, lnα₃₂ vs. ln D_T and ln α₃₂ vs. ln α_max gave straight lines.     

3D Single Bubble Breakup Tracking in a Stirred Tank

A detailed understanding of turbulent fluid particle breakup mechanisms is essential for the accurate modeling of gas/liquid and liquid/liquid dispersions. The design of a fully automated setup for the three‐dimensional serial examination of the single bubble breakup process in a stirred tank, ensuring high repetition rates necessary for the additionally automated statistical analysis, is described. The implementation of a three‐dimensional automatic bubble breakup tracking tool is illustrated. At last, exemplary bubble breakup trajectories that show the benefits and limitations of the developed system and method are discussed.     

原油管道停输温降模拟研究

原油在管道输送的过程中不可避免会出现停输现象。针对原油管道停输再启动存在的技术难题。以热力水力分析为基础,应用仿真模拟的方法利用Pipeline Studio(TLNET)软件模拟管道停输温降过程。以庆哈管道为例,模拟管道停输温降过程,根据模拟结果绘制了三维温降图,以原油凝固点以上3℃为判据确定了安全停输时间。最终确定庆哈输油管道冬季安全停输时间为24 h,为管道安全运行提供了可靠的理论依据。