Local investigations of gas-liquid mass transfer around Taylor bubbles flowing in straight and meandering millimetric channels using a colorimetric method
Local investigations of gas-liquid mass transfer around Taylor bubbles flowing in straight and meandering millimetric channels using a colorimetric method
复制标题
DOI：
--
复制
发表时间：
2017-03
期刊：
影响因子：
--
通讯作者：
Lixia Yang
中科院分区：
文献类型：
--
作者：
Lixia Yang
紧凑型换热器反应器（HEX）是过程强化技术的重要组成部分。然而，大多数现有的研究处理这种类型的设备一直集中在单相反应流的应用。对于气液反应，很少有人进行过研究。本论文的目的是在本地研究气液传质泰勒气泡周围流动的直线和曲折毫米通道使用比色法，这是一个初步的步骤之前，实现两相反应系统必不可少。首先，研究了化学反应对气液传质可能的强化作用。其次，研究了微反应器中气泡形成阶段后Taylor流中的气液传质。第三，在一个毫米级弯曲通道中，对气液流体力学进行了表征，并局部研究了弯曲对传质机理的影响。最后，对弯曲河道与平直河道进行了严格的比较。结果表明，弯曲几何形状是如何以及为什么导致强化气液传质的。所有这些研究结果使制定的标度律，表示在舍伍德，格雷茨和Peclet数，能够描述的演变的气液传质作为轴向位置和操作条件的函数。
Compact Heat-EXchanger reactors (HEX) are an important part of process intensification technology. However, most of the existed research dealing with such type of equipment has been focused on the application of one-phase reactive flows. For gas-liquid reactions, few investigations have been out carried. This thesis aims at locally studying gas-liquid mass transfer around Taylor bubbles flowing in straight and meandering millimetric channels using a colorimetric method; this is a preliminary step essential before implementing two-phase reactive systems. Firstly, the occurrence of a possible enhancement of the gas-liquid mass transfer by the chemical reaction involved was investigated. Secondly, the gas-liquid mass transfer occurring in Taylor flows right after the bubble formation stage in a microreactor was studied. Thirdly, the gas-liquid hydrodynamics were characterized and the effects of bends on the mass transfer mechanism were locally investigated in a millimetric meandering channel. At last, a rigorous comparison could be made between the meandering and straight channels. It showed how and why the meandering geometry leads to intensify gas-liquid mass transfer. All these findings enabled to formulate a scaling law, expressed in terms of Sherwood, Graetz and Peclet numbers, able to describe the evolution of gas-liquid mass transfer as a function of axial position and operating conditions.