Abstract

In 1871, Josef Stefan established the theoretical framework which allowed the design of his diffusion column. It consisted of a volatile liquid A overlaid with gases A and B. A steady gas B sweep flowed at the top, maintaining the concentration of gas A close to zero at that location. Binary gas diffusion coefficients, whose magnitudes are crucial in many mass transfer operations, were estimated with this device. This line of work was continued uninterruptedly by many research groups around the world for over eight decades. However, in the 1950s inaccuracies in the diffusivity estimates were detected mainly due to column end effects such as gas turbulence/eddy formation resulting from the sweeping stream as well as interfacial curvature. The latter affects the transport area and the path length of gas A to the top. Studies departing from the traditional Stefan column role of binary diffusivity estimation were promptly initiated to attain a better understanding of transport phenomena within the column. These efforts, which endure to this day, applied fundamental chemical engineering principles to determine the source of the diffusivity inaccuracies, the dimensionality of gas transport, the importance of interfacial curvature and nonisothermal column operation, and how liquid-phase events such as mixing affect device performance. These research initiatives have led to an in-depth description of transport phenomena within the Stefan column. Historical references are thoroughly analyzed, chemical engineering contributions to this field are highlighted, and perspectives for future theoretical and experimental work along these lines are presented.

摘要

1871 年，约瑟夫·斯特凡（Josef Stefan）建立了允许设计扩散柱的理论框架。它由覆盖有气体 A 和 B 的挥发性液体 A 组成。稳定的气体 B 吹扫在顶部流动，使气体 A 在该位置的浓度接近于零。二元气体扩散系数，其大小在许多传质操作中是至关重要的，是用该装置估计的。世界各地的许多研究小组在八年多的时间里不间断地继续这项工作。然而，在 1950 年代检测到扩散率估计的不准确主要是由于柱端效应，例如由扫掠流和界面曲率引起的气体湍流/涡流形成。后者影响气体 A 到顶部的传输面积和路径长度。与传统的 Stefan 柱作用的二元扩散率估计不同的研究被迅速启动，以更好地了解柱内的传输现象。这些一直持续到今天的努力应用了基本的化学工程原理来确定扩散率不准确的根源、气体传输的维度、界面曲率和非等温柱操作的重要性，以及液相事件（如混合）如何影响设备表现。这些研究举措导致了对 Stefan 柱内传输现象的深入描述。对历史参考资料进行了深入分析，突出了化学工程对该领域的贡献，并提出了沿这些方向进行的未来理论和实验工作的前景。