Augmented Mass Transport in Sheared Suspensions

研究摘要：本研究项目旨在提高目前对剪切悬浮液中大分子溶质在层流状态下的输运现象的理解。利用多重内反射荧光（MIRF）的新技术，增强传质具有有效的扩散率，并使用旋转圆盘流系统来确定。我们测量了几种表征良好的大分子溶质在水悬浮液中的扩散系数，并将其作为悬浮液颗粒体积分数、粒径、颗粒刚度、悬浮液粘度/粘弹性和体系剪切速率的函数。实际意义：本研究通过确定和表征大分子溶质在剪切悬浮液中增强扩散率的重要实验参数和机制，可以提高我们目前对剪切悬浮液中增强传质的理解。可能受益的化学和生物系统领域包括：1)更好地理解涉及相变流动（结晶、熔化等）以及分散和分层多相流的聚合物加工操作；2)改进非等温管式反应器和CSTR反应器、填料床反应器和流化床反应器以及血液透析器和血氧器等体外流动系统的设计；3)更好地了解诸如血栓形成、动脉粥样硬化和溶血等疾病的生物医学过程。

Research Summary: This research program is aimed at improving current understanding of transport phenomenon of macromolecular solutes in sheared suspensions in the laminar flow regime. Using the novel technique of multiple internal reflection fluorescence (MIRF), augmented mass transfer is characterized by an effective diffusivity and is determined using a rotating disc flow system. The diffusion coefficients of several well characterized macromolecular solutes are measured in aqueous suspensions as a function of suspension particle volume fraction, particle size, particle rigidity, suspension viscosity/viscoelasticity, and system shear rate. Practical Significance: This study could lead to results that improve our current understanding of augmented mass transfer in sheared suspensions by identifying and characterizing the important experimental parameters and mechanisms involved in enhancing the diffusivities of macromolecular solutes in sheared suspensions. Chemical and biological system areas that could benefit include: 1) better understanding of polymer processing operations involving flows with phase change (crystallization, melting, etc.) as well as with dispersed and stratified multiphase flows; 2) better design of nonisothermal tubular and CSTR reactors, packed and fluidized bed reactors, and extracorporeal flow systems such as hemodialyzers and blood oxygenators; and 3) better biomedical understanding of such disease processes as thrombogenesis, atherogenesis, and hemolysis.