The Chemical Engineering Journal and the Biochemical Engineering Journal最新文献_第5页

Deterministic chaos analysis of pressure fluctuations in a horizontal pipe at intermittent flow regime 断流状态下水平管道压力波动的确定性混沌分析

The Chemical Engineering Journal and the Biochemical Engineering Journal Pub Date : 1996-10-01 DOI: 10.1016/S0923-0467(96)03128-4

J. Drahoš , J. Tihon , C. Serio , A. Lübbert

引用次数: 29

Catalyst design accounting for the fractal surface morphology 催化剂设计占分形表面形态

The Chemical Engineering Journal and the Biochemical Engineering Journal Pub Date : 1996-10-01 DOI: 10.1016/S0923-0467(96)03105-3

Marc-Olivier Coppens, Gilbert F. Froment

{"title":"Catalyst design accounting for the fractal surface morphology","authors":"Marc-Olivier Coppens, Gilbert F. Froment","doi":"10.1016/S0923-0467(96)03105-3","DOIUrl":"10.1016/S0923-0467(96)03105-3","url":null,"abstract":"<div>Fractal geometry can be used in the development of porous catalysts with higher conversions and selectivities for desirable products. The fractal surface morphology, which can be tuned by changing the preparation conditions, has an influence on the Knudsen diffusivities and on the intrinsic reaction rates per unit catalyst mass. Depending on the catalyst and the operating conditions, the effective reaction rate of a first-order reaction can either increase or decrease with the fractal dimension of the surface. The simulation of an industrial unit for the catalytic reforming of naphtha is used as an example of how the design of the fractal catalyst surface can influence iso-paraffins, aromatics and hydrogen yields. The hydrogen yields exhibit a maximum of around 3.6 wt.% for an intermediate fractal surface dimension, Dsads = 2.6. The highest isoparaffins yield is obtained for a smooth surface (23 wt.%), while surfaces with a high Dxads lead to the highest aromatics yields (up to 76 wt.% for Dsads = 3).</div>","PeriodicalId":101226,"journal":{"name":"The Chemical Engineering Journal and the Biochemical Engineering Journal","volume":"64 1","pages":"Pages 69-76"},"PeriodicalIF":0.0,"publicationDate":"1996-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0923-0467(96)03105-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75056167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 8

Correlating dimension for a gas-liquid contactor 气液接触器的相关尺寸

The Chemical Engineering Journal and the Biochemical Engineering Journal Pub Date : 1996-10-01 DOI: 10.1016/S0923-0467(96)03127-2

J.M. Hay, C. Hudson, C.L. Briens

引用次数: 3

Effect of chaotic interfacial stretching on bimolecular chemical reaction in helical-coil reactors 螺旋盘管反应器中混沌界面拉伸对双分子化学反应的影响

The Chemical Engineering Journal and the Biochemical Engineering Journal Pub Date : 1996-10-01 DOI: 10.1016/S0923-0467(96)03132-6

David R. Sawyers , Mihir Sen , Hsueh-Chia Chang

{"title":"Effect of chaotic interfacial stretching on bimolecular chemical reaction in helical-coil reactors","authors":"David R. Sawyers , Mihir Sen , Hsueh-Chia Chang","doi":"10.1016/S0923-0467(96)03132-6","DOIUrl":"10.1016/S0923-0467(96)03132-6","url":null,"abstract":"<div>We investigate the yield of bimolecular chemical reaction between two initially separated reactants in a tubular reactor of different coiling geometries. Laminar and steady flow with high mass Peclet number, Pe, are assumed. Asymptotic approximations for slow reactions are obtained by studying the reaction at a thin interfacial boundary layer. For a straight tube it is found that the area-averaged product mass fraction at a given axial position z goes z<math><mtext>3</mtext><mtext>2</mtext></math> Λ(z) Pe−<math><mtext>1</mtext><mtext>2</mtext></math>, where Λ(z) is the length of the interface separating the two reactants. Coiling and flow kinematics have a strong effect on Λ(z). Regular mixing produced by secondary transverse flow in a helical coil stretches the interface linearly with z, yielding a z<math><mtext>5</mtext><mtext>2</mtext></math> dependence for hte product mass fraction. Further enhancement derived from chaotic mixing and stretching is possible in a coil with a coiling axis that is periodically changed in the flow direction. If the switching length exceeds a critical value, the folding and stretching of the chaotic action leads to an exponentially growing length that can be related to a positive Lyapunov exponent. Numerical solutions show that this enhancement by chaotic mixing also exists for fast reactions, and that the stretching effect can be overwhelmed by tight and uneven interfacial separation in a long, high-yield reactor when the reaction boundary layers begin to overlap or interact with the wall.</div>","PeriodicalId":101226,"journal":{"name":"The Chemical Engineering Journal and the Biochemical Engineering Journal","volume":"64 1","pages":"Pages 129-139"},"PeriodicalIF":0.0,"publicationDate":"1996-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0923-0467(96)03132-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87594072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 22

Author index of volume 64, no. 1 第64卷作者索引。1

The Chemical Engineering Journal and the Biochemical Engineering Journal Pub Date : 1996-10-01 DOI: 10.1016/S0923-0467(96)85008-1

引用次数: 0

Rheological modeling of fractal and dense suspensions 分形和致密悬浮液的流变建模

The Chemical Engineering Journal and the Biochemical Engineering Journal Pub Date : 1996-10-01 DOI: 10.1016/S0923-0467(96)03107-7

Romano Lapasin, Mario Grassi, Sabrina Pricl

{"title":"Rheological modeling of fractal and dense suspensions","authors":"Romano Lapasin, Mario Grassi, Sabrina Pricl","doi":"10.1016/S0923-0467(96)03107-7","DOIUrl":"10.1016/S0923-0467(96)03107-7","url":null,"abstract":"<div>The development of a rheological model for aggregated suspensions is necessarily based upon a suitable characterization of the structure of the disperse phase and of the structural modifications produced by a deformation or a velocity field. The disperse phases of real aggregate particle suspensions, both dilute and concentrated, may present a wide variety of structures, which can be conveniently characterized by using the concepts of fractal geometry. In the present paper we formulate a rheological model able to correlate the structural processes induced by shear sflow conditions and the consequent shear dependence of viscosity with the shear stress changes experienced by the suspension. The flow curves calculated from the model, both for dense and fractal aggregates, closely resemble those observed for real colloidal and non-colloidal suspensions. The model appears particularly advantageous in describing the transition from shear thinning to plastic behavior, which usually occurs with increasing volume fraction or aggregation of the disperse phase. The role played by the aggregation state of the disperse phase become predominant in the low shear stress range, where aggregates may be composed of many particles, and, consequently, where the fractal dimensionality D becomes an important parameter in determining the compactness of the aggregate structure and the rheological behavior of concentrated suspensions. The validity of the proposed model is checked further through an analysis of experimental viscosity data relative to two series of epoxy-acrylic systems, containing titanium dioxide and aluminum silicate at different disperse phase concentrations.</div>","PeriodicalId":101226,"journal":{"name":"The Chemical Engineering Journal and the Biochemical Engineering Journal","volume":"64 1","pages":"Pages 99-106"},"PeriodicalIF":0.0,"publicationDate":"1996-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0923-0467(96)03107-7","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90247561","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 12

Rapid characterization of flow regimes in multiphase reactors through box-counting dimensions with an embedding dimension of two 用嵌入维数为2的盒计数维快速表征多相反应器的流动状态

The Chemical Engineering Journal and the Biochemical Engineering Journal Pub Date : 1996-10-01 DOI: 10.1016/S0923-0467(96)03129-6

C.L. Briens, C. Hudson, L.A. Briens

{"title":"Rapid characterization of flow regimes in multiphase reactors through box-counting dimensions with an embedding dimension of two","authors":"C.L. Briens, C. Hudson, L.A. Briens","doi":"10.1016/S0923-0467(96)03129-6","DOIUrl":"10.1016/S0923-0467(96)03129-6","url":null,"abstract":"<div>The performance of multiphase reactors is greatly affected by their flow regime. The box-counting dimension of a probe signal characterizes its intrinsic, dimensionless structure and is not significantly affected by moderate changes in probe calibration constants. Using the box-counting dimension to characterize the flow regime can, thus, eliminate problems associated with changes in probe, liquid or solid characteristics. This study uses an approximate box-counting dimension which is so rapidly calculated that it could be used for on-line control. The box-counting dimension of the raw signal from a bubble probe allows the accurate detection of gas maldistribution in bubble columns and gas-liquid-solid fluidized beds. The box-counting dimension of the raw signal from a local conductivity probe allows the accurate detection of liquid maldistribution in bubble columns and gas-liquid-solid fluidized beds. The fluidization regime of liquid-solid and gas-liquid-solid beds can be accurately identified from the box-counting dimension of the signal recorded with either local probes or cross-sectional probes. The complete fluidization of a liquid-solid bed of splinter-like particles can be determined from the box-counting dimension of the signals from either a local probe or trace rinjection experiments.</div>","PeriodicalId":101226,"journal":{"name":"The Chemical Engineering Journal and the Biochemical Engineering Journal","volume":"64 1","pages":"Pages 169-178"},"PeriodicalIF":0.0,"publicationDate":"1996-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0923-0467(96)03129-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91400023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Application partially scaled fractals in the analysis of natural objects 部分缩放分形在自然物体分析中的应用

The Chemical Engineering Journal and the Biochemical Engineering Journal Pub Date : 1996-10-01 DOI: 10.1016/S0923-0467(96)03102-8

M. Punčochář, J. Drahoš, J. Slezák

引用次数: 0

Multifractal characterization of flow in circulating fluidized beds 循环流化床流动的多重分形表征

The Chemical Engineering Journal and the Biochemical Engineering Journal Pub Date : 1996-10-01 DOI: 10.1016/S0923-0467(96)03131-4

Huang Zhong, Bhavik R. Bakshi, Peijun Jiang, Liang-Shih Fan

引用次数: 3

Control of a chaotic polymerization reaction using linear and nonlinear controllers 用线性和非线性控制器控制一个混沌聚合反应

The Chemical Engineering Journal and the Biochemical Engineering Journal Pub Date : 1996-10-01 DOI: 10.1016/S0923-0467(96)03096-5

H. Qammar, K.R. Seshadhri, R. Gomatam, A. Venkatesan

{"title":"Control of a chaotic polymerization reaction using linear and nonlinear controllers","authors":"H. Qammar, K.R. Seshadhri, R. Gomatam, A. Venkatesan","doi":"10.1016/S0923-0467(96)03096-5","DOIUrl":"10.1016/S0923-0467(96)03096-5","url":null,"abstract":"<div>Chaos has been found in a number of nonlinear chemical processes including electrochemical reactions, fluidized beds, pulsed combustors, and polymerization reactions. While the control of chaos has recently a received a great deal of attention, the performance of traditional control schemes is poorly understood. Rather than implement a specific chaos control scheme, such as the well-known OGY method, we examine the feedback control of a chaotic polymerization reaction to a steady state using conventional linear and nonlinear control techniques. We show that it is possible to control a chaotic reaction system using a simple proportional controller, a discrete controller, a nonlinear model predictive controller which includes process-model mismatch. The performance of each control scheme is evaluated from the basin of successful control. While model predictive control yields a the most extensive basin and thus the best performance, in all cases the basin has a fractal structure for some values of the control parameter. The implications of a fractal basin to the robustness of the controller and the likelihood of successful control are discussed.</div>","PeriodicalId":101226,"journal":{"name":"The Chemical Engineering Journal and the Biochemical Engineering Journal","volume":"64 1","pages":"Pages 141-148"},"PeriodicalIF":0.0,"publicationDate":"1996-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0923-0467(96)03096-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78382749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5