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Journal articles on the topic 'Plug-flow model'

Author: Grafiati

Published: 4 June 2021

Last updated: 15 February 2022

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1

KAWAGUCHI, Toshihiro, Yuu HORII, Toshitsugu TANAKA, and Yutaka TSUJI. "Development of One-Dimensional Plug Flow Model for Standpipe Flow." Proceedings of the Fluids engineering conference 2003 (2003): 185. http://dx.doi.org/10.1299/jsmefed.2003.185.

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2

Drescher, A., and M. Ferjani. "Revised model for plug/funnel flow in bins." Powder Technology 141, no. 1-2 (March 2004): 44–54. http://dx.doi.org/10.1016/j.powtec.2004.02.011.

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3

K. G. Gebremedhin, B. Wu, C. Gooch, P. Wright, and S. Inglis. "HEAT TRANSFER MODEL FOR PLUG-FLOW ANAEROBIC DIGESTERS." Transactions of the ASAE 48, no. 2 (2005): 777–85. http://dx.doi.org/10.13031/2013.18320.

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4

Hasan Ali San. "A kinetic model for ideal plug-flow reactors." Water Research 23, no. 5 (May 1989): 647–54. http://dx.doi.org/10.1016/0043-1354(89)90031-6.

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5

Muñoz Sierra, J. D., C. Picioreanu, and M. C. M. van Loosdrecht. "Modeling phototrophic biofilms in a plug-flow reactor." Water Science and Technology 70, no. 7 (August 23, 2014): 1261–70. http://dx.doi.org/10.2166/wst.2014.368.

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The use of phototrophic biofilms in wastewater treatment has been recognized as a potential option for development of new reactor configurations. For better understanding of these systems, a numerical model was developed including relevant microbial processes. As a novelty, this model was implemented in COMSOL Multiphysics, a modern computational environment for complex dynamic models. A two-dimensional biofilm model was used to study the spatial distribution of microbial species within the biofilm and along the length of the reactor. The biofilm model was coupled with a one-dimensional plug-flow bulk liquid model. The impact of different operational conditions on the chemical oxygen demand (COD) and ammonia conversions was assessed. The model was tuned by varying two parameters: the half-saturation coefficient for light use by phototrophs and the oxygen mass transfer coefficient. The mass transfer coefficient was found to be determining for the substrate conversion rate. Simulations indicate that heterotrophs would overgrow nitrifiers and phototrophs within the biofilm until a low biodegradable COD value in the wastewater is reached (organic loading rate <2.32 gCOD/(m2 d)). This limits the proposed positive effect of treating wastewater with a combination of algae and heterotrophs/autotrophs. Mechanistic models like this one are made for understanding the microbial interactions and their influence on the reactor performance.

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6

Ramli, Wan, and Wan Daud. "A Cross-Flow Model for Continuous Plug Flow Fluidized-Bed Cross-Flow Dryers." Drying Technology 25, no. 7-8 (August 2007): 1229–35. http://dx.doi.org/10.1080/07373930701438618.

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7

Tseng, S. K., R. T. Lin, and K. L. Liau. "Verification of Dispersion Model on Anaerobic Reaction Simulation." Water Science and Technology 26, no. 9-11 (November 1, 1992): 2377–80. http://dx.doi.org/10.2166/wst.1992.0741.

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A dispersion model was established on the combination of biological reaction and related physical-operational characteristics, such as dispersion, diffusion, cell accumulation and transportation. Also, the feasibility of the dispersion model in anaerobic filter digester simulation was identified. Under low loading rate and without recirculation, the digester behaves like a plug flow reactor. Therefore, the simulated results of dispersion model and plug flow model are similiar. However, at higher loading rate, the dispersion of digester increases, and the simulated results of the dispersion model are closer to experimental data than the plug model. That proved the applicability of dispersion model in anaerobic reaction simulation.

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8

Alopaeus, Ville, Helena Laavi, and Juhani Aittamaa. "A dynamic model for plug flow reactor state profiles." Computers & Chemical Engineering 32, no. 7 (July 2008): 1494–506. http://dx.doi.org/10.1016/j.compchemeng.2007.06.025.

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9

Vasek, Lubomir, Viliam Dolinay, and Vladimir Vasek. "Pulled Plug-flow Model for 4th Generation District Heating." IFAC-PapersOnLine 52, no. 4 (2019): 12–17. http://dx.doi.org/10.1016/j.ifacol.2019.08.147.

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10

ZHAO, X. P., X. Y. GAO, and D. J. GAO. "EVOLUTION OF CHAIN STRUCTURE OF ELECTRORHEOLOGICAL FLUIDS IN FLOW MODEL." International Journal of Modern Physics B 16, no. 17n18 (July 20, 2002): 2697–703. http://dx.doi.org/10.1142/s0217979202012864.

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The movement of particles in electrorheological (ER) fluids is analyzed by means of molecular dynamic simulations. We found that the velocity profile of particles can be divided into two zones. One zone near electrodes where particles' velocity profiles change periodically like "breathing type" is called transition zone. The other in the middle of two electrodes where particles move smoothly like a plug is called "plug zone". In addition, the relationship between volume flow rate and relative pressure gradient is simulated out. Factors such as volume flow rate, critical electric field, critical pressure gradient and response time of shutting up were also analyzed respectively.

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11

Liu, Daoyin, Zhonglin Zhang, Yaming Zhuang, and Xiaoping Chen. "Comparison of CFD Simulation and Simplified Modeling of a Fluidized Bed CO2 Capture Reactor." International Journal of Chemical Reactor Engineering 14, no. 1 (February 1, 2016): 133–41. http://dx.doi.org/10.1515/ijcre-2015-0058.

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AbstractCO2 capture using solid sorbents in fluidized bed reactors is a promising technology. The multiphase CFD model is increasingly developed to study the reactors, but it is difficult to model all the realistic details and it requires significant computational time. In this study, both the multiphase CFD model (i.e., CFD-DEM model coupled with reaction) and the simplified reactor models (i.e., plug flow model and bubbling two-phase model) are developed for modeling a fluidized bed CO2 capture reactor. The comparisons are made at different gas velocities from fixed bed to fluidized bed. The DEM based model reveals a detailed view of CO2 adsorption process with particle flow dynamics, based on which the assumptions in the simplified models can be evaluated. The plug flow model predictions generally show similar trends to the DEM model but there are quantitative differences; thus, it can be used to determine the reactor performance limit. The bubbling two-phase model gives better predictions than the plug flow model because the effect of bubbles on the inter-phase mass transfer and reaction is included. In the future, a closer combination of the multiphase CFD simulation and the simplified reactor models will likely be an efficient design method of CO2 capture fluidized bed reactors.

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12

Sankar, D. S., and Yazariah Yatim. "Comparative Analysis of Mathematical Models for Blood Flow in Tapered Constricted Arteries." Abstract and Applied Analysis 2012 (2012): 1–34. http://dx.doi.org/10.1155/2012/235960.

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Pulsatile flow of blood in narrow tapered arteries with mild overlapping stenosis in the presence of periodic body acceleration is analyzed mathematically, treating it as two-fluid model with the suspension of all the erythrocytes in the core region as non-Newtonian fluid with yield stress and the plasma in the peripheral layer region as Newtonian. The non-Newtonian fluid with yield stress in the core region is assumed as (i) Herschel-Bulkley fluid and (ii) Casson fluid. The expressions for the shear stress, velocity, flow rate, wall shear stress, plug core radius, and longitudinal impedance to flow obtained by Sankar (2010) for two-fluid Herschel-Bulkley model and Sankar and Lee (2011) for two-fluid Casson model are used to compute the data for comparing these fluid models. It is observed that the plug core radius, wall shear stress, and longitudinal impedance to flow are lower for the two-fluid H-B model compared to the corresponding flow quantities of the two-fluid Casson model. It is noted that the plug core radius and longitudinal impedance to flow increases with the increase of the maximum depth of the stenosis. The mean velocity and mean flow rate of two-fluid H-B model are higher than those of the two-fluid Casson model.

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13

Sankar, D. S., and Atulya K. Nagar. "Nonlinear Fluid Models for Biofluid Flow in Constricted Blood Vessels under Body Accelerations: A Comparative Study." Journal of Applied Mathematics 2012 (2012): 1–27. http://dx.doi.org/10.1155/2012/950323.

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Pulsatile flow of blood in constricted narrow arteries under periodic body acceleration is analyzed, modeling blood as non-Newtonian fluid models with yield stress such as (i) Herschel-Bulkley fluid model and (ii) Casson fluid model. The expressions for various flow quantities obtained by Sankar and Ismail (2010) for Herschel-Bulkley fluid model and Nagarani and Sarojamma (2008), in an improved form, for Casson fluid model are used to compute the data for comparing these fluid models. It is found that the plug core radius and wall shear stress are lower for H-B fluid model than those of the Casson fluid model. It is also noted that the plug flow velocity and flow rate are considerably higher for H-B fluid than those of the Casson fluid model. The estimates of the mean velocity and mean flow rate are considerably higher for H-B fluid model than those of the Casson fluid model.

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14

Li, Yifeng, Maria Skyllas-Kazacos, and Jie Bao. "A dynamic plug flow reactor model for a vanadium redox flow battery cell." Journal of Power Sources 311 (April 2016): 57–67. http://dx.doi.org/10.1016/j.jpowsour.2016.02.018.

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15

Zubair, Mohammed, Vizy Nazira Riazuddin, Mohammad Zulkifly Abdullah, Ismail Rushdan, Ibrahim Lutfi Shuaib, and Kamarul Arifin Ahmad. "COMPUTATIONAL FLUID DYNAMICS STUDY OF PULL AND PLUG FLOW BOUNDARY CONDITION ON NASAL AIRFLOW." Biomedical Engineering: Applications, Basis and Communications 25, no. 04 (August 2013): 1350044. http://dx.doi.org/10.4015/s1016237213500440.

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The recent advances in the computer based computational fluid dynamics (CFD) software tools in the study of airflow behavior in the nasal cavity have opened an entirely new field of medical research. This numerical modeling method has provided both engineers and medical specialists with a clearer understanding of the physics associated with the flow in the complicated nasal domain. The outcome of any CFD investigation depends on the appropriateness of the boundary conditions applied. Most researchers have employed plug boundary condition as against the pull flow which closely resembles the physiological phenomenon associated with the breathing mechanism. A comparative study on the effect of using the plug and pull flow boundary conditions are evaluated and their effect on the nasal flow are studied. Discretization error estimation using Richardson's extrapolation (RE) method has also been carried out. The study is based on the numerical model obtained from computed tomographic data of a healthy Malaysian subject. A steady state Reynold averaged Navier–Stokes and continuity equations is solved for inspiratory flow having flow rate 20 L/min representing turbulent boundary conditions. Comparative study is made between the pull and plug flow model. Variation in flow patterns and flow features such as resistance, pressure and velocity are presented. At the nasal valve, the resistance for plug flow is 0.664 Pa-min/L and for pull flow the value is 0.304 Pa-min/L. The maximum velocity at the nasal valve is 3.28 m/s for plug flow and 3.57 m/s for pull flow model.

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16

Wilson, L., Arunn Narasimhan, and S. P. Venkateshan. "Permeability and Form Coefficient Measurement of Porous Inserts With Non-Darcy Model Using Non-Plug Flow Experiments." Journal of Fluids Engineering 128, no. 3 (September 24, 2005): 638–42. http://dx.doi.org/10.1115/1.2175172.

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Permeability (K) and form coefficient (C) are the characteristic hydraulic properties of any porous medium. They are determined simultaneously, for known fluid thermo-physical properties by using the Hazen-Dupuit-Darcy model (HDD) to curve-fit the longitudinal global pressure-drop versus average fluid speed data from an isothermal, steady flow, hydraulic experiment across a test section of the porous medium. The K and C thus measured are global parameters, i.e., valid for the entire porous medium and universal provided the flow throughout the porous medium is of plug flow nature. We report here experimental evidence on the influence of non-plug flow velocity profiles at the inlet, on the simultaneous determination of K and C of fissure- and rod bundle-type porous inserts. Although variation in K is minimal, as much as 12.1% variation in C is observed, when going from a fully developed velocity profile to a plug flow profile at the inlet.

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17

Sankar, D. S. "Pulsatile Flow of a Two-Fluid Model for Blood Flow through Arterial Stenosis." Mathematical Problems in Engineering 2010 (2010): 1–26. http://dx.doi.org/10.1155/2010/465835.

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Pulsatile flow of a two-fluid model for blood flow through stenosed narrow arteries is studied through a mathematical analysis. Blood is treated as two-phase fluid model with the suspension of all the erythrocytes in the as Herschel-Bulkley fluid and the plasma in the peripheral layer as a Newtonian fluid. Perturbation method is used to solve the system of nonlinear partial differential equations. The expressions for velocity, wall shear stress, plug core radius, flow rate and resistance to flow are obtained. The variations of these flow quantities with stenosis size, yield stress, axial distance, pulsatility and amplitude are analyzed. It is found that pressure drop, plug core radius, wall shear stress and resistance to flow increase as the yield stress or stenosis size increases while all other parameters held constant. It is observed that the percentage of increase in the magnitudes of the wall shear stress and resistance to flow over the uniform diameter tube is considerably very low for the present two-fluid model compared with that of the single-fluid model of the Herschel-Bulkley fluid. Thus, the presence of the peripheral layer helps in the functioning of the diseased arterial system.

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18

Li, Shu Xun, Xiao Gang Xu, Ying Zhe Hou, and Que Li. "Numerical Analysis of Flow Field and Performance Optimization of Axial-Flow Pressure Reducing Valve." Applied Mechanics and Materials 271-272 (December 2012): 1362–65. http://dx.doi.org/10.4028/www.scientific.net/amm.271-272.1362.

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In order to promote the technical progress of pressure reducing valve in nature gas transport system, a high pressure pilot operated axial-flow pressure reducing valve was designed and developed. The three-dimensional modeling of the natural gas pressure reducing valve internal flow passage was found by using Solidworks software. Import the flow channel model into meshing in CFD software based on the internal flow channel geometry and flow characteristics. The ideal gas compressible fluid model of natural gas and improved RNG k-Epsilon model were used to solve the pressure and velocity distribution as well as other flow related parameters of the natural gas pilot operated pressure reducing valve. The flow fields of the pressure reducing valve with different valve plug shape were analyzed. Changes of valve plug shape were made to improve the performance of the valve.

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19

Khvostov, Anatoly, Anatoly Khvostov, Viktor Ryazhskikh, Viktor Ryazhskikh, Gazibeg Magomedov, Gazibeg Magomedov, Aleksey Zhuravlev, and Aleksey Zhuravlev. "Matrix dynamic models of elements of technological systems with perfect mixing and plug-flow hydrodynamics in Simulink." Foods and Raw Materials 6, no. 2 (December 20, 2018): 483–92. http://dx.doi.org/10.21603/2308-4057-2018-2-483-492.

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The dynamic models of elements of technological systems with perfect mixing and plug-flow hydrodynamics are based on the systems of algebraic and differential equations that describe a change in the basic technological parameters. The main difficulty in using such models in MathWorks Simulink™ computer simulation systems is the representation of ordinary differential equations (ODE) and partial differential equations (PDE) that describe the dynamics of a process as a MathWorks Simulink™ block set. The study was aimed at developing an approach to the synthesis of matrix dynamic models of elements of technological systems with perfect mixing and plug-flow hydrodynamics that allows for transition from PDE to an ODE system on the basis of matrix representation of discretization of coordinate derivatives. A sugar syrup cooler was chosen as an object of modeling. The mathematical model of the cooler is formalized by a set of perfect reactors. The simulation results showed that the mathematical model adequately describes the main regularities of the process, the deviation of the calculated data from the regulations did not exceed 10%. The proposed approach significantly simplifies the study and modernization of the current and the development of new technological equipment, as well as the synthesis of algorithms for controlling the processes therein.

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20

von Sperling, M. "Relationship between first-order decay coefficients in ponds, for plug flow, CSTR and dispersed flow regimes." Water Science and Technology 45, no. 1 (January 1, 2002): 17–24. http://dx.doi.org/10.2166/wst.2002.0003.

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Adequate consideration of the hydraulic regime of a pond is essential in the analysis of BOD and coliform removal, and considerable divergence exists in the literature when reporting removal coefficients. This paper aims at integrating the existing approaches, by quantifying the relationship between the first-order removal coefficients K from the three main hydraulic regimes (CSTR, plug flow and dispersed flow) adopted in the design and performance evaluation of ponds. Based on theoretical considerations and statistical regression analyses, the relationship between the K values is investigated, quantified and modelled. Two tables are presented and two equations are proposed, which allow conversion of K values obtained for dispersed flow to (a) K for CSTR and (b) K for plug flow, based on the hydraulic detention time t and the dispersion number d. These coefficients, when applied in the CSTR or plug-flow equations, will give approximately the same prediction of the effluent concentration as that obtained when using the dispersed-flow model with its proper coefficient. With this approach designers can apply, and researchers can report, K values for the two idealised flow patterns (CSTR and plug flow).

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21

Joe Middlebrooks, E. "Design Equations for Bod Removal in Facultative Ponds." Water Science and Technology 19, no. 12 (December 1, 1987): 187–93. http://dx.doi.org/10.2166/wst.1987.0145.

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Facultative pond performance data collected for the US Environmental Protection Agency (USEPA) at four locations throughout the USA and data collected by others were used to evaluate the most frequently used design equations and to develop non-linear design equations. Empirical models were evaluated as well as the classical plug flow and complete mix models. The first order plug flow model gave the best fit of all the rational models. The empirical non-linear models did not fit the data, nor did the other empirical models with the exception being the areal loading and removal model. Attempts to verify the models developed with the USEPA data using data collected by others were not successful with the exception of the areal loading and removal model.

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22

HORII, Yuu, Toshihiro KAWAGUCHI, Toshitsugu TANAKA, and Yutaka TSUJI. "One-dimensional Flow Structure in Standpipe Flow : Experiment, DEM Analysis and Development of Plug Flow Model." Proceedings of Conference of Kansai Branch 2003.78 (2003): _14–39_—_14–40_. http://dx.doi.org/10.1299/jsmekansai.2003.78._14-39_.

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23

Liu, Jian-Hong, Fu-Min Shang, and Wei Qiao. "Numerical Simulation on Flow and Heat Transfer in Pulsating Heat Pipe with Different Models." E3S Web of Conferences 165 (2020): 01031. http://dx.doi.org/10.1051/e3sconf/202016501031.

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Based on Mixture and Euler model, numerical simulation was used to study the flow and heat transfer in pulsating heat pipe by unsteady method. By comparing the gas volume fraction and gas velocity by different models at different time, the results showed that both models could simulate the evaporation and condensation process of the working fluid, and the liquid plug and gas plug were formed in the tube. By comparing the gas volume fraction and gas velocity at 5s and 10s, it was indicated that the fluid dynamics and heat transfer were more violent by Mixture model in the tube.

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24

Kotov, V., and P. M. J. Koelman. "Plug flow reactor model of the plasma chemical conversion of CO2." Plasma Sources Science and Technology 28, no. 9 (September 24, 2019): 095002. http://dx.doi.org/10.1088/1361-6595/ab3774.

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25

Dogan, Sifa, and Rana Kidak. "A Plug flow reactor model for UV-based oxidation of amoxicillin." Desalination and Water Treatment 57, no. 29 (June 17, 2015): 13586–99. http://dx.doi.org/10.1080/19443994.2015.1058728.

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26

Aksikas, Ilyasse, Joseph Winkin, and Denis Dochain. "Asymptotic stability of a nonisothermal plug flow reactor infinite-dimensional model." IFAC Proceedings Volumes 37, no. 13 (September 2004): 781–86. http://dx.doi.org/10.1016/s1474-6670(17)31320-4.

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27

FALCONER, R. A., and S. Q. LIU. "Mathematical Model Study of Plug Flow in a Chlorine Contact Tank." Water and Environment Journal 1, no. 3 (December 1987): 279–90. http://dx.doi.org/10.1111/j.1747-6593.1987.tb01227.x.

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28

Mahfud, Mahfud, Lailatul Qadariyah, and Donny S. Bhuwana. "MODEL DISPERSI PLUG-FLOW UNTUK ALIRAN FASA CAIR DALAM REAKTOR TRICKLE BED." Sains & Teknologi 2, no. 1 (October 17, 2019): 1. http://dx.doi.org/10.24123/jst.v2i1.2241.

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Dalam industri kimia, petrokimia, dan perminyakan, reaktor trickle bed sering dipakai untuk mengendalikan polusi dan pengolahan air. Unjuk kerja dari reaktor tricke bed ini tidak hanya dipengaruhi oleh kinetika reaksi, melainkan juga oleh faktor perpindahan massa dan hidrodinamikanya. Penelitian ini bertujuan mempelajari distribusi waktu tinggal fasa liquid dalam reaktor trickle bed dan memodelkan alirannya dengan model dispersed plug flow untuk berbagai kondisi operasi (laju alir gas & laju alir liquid). Reaktor trickle-bed yang digunakan pada percobaan ini terdiri dari kolom acrylic yang berdiameter dalam 4,8.10-2 m dengan tinggi 7.10-2 m dengan menggunakan packing granular (drata-rata = 0,476 cm). Kondisi operasinya adalah sbb : laju alir gas antara 1,33 – 2,4.10-4 m3/s, laju alir liquid antara 1,2 – 2,37.10-5 m3/s, tekanan atmosferik dan suhu kamar (29 oC). Metode Stimulus response digunakan untuk memperoleh distribusi waktu tinggal dengan menggunakan larutan NaCL sebagai pelacak yang dinijeksikan secara pulse pada bagian masuk reaktor dan konsentrasi keluar reaktor diukur dengan menggunakan konduktometer (OMEGA CDTX-83). Kurva distribusi waktu tinggal yang diperoleh disesuaikan dengan model dispersed plug-flow, dengan Bilangan dispersi (D/uL) sebagai parameter model. Hasil experimen menunjukkan bahwa distribusi waktu tinggal sangat dipengaruhi oleh laju alir gas maupun cairan dalam reaktor dan model dispersi menunjukkan kesesuain antara model dengan data percobaan. Harga bilangan Dispersi (D/uL) menurun dengan meningkatnya laju alir liquid maupun gas, yang berarti pola aliran makin mendekati pola plug flow.

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29

Givler, R. C., and R. R. Mikatarian. "Numerical Simulation of Fluid-Particle Flows: Geothermal Drilling Applications." Journal of Fluids Engineering 109, no. 3 (September 1, 1987): 324–31. http://dx.doi.org/10.1115/1.3242668.

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In order to understand how a particulate plug may evolve within the flow of an essentially homogeneous suspension, we have developed a fluid-particle flow model. This theoretical model is based upon a monodisperse collection of rigid, spherical particles suspended in an incompressible, Newtonian liquid. Balance equations of mass and momentum are given for each phase within the context of a continuum mixture theory. The interactions between the phases are dominated by interfacial drag forces and unequilibrated pressure forces. The pressure associated with the solid particles is given by a phenomenological model based upon the flow dynamics. Of primary concern is the calculation of solid particle concentrations within a flow field to indicate the initiation of a particulate plug.

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30

Bochdansky, Alexander B., and Don Deibel. "Consequences of model specification for the determination of gut evacuation rates: redefining the linear model." Canadian Journal of Fisheries and Aquatic Sciences 58, no. 5 (May 1, 2001): 1032–42. http://dx.doi.org/10.1139/f01-041.

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The combination of gut contents and evacuation rate is an important tool to determine in situ feeding rates of many organisms. Traditionally used equations of gut evacuation models, however, have made a systematic comparison among models difficult. We changed the notation of the linear gut evacuation model to provide an algorithm compatible with the commonly used exponential model. Using examples from the literature, we demonstrate that prolonged retention of food after a true linear pattern of gut evacuation can be mistaken for an exponential pattern. In many of these examples, use of an exponential gut evacuation model causes overestimation of food consumption by approximately twofold. In situations where the entire gastrointestinal tract is examined instead of the stomach only, the time course of the gut content is best described by a plug-flow reactor for which the "input = output" rule applies. In contrast, the assumption of a "proportional release" must be met rigorously for the exponential model to be valid, which requires more complex feedback mechanisms than the simple plug-flow reactor. The new algorithm for the linear model is also consistent with the empirical observation that the gut evacuation rate is proportional to the initial gut content.

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31

Liu, Chang Yun, Xue Zeng Zhao, and Fang Chen. "Application of Numerical Simulation in Analysis and Optimization of Constant Flux Blanking Plug." Materials Science Forum 532-533 (December 2006): 765–68. http://dx.doi.org/10.4028/www.scientific.net/msf.532-533.765.

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The constant flux blanking plug is a downhole flow control device used in the separate layer water injection system of oil-field, its flow characteristic and reliability are the most important matters that people care about. So these performances of the constant flux blanking plug are analyzed by numerical methods here. The dynamic model of the constant flux blanking plug is established by bond-graph, then the simulation is made by the 20-SIM software. The influence of local flow field is studied by CFD (computational fluid dynamics), with which some different valve spools and pockets are compared. The discrete particles’ trajectories are analyzed by the Lagrangian method, and the particle erosion rates of different materials are calculated with Bitter’s erosion model. All the simulation data show that the structure and material have great influence on the flow control precision and reliability which need to improve at present. The simulation results are verified through ground or field tests in the end.

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32

Lu, Yuanxiang, Zeyi Jiang, Xinru Zhang, Jingsong Wang, and Xinxin Zhang. "Vertical Section Observation of the Solid Flow in a Blast Furnace with a Cutting Method." Metals 9, no. 2 (January 25, 2019): 127. http://dx.doi.org/10.3390/met9020127.

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The solid flow plays an important role in blast furnace (BF) ironmaking. In the paper, the descending behavior of solid flow in BFs was investigated by a cold experimental BF model and numerical simulation via the discrete element method (DEM). To eliminate the flat wall effect on the structure of solid flow in lab observations, a cutting method was developed to observe the vertical section of the solid flow by inserting a transparent plate into the experimental BF model. Both the experimental and numerical results indicated that plug flow is the main solid flow pattern in the upper and middle zones of BFs during burden descending. Meanwhile, a slight convergence flow and a deadman zone form at the lower part of the bosh. In addition, the boundary between the plug flow and convergence flow in BFs was determined by analyzing the velocity of the burden in vertical directions and the Wilcox–Swailes coefficient (Uws). The results indicated that the Uws can be defined as a critical value to determine the solid flow patterns. When Uws ≥ 0.65, the plug flow is dominant. When Uws < 0.65, the convergence flow is dominant. The findings may have important implications to understand the structure of the solid flow in BFs.

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33

Abbott, Matthew Stanley Richard, Adam P. Harvey, and Michelle I. Morrison. "Rapid Determination of the Residence Time Distribution (RTD) Function in an Oscillatory Baffled Reactor (OBR) Using a Design of Experiments (DoE) Approach." International Journal of Chemical Reactor Engineering 12, no. 1 (January 1, 2014): 575–86. http://dx.doi.org/10.1515/ijcre-2014-0040.

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Abstract Residence time distribution (RTD) profiles were investigated in a standard oscillatory baffled reactor (OBR) as a function of oscillatory and bulk flow components using a design of experiments (DoE) approach. A second-order, polynomial model (R2=92.1%) was fitted to N values estimated from concentration profiles and used to maximise plug flow conditions. The velocity ratio (Ψ) required to maximise plug flow was 1.9, agreeing well with the range previously identified by Stonestreet and van der Veeken (1.8 < Ψ < 2.0), suggesting that the approach used here is valid. This method could be used to rapidly quantify and maximise plug flow in various OBR designs in a simple and robust manner which could prove valuable for the operation and design of continuous processes using OBR technology.

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Mott, Henry V., and Zane A. Green. "On Danckwerts’ Boundary Conditions for the Plug-Flow with Dispersion/Reaction Model." Chemical Engineering Communications 202, no. 6 (January 22, 2015): 739–45. http://dx.doi.org/10.1080/00986445.2013.871708.

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James, A., J. Brindley, and A. C. McIntosh. "Classification of behaviour in a steady plug-flow model of catalytic combustion." Chemical Engineering Science 56, no. 15 (August 2001): 4649–58. http://dx.doi.org/10.1016/s0009-2509(01)00111-7.

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Che, Zhizhao, Teck Neng Wong, and Nam-Trung Nguyen. "An analytical model for plug flow in microcapillaries with circular cross section." International Journal of Heat and Fluid Flow 32, no. 5 (October 2011): 1005–13. http://dx.doi.org/10.1016/j.ijheatfluidflow.2011.06.009.

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Hastir, Anthony, and François Lamoline. "Optimal equilibrium stabilization for a nonlinear infinite-dimensional plug-flow reactor model." Automatica 130 (August 2021): 109722. http://dx.doi.org/10.1016/j.automatica.2021.109722.

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Picado, Apolinar, and Rafael Gamero. "Simulation of a continuous plug-flow fluidised bed dryer for rough rice." Nexo Revista Científica 27, no. 2 (December 30, 2014): 115–24. http://dx.doi.org/10.5377/nexo.v27i2.1947.

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In this study, a mathematical model to simulate the drying of rough rice in a continuous plug-flow fluidised bed dryer ispresented. Equipment and material models were applied to describe the process. The equipment model was based on thedifferential equations obtained by applying mass and energy balances to each element of the dryer. Concerning the materialmodel, mass and heat transfer rates in a single isolated particle were considered. Mass and heat transfer within the particles wasdescribed by analytical solutions with constant effective transport coefficients. To simulate the dryer, the material model wasimplemented in the equipment model in order to describe the whole process. Calculation results were verified by comparisonwith experimental data from the literature. There was very good agreement between experimental data and simulation. Theeffects of gas temperature and velocity, particle diameter, dry solid flow and solid temperature on the drying process wereinvestigated. It was found that the changes in gas velocity, dry solids flow and solid temperature had essentially no effect ondrying behaviour.DOI: http://dx.doi.org/10.5377/nexo.v27i2.1947

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Houweling, D., F. Chazarenc, R. Leduc, and Y. Comeau. "Effect of baffles on nitrification in aerated facultative lagoons in a cold climate." Water Science and Technology 55, no. 11 (June 1, 2007): 73–79. http://dx.doi.org/10.2166/wst.2007.345.

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Tracer studies performed in two aerated facultative lagoons indicate some bypass and an overall hydraulic regime close to completely-mixed. Results were used to calibrate a hydraulic model based on the tanks-in-series approach. The hydraulic model was combined with a simple “death-regeneration” biokinetic model to simulate seasonal nitrification as observed over a three year period. Modifications were made to the hydraulic model to represent the effect of baffle installations to 1) eliminate bypass and 2) impose a plug-flow regime. Simulation results indicate there is some gain to eliminating bypass but that imposing a plug-flow regime would increase biomass washout rates and hinder nitrification.

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Mathis, DE. "Flow Rate Dependence of Ventilation." Beiträge zur Tabakforschung International/Contributions to Tobacco Research 14, no. 1 (December 1, 1987): 11–19. http://dx.doi.org/10.2478/cttr-2013-0579.

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AbstractA quantitative model describing the effects of puffing conditions on the level of filter ventilation was developed and evaluated. The development of the model was based on a quadratic flow-pressure drop relationship which was validated with experimental measurements for numerous plug wraps, tipping papers, and combinations of the two. This relationship was used to derive an equation describing the level of filter ventilation as a function of the flow rate of air exiting the filter. This equation was shown to accurately predict the measured ventilations of six brands of commercial cigarettes over a range of continuous flow rates. The instantaneous ventilation values predicted by the equation were utilized to model ventilation during a puff by integrating the equation with respect to flow rate over the duration of the puff. This method for predicting the effects of specific puffing conditions on ventilation was demonstrated for sinusoidally shaped puffs spanning a wide range of volume and duration. Finally, the effects on the flow dependence of ventilation of different combinations of plug wrap and tipping papers were described qualitatively based on experimental measurements of paper flow-pressure drop linearity.

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Signe Mamba, S., J. C. Magniez, F. Zoueshtiagh, and M. Baudoin. "Dynamics of a liquid plug in a capillary tube under cyclic forcing: memory effects and airway reopening." Journal of Fluid Mechanics 838 (January 12, 2018): 165–91. http://dx.doi.org/10.1017/jfm.2017.828.

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In this paper, we investigate both experimentally and theoretically the dynamics of a liquid plug driven by a cyclic periodic forcing inside a cylindrical rigid capillary tube. First, it is shown that, depending on the type of forcing (flow rate or pressure cycle), the dynamics of the liquid plug can either be stable and periodic, or conversely accelerative and eventually leading to plug rupture. In the latter case, we identify the sources of the instability as: (i) the cyclic diminution of the plug viscous resistance to motion due to the decrease in the plug length and (ii) a cyclic reduction of the plug interfacial resistance due to a lubrication effect. Since the flow is quasi-static and the forcing periodic, this cyclic evolution of the resistances relies on the existence of flow memories stored in the length of the plug and the thickness of the trailing film. Second, we show that, contrary to unidirectional pressure forcing, cyclic forcing enables breaking of large plugs in a confined space although it requires longer times. All the experimentally observed tendencies are quantitatively recovered from an analytical model. This study not only reveals the underlying physics but also opens up the prospect for the simulation of ‘breathing’ of liquid plugs in complex geometries and the determination of optimal cycles for obstructed airways reopening.

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Soeprijanto, Soeprijanto, I. Dewa Ayu Agung Warmadewanthi, Melania Suweni Muntini, and Arino Anzip. "The Utilization of Water Hyacinth for Biogas Production in a Plug Flow Anaerobic Digester." International Journal of Renewable Energy Development 10, no. 1 (February 1, 2020): 27–35. http://dx.doi.org/10.14710/ijred.2021.21843.

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Water hyacinth (Eichhornia crassipes) causes ecological and economic problems because it grows very fast and quickly consumes nutrients and oxygen in water bodies, affecting both the flora and fauna; besides, it can form blockages in the waterways, hindering fishing and boat use. However, this plant contains bioactive compounds that can be used to produce biofuels. This study investigated the effect of various substrates as feedstock for biogas production. A 125-l plug-flow anaerobic digester was utilized and the hydraulic retention time was 14 days; cow dung was inoculated into water hyacinth at a 2:1 mass ratio over 7 days. The maximum biogas yield, achieved using a mixture of natural water hyacinth and water (NWH-W), was 0.398 l/g volatile solids (VS). The cow dung/water (CD-W), hydrothermally pretreated water hyacinth/digestate, and hydrothermally pretreated water hyacinth/water (TWH-W) mixtures reached biogas yields of 0.239, 0.2198, and 0.115 l/g VS, respectively. The NWH-W composition was 70.57% CH4, 12.26% CO2, 1.32% H2S, and 0.65% NH3. The modified Gompertz kinetic model provided data satisfactorily compatible with the experimental one to determine the biogas production from various substrates. TWH-W and NWH-W achieved, respectively, the shortest and (6.561 days) and the longest (7.281 days) lag phase, the lowest (0.133 (l/g VS)/day) and the highest (0.446 (l/g VS)/day) biogas production rate, and the maximum and (15.719 l/g VS) and minimum (4.454 l/g VS) biogas yield potential.

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Yang, Da Yong. "Analytical Solution of Mixed Electroosmotic and Pressure-Driven Flow in Rectangular Microchannels." Key Engineering Materials 483 (June 2011): 679–83. http://dx.doi.org/10.4028/www.scientific.net/kem.483.679.

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Analytical solutions for potential distributions, velocity distributions of the mixed electroosmotic and pressure-driven flow in rectangular microchannels are discussed. To simulate the flow, a mathematical model, which includes the Poisson-Boltzmann equation and the modified Navier-Stokes equations, is presented and solved using the finite element method based on the Matlab software. The results show that the velocity distribution of mixed flow is compound of the “plug-like” and paraboloid at the steady state, and the pure electroosmotic flow is “plug-like”, which is similar with the electric double layer potential profile. The results provide the guidelines for the application of mix driven flow in microfluidic chips.

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Rendall, Joseph, Fernando Karg Bulnes, Kyle Gluesenkamp, Ahmad Abu-Heiba, William Worek, and Kashif Nawaz. "A Flow Rate Dependent 1D Model for Thermally Stratified Hot-Water Energy Storage." Energies 14, no. 9 (May 2, 2021): 2611. http://dx.doi.org/10.3390/en14092611.

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Stratified tank models are used to simulate thermal storage in applications such as residential or commercial hot-water storage tanks, chilled-water storage tanks, and solar thermal systems. The energy efficiency of these applications relates to the system components and the level of stratification maintained during various flow events in the tank. One-dimensional (1D) models are used in building energy simulations because of the short computation time but often do not include flow-rate dependent mixing. The accuracy of 1D models for plug flow, plug flow with axial conduction, and two convection eddy-diffusivity models were compared with experimental data sets for discharging a 50-gal residential tank and recharging the tank with hot water from an external hot-water source. A minimum and maximum relationship for the eddy diffusivity factor were found at Re <2100 and >10,000 for recirculation of hot water to the top of the tank and vertical tubes inletting cold water at the bottom. The root mean square error decreased from >4 °C to near 2 °C when considering flow-based mixing models during heating, while the exponential decay of the eddy diffusion results in a root mean square error reduction of 1 °C for cone-shaped diffusers that begin to relaminarize flow at the inlet.

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Shen, Xiao Yang, Ping Wang, and Shao Gang Liu. "Extrusion Modeling of Solid Plug Flow of Co-Rotating Twin Screw Pulping Extruder." Advanced Materials Research 97-101 (March 2010): 240–44. http://dx.doi.org/10.4028/www.scientific.net/amr.97-101.240.

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In order to calculate important design parameters, screw axial force and power consumption of twin screw pulping extruder (TSPE), considering actions of the solid material plug in reverse thread of the TSPE and according to static balance principle, an extrusion model including plug flowing and shearing in reverse thread is proposed in the paper. Based on the model, screw axial force, screw torque, power consumption and flow rate can be derived. When changing thread lead numbers or slot width on the flight of the reverse thread, theoretical calculating results and testing results are better consistent.

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König, S., M. R. Suriyah, and T. Leibfried. "A plug flow reactor model of a vanadium redox flow battery considering the conductive current collectors." Journal of Power Sources 360 (August 2017): 221–31. http://dx.doi.org/10.1016/j.jpowsour.2017.05.085.

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47

King, Andrew C., Cynthia A. Mitchell, and Tony Howes. "Hydraulic tracer studies in a pilot scale subsurface flow constructed wetland." Water Science and Technology 35, no. 5 (March 1, 1997): 189–96. http://dx.doi.org/10.2166/wst.1997.0195.

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Current design procedures for Subsurface Flow (SSF) Wetlands are based on the simplifying assumptions of plug flow and first order decay of pollutants. These design procedures do yield functional wetlands but result in over-design and inadequate descriptions of the pollutant removal mechanisms which occur within them. Even though these deficiencies are often noted, few authors have attempted to improve modelling of either flow or pollutant removal in such systems. Consequently the Oxley Creek Wetland, a pilot scale SSF wetland designed to enable rigorous monitoring, has recently been constructed in Brisbane, Australia. Tracer studies have been carried out in order to determine the hydraulics of this wetland prior to commissioning it with settled sewage. The tracer studies will continue during the wetland's commissioning and operational phases. These studies will improve our understanding of the hydraulics of newly built SSF wetlands and the changes brought on by operational factors such as biological films and wetland plant root structures. Results to date indicate that the flow through the gravel beds is not uniform and cannot be adequately modelled by a single parameter, plug flow with dispersion, model. We have developed a multiparameter model, incorporating four plug flow reactors, which provides a better approximation of our experimental data. With further development this model will allow improvements to current SSF wetland design procedures and operational strategies, and will underpin investigations into the pollutant removal mechanisms at the Oxley Creek Wetland.

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Menon, Sananth H., G. Madhu, and Jojo Mathew. "Modeling Residence Time Distribution (RTD) Behavior in a Packed-Bed Electrochemical Reactor (PBER)." International Journal of Chemical Engineering 2019 (February 26, 2019): 1–9. http://dx.doi.org/10.1155/2019/7856340.

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This paper focuses on understanding the electrolyte flow characteristics in a typical packed-bed electrochemical reactor using Residence Time Distribution (RTD) studies. RTD behavior was critically analyzed using tracer studies at various flow rates, initially under nonelectrolyzing conditions. Validation of these results using available theoretical models was carried out. Significant disparity in RTD curves under electrolyzing conditions was examined and details are recorded. Finally, a suitable mathematical model (Modified Dispersed Plug Flow Model (MDPFM)) was developed for validating these results under electrolyzing conditions.

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El-Din, M. G., and D. W. Smith. "Ozone mass transfer in water treatment: hydrodynamics and mass transfer modeling of ozone bubble columns." Water Supply 1, no. 2 (March 1, 2001): 123–30. http://dx.doi.org/10.2166/ws.2001.0029.

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Most of the mathematical models that are employed to model the performance of bubble columns are based on the assumption that either plug flow or complete mixing conditions prevail in the liquid phase. Although due to the liquid-phase axial dispersion, the actual flow pattern in bubble columns is usually closer to being mixed flow rather than plug flow, but still not completely mixed flow. Therefore, the back flow cell model (BFCM), that hypothesises both back flow and exchange flow to characterise the liquid-phase axial dispersion, is presented as an alternative approach to describe the hydrodynamics and mass transfer of ozone bubble columns. BFCM is easy to formulate and solve. It is an accurate and reliable design model. Transient BFCM consists of NBFCM ordinary-first-order differential equations in which NBFCM unknowns (Yj) are to be determined. That set of equations was solved numerically as NBFCM linear algebraic equations. Steady-state BFCM consists of 3 × NBFCM non-linear algebraic equations in which 3 × NBFCM unknowns (qG,j, Xj, and Yj) are to be determined. Those non-linear algebraic equations were solved numerically using Newton–Raphson technique. Steady-state BFCM was initially tested using the pilot-scale experimental data of Zhou. BFCM provided excellent predictions of the dissolved ozone profiles under different operating conditions for both counter and co-current flow modes.

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Harris, A., S. Mannini, S. Thivet, M. O. Chevrel, L. Gurioli, N. Villeneuve, A. Di Muro, and A. Peltier. "How shear helps lava to flow." Geology 48, no. 2 (November 22, 2019): 154–58. http://dx.doi.org/10.1130/g47110.1.

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Abstract Understanding the thermo-rheological regime and physical character of lava while it is flowing is crucial if we are to adequately model lava flow emplacement dynamics. We present measurements from simultaneous sampling and thermal imaging across the full width of an active channel at Piton de la Fournaise (La Réunion, France). Our data set involves measurements of flow dynamics at three sites down-channel from the vent. Quantification of flow velocities, cooling rates, sample texture, and rheology allows all thermo-rheological parameters to be linked, and down- as well as cross-channel variations to be examined. Within 150 m from the vent, we recorded an unexpected velocity increase (from 0.07 to 0.1 m/s), in spite of cooling rates of 0.19–0.29 °C/m and constant slope. This change requires a switch from a Newtonian-dominated regime to a Bingham plug–dominated regime. Sample analysis revealed that the plug consists of foam-like lava, and the shear zones involve vesicle-poor (low-viscosity) lava. With distance from the vent, shear zones develop, carrying the vesicular plug between them. This causes flow to initially accelerate, helped by bubble shearing in narrow lateral shear zones, until cooling takes over as the main driver for viscosity increase and, hence, velocity decrease.

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