振荡流反应器注入分散特性的实验研究
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摘要
本论文建立了振荡流场混合器(OFM)实验装置，并对OFM内的注入分散过程进行了研究。实验采用了染料作为示踪剂的流动显形技术，利用摄像机拍连续拍摄整个注入分散过程，然后使用计算机图像处理技术获得注入分散特性的定量描述。
文中首次提出用流场图象的象素点灰度值的方差和来表征浓度场的非均匀度，用该方差和随时间衰减的变化规律来表征流场的注入分散特性。本文主要对振荡雷诺数(Re_o)和斯特劳准数(St)对振荡流场中注入分散特性的影响做了比较深入的研究，并对净流雷诺数(Re_o)的影响做了初步的探讨。
通过观察实验现象与分析实验数据，我们发现振荡特性参数Re_o和St对注入分散特性的影响显著，当St较小时，非均匀度(方差和)随时间呈指数性衰减，衰减速率随Re_o增大而增大：St较大时，分散效果不良，在大Re_o值下仍不能良好分散。在振荡强度不是很大的情况下，净流量的引入对腔室内整体涡流的影响较大，St较大时，这种变化尤其明显。当Re_o＞＞Re_n时，振荡流场的注入分散特性随Re_n变化很小。
实验研究证明：OFM能够实现高效注入分散过程并且容易控制注入分散过程的时间特性，可以适应不同反应过程对注入区浓度场的要求。
In this work an experimental setup of oscillatory flow mixer (OFM) was built up and the study on the injection dispersion in OFM was carried out.
In the experiment, the flow visualization technique was used with a solution of blue dye as the tracer, the injection dispersion process was monitored with a digital video camera, and the recorded image was treated with computer image processing technique to obtain the quantitative description of injection dispersion performance.
It is first time that the variance sum of gray scale values of pixels was used to characterize the inhomogeneous degree of concentration fields and that the attenuation rate was used to characterize the injection dispersion performance of flow field. The work focused on the influence of oscillatory Reynolds number(Re0) and Strouhal number(St) to the injection dispersion performance of OFM, and the effect of net flow Reynolds number(Ren) was explored preliminarily.
The observation of experimental phenomena and analysis of experimental data showed that the oscillatory parameters Re0 and St have a strong influence to the injection dispersion performance of OFM. At small St, the inhomogeneous degree(the variance sum) attenuates exponentially with time increasing, and the rate of attenuation increases with Re0. At large St, the dispersion is poor even at very large Re0. Ren takes effect only at large St and small Re0. As Re0籖en. the changes little with Ren.
The experimental study suggests that OFM should provide high-efficient injection dispersion performance and good controllability on the time character of dispersion process, and is able to satisfy the requirement of various reaction processes to the concentration distribution in the injection area.
文中首次提出用流场图象的象素点灰度值的方差和来表征浓度场的非均匀度，用该方差和随时间衰减的变化规律来表征流场的注入分散特性。本文主要对振荡雷诺数(Re_o)和斯特劳准数(St)对振荡流场中注入分散特性的影响做了比较深入的研究，并对净流雷诺数(Re_o)的影响做了初步的探讨。
通过观察实验现象与分析实验数据，我们发现振荡特性参数Re_o和St对注入分散特性的影响显著，当St较小时，非均匀度(方差和)随时间呈指数性衰减，衰减速率随Re_o增大而增大：St较大时，分散效果不良，在大Re_o值下仍不能良好分散。在振荡强度不是很大的情况下，净流量的引入对腔室内整体涡流的影响较大，St较大时，这种变化尤其明显。当Re_o＞＞Re_n时，振荡流场的注入分散特性随Re_n变化很小。
实验研究证明：OFM能够实现高效注入分散过程并且容易控制注入分散过程的时间特性，可以适应不同反应过程对注入区浓度场的要求。
In this work an experimental setup of oscillatory flow mixer (OFM) was built up and the study on the injection dispersion in OFM was carried out.
In the experiment, the flow visualization technique was used with a solution of blue dye as the tracer, the injection dispersion process was monitored with a digital video camera, and the recorded image was treated with computer image processing technique to obtain the quantitative description of injection dispersion performance.
It is first time that the variance sum of gray scale values of pixels was used to characterize the inhomogeneous degree of concentration fields and that the attenuation rate was used to characterize the injection dispersion performance of flow field. The work focused on the influence of oscillatory Reynolds number(Re0) and Strouhal number(St) to the injection dispersion performance of OFM, and the effect of net flow Reynolds number(Ren) was explored preliminarily.
The observation of experimental phenomena and analysis of experimental data showed that the oscillatory parameters Re0 and St have a strong influence to the injection dispersion performance of OFM. At small St, the inhomogeneous degree(the variance sum) attenuates exponentially with time increasing, and the rate of attenuation increases with Re0. At large St, the dispersion is poor even at very large Re0. Ren takes effect only at large St and small Re0. As Re0籖en. the changes little with Ren.
The experimental study suggests that OFM should provide high-efficient injection dispersion performance and good controllability on the time character of dispersion process, and is able to satisfy the requirement of various reaction processes to the concentration distribution in the injection area.
引文
1． T.Howes,M.Mackley and EPL.Roberts,The simulation of chaotic mixing and dispersion for periodic flows in baffled channels,Chem.Engdg.Sci,1991． 46,pp: 1669-1677．
2． MHI.Baird,G.Duncan,Jl.Smith and J.Taylor,Tansfer in pulsed turblurt flow.Shorter Communition,Chem.Engng.Sci,1966,2l,pp: 197-199．
3． M.R.Mackley and R.M.C.Neves Saraiva,The quantitave description of fluid mixing using Lagrangian and concentration based numerical approaches.Chem.Engdg.Sci,1997．
4． 陈甘棠,化学反应工程,化学工业出版社,1989．
5． M.R.Mackley,P.Stonesttreet,E.P,L,Roberts and x.Ni,Residensce time distribution enhancement in reactors using oscillatory flow.Institution os Chemical Engineers,1996,pp:541-545．
6． A.W.Dickens,M.R.Mackley,and H.R.Williums,Experimental residence time distribution measurements for unsteady flow in a baffled channel,Chem.Eng.Sci,1989,44,pp: 1471-1479．
7． T.Howes and M.R.Mackley,Experimental axial dispersion for oscillatory flow through a baffled tube ,Chem.Eng.Sci,1990,45,pp: 1349-1358．
8． M.E.Mackay,M.R.Mackley and Y.Wang ,Oscillatory flow within tubes containing wall or central baffles,Tans.IchemE,1991． 69． Part A,pp:506-513．
9． M.R.Mackley and X.Ni,Experimental fluid dispersion measurements in periodic baffled arrays,Chem.Eng.Sci,1993,48,pp: 171-178．
10． M.R.Mackley ,G.M.Tuedde and I.D.Wyart,Experimental heat transfer measurements for pulsatile flow in a baffled tube.Chem.Eng.Sci.1990,45,pp:1237-1242．
11． T.Nishinura,S.Arakawa,S.Murakami and Y.Kawamuya.Oscillatory viscous flow in symmetric wary walled chanels,Chem.Eng.Sci,1989． 44． pp:2137-2148．
12． M.R.Hewgill,M.R.Mackley,A.B.Pandit and S.S.Panna.Enhancement of gas-liquid mass transfer using oscillatory flow in a baffled tube.Chem.Eng.Sci.1993,48,pp:799-809．
13． J.Gregory,Stability and flocculation of suspensions.Processing of Solid-Liquid Suspensions,1993,pp:59-92．
14． C.D.Rielly,D.L.O.Smith,S.A.Lindley,K.Niranjan and V.P.Philips.Mixing processes for agricultural and food materials:par4,Assessment and amonitoring of mixing systems,J.Agis.Engng.Res,1994,59,pp:1-18
15． K.R.Hall and J.C.Godfrey,The mixing rates of highly viscous Newtonian and non-Newtonian fluids in a laboratory sigma-blade mixer.Trans.Inst.Chem.Eng.1968,46,pp:205-212．
16． M.K.Popovic and C.W.Robinson,Mixing characteristics of extermal-loop airlifts-non Newtonian systems,Chem.Eng.Sci,1993． 48． pp:1405-1413．
17． P.V.Panckwerts,The definition and measurement of some characteristics of
mixtures,Appl.Sci.Res.A3,1952,pp:279-296．
18． J.W.Hiby,Definition and measurement of the degree of mixing in liquid mixteres,Int.Chem.Engng,1981,21 ,pp: 197-204．
19． C.D.Pielly,P.L.O.Smith,J.A.Lindley,K.Niranjan and V.R.Philips.Mixing processes for agricultural and food material,Assessment and monitoring of mixing systerms.J.Agri.Engng.Res,1994,59,pp:435-441．
20． K.Ogama and S.Ito,A definition of quality of mixedmess.J.Chem.Eng.Jap.1975,8,pp:148-151．
21． D.W.Mohr,R.L.Saxton and C.H.Jepson,Mixing in laminar-flow systems.Ind.Rng,1957,49,pp: 1855-1856．
22． E.P.L.Roberts and M.R.Mackley ,The simulation of stretch rates for the quantitative prediction and mapping of mixing within a channel flow.Chem.Eng.Sci,1995,50,pp:3727-3746．
23． J.M.Ottino,W.E.Ranz and C.W.Macosko,A framework foe description of mechanical mixing of fluid,A.I.Ch.E.J,1981,27,pp:565-577．
24． D.V.Khakhar,H.Rising and J.M.Ottino,Analysis of chaotic mixing in two model systems,J.Fluid.Mech,1986,172,pp:419-451．
25． M.R.Mackley ,K.B.Smith and N.P.Wise,The mixing and seperation of particle suspensions using oscillatory flow in baffled tubes.Trans.Ichem.E,1993． 73． pp:649-656
26． A.W.Nienow.The suspension of solid particle in mixing in the Process Industries.Butterworth&Co.,1985,297-321．
27． J.F.Davidson and D.Harrison,Fluidisution,Academic.London and New York.1971．
28． C.R.Brunold,J.C.B.Hunns,M.R.Mackley and J.W.Thompson.Experimental observations on flow patterns and energy losses for oscillatory flow in ducts containing sharp edges,Chem.Eng.Sci,1989,44(5) .pp:1227-1244．
29． I.J.Sobey,Dispersion caused by seperation during oscillatory flow through a furrowed channel,Chem.Eng.Sci,1985,40,pp:2129-2134．
30． T.Howes ,M.R.Mackley and E.P.L.Roberts,The simulation of chaotic mixing and dispersion for periodic flows in baffled channeld.Chem.Eng.Sci.1991,46,pp:1669-1677．
31． S.L.Daniels,Flocculation,Unit Operation Handbook.V.2． 1993． pp:140-l 76．
32． D.F.Bagster,Flocculation,Aggregate behaviour in stirred vessels.Processing od Solid-Liquid Suspensions,1993,pp:26-58．
33． R.H.Smellie and La Mer,Flocculation subsidence and filtration of phosphate slimes.Part Ⅵ,A quantitative theory of filtration of flocculated suspensions.J Colloid Sci.,1958,23,pp:589-599．
34． V.K.La Mer and T.W.Healy,The role of filtration in investigating flocculation and redispersion of colloidal dispersions.J.Phys.Chem.,1963． 67． pp:2417-2420．
35． P.A.Shamlou and N.Titchener-Hooker.Turbulent aggregation and breakup of particles in liquids in stirred vessles.Processing of Solid-Liquid Suspensions.1993,pp:1-25．
36． C.W.Lee and R.S.Brodley,AICHE J,1987,33,pp:297-302．
37． J.Wu and M.R.Mackley,An experimental study of the continuous flocculation process of clay suspensions using an OFM.
38． M.R.Mackley,K.B.Smith and N.P.Wise,The mixing and seperation of particle suspensions using oscillatory flow in baffled tubes,Trans IchemE,1993,71 A,pp:649-656．
39． I.J.Sobey,Dispersion caused by separation during oscillatory flow through a furrowed channel,Chem.Eng.Sci.,1985,40,pp:2129-2134．
40． A.E.Karr,Performance of areciprocating plate extraction column,AICHEJ,1959,5,pp:446-452．
41． H.B.Winzler and G.Belfort,Enhanced performance for pressure driven membrance processes:the argument for fluid instabilities,J Membrance Sci.,1993,80,pp:35-47．
42． M.R.Mackley and N.E.Sherman,Cross-flow filtration with and without cake formation,Chem.Rng.Sci.,1994,49,pp:171-178．
43． H.R.Millward,B.J.Bellhouse,I.J.Sobey and R.W.H.Lewis,Enhancement of plasma filtration using the concept of the vortex wave,Jmembrance Sci.,1995,100,pp:121-129．
44． S.M.Finnigan and J.A.Howell,The effect of pulsatile flow on ultrafiltration fluxes in a baffled tubular membrane system,Chem Eng Res Des,1989． 67,pp:278-280．
2． MHI.Baird,G.Duncan,Jl.Smith and J.Taylor,Tansfer in pulsed turblurt flow.Shorter Communition,Chem.Engng.Sci,1966,2l,pp: 197-199．
3． M.R.Mackley and R.M.C.Neves Saraiva,The quantitave description of fluid mixing using Lagrangian and concentration based numerical approaches.Chem.Engdg.Sci,1997．
4． 陈甘棠,化学反应工程,化学工业出版社,1989．
5． M.R.Mackley,P.Stonesttreet,E.P,L,Roberts and x.Ni,Residensce time distribution enhancement in reactors using oscillatory flow.Institution os Chemical Engineers,1996,pp:541-545．
6． A.W.Dickens,M.R.Mackley,and H.R.Williums,Experimental residence time distribution measurements for unsteady flow in a baffled channel,Chem.Eng.Sci,1989,44,pp: 1471-1479．
7． T.Howes and M.R.Mackley,Experimental axial dispersion for oscillatory flow through a baffled tube ,Chem.Eng.Sci,1990,45,pp: 1349-1358．
8． M.E.Mackay,M.R.Mackley and Y.Wang ,Oscillatory flow within tubes containing wall or central baffles,Tans.IchemE,1991． 69． Part A,pp:506-513．
9． M.R.Mackley and X.Ni,Experimental fluid dispersion measurements in periodic baffled arrays,Chem.Eng.Sci,1993,48,pp: 171-178．
10． M.R.Mackley ,G.M.Tuedde and I.D.Wyart,Experimental heat transfer measurements for pulsatile flow in a baffled tube.Chem.Eng.Sci.1990,45,pp:1237-1242．
11． T.Nishinura,S.Arakawa,S.Murakami and Y.Kawamuya.Oscillatory viscous flow in symmetric wary walled chanels,Chem.Eng.Sci,1989． 44． pp:2137-2148．
12． M.R.Hewgill,M.R.Mackley,A.B.Pandit and S.S.Panna.Enhancement of gas-liquid mass transfer using oscillatory flow in a baffled tube.Chem.Eng.Sci.1993,48,pp:799-809．
13． J.Gregory,Stability and flocculation of suspensions.Processing of Solid-Liquid Suspensions,1993,pp:59-92．
14． C.D.Rielly,D.L.O.Smith,S.A.Lindley,K.Niranjan and V.P.Philips.Mixing processes for agricultural and food materials:par4,Assessment and amonitoring of mixing systems,J.Agis.Engng.Res,1994,59,pp:1-18
15． K.R.Hall and J.C.Godfrey,The mixing rates of highly viscous Newtonian and non-Newtonian fluids in a laboratory sigma-blade mixer.Trans.Inst.Chem.Eng.1968,46,pp:205-212．
16． M.K.Popovic and C.W.Robinson,Mixing characteristics of extermal-loop airlifts-non Newtonian systems,Chem.Eng.Sci,1993． 48． pp:1405-1413．
17． P.V.Panckwerts,The definition and measurement of some characteristics of
mixtures,Appl.Sci.Res.A3,1952,pp:279-296．
18． J.W.Hiby,Definition and measurement of the degree of mixing in liquid mixteres,Int.Chem.Engng,1981,21 ,pp: 197-204．
19． C.D.Pielly,P.L.O.Smith,J.A.Lindley,K.Niranjan and V.R.Philips.Mixing processes for agricultural and food material,Assessment and monitoring of mixing systerms.J.Agri.Engng.Res,1994,59,pp:435-441．
20． K.Ogama and S.Ito,A definition of quality of mixedmess.J.Chem.Eng.Jap.1975,8,pp:148-151．
21． D.W.Mohr,R.L.Saxton and C.H.Jepson,Mixing in laminar-flow systems.Ind.Rng,1957,49,pp: 1855-1856．
22． E.P.L.Roberts and M.R.Mackley ,The simulation of stretch rates for the quantitative prediction and mapping of mixing within a channel flow.Chem.Eng.Sci,1995,50,pp:3727-3746．
23． J.M.Ottino,W.E.Ranz and C.W.Macosko,A framework foe description of mechanical mixing of fluid,A.I.Ch.E.J,1981,27,pp:565-577．
24． D.V.Khakhar,H.Rising and J.M.Ottino,Analysis of chaotic mixing in two model systems,J.Fluid.Mech,1986,172,pp:419-451．
25． M.R.Mackley ,K.B.Smith and N.P.Wise,The mixing and seperation of particle suspensions using oscillatory flow in baffled tubes.Trans.Ichem.E,1993． 73． pp:649-656
26． A.W.Nienow.The suspension of solid particle in mixing in the Process Industries.Butterworth&Co.,1985,297-321．
27． J.F.Davidson and D.Harrison,Fluidisution,Academic.London and New York.1971．
28． C.R.Brunold,J.C.B.Hunns,M.R.Mackley and J.W.Thompson.Experimental observations on flow patterns and energy losses for oscillatory flow in ducts containing sharp edges,Chem.Eng.Sci,1989,44(5) .pp:1227-1244．
29． I.J.Sobey,Dispersion caused by seperation during oscillatory flow through a furrowed channel,Chem.Eng.Sci,1985,40,pp:2129-2134．
30． T.Howes ,M.R.Mackley and E.P.L.Roberts,The simulation of chaotic mixing and dispersion for periodic flows in baffled channeld.Chem.Eng.Sci.1991,46,pp:1669-1677．
31． S.L.Daniels,Flocculation,Unit Operation Handbook.V.2． 1993． pp:140-l 76．
32． D.F.Bagster,Flocculation,Aggregate behaviour in stirred vessels.Processing od Solid-Liquid Suspensions,1993,pp:26-58．
33． R.H.Smellie and La Mer,Flocculation subsidence and filtration of phosphate slimes.Part Ⅵ,A quantitative theory of filtration of flocculated suspensions.J Colloid Sci.,1958,23,pp:589-599．
34． V.K.La Mer and T.W.Healy,The role of filtration in investigating flocculation and redispersion of colloidal dispersions.J.Phys.Chem.,1963． 67． pp:2417-2420．
35． P.A.Shamlou and N.Titchener-Hooker.Turbulent aggregation and breakup of particles in liquids in stirred vessles.Processing of Solid-Liquid Suspensions.1993,pp:1-25．
36． C.W.Lee and R.S.Brodley,AICHE J,1987,33,pp:297-302．
37． J.Wu and M.R.Mackley,An experimental study of the continuous flocculation process of clay suspensions using an OFM.
38． M.R.Mackley,K.B.Smith and N.P.Wise,The mixing and seperation of particle suspensions using oscillatory flow in baffled tubes,Trans IchemE,1993,71 A,pp:649-656．
39． I.J.Sobey,Dispersion caused by separation during oscillatory flow through a furrowed channel,Chem.Eng.Sci.,1985,40,pp:2129-2134．
40． A.E.Karr,Performance of areciprocating plate extraction column,AICHEJ,1959,5,pp:446-452．
41． H.B.Winzler and G.Belfort,Enhanced performance for pressure driven membrance processes:the argument for fluid instabilities,J Membrance Sci.,1993,80,pp:35-47．
42． M.R.Mackley and N.E.Sherman,Cross-flow filtration with and without cake formation,Chem.Rng.Sci.,1994,49,pp:171-178．
43． H.R.Millward,B.J.Bellhouse,I.J.Sobey and R.W.H.Lewis,Enhancement of plasma filtration using the concept of the vortex wave,Jmembrance Sci.,1995,100,pp:121-129．
44． S.M.Finnigan and J.A.Howell,The effect of pulsatile flow on ultrafiltration fluxes in a baffled tubular membrane system,Chem Eng Res Des,1989． 67,pp:278-280．