Microchemical Engineering: Components, Plant Concepts User Acceptance – Part I

Abstract

Over the last five years, many activities have focused on the unexploited field of carrying out reactions on small scales. Due to the rapid development of new components, this paper deals with recent developments only in a compressed form. An important point is the analysis of possible plant concepts for microreactors and whether these are a sensible option. Due to the enormous difference in size between the microchannels and the fluid periphera of possible components this is not just a technical question. It touches on the microtechnology concept as a whole. The direction in which the field should be developed and which measures can be taken to influence its development are questions that are addressed here with respect to the big industrial interest in microreactors.

Ideal micromixing performance in packed microchannels

“…As one of the most important methods to intensify micromixing, microscale devices such as micromixers and microreactors have attracted increasing attention in both laboratories and commercial areas in recent years (Ehrfeld et al, 1999;Hessel and Löwe, 2003;Wiles andWatts, 2008, Wong et al, 2004). The values of Reynolds number are usually low in microstructure devices due to their small characteristic dimension; therefore, the flow in micromixers and microreactors is generally within the laminar flow regime, and the mixing is mainly driven by the molecular diffusion.…”

Influence of hydrodynamics on liquid mixing during Taylor flow in a microchannel

“…10,11 Many microscale devices such as micromixers and microreactors have been designed elaborately, and attracted increasing attention in both laboratories and commercial areas in recent years. [12][13][14][15][16][17][18] Highly efficient mixing performance is a general character of these devices, and most of them are designed to realize rapid mixing.…”

A review of passive and active mixing systems in microfluidic devices

“…Ultrasonic devices, a sub-section of acoustic devices, work on two principles, three if the use of ultrasound to provide the flow with a driving force is included, and then some other method to actually achieve the mixing. One mixing method is simple vibration, which increases both the transient and convective terms of eqn (2). Another is the inducement of chaotic advection, which increases the convection terms of eqn (2), and causes distortion of the concentration profile, increasing the diffusion area.…”

“…Another important dimensionless group used for characterising a system is the Schmidt number, given by (2) where υ is the kinematic viscosity and D is the diffusion coefficient, and relates the ratio of viscous to diffusive transport. For gaseous mixing, the Schmidt number is typically Sc ≈ 1, and therefore diffusion and viscous action are comparable.…”