NETmix V R , A New Type of Static Mixer: Modeling, Simulation, Macromixing, and Micromixing Characterization Paulo E. Laranjeira, Anto´nio A. Martins, Jose´ Carlos B. Lopes, and Madalena M. Dias Laboratory of Separation and Reaction Engineering, Departamento de Engenharia Quı ´mica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal DOI 10.1002/aic.11815 Published online July 7, 2009 in Wiley InterScience (www.interscience.wiley.com). NETmix VR is a new technology for static mixing based on a network of chambers connected by channels. The NETmix VR model is the basis of a flow simulator coupled with chemical reaction used to characterize macro and micromixing in structured po- rous media. The chambers are modeled as perfectly mixing zones and the channels as plug flow perfect segregation zones. A segregation parameter is introduced as the ratio between the channels volume and the whole network volume. Different kinetics and reactants injection schemes can be implemented. Results show that the number of rows in the flow direction and the segregation parameter control both macro and micromix- ing, but the degree of micromixing is also controlled by the reactants injection scheme. The NETmix VR model enables the systematic study of micromixing and macromixing for different network structures and reaction schemes, enabling the design of network structures to ensure the desired yield and selectivity. V VC 2009 American Institute of Chemical Engineers AIChE J, 55: 2226–2243, 2009 Keywords: mixing, network models, porous media, static mixers Introduction The importance of mixing can hardly be exaggerated. Mixing is at the heart of many operations in the chemical, petrochemical, and pharmaceutical process industries, and is often accompanied by chemical reactions whose outcome depends strongly upon the efficiency of the mixing pro- cess. 1,2 Examples include chemical reactors, dispersion, and transport of contaminants in porous media, among many other examples. 3,4 Therefore, a computationally efficient mathematical model capable of predicting mixing and chem- ical reaction is clearly desirable for the design of process equipment such as static mixers. 5 Network models have been widely adopted as a basis for describing the void structure and transport properties of po- rous media for over 40 years. A network model is intuitively desirable, because it avoids a detailed geometric description of the void space in favor of an idealized description that is amenable to a computational and even a analytical treatment. The concept that fluid paths in a porous medium may split and, later on, join other paths, has prompted most authors to think of a network model of pore space in which the branches represent the pore throats or the narrow channels that connect the nodes that represent the pore bodies. Many authors ignore nodes and assign them no volume, although there have been several papers in which this assumption has been relaxed, 6–8 and currently it is even considered that most of the void space of a porous medium is associated not with the network branches but with the nodes. 9 One of the earliest attempts of using network models to model flow through a porous medium was the work of Fatt (1956). 10 Network models were later used to predict the macroscopic transport and capillary equilibrium properties of porous media, for example: simulation of mercury intrusion porosimetry curves of sandstones and catalyst particles; 11–14 prediction of air-mercury and oil-water drainage capillary Correspondence concerning this article should be addressed to M. M. Dias at dias@fe.up.pt V VC 2009 American Institute of Chemical Engineers 2226 AIChE Journal September 2009 Vol. 55, No. 9