Effect of aspect ratio of elliptical stirred vessel on mixing time and flow field characteristics in the absence of baffles

doi:10.1016/j.cjche.2023.06.010

Chinese Journal of Chemical Engineering ›› 2024, Vol. 65 ›› Issue (1): 63-74.DOI: 10.1016/j.cjche.2023.06.010

Previous Articles Next Articles

Effect of aspect ratio of elliptical stirred vessel on mixing time and flow field characteristics in the absence of baffles

Yuan Yao¹, Peiqiao Liu¹, Qian Zhang¹, Zequan Li¹, Benjun Xi², Changyuan Tao¹, Yundong Wang³, Zuohua Liu¹

1 School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China;
2 Hubei Three Gorges Laboratory, Yichang 443007, China;
3 Department of Chemical Engineering, Tsinghua University, Beijing 100084, China

Received:2023-04-18 Revised:2023-06-26 Online:2024-04-17 Published:2024-01-28
Contact: Zuohua Liu,E-mail:liuzuohua@cqu.edu.cn
Supported by:
This work was supported by the National Key Research and Development Project (2022YFB3504305, 2019YFC1905802), National Natural Science Foundation of China (22078030), Joint Funds of the National Natural Science Foundation of China (U1802255), Key Project of Independent Research Project of State Key Laboratory of Coal Mine Disaster Dynamics and Control (2011DA105287-zd201902), Three Gorges Laboratory Open Fund of Hubei Province (SK211009, SK215001).

Effect of aspect ratio of elliptical stirred vessel on mixing time and flow field characteristics in the absence of baffles

Yuan Yao¹, Peiqiao Liu¹, Qian Zhang¹, Zequan Li¹, Benjun Xi², Changyuan Tao¹, Yundong Wang³, Zuohua Liu¹

1 School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China;
2 Hubei Three Gorges Laboratory, Yichang 443007, China;
3 Department of Chemical Engineering, Tsinghua University, Beijing 100084, China

通讯作者: Zuohua Liu,E-mail:liuzuohua@cqu.edu.cn
基金资助:
This work was supported by the National Key Research and Development Project (2022YFB3504305, 2019YFC1905802), National Natural Science Foundation of China (22078030), Joint Funds of the National Natural Science Foundation of China (U1802255), Key Project of Independent Research Project of State Key Laboratory of Coal Mine Disaster Dynamics and Control (2011DA105287-zd201902), Three Gorges Laboratory Open Fund of Hubei Province (SK211009, SK215001).

Abstract

Abstract: Elliptical tanks were used as an alternative to circular tanks in order to improve mixing efficiency and reduce mixing time in unbaffled stirred tanks (USTs). Five different aspect ratios of elliptical vessels were designed to compare their mixing time and flow field. Computational fluid dynamics (CFD) simulations were performed using the k-ε model to calculate the mixing time and simulate turbulent flow field features, such as streamline shape, velocity distribution, vortex core region distribution, and turbulent kinetic energy (TKE) transfer. Visualization was also carried out to track the tinctorial evolution of the liquid phase. Results reveal that elliptical stirred tanks can significantly improve mixing performance in USTs. Specifically, the mixing time at an aspect ratio of 2.00 is only 45.3% of the one of a circular stirred tank. Furthermore, the secondary flow is strengthened and the vortex core region increases with the increase of aspect ratio. The axial velocity is more sensitive to the aspect ratio than the circumferential and radial velocity. Additionally, the TKE transfer in elliptical vessels is altered. These findings suggest that elliptical vessels offer a promising alternative to circular vessels for enhancing mixing performance in USTs.

Key words: Mixing time, CFD, Stirred tank, Secondary flow, Mixing performance

摘要： Elliptical tanks were used as an alternative to circular tanks in order to improve mixing efficiency and reduce mixing time in unbaffled stirred tanks (USTs). Five different aspect ratios of elliptical vessels were designed to compare their mixing time and flow field. Computational fluid dynamics (CFD) simulations were performed using the k-ε model to calculate the mixing time and simulate turbulent flow field features, such as streamline shape, velocity distribution, vortex core region distribution, and turbulent kinetic energy (TKE) transfer. Visualization was also carried out to track the tinctorial evolution of the liquid phase. Results reveal that elliptical stirred tanks can significantly improve mixing performance in USTs. Specifically, the mixing time at an aspect ratio of 2.00 is only 45.3% of the one of a circular stirred tank. Furthermore, the secondary flow is strengthened and the vortex core region increases with the increase of aspect ratio. The axial velocity is more sensitive to the aspect ratio than the circumferential and radial velocity. Additionally, the TKE transfer in elliptical vessels is altered. These findings suggest that elliptical vessels offer a promising alternative to circular vessels for enhancing mixing performance in USTs.

关键词: Mixing time, CFD, Stirred tank, Secondary flow, Mixing performance

Yuan Yao, Peiqiao Liu, Qian Zhang, Zequan Li, Benjun Xi, Changyuan Tao, Yundong Wang, Zuohua Liu. Effect of aspect ratio of elliptical stirred vessel on mixing time and flow field characteristics in the absence of baffles[J]. Chinese Journal of Chemical Engineering, 2024, 65(1): 63-74.

References

[1] T. Płusa, J. Talaga, A. Duda, P. Duda, Modeling mixing dynamics in uncovered baffled and unbaffled stirred tanks, AlChE. J. 67(9)(2021)17322-17339.
[2] M. Rotondi, N. Grace, J. Betts, N. Bargh, E. Costariol, B. Zoro, C.J. Hewitt, A.W. Nienow, Q.A. Rafiq, Design and development of a new ambr250^® bioreactor vessel for improved cell and gene therapy applications, Biotechnol. Lett. 43(5)(2021)1103-1116.
[3] A. Tamburini, A. Brucato, M. Ciofalo, G. Gagliano, G. Micale, F. Scargiali, CFD simulations of early-to fully-turbulent conditions in unbaffled and baffled vessels stirred by a Rushton turbine, Chem. Eng. Res. Des. 171(2021)36-47.
[4] J. Ramírez-Cruz, M. Salinas-Vázquez, G. Ascanio, W. Vicente-Rodríguez, C. Lagarza-Córtes, Mixing dynamics in an uncovered unbaffled stirred tank using large-eddy simulations and a passive scalar transport equation, Chem. Eng. Sci. 222(2020)115658.
[5] T. Yamamoto, Y. Fang, S.V. Komarov, Surface vortex formation and free surface deformation in an unbaffled vessel stirred by on-axis and eccentric impellers, Chem. Eng. J. 367(2019)25-36.
[6] A. Tamburini, A. Brucato, A. Busciglio, A. Cipollina, F. Grisafi, G. Micale, F. Scargiali, G. Vella, Solid-liquid suspensions in top-covered unbaffled vessels:Influence of particle size, liquid viscosity, impeller size, and clearance, Ind. Eng. Chem. Res. 53(23)(2014)9587-9599.
[7] Y.A. Yao, Z.H. Liu, G.C. Zheng, C.Y. Tao, Y.D. Wang, B.J. Xi, Intensification of solid-liquid suspension performance in an elliptical uncovered unbaffled stirred tank, Ind. Eng. Chem. Res. 62(12)(2023)5315-5325.
[8] S.S. Deshpande, K.K. Kar, J. Walker, J. Pressler, W. Su, An experimental and computational investigation of vortex formation in an unbaffled stirred tank, Chem. Eng. Sci. 168(2017)495-506.
[9] F. Scargiali, A. Brucato, G. Micale, A. Tamburini, On the reduction of power consumption in vortexing unbaffled bioslurry reactors, Ind. Eng. Chem. Res. 59(16)(2020)8037-8045.
[10] Y.W. Fan, C.L. Li, S.B. Wang, H. Wang, Y.G. Wei, J.X. Xu, Q.T. Xiao, Enhancement of mixing efficiency in mechanical stirring reactors via chaotic stirring techniques:Application to the treatment of zinc-containing solid waste, Chem. Eng. Sci. 249(2022)117367.
[11] D.Y. Gu, Z.H. Liu, J. Li, Z.M. Xie, C.Y. Tao, Y.D. Wang, Intensification of chaotic mixing in a stirred tank with a punched rigid-flexible impeller and a chaotic motor, Chem. Eng. Process. 122(2017)1-9.
[12] Y. Fan, J.A. Sun, J.E. Jin, H. Zhang, W.Y. Chen, The effect of baffle on flow structures and dynamics stirred by pitch blade turbine, Chem. Eng. Res. Des. 168(2021)227-238.
[13] M.M. Alvarez, P.E. Arratia, F.J. Muzzio, Laminar mixing in eccentric stirred tank systems, Can. J. Chem. Eng. 80(4)(2008)546-557.
[14] F. Cabaret, L. Fradette, P.A. Tanguy, Effect of shaft eccentricity on the laminar mixingperformanceofaradialimpeller, Can.J. Chem.Eng.86(6)(2008)971-977.
[15] J. Karcz, M. Cudak, J. Szoplik, Stirring of a liquid in a stirred tank with an eccentrically located impeller, Chem. Eng. Sci. 60(8-9)(2005)2369-2380.
[16] G. Montante, A. Bakker, A. Paglianti, F. Magelli, Effect of the shaft eccentricity on the hydrodynamics of unbaffled stirred tanks, Chem. Eng. Sci. 61(9)(2006)2807-2814.
[17] C. Galletti, E. Brunazzi, On the main flow features and instabilities in an unbaffled vessel agitated with an eccentrically located impeller, Chem. Eng. Sci. 63(18)(2008)4494-4505.
[18] S. Woziwodzki, L. Broniarz-Press, M. Ochowiak, Effect of eccentricity on transitional mixing in vessel equipped with turbine impellers, Chem. Eng. Res. Des. 88(12)(2010)1607-1614.
[19] Y.K. Huang, F. MahmoodPoor Dehkordy, Y. Li, S. Emadi, A. Bagtzoglou, B.K. Li, Enhancing anaerobic fermentation performance through eccentrically stirred mixing:Experimental and modeling methodology, Chem. Eng. J. 334(2018)1383-1391.
[20] D. Bulnes-Abundis, M.M. Alvarez, The simplest stirred tank for laminar mixing:Mixing in a vessel agitated by an off-centered angled disc, AIChE J. 59(8)(2013)3092-3108.
[21] D.Y. Gu, L. Wen, H. Xu, M. Ye, Study on hydrodynamics characteristics in a gas-liquid stirred tank with a self-similarity impeller based on CFD-PBM coupled model, J. Taiwan Inst. Chem. Eng. 143(2023)104688.
[22] D.Y. Gu, C. Cheng, Z.H. Liu, Y.D. Wang, Numerical simulation of solid-liquid mixing characteristics in a stirred tank with fractal impellers, Adv. Powder Technol. 30(10)(2019)2126-2138.
[23] S. Başbuğ, G. Papadakis, J.C. Vassilicos, Reduced mixing time in stirred vessels by means of irregular impellers, Phys. Rev. Fluids 3(8)(2018)084502.
[24] D.Y. Luan, Z.R. Wang, H. Wang, S.S. Wang, L.B. Li, Y.M. Chen, Determination method of the cavern boundary viscosity in a stirred tank with pseudoplastic fluid, AlChE. J. 66(5)(2020)16941-16950.
[25] D.Y. Luan, Y.M. Chen, H. Wang, Z.R. Wang, S.S. Wang, L.B. Li, Formation of heart-shaped cavern model in stirring pseudoplastic fluid with the impeller of perturbed six-bend-blade turbine, AlChE. J. 65(5)(2019) -16572.
[26] H. Yao, J.J. Tang, Z.H. Liu, C.Y. Tao, Y.D. Wang, Chaotic mixing intensification and flow field evolution mechanism in a stirred reactor using a dual-shaft eccentric impeller, Ind. Eng. Chem. Res. 61(26)(2022)9498-9513.
[27] X.Y. Tang, F.C. Qiu, H. Li, Q.A. Zhang, X.J. Quan, C.Y. Tao, Y.D. Wang, Z.H. Liu, Investigation of the intensified chaotic mixing and flow structures evolution mechanism in stirred reactor with torsional rigid-flexible impeller, Ind. Eng. Chem. Res. 62(4)(2023)1984-1996.
[28] Y.Y. Liang, D.E. Shi, B.H. Xu, Z.Q. Cai, Z.M. Gao, Turbulent flow field in a stirred vessel agitated by an impeller with flexible blades, AlChE. J. 64(11)(2018)4148-4161.
[29] G. Delaplace, R.K. Thakur, L. Bouvier, C. André, C. Torrez, Dimensional analysis for planetary mixer:Mixing time and Reynolds numbers, Chem. Eng. Sci. 62(5)(2007)1442-1447.
[30] U.D. Kück, U. Mießner, M. Aydin, J. Thöming, Mixing time and mass transfer of rising bubbles in swarm turbulence, Chem. Eng. Sci. 187(2018)367-376.
[31] J. Szoplik, M. Ciuksza, Mixing time prediction with artificial neural network model, Chem. Eng. Sci. 246(2021)116949.
[32] G. Delaplace, M.H. Liu, R. Jeantet, J.E. Xiao, X.D. Chen, Predicting the mixing time of soft elastic reactors:Physical models and empirical correlations, Ind. Eng. Chem. Res. 59(13)(2020)6258-6268.
[33] D.J. Lamberto, F.J. Muzzio, P.D. Swanson, A.L. Tonkovich, Using time-dependent RPM to enhance mixing in stirred vessels, Chem. Eng. Sci. 51(5)(1996)733-741.

Effect of aspect ratio of elliptical stirred vessel on mixing time and flow field characteristics in the absence of baffles

Effect of aspect ratio of elliptical stirred vessel on mixing time and flow field characteristics in the absence of baffles

PDF (PC)

Knowledge

Abstract

Cite this article

share this article

References

Related Articles 15

Recommended Articles

Metrics

Comments

[1]	Chaojie Li, Xianxin Fang, Meiling Sun, Jihai Duan, Weiwen Wang. Study on two-phase cloud dispersion from liquefied CO₂ release [J]. Chinese Journal of Chemical Engineering, 2023, 60(8): 37-45.
[2]	Lijuan Zhao, Zhe Tan, Xiaoguang Zhang, Qijun Zhang, Wei Wang, Qiang Deng, Jie Ma, De'an Pan. Research on process modeling and simulation of spent lead paste desulfurization enhanced reactor [J]. Chinese Journal of Chemical Engineering, 2023, 60(8): 293-303.
[3]	Hongwei Liang, Wenling Li, Zisheng Feng, Jianming Chen, Guangwen Chu, Yang Xiang. Numerical simulation of gas-liquid flow in the bubble column using Wray-Agarwal turbulence model coupled with population balance model [J]. Chinese Journal of Chemical Engineering, 2023, 58(6): 205-223.
[4]	Chengang Yang, Huaizhi Han, Quan Zhu, Xiangyuan Li. Cracking and buoyancy effect on hydrocarbon endothermic and heat transfer characteristics in rectangular mini-channel [J]. Chinese Journal of Chemical Engineering, 2023, 56(4): 242-254.
[5]	Shuangfei Zhao, Yingying Nie, Wenyan Zhang, Runze Hu, Lianzhu Sheng, Wei He, Ning Zhu, Yuguang Li, Dong Ji, Kai Guo. Microfluidic field strategy for enhancement and scale up of liquid–liquid homogeneous chemical processes by optimization of 3D spiral baffle structure [J]. Chinese Journal of Chemical Engineering, 2023, 56(4): 255-265.
[6]	Qi Han, Xin-Yuan Zhang, Hai-Bo Wu, Xian-Tai Zhou, Hong-Bing Ji. Different efficiency toward the biomimetic aerobic oxidation of benzyl alcohol in microchannel and bubble column reactors: Hydrodynamic characteristics and gas–liquid mass transfer [J]. Chinese Journal of Chemical Engineering, 2023, 55(3): 84-92.
[7]	Songsong Wang, Hong Li, Changyuan Tao, Renlong Liu, Yundong Wang, Zuohua Liu. Study on cavern evolution and performance of three mixers in agitation of yield-pseudoplastic fluids [J]. Chinese Journal of Chemical Engineering, 2023, 55(3): 111-122.
[8]	Shuaishuai Zhou, Jing Li, Kaixiang Pang, Chunxi Lu, Feng Zhu, Congzhen Qiao, Yajie Tian, Jingwei Zhang. Computational fluid dynamics-discrete element method simulation of stirred tank reactor for graphene production [J]. Chinese Journal of Chemical Engineering, 2023, 64(12): 196-207.
[9]	Tianpeng LiZhou, Jiajia Luo, Tiefeng Wang. Enhancement of acetylene and ethylene yields in partially decoupled oxidation of ethane by changing the composition of heat carrier [J]. Chinese Journal of Chemical Engineering, 2022, 47(7): 71-78.
[10]	Zewen Chen, Yongjun Wu, Jian Wang, Peicheng Luo. Study on the solid–liquid suspension behavior in a tank stirred by the long-short blades impeller [J]. Chinese Journal of Chemical Engineering, 2022, 47(7): 79-88.
[11]	Yongjun Wu, Pan You, Peicheng Luo. Effect of pitched short blades on the flow characteristics in a stirred tank with long-short blades impeller [J]. Chinese Journal of Chemical Engineering, 2022, 45(5): 143-152.
[12]	Mohsen Rezaeimanesh, Ali Asghar Ghoreyshi, S.M. Peyghambarzadeh, Seyed Hassan Hashemabadi. A coupled CFD simulation approach for investigating the pyrolysis process in industrial naphtha thermal cracking furnaces [J]. Chinese Journal of Chemical Engineering, 2022, 44(4): 528-542.
[13]	Guina Yi, Ziqi Cai, Zhengming Gao, J.J. Derksen. Impingement and mixing dynamics of micro-droplets on a solid surface [J]. Chinese Journal of Chemical Engineering, 2022, 52(12): 66-77.
[14]	Anshi Hong, Zisheng Zhang, Xingang Li, Xin Gao. A generalized CFD model for evaluating catalytic separation process in structured porous materials [J]. Chinese Journal of Chemical Engineering, 2022, 51(11): 168-177.
[15]	Zhuotai Jia, Lele Xu, Xiaoxia Duan, Zai-Sha Mao, Qinghua Zhang, Chao Yang. CFD simulation of flow and mixing characteristics in a stirred tank agitated by improved disc turbines [J]. Chinese Journal of Chemical Engineering, 2022, 50(10): 95-107.