Micromixing efficiency and enhancement methods for non-Newtonian fluids in millimeter channel reactors

doi:10.1016/j.cjche.2024.08.006

Abstract

Abstract: Millimeter channel reactors (MCRs) have received increasing attention because of their ability to enhance treatment capacity in addition to the advantages of microchannels. In previous studies, less work has been conducted on the micromixing process and enhancement strategies for non-Newtonian fluids in MCRs. In this study, the micromixing efficiency in MCRs was experimentally investigated using CMC (carboxymethyl cellulose sodium) aqueous solution to simulate a non-Newtonian fluid, and the enhanced mechanism of micromixing efficiency by the addition of internals and rotation was analyzed by computational fluid dynamics (CFD) simulations. The results show that in the conventional channel, increasing the flow rate improves the micromixing efficiency when the CMC concentration is low. However, when the CMC concentration is higher, the higher the flow rate, the lower the micromixing efficiency. The highest micromixing efficiency is obtained for the rotationally coupled inner components, followed by the single rotation and the lowest is for the internals only. CFD simulations reveal that the most effective way to improve the micromixing efficiency of non-Newtonian fluids with shear-thinning behavior is to increase the shear force in the reactor, which effectively reduces the apparent viscosity. These results provide the theoretical foundation for enhancing the micromixing process of non-Newtonian fluids in small-size reactors.

Key words: Millimeter channel, Micromixing, CFD, Viscous, Non-Newtonian fluid

摘要： Millimeter channel reactors (MCRs) have received increasing attention because of their ability to enhance treatment capacity in addition to the advantages of microchannels. In previous studies, less work has been conducted on the micromixing process and enhancement strategies for non-Newtonian fluids in MCRs. In this study, the micromixing efficiency in MCRs was experimentally investigated using CMC (carboxymethyl cellulose sodium) aqueous solution to simulate a non-Newtonian fluid, and the enhanced mechanism of micromixing efficiency by the addition of internals and rotation was analyzed by computational fluid dynamics (CFD) simulations. The results show that in the conventional channel, increasing the flow rate improves the micromixing efficiency when the CMC concentration is low. However, when the CMC concentration is higher, the higher the flow rate, the lower the micromixing efficiency. The highest micromixing efficiency is obtained for the rotationally coupled inner components, followed by the single rotation and the lowest is for the internals only. CFD simulations reveal that the most effective way to improve the micromixing efficiency of non-Newtonian fluids with shear-thinning behavior is to increase the shear force in the reactor, which effectively reduces the apparent viscosity. These results provide the theoretical foundation for enhancing the micromixing process of non-Newtonian fluids in small-size reactors.

关键词: Millimeter channel, Micromixing, CFD, Viscous, Non-Newtonian fluid

Zhaoyi Song, Yuanxi Zhang, Guangwen Chu, Lei Shao, Yang Xiang. Micromixing efficiency and enhancement methods for non-Newtonian fluids in millimeter channel reactors[J]. Chinese Journal of Chemical Engineering, 2025, 78(2): 108-119.

Zhaoyi Song, Yuanxi Zhang, Guangwen Chu, Lei Shao, Yang Xiang. Micromixing efficiency and enhancement methods for non-Newtonian fluids in millimeter channel reactors[J]. 中国化学工程学报, 2025, 78(2): 108-119.

References

[1] S. Ookawara, N. Oozeki, K. Ogawa, P. Lob, V. Hessel, Process intensification of particle separation by lift force in arc microchannel with bifurcation, Chem. Eng. Process. Process. Intensif. 49 (7) (2010) 697-703.
[2] J.J. Lerou, A.L. Tonkovich, L. Silva, S. Perry, J. McDaniel, Microchannel reactor architecture enables greener processes, Chem. Eng. Sci. 65 (1) (2010) 380-385.
[3] C. Kleinstreuer, J. Li, J. Koo, Microfluidics of nano-drug delivery, Int. J. Heat Mass Transf. 51 (23-24) (2008) 5590-5597.
[4] C.H. Cheng, C.K. Chan, G.J. Lai, Shape design of millimeter-scale air channels for enhancing heat transfer and reducing pressure drop, Int. J. Heat Mass Transf. 51 (9-10) (2008) 2335-2345.
[5] K.F. Jensen, Microreaction engineering-is small better? Chem. Eng. Sci. 56 (2) (2001) 293-303.
[6] A. Pawlowska-Zygarowicz, R. Kukawka, H. Maciejewski, M. Smiglak, Optimization and intensification of hydrosilylation reactions using a microreactor system, New J. Chem. 42 (18) (2018) 15332-15339.
[7] M. Damm, T.N. Glasnov, C.O. Kappe, Translating high-temperature microwave chemistry to scalable continuous flow processes, Org. Process Res. Dev. 14 (1) (2010) 215-224.
[8] R. Morschhauser, M. Krull, C. Kayser, C. Boberski, R. Bierbaum, P.A. Puschner, T.N. Glasnov, C.O. Kappe, Microwave-assisted continuous flow synthesis on industrial scale, Green Process. Synth. 1 (3) (2012) 281-290.
[9] P.R.D. Murray, D.L. Browne, J.C. Pastre, S.V. Ley, Continuous flow-processing of organometallic reagents using an advanced peristaltic pumping system and the telescoped flow synthesis of (E/Z)-tamoxifen, Org. Process Res. Dev. 17 (9) (2013) 1192-1208.
[10] M.W. Bedore, N. Zaborenko, K.F. Jensen, T.F. Jamison, Aminolysis of epoxides in a microreactor system: a continuous flow approach to β-amino alcohols, Org. Process Res. Dev. 14 (2) (2010) 432-440.
[11] J.M. Commenge, L. Falk, Villermaux-Dushman protocol for experimental characterization of micromixers, Chem. Eng. Process. Process. Intensif. 50 (10) (2011) 979-990.
[12] S.H. Wong, M.C.L. Ward, C.W. Wharton, Micro T-mixer as a rapid mixing micromixer, Sens. Actuat. B Chem. 100 (3) (2004) 359-379.
[13] J.R. Bourne, F. Kozicki, P. Rys, Mixing and fast chemical reaction-I. Test reactions to determine segregation, Chem. Eng. Sci. 36 (10) (1981) 1643-1648.
[14] J.R. Bourne, S.Y. Yu, Investigation of micromixing in stirred tank reactors using parallel reactions, Ind. Eng. Chem. Res. 33 (1) (1994) 41-55.
[15] M.C. Fournier, L. Falk, J. Villermaux, A new parallel competing reaction system for assessing micromixing efficiency-experimental approach, Chem. Eng. Sci. 51 (22) (1996) 5053-5064.
[16] P. Guichardon, L. Falk, Characterisation of micromixing efficiency by the iodide-iodate reaction system. Part I: experimental procedure, Chem. Eng. Sci. 55 (19) (2000) 4233-4243.
[17] B.H. Li, X.C. Lan, T.F. Wang, Intensification of diethyl methylphosphite synthesis based on kinetics study and CFD modeling, AIChE J. 70 (1) (2024) e18264.
[18] A. Kölbl, M. Kraut, K. Schubert, The iodide iodate reaction method: on the determination of mixing times from UV measurements, The 2009 AIChE, Spring National, Meeting, USA, 2009.
[19] Z.W. Liu, L. Guo, T.H. Huang, L.X. Wen, J.F. Chen, Experimental and CFD studies on the intensified micromixing performance of micro-impinging stream reactors built from commercial T-junctions, Chem. Eng. Sci. 119 (2014) 124-133.
[20] H. Ringkai, K.F. Tamrin, N.A. Sheikh, P. Barroy, Characterization of dissimilar liquids mixing in T-junction and offset T-junction microchannels, Proc. Inst. Mech. Eng. Part E J. Process. Mech. Eng. 235 (6) (2021) 1797-1806.
[21] K. Yang, G.W. Chu, L. Shao, Y. Xiang, L.L. Zhang, J.F. Chen, Micromixing efficiency of viscous media in micro-channel reactor, Chin. J. Chem. Eng. 17 (4) (2009) 546-551.
[22] Z.M. Gao, J. Han, Y.Y. Bao, Z.P. Li, Micromixing efficiency in a T-shaped confined impinging jet reactor, Chin. J. Chem. Eng. 23 (2) (2015) 350-355.
[23] H.S. Gaikwad, G. Kumar, P.K. Mondal, Efficient electroosmotic mixing in a narrow-fluidic channel: the role of a patterned soft layer, Soft Matter 16 (27) (2020) 6304-6316.
[24] A.N. Manzano Martinez, A. Chaudhuri, M. Assirelli, J. van der Schaaf, Effects of increased viscosity on micromixing in rotor-stator spinning disk reactors, Chem. Eng. J. 434 (2022) 134292.
[25] P. Kaushik, S. Shyam, P.K. Mondal, Mixing in small scale fluidic systems swayed by rotationality effects, Phys. Fluids 34 (6) (2022) 062008.
[26] S. Shyam, P.K. Mondal, B. Mehta, Magnetofluidic mixing of a ferrofluid droplet under the influence of a time-dependent external field, J. Fluid Mech. 917 (2021) A15.
[27] X.Y. Chen, T.C. Li, H. Zeng, Z.L. Hu, B.D. Fu, Numerical and experimental investigation on micromixers with serpentine microchannels, Int. J. Heat Mass Transf. 98 (2016) 131-140.
[28] X.Y. Chen, T.C. Li, A novel passive micromixer designed by applying an optimization algorithm to the zigzag microchannel, Chem. Eng. J. 313 (2017) 1406-1414.
[29] X.K. Chen, X.Y. Chen, A novel electrophoretic assisted hydrophobic microdevice for enhancing blood cell sorting: design and numerical simulation, Anal. Methods 16 (15) (2024) 2368-2377.
[30] X. Shi, Y. Xiang, L.X. Wen, J.F. Chen, CFD analysis of flow patterns and micromixing efficiency in a Y-type microchannel reactor, Ind. Eng. Chem. Res. 51 (43) (2012) 13944-13952.
[31] Y. Ouyang, Y. Xiang, H.K. Zou, G.W. Chu, J.F. Chen, Flow characteristics and micromixing modeling in a microporous tube-in-tube microchannel reactor by CFD, Chem. Eng. J. 321 (2017) 533-545.
[32] Y. Ouyang, Y. Xiang, X.Y. Gao, H.K. Zou, G.W. Chu, R.K. Agarwal, J.F. Chen, Micromixing efficiency optimization of the premixer of a rotating packed bed by CFD, Chem. Eng. Process. Process. Intensif. 142 (2019) 107543.
[33] P. Ritter, A. Osorio-Nesme, A. Delgado, 3D numerical simulations of passive mixing in a microchannel with nozzle-diffuser-like obstacles, Int. J. Heat Mass Transf. 101 (2016) 1075-1085.
[34] Y. Ouyang, S.W. Wang, Y. Xiang, Z.M. Zhao, J.X. Wang, L. Shao, CFD analyses of liquid flow characteristics in a rotor-stator reactor, Chem. Eng. Res. Des. 134 (2018) 186-197.
[35] Y. Ouyang, Y. Xiang, X.Y. Gao, W.L. Li, H.K. Zou, G.W. Chu, J.F. Chen, Micromixing efficiency in a rotating packed bed with non-Newtonian fluid, Chem. Eng. J. 354 (2018) 162-171.
[36] W.P. Li, F.S. Xia, H.Y. Qin, M.Q. Zhang, W. Li, J.L. Zhang, Numerical and experimental investigations of micromixing performance and efficiency in a pore-array intensified tube-in-tube microchannel reactor, Chem. Eng. J. 370 (2019) 1350-1365.
[37] H.Z. Li, X. Frank, D. Funfschilling, Y. Mouline, Towards the understanding of bubble interactions and coalescence in non-Newtonian fluids: a cognitive approach, Chem. Eng. Sci. 56 (21-22) (2001) 6419-6425.
[38] J.I. Yoshida, A. Nagaki, T. Yamada, Flash chemistry: fast chemical synthesis by using microreactors, Chemistry 14 (25) (2008) 7450-7459.
[39] B.Q. Liu, P.F. Gao, N. Sun, Y.K. Zhang, Z.J. Jin, B. Sunden, Experimental investigation on micromixing characteristics of coaxial mixers in viscous system, Can. J. Chem. Eng. 98 (8) (2020) 1815-1824.
[40] Y.C. Yang, X.H. Yu, Q.J. Yu, S.Y. Yang, M. Arowo, Micromixing efficiency in a multiphase reactor with a foam block stirrer, Can. J. Chem. Eng. 97 (S1) (2019) 1560-1567.
[41] J.R. Bourne, Comments on the iodide/iodate method for characterising micromixing, Chem. Eng. J. 140 (2008) 638-641.
[42] A. Kolbl, M. Kraut, R. Dittmeyer, Kinetic investigation of the Dushman reaction at concentrations relevant to mixing studies in microstructured cyclone type mixers, Chem. Eng. Sci. 101 (2013) 454-460.
[43] P. Guichardon, L. Falk, J. Villermaux, Characterisation of micromixing efficiency by the iodide-iodate reaction system. Part II: kinetic study, Chem. Eng. Sci. 55 (19) (2000) 4245-4253.
[44] T.Y. Guo, X. Shi, G.W. Chu, Y. Xiang, L.X. Wen, J.F. Chen, Computational fluid dynamics analysis of the micromixing efficiency in a rotating-packed-bed reactor, Ind. Eng. Chem. Res. 55 (17) (2016) 4856-4866.
[45] X.H. Yang, W.L. Zhu, Viscosity properties of sodium carboxymethylcellulose solutions, Cellulose 14 (5) (2007) 409-417.
[46] D. Pfund, D. Rector, A. Shekarriz, A. Popescu, J. Welty, Pressure drop measurements in a microchannel, AIChE J. 46 (8) (2000) 1496-1507.
[47] O. Mokrani, B. Bourouga, C. Castelain, H. Peerhossaini, Fluid flow and convective heat transfer in flat microchannels, Int. J. Heat Mass Transf. 52 (5-6) (2009) 1337-1352.
[48] N. Kockmann, S. Dreher, P. Woias, Unsteady laminar flow regimes and mixing in T-shaped micromixers, In: ASME 5th International Conference on Nanochannels, Microchannels, and Minichannels, Puebla, Mexico, 2007.
[49] A. Benchabane, K. Bekkour, Rheological properties of carboxymethyl cellulose (CMC) solutions, Colloid Polym. Sci. 286 (10) (2008) 1173-1180.
[50] H.A. Barnes, J.F. Hutton, K. Walters, An Introduction to Rheology, Elsevier, Amsterdam, 1989.
[51] M.P. Escudier, P.J. Oliveira, F.T. Pinho, Fully developed laminar flow of purely viscous non-Newtonian liquids through annuli, including the effects of eccentricity and inner-cylinder rotation, Int. J. Heat Fluid Flow 23 (1) (2002) 52-73.
[52] K. Guo, F. Guo, Y.D. Feng, J.F. Chen, C. Zheng, N.C. Gardner, Synchronous visual and RTD study on liquid flow in rotating packed-bed contactor, Chem. Eng. Sci. 55 (9) (2000) 1699-1706.
[53] K.P. Cheng, C.Y. Liu, T.Y. Guo, L.X. Wen, CFD and experimental investigations on the micromixing performance of single countercurrent-flow microchannel reactor, Chin. J. Chem. Eng. 27 (5) (2019) 1079-1088.
[54] M. Xiong, J.D. Yang, X.H. Ding, H. Li, H. Zhang, Topology optimization design of micromixer based on principle of Tesla valve: an experimental and numerical study, Chem. Eng. Process. Process. Intensif. 193 (2023) 109560.