Influence of Hydrodynamic Conditions on Micromixing in Microreactors with Free Impinging Jets

Abstract

An experimental study and mathematical modeling of micromixing in a microreactor with free impinging jets (MRFIJ) with a diameter of 1 mm was carried out. In the experimental part, the iodide-iodate technique was used (involving parallel competing Villermaux–Dushman reactions with the formation of I3–). Theoretical assessment revealed that more than 50% of the introduced energy is dissipated in the jets collision region. Through the use of differentiated sampling, an uneven quality distribution of micro mixing in the central and peripheral zones of the reactor was found: at moderate flow rates (700–1000 mL/min, jets velocity of 15–21 m/s) the micromixing in the central part of reactor is up to 12 times better than that in the periphery. Furthermore, the weight fraction of the probes in the central zones of MRFIJ is reduced with increasing jet velocity; this effect is attributed to a more intense formation of ligaments and droplets upon collision of jets and their secondary mixing on the walls of the apparatus. In terms of the weighted average concentration, the best quality of micromixing in the samples is achieved at a flow rate of 300 mL/min. With an increase in the flow rate (and velocity) of the jets, the dependence of the I3– concentration on the flow rate has a nonmonotonic character, which is explained by a change in the nature of the flow in the collision zone of the jets: the transition from the formation of a liquid sheet to the intensive formation of ligaments and drops and secondary mixing of the liquid film formed on the walls of the reactor. The effect of “freshness” of solutions on the concentration of reaction products was studied.

Non-fouling flow reactors for nanomaterial synthesis

“…Similar to confined jet reactors, free impinging jet reactors provide intense mixing due to rapid energy dissipation during the impingement, [148][149][150] and confine the mixing zone mid-air (see Fig. 8f), hence limiting the interaction with the walls during and after mixing.…”

Process Intensification Approach Using Microreactors for Synthesizing Nanomaterials—A Critical Review

“…The extremely high energy streams when passing through the closed conduct of flow area in microscale (microchannel) induce the high level of mixing in the microreactor. The density of kinetic energy associated with the reacting stream often remains constant and creates a well-mixed environment in a small space which is favorable for the nucleation and controlled growth of crystals [ 66 ]. The synthesis of nanocrystalline BiFeO 3 [ 67 ], rhabdophane-structured LaPO 4 [ 68 ], nanocrystalline TiO 2 [ 69 , 70 ] by using an impinging-jets microreactor has been reported in the literature.…”

“…The extremely high energy streams when passing through the closed conduct of flow area in microscale (microchannel) induce the high level of mixing in the microreactor. The density of kinetic energy associated with the reacting stream often remains constant and creates a well-mixed environment in a small space which is favorable for the nucleation and controlled growth of crystals [66]. The synthesis Nanosizing via SDP is one of the attractive approaches used to alleviate poor drug dissolution problems (for example, preparation of curcumin-a yellow polyphenol nanoparticle).…”

Micromixing in a Novel Microannular Rotating Bed

“…To achieve proper molecular-level micromixing, researchers have explored various reactors, including microchannel reactors/mixers, microreactors with impinging jets and swirled flows, − rotating packed bed, helical tube reactor, dynamic inline rotor–stator mixer, gas–liquid vortex reactor, and rotor–stator spinning disk reactor . Among these, microchannel reactors, featured by dimensions ranging from several hundred micrometers to several millimeters, have garnered significant attention from both industry and academia. , The large specific surface area, good micromixing performance, and high mass/heat transfer efficiency make them versatile reactors for many fields, such as nanoparticle preparation, − polymerization, and chemical synthesis. ,, However, the absence of external mechanical energy input in microreactors leads to underdeveloped turbulence and limited chaotic advection, consequently compromising micromixing efficiency.…”