Applied sciences

Chemical and Process Engineering

Content

Chemical and Process Engineering | 2014 | No 1 March |

Abstract

This study is concerned with liquid flow induced by a disk which rotates steadily around its axis and touches the free surface of liquid contained in a cylindrical vessel. It is a simplified model of the flow in the inlet part of a vertical cooling crystallizer where a rotary distributor of inflowing solution is situated above the free surface of solution contained in the crystalliser. Numerical simulations of flow phenomena were conducted and the simulation results were interpreted assuming an analogy with Kármán’s theoretical equations. In a cylindrical coordinate system, the components of flow velocity were identified as functions of distance from the surface of the rotating disk. The experimental setup was developed to measure velocity fields, using digital particle velocimetry and optical flow. Conclusions concerning the influence of disc rotation on liquid velocity fields were presented and the experimental results were found to confirm the results of numerical simulation. On the basis of simulation data, an approximation function was determined to describe the relationship between the circumferential component of flow velocity and the distance from the disk.

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Abstract

An optical tomograph in which a tested object is illuminated from five directions has been presented in the paper. The measurements of luminous intensity after changing into discrete signals (0 or 1) in the detectors equipped with 64 optical sensors were subjected to reconstruction by means of the matrix algorithm. Detailed description of the measuring sensor, as well as the principles of operation of the electronic system, has been given in the paper. Optical phenomena occurring at the phase boundary while transmitted through the sensor wall and phenomena inside the measuring space have also been taken into account. The method of the sensor calibration has been analysed and a way of technical solution of the problem under consideration has been discussed. The elaborated method has been tested using objects of the known shape and dimensions. It was found that reconstruction of the shapes of moving bubbles and determination of their main parameters is also possible with a reasonable accuracy.

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Abstract

Gas-liquid microreactors find an increasing range of applications both in production, and for chemical analysis. The most often employed flow regime in these microreactors is Taylor flow. The rate of absorption of gases in liquids depends on gas-side and liquid-side resistances. There are several publications about liquid-side mass transfer coefficients in Taylor flow, but the data about gas-side mass transfer coefficients are practically non existent. We analysed the problem of gas-side mass transfer resistance in Taylor flow and determined conditions, in which it may influence the overall mass transfer rate. Investigations were performed using numerical simulations. The influence of the gas diffusivity, gas viscosity, channel diameter, bubble length and gas bubble velocity has been determined. It was found that in some case the mass transfer resistances in both phases are comparable and the gas-side resistance may be significant. In such cases, neglecting the gas-side coefficient may lead to errors in the experimental data interpretation.

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Abstract

This paper extends knowledge about flow in an agitated batch with pitched blade multi-stage impellers. Effects of various geometrical parameters (blade number, distance between impellers) of pitched blade multi-stage impellers on pumping ability have been investigated. Axial velocity profiles were measured by LDA (Laser Doppler Anemometry). Axial pumping capacities were obtained by integration of measured axial velocity profiles in outflow from impellers. Main attention was focused on the effect of the distance between impellers in multi-stage configurations, on their pumping capacity and flow in the mixing bath in comparison with an independently operating pitched blade impeller with the same geometry. In case of a relatively close distance between impellers H3/d = 0.5 - 0.75, the multi-stage impeller creates only one circulation loop and the impellers itself behave identically as pumps in series. However for relative higher distance of impellers than H3/d = 1.25, the multi-stage impeller creates two separated circulation loops.

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Abstract

The main topic of this study is the experimental measurement and mathematical modelling of global gas hold-up and bubble size distribution in an aerated stirred vessel using the population balance method. The air-water system consisted of a mixing tank of diameter T = 0.29 m, which was equipped with a six-bladed Rushton turbine. Calculations were performed with CFD software CFX 14.5. Turbulent quantities were predicted using the standard k-ε turbulence model. Coalescence and breakup of bubbles were modelled using the homogeneous MUSIG method with 24 bubble size groups. To achieve a better prediction of the turbulent quantities, simulations were performed with much finer meshes than those that have been adopted so far for bubble size distribution modelling. Several different drag coefficient correlations were implemented in the solver, and their influence on the results was studied. Turbulent drag correction to reduce the bubble slip velocity proved to be essential to achieve agreement of the simulated gas distribution with experiments. To model the disintegration of bubbles, the widely adopted breakup model by Luo & Svendsen was used. However, its applicability was questioned.

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Abstract

The majority of publications and monographs present investigations which concern exclusively twophase flows and particulary dispersed flows. However, in the chemical and petrochemical industries as well as in refineries or bioengineering, besides the apparatuses of two-phase flows there is an extremely broad region of three-phase systems, where the third phase constitutes the catalyst in form of solid particles (Duduković et al., 2002; Martinez et al., 1999) in either fixed bed or slurry reactors. Therefore, the goal of this study is to develop macroscopic, averaged balances of mass, momentum and energy for systems with three-phase flow. Local instantaneous conservation equations are derived, which constitute the basis of the method applied, and are averaged by means of Euler’s volumetric averaging procedure. In order to obtain the final balance equations which define the averaged variables of the system, the weighted averaging connected with Reynolds decomposition is used. The derived conservation equations of the trickle-bed reactor (mass, momentum and energy balance) and especially the interphase effects appearing in these equations are discussed in detail.

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Abstract

The aim of the research presented in this paper was determination of power consumption and gas hold-up in mechanically agitated aerated aqueous low concentration sucrose solutions. Experimental studies were conducted in a vessel of diameter 0.634 m equipped with high-speed impellers (Rushton turbine, Smith turbine or A 315). The following operating parameters were changed: volumetric gas flow rate (expressed by superficial gas velocity), impeller speed, sucrose concentration and type of impeller. Based on the experiments results, impellers with a modified shape of blades, e.g. CD 6 or A 315, could be recommended for such gas-liquid systems. Power consumption was measured using strain gauge method. The results of gas holdup measurements have been approximated by an empirical relationship containing dimensionless numbers (Eq. (2)).

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Abstract

This paper is devoted to application of adsorption process for cooling power generation in a cooling devices. Construction and working principle of a water-silica gel adsorption chiller has been presented and the basic refrigeration cycle has been discussed. The article outlines behavior of a single-stage adsorption system influenced by changes in cycle time. The effect of cycle time and inlet chilled water temperatures on the main system performance parameters has been analysed

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Abstract

The paper presents the summary of research on polymer melt particle motion trajectories in a disc zone of a screw-disk extruder. We analysed two models of its structure, different in levels of taken simplifications. The analysis includes computer simulations of material particle flow and results of experimental tests to determine the properties of the resultant extrudate. Analysis of the results shows that the motion of melt in the disk zone of a screw-disk extruder is a superposition of pressure and dragged streams. The observed trajectories of polymer particles and relations of mechanical properties and elongation of the molecular chain proved the presence of a stretching effect on polymer molecular chains.

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Abstract

The velocity field around the standard Rushton turbine was investigated by the Laser Doppler Anemometry (LDA) and Particle Image Velocimetry (PIV) measurements. The mean ensembleaveraged velocity profiles and root mean square values of fluctuations were evaluated at two different regions. The first one was in the discharge stream in the radial direction from the impeller where the radial flow is dominant and it is commonly modelled as a swirling turbulent jet. The validity range of the turbulent jet model was studied. The second evaluated region is under the impeller where flow seems to be at first sight rather rigorous but obtained results show nonnegligible values of fluctuation velocity.

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Abstract

The modelling of colloidal fouling and defouling of hollow fibre membranes in the presence of membrane oscillations is analysed by means of numerical simulations as an effect of complex coupling between hydrodynamic and surface forces. To describe the latter the Derjaguin-Landau- Vervey-Overbeek (DLVO) model has been employed. We have investigated the influence of various parameters of the process like flow rate, mean particle diameter, amplitude and frequency of the oscillations, and others, on the efficiency of the defouling process. The investigated parameters is close to that of a silica suspension in , a typical system modelling used to investigate membrane separation. On the basis of numerical simulation results e have defined an optimal set of parameters preventing membrane fouling.

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Editorial office

Editor-in-Chief
Andrzej K. Biń, Warsaw University of Technology, Poland

Editorial Board
Andrzej Burghardt (Chairman), Polish Academy of Sciences, Gliwice, Poland
Jerzy Bałdyga, Warsaw University of Technology, Poland
Andrzej Górak, T.U. Dortmund, Germany
Leon Gradoń, Warsaw University of Technology, Poland
Andrzej Jarzębski, Silesian University of Technology, Poland
Zdzisław Jaworski, West Pomeranian University of Technology, Szczecin, Poland
Władysław Kamiński, Technical University of Łódź, Poland
Stefan Kowalski, Poznań University of Technology, Poland
Andrzej Krasławski, Lappeenranta University of Technology, Finland
Stanisław Ledakowicz, Technical University of Łódź, Poland
Eugeniusz Molga, Warsaw University of Technology, Poland
Alvin W. Nienow, University of Birmingham, United Kingdom
Andrzej Noworyta, Wrocław University of Technology, Poland
Ryszard Pohorecki, Warsaw University of Technology, Poland
Andrzej Stankiewicz, Delft University of Technology, The Netherlands
Czesław Strumiłło, Technical University of Łódź, Poland
Stanisław Sieniutycz, Warsaw University of Technology, Poland
Krzysztof Warmuziński, Polish Academy of Sciences, Gliwice, Poland
Laurence R. Weatherley, University of Kansas, Lawrence, United States
Günter Wozny, T.U. Berlin, Germany
Ireneusz Zbiciński, Technical University of Łódź, Poland

Technical Editor
Barbara Zakrzewska, West Pomeranian University of Technology, Szczecin, Poland
Language Editor
Marek Stelmaszczyk, West Pomeranian University of Technology, Szczecin, Poland

 

Contact

Editorial Office
ul. Waryńskiego 1
00-645 Warszawa
Poland
email: andrzej.bin@outlook.com

 

Instructions for authors

All manuscripts submitted for publication in Chemical and Process Engineering must comprise a description of original research that has neither been published nor submitted for publication elsewhere.

The content, aim and scope of the proposals should comply with the main subject of the journal, i.e. they should deal with mathematical modelling and/or experimental investigations on momentum, heat and mass transfer, unit processes and operations, integrated processes, biochemical engineering, statics and kinetics of chemical reactions. The experiments and modelling may cover different scales and processes ranging from the molecular phenomena up to production systems. The journal language is grammatically correct British English.

Chemical and Process Engineering publishes: i) full text research articles, ii) invited reviews, iii) letters to the editor and iv) short communications, aiming at important new results and/or applications. Each of the publication form is peer-reviewed by at least two independent referees.  

Submission of materials for publication

The manuscripts are submitted for publication via Internet site www.chpe.pl and its subfolder Authors Pathway or e-mail address andrzej.bin@outlook.com. When writing the manuscript, authors should preferably use the template for articles, which is available on the www.chpe.pl page in section Instructions for Authors.   

Proposals of a paper should be uploaded using the Internet site of the journal and should contain:

  • a manuscript file in Word format (*.doc, *.docx),
  • the manuscript mirror in PDF format,
  • all graphical figuresin separate graphics files.

In the following paragraphthe general guidelines for the manuscript preparation are presented.

Manuscript outline

        1. Header details
          1. Title of paper
          2. Names (first name and further initials) and surnames of authors
          3. Institution(s) (affiliation)
          4. Address(es) of authors
          5. Information about the corresponding author; academic title, name and surname, email address, address for correspondence
        2. Abstract – should contain a short summary of the proposed paper. In the maximum of 200 words the authors should present the main assumptions, results and conclusions drawn from the presented study.
        3. Keywords– Up to 5 characteristic keyword items should be provided.
        4. Text
          1. Introduction. In this part, description of motivation for the study and formulation of the scientific problem should be included and supported by a concise review of recent literature.
          2. Main text. It should contain all important elements of the scientific investigations, such as presentation of experimental rigs, mathematical models, results and their discussion. This part may be divided into subchapters.
          3. Conclusions. The major conclusions can be put forward in concise style in a separate chapter. Presentation of conclusions from the reported research work accompanied by a short commentary is also acceptable.
          4. Figures: drawings, diagrams and photographs can be in colour and should be located in appropriate places in the manuscript text according to the template provided on the www.chpe.pl page. Their graphical form should be of vector or raster type with the minimum resolution of 900 dpi. In addition, separate files containing each of the drawings, graphs and photos should be uploaded onto the journal Web site in one of the following formats: bmp, gif, tiff, jpg, eps. Due to rigid editorial reasons, graphical elements created within MS Word and Excel are not acceptable. The final length of figures should be intended typically for 8 cm (single column) or 16 cm in special cases of rich-detail figures. The basic font size of letters in figures should be at least 10 pts after adjusting graphs to the final length.  

          Figures: drawings, diagrams and photographs should be in gray scale. In case of coloured graphs or photo an additional payment of 300 PLN (72 €) per 1 page containing coloured figures on both sides, or 150 PLN (36 €) per page containing coloured figures on one side will be required.

          Tables should be made according to the format shown in the template.

        5. All figures and tables should be numbered and provided with appropriate title and legend, if necessary. They have to be properly referenced to and commented in the text of the manuscript.

        6. List of symbols should be accompanied by their units
        7. Acknowledgements may be included before the list of literature references
        8. Literature citations

 

The method of quoting literature source in the manuscript depends on the number of its authors:

  • single author – their surname and year of publication should be given, e.g. Marquardt (1996) or (Marquardt, 1996),
  • two authors – the two surnames separated by the conjunction “and” with the publication year should be given, e.g. Charpentier and McKenna (2004) or (Charpentier and McKenna, 2004),
  • three and more authors – the surname of the first author followed by the abbreviation “et al.” and year of publication should be given, e.g. Bird et al. (1960) or (Bird et al., 1960).

In the case of citing more sources in one bracket, they should be listed in alphabetical order using semicolon for separation, e.g. (Bird et al., 1960; Charpentier and McKenna, 2004; Marquardt, 1996). Should more citations of the same author(s) and year appear in the manuscript then letters “a, b, c, ...” should be successively applied after the publication year.

Bibliographic data of the quoted literature should be arranged at the end of the manuscript text in alphabetic order of surnames of the first author. It is obligatory to indicate the DOI number of those literature items, which have the numbers already assigned. Journal titles should be specified by typingtheir right abbreviationsor, in case of doubts, according to the List of Title Word Abbreviations available at http://www.issn.org/2-22661-LTWA-online.php.

Examples of citation for:

Articles
Charpentier J. C., McKenna T. F., 2004.Managing complex systems: some trends for the future of chemical and process engineering. Chem. Eng. Sci., 59, 1617-1640. DOI: 10.1016/j.ces.2004.01.044.

Information from books (we suggest adding the page numbers where the quoted information can be found)
Bird R. B., Stewart W.E., Lightfood E.N., 2002. Transport Phenomena. 2nd edition, Wiley, New York, 415-421.

Chapters in books
Hanjalić K., Jakirlić S., 2002. Second-moment turbulence closure modelling, In: Launder B.E., Sandham N.D. (Eds.), Closure strategies for turbulent and transitional flows. Cambridge University Press, Cambridge, 47-101.

Conferences
ten Cate A., Bermingham S.K., Derksen J.J., Kramer H.M.J., 2000. Compartmental modeling of an 1100L DTB crystallizer based on Large Eddy flow simulation. 10th European Conference on Mixing. Delft, the Netherlands, 2-5 July 2000, 255-264.

8. Payments

Starting from 2014 a principle of publishing articles against payment is introduced, assuming non-profit making editorial office. According to the principle authors or institutions employing them, will have to cover the expenses amounting to 40 PLN (or 10 €) per printed page. The above amount will be used to supplement the limited financial means received from the Polish Academy of Sciences for the editorial and publishing; and in particular to increase the capacity of the next CPE volumes and to proofread the linguistic correctness of the articles. The method of payment will be indicated in an invoice sent to the authors or institutions after acceptance of their manuscripts to be published. In justifiable cases presented in writing, the editorial staff may decide to relieve authors from basic payment, either partially or fully. All correspondence should be sent to Editor-in-Chief, Prof. Andrzej K. Biń, email address: andrzej.bin@outlook.com.


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