Numerical study on the hydrodynamics behavior of a central insert microchannel

doi:10.1016/j.cjche.2022.01.019

Abstract

Abstract: In this work, the computational fluid dynamics method is used to study the liquid hydrodynamics behavior in the microchannel without central insert (MC1) and the central insert microchannel (MC2), respectively. The maximum deviation between simulation and experiment is 24%. The formations of flow patterns are explained based on contours and force analysis where the flow pattern maps are established by two-phase flow rate. The effects of aqueous phase viscosity and two-phase flow rate on the characteristic sizes of each flow pattern are also explored. Specifically, four unconventional flow patterns are found in MC2, namely the unique droplet flow, the unique slug flow, the unique coarse annular flow and the unique film annular flow. Though the insert occupies part of the channel, the pressure difference in the channel is significantly reduced compared with MC1. Moreover, the insert significantly changes the formation velocity range of each flow pattern, greatly broadens the formation range of annular flow and also has an important influence on the characteristic size of the flow pattern. The organic-phase dimensionless axial size (L_o/W) and the dimensionless radial size (D_o/W) of the droplet (slug) are negatively related to the aqueous-phase viscosity (μ_a) and flow rate (u_a). The D_o/W of the annular is negatively correlated with μ_a and positively correlated with organic-phase flow rate (u_o). This study provides direct numerical evidence that the insert is key to the formation of bicontinuous phase flow pattern, as well as further strengthens our understanding of the flow characteristics and optimization design of insert microchannels.

Key words: Microchannel, Process intensification, Computational fluid dynamics, Liquid–liquid flow pattern, Central insert

摘要： In this work, the computational fluid dynamics method is used to study the liquid hydrodynamics behavior in the microchannel without central insert (MC1) and the central insert microchannel (MC2), respectively. The maximum deviation between simulation and experiment is 24%. The formations of flow patterns are explained based on contours and force analysis where the flow pattern maps are established by two-phase flow rate. The effects of aqueous phase viscosity and two-phase flow rate on the characteristic sizes of each flow pattern are also explored. Specifically, four unconventional flow patterns are found in MC2, namely the unique droplet flow, the unique slug flow, the unique coarse annular flow and the unique film annular flow. Though the insert occupies part of the channel, the pressure difference in the channel is significantly reduced compared with MC1. Moreover, the insert significantly changes the formation velocity range of each flow pattern, greatly broadens the formation range of annular flow and also has an important influence on the characteristic size of the flow pattern. The organic-phase dimensionless axial size (L_o/W) and the dimensionless radial size (D_o/W) of the droplet (slug) are negatively related to the aqueous-phase viscosity (μ_a) and flow rate (u_a). The D_o/W of the annular is negatively correlated with μ_a and positively correlated with organic-phase flow rate (u_o). This study provides direct numerical evidence that the insert is key to the formation of bicontinuous phase flow pattern, as well as further strengthens our understanding of the flow characteristics and optimization design of insert microchannels.

关键词: Microchannel, Process intensification, Computational fluid dynamics, Liquid–liquid flow pattern, Central insert

Yongbo Zhou, Yang Jin, Jun Li, Qinyan Wang, Ming Chen. Numerical study on the hydrodynamics behavior of a central insert microchannel[J]. Chinese Journal of Chemical Engineering, 2023, 53(1): 361-373.

Yongbo Zhou, Yang Jin, Jun Li, Qinyan Wang, Ming Chen. Numerical study on the hydrodynamics behavior of a central insert microchannel[J]. 中国化学工程学报, 2023, 53(1): 361-373.

References

[1] K. Jähnisch, V. Hessel, H. Löwe, M. Baerns, Chemistry in microstructured reactors, Angew. Chem. Int. Ed. 43 (4) (2004) 406–446.
[2] G.J. Harmsen, Reactive distillation: The front-runner of industrial process intensification, Chem. Eng. Process. Process.Intensif. 46 (9) (2007) 774–780.
[3] T.T. Guan, Q. Yan, L.Z. Wan, S.H. Zhang, L.H. Xu, J.L. Wang, J.X. Yun, Liquid–liquid flow patterns and slug characteristics in cross-shaped square microchannel for cryogel beads preparation, Chem. Eng. Res. Des. 148 (2019) 312–320.
[4] A. MohdLaziz, K. KuShaari, B. Azeem, S. Yusup, J. Chin, J. Denecke, Rapid production of biodiesel in a microchannel reactor at room temperature by enhancement of mixing behaviour in methanol phase using volume of fluid model, Chem. Eng. Sci. 219 (2020) 115532.
[5] M. Kashid, L. Kiwi-Minsker, Quantitative prediction of flow patterns in liquid–liquid flow in micro-capillaries, Chem. Eng. Process.Process. Intensif. 50 (10) (2011) 972–978.
[6] J. Jovanović, E.V. Rebrov, T.A.X. Nijhuis, M.T. Kreutzer, V. Hessel, J.C. Schouten, Liquid–liquid flow in a capillary microreactor: Hydrodynamic flow patterns and extraction performance, Ind. Eng. Chem. Res. 51 (2) (2012) 1015–1026.
[7] Y.C. Zhao, G.W. Chen, Q. Yuan, Liquid–liquid two-phase flow patterns in a rectangular microchannel, AIChE J. 52 (12) (2006) 4052–4060.
[8] S.K.R. Cherlo, S. Kariveti, S. Pushpavanam, Experimental and numerical investigations of two-phase (liquid-liquid) flow behavior in rectangular microchannels, Ind. Eng. Chem. Res. 49 (2) (2010) 893–899.
[9] J.H. Xu, G.S. Luo, S.W. Li, G.G. Chen, Shear force induced monodisperse droplet formation in a microfluidic device by controlling wetting properties, Lab Chip 6 (1) (2006) 131–136.
[10] T.T. Fu, L.J. Wei, C.Y. Zhu, Y.G. Ma, Flow patterns of liquid–liquid two-phase flow in non-Newtonian fluids in rectangular microchannels, Chem. Eng. Process. Process. Intensif. 91 (2015) 114–120.
[11] M. Darekar, K.K. Singh, S. Mukhopadhyay, K.T. Shenoy, Liquid–liquid two-phase flow patterns in Y-Junction microchannels, Ind. Eng. Chem. Res. 56 (42) (2017) 12215–12226.
[12] Z. Wu, Z. Cao, B. Sundén, Liquid–liquid flow patterns and slug hydrodynamics in square microchannels of cross-shaped junctions, Chem. Eng. Sci. 174 (2017) 56–66.
[13] H. Foroughi, M. Kawaji, Viscous oil–water flows in a microchannel initially saturated with oil: Flow patterns and pressure drop characteristics, Int. J. Multiph. Flow 37 (9) (2011) 1147–1155.
[14] W.J. Lan, S.W. Li, G.S. Luo, Numerical and experimental investigation of dripping and jetting flow in a coaxial micro-channel, Chem. Eng. Sci. 134 (2015) 76–85.
[15] Y.R. Yin, C.Y. Zhu, T.T. Fu, Y.G. Ma, K. Wang, G.S. Luo, Enhancement effect and mechanism of gas–liquid mass transfer by baffles embedded in the microchannel, Chem. Eng. Sci. 201 (2019) 264–273.
[16] R.K. Verma, S. Ghosh, Effect of phase properties on liquid–liquid two-phase flow patterns and pressure drop in serpentine mini geometry, Chem. Eng. J. 397 (2020) 125443.
[17] H.C.Lv, Z.R. Yang, J. Zhang, G. Qian, X.Z. Duan, Z.M. Shu, X.G. Zhou, Liquid flow and mass transfer behaviors in a butterfly-shaped microreactor, Micromachines 12 (8) (2021) 883.
[18] S. Haase, D.Y. Murzin, T. Salmi, Review on hydrodynamics and mass transfer in minichannel wall reactors with gas–liquid Taylor flow, Chem. Eng. Res. Des. 113 (2016) 304–329.
[19] F. Shehzad, I.A. Hussein, M.S. Kamal, W. Ahmad, A.S. Sultan, M.S. Nasser, Polymeric surfactants and emerging alternatives used in the demulsification of produced water: A review, Polym. Rev. 58 (1) (2018) 63–101.
[20] A.A. Yagodnitsyna, A.V. Kovalev, A.V. Bilsky, Flow patterns of immiscible liquid–liquid flow in a rectangular microchannel with T-junction, Chem. Eng. J. 303 (2016) 547–554.
[21] A. Ghaini, A. Mescher, D.W. Agar, Hydrodynamic studies of liquid–liquid slug flows in circular microchannels, Chem. Eng. Sci. 66 (6) (2011) 1168–1178.
[22] M.N. Kashid, D.W. Agar, S. Turek, CFD modelling of mass transfer with and without chemical reaction in the liquid–liquid slug flow microreactor, Chem. Eng. Sci. 62 (18–20) (2007) 5102–5109.
[23] A. Abdollahi, S.E. Norris, R.N. Sharma, Pressure drop and film thickness of liquid–liquid Taylor flow in square microchannels, Int. J. Heat Mass Transf. 156 (2020) 119802.
[24] Q. Li, P. Angeli, Experimental and numerical hydrodynamic studies of ionic liquid–aqueous plug flow in small channels, Chem. Eng. J. 328 (2017) 717–736.
[25] C.W. Hirt, B.D. Nichols, Volume of fluid (VOF) method for the dynamics of free boundaries, J. Comput. Phys. 39 (1) (1981) 201–225.
[26] J.U.Brackbill, D.B.Kothe, C. Zemach, A continuum method for modeling surface tension, J. Comput. Phys. 100 (2) (1992) 335–354.
[27] R. Gupta, D.F. Fletcher, B.S. Haynes, On the CFD modelling of Taylor flow in microchannels, Chem. Eng. Sci. 64 (12) (2009) 2941–2950.
[28] P. Desir, T.Y. Chen, M. Bracconi, B. Saha, M. Maestri, D.G. Vlachos, Experiments and computations of microfluidic liquid–liquid flow patterns, React. Chem. Eng. 5 (1) (2020) 39–50.
[29] J.Y. Qian, X.J. Li, Z. Wu, Z.J.Jin, B. Sunden, A comprehensive review on liquid–liquid two-phase flow in microchannel: Flow pattern and mass transfer, Microfluid. Nanofluid. 23 (10) (2019) 1–30.
[30] X. Chao, F.S. Xu, C.Q. Yao, T.T. Liu, G.W. Chen, CFD simulation of internal flow and mixing within droplets in a T-junction microchannel, Ind. Eng. Chem. Res. 60 (16) (2021) 6038–6047.
[31] A.S. Utada, A. Fernandez-Nieves, H.A. Stone, D.A. Weitz, Dripping to jetting transitions in coflowing liquid streams, Phys. Rev. Lett. 99 (9) (2007) 094502.
[32] Z. Cao, Z. Wu, B. Sundén, Dimensionless analysis on liquid-liquid flow patterns and scaling law on slug hydrodynamics in cross-junction microchannels, Chem. Eng. J. 344 (2018) 604–615.
[33] Z. Wu, Z. Cao, B. Sunden, Flow patterns and slug scaling of liquid–liquid flow in square microchannels, Int. J. Multiph. Flow 112 (2019) 27–39.
[34] S.G. Sontti, A. Atta, Numerical insights on controlled droplet formation in a microfluidic flow-focusing device, Ind. Eng. Chem. Res. 59 (9) (2020) 3702–3716.