Characterization of Mixing Efficiency in Narrow Channels by Using the Iodide-Iodate Reaction System

Abstract

Microreactors and narrow channel reactors have found an increasing number of applications in the last few years for their enhanced heat and mass transfer properties if compared to traditional process equipment. In this investigation, mixing efficiency in a narrow channel reactor system has been studied by using the iodide-iodate scheme of parallel competing reactions that leads to the formation of iodine. The tested system is constituted by two reactors machined in Perspex. The two channels have identical configuration and a square cross section with diagonal lines of 1·10−3 m and 2·10−3 m respectively. Influence of flow rate on the selectivity towards iodine has been studied for both reactors. This allows the characterization of mixing intensity at varying operating conditions. The results obtained reflect the expected influence of flow rate and channel characteristic dimension on mixing efficiency. This investigation has been carried out on the same reactor system that had been previously used for studying the precipitation of calcium carbonate from solutions of sodium carbonate and calcium nitrate. In fact, a study on mixing efficiency is particularly useful in the case of precipitation reactions as poor mixing can lead to a final product that does not respect marketing requirements in terms of particle size and particle size distribution. The information acquired in the two investigations can constitute the basis for the design of modules based on narrow channel technology for the production of powders and slurries with controlled properties.