Heat transfer performance of NETmix—A novel micro‐meso structured mixer and reactor

Abstract

NETmix is a novel static mixing technology consisting on a network of unit cells, comprising chambers interconnected by channels. To assess the heat transfer capacity of NETmix, the NUB model was implemented to perform hydrodynamics and heat transfer simulations. Due to the periodic nature of the NETmix structure, two central chambers and six half‐chambers were found to be sufficient to be representative of the whole network. The Nusselt numbers were determined based on the CFD simulations, and when compared with theoretical results for laminar flow between parallel plates, 3–5 times higher Nusselt number values were obtained with NETmix. This observed heat transfer rate enhancement, makes it suitable for fast reactions where heat transfer is crucial. Finally, results obtained from this study show that NETmix presents a heat transfer capacity one order of magnitude greater than microreactors, and 2–5 orders of magnitude greater than the most commonly used devices in industry. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2496–2508, 2017

Mixing in the NETmix Reactor

“…Previous works have shown that the geometry and the flow in NETmix obey to a repetitive pattern (visible in Figure 1) which enables to simulate only a subdomain of the full network to study the NETmix reactor (Fonte et al, 2013;Costa et al, 2017). Fonte (2013) and Fonte et al (2013) developed a 3D geometry that consisted of three full chambers interconnected to 6 half chambers, the NETmix Unit Block (NUB) shown in Figure 3 (left).…”

“…Since 2016, a photocatalytic NETmix was designed (Lima et al, 2016) which is used to perform photocatalysis studies such as kinetic modelling (Marinho et al, 2017;Santos et al, 2019;Santos et al, 2021) and ozonation (Filho et al, 2019). In 2017, a NETmix device coupled to heat exchangers was developed for the continuous production of CO 2 hydrates (Costa et al, 2017;Lopes et al, 2018;Lopes et al, 2019). The NETmix reactor has also been used for microencapsulation (Moreira et al, 2020) and Pickering emulsions (Ribeiro et al, 2021).…”

“…Figure 1 shows the mixing patterns inside the NETmix reactor which are repetitive along each row of mixing chambers. In this way, it is possible to study how mixing occurs inside the NETmix chambers, i.e., micromixing, through the simulation of a reduced domain of the network (Fonte et al, 2013;Costa et al, 2017), replacing the full network by periodic boundary conditions (PBCs). Previous reduced physical domains of NETmix include the NETmix Unit Block (NUB) (Fonte et al, 2013;Costa et al, 2017) which will be revised in this work.…”

Carbon Capture and Storage Toward Industrialization: A Novel Continuous Process for the Production of Carbon Dioxide Clathrates

“…NetMIX is an extremely efficient device for heat transfer, particularly under chaotic regime. Through the evaluation of the specific heat transfer capacity, defined as the heat power transferred by convection per unit volume of the device and per unit temperature, using a computational fluid dynamics (CFD) model, Costa et al [ 45 ] showed that NetMIX is a few orders of magnitude more effective for heat transfer than typical stirred tanks or tubular reactors and at least one order of magnitude larger than microreactors, resulting in more compact devices. [ 45 ] Specific heat transfer rate values in the range of 10 7 –10 9 were obtained in NetMIX, surpassing state‐of‐the‐art existing microdevices that present typical values in the range of 10 5 –10 8 .…”

Computational Fluid Dynamics Model of Two‐Phase Flow in NETmix Reactors

“…NETmix operation is based on this mixing pattern of fluid contact and separation with successive expansions and contractions from channels to the chamber, enabling a large interfacial area generation. The best design and operating conditions of NETmix reactors have been studied for single-phase flow in previous works [8,9]. Complete knowhow on the mixing of multiphase flows using NETmix technology is still being built.…”