Applied sciences

Chemical and Process Engineering

Content

Chemical and Process Engineering | 2014 | No 3 September |

Abstract

The paper presents investigation results of the migration of a chemical compound contained in fly ash deposited on a dry furnace waste landfill site exposed to weather conditions. Climate conditions are able to significantly affect chemical component distribution in a block of deposited, moving chemical compounds to different depths. The main aim of the investigations was to determine the chemical component distribution of deposited fly ash in the landfill. Identification of chemical components based on XRF analysis indicated the existence of differences in both tested storage layer and the fraction of fly ash.

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Abstract

Periodic adsorption in a perfect mixing tank of a limited volume was considered. It was assumed that the adsorption rate is limited by diffusion resistance in a pellet. The approximate model of diffusion kinetics based on a continued fraction approximation was compared with the exact analytical solution. For the approximate model an algorithm was developed to determine a temporal variation of the adsorbate concentration in the pellet. The comparison was made for different values of the adsorbent load factor. In the numerical tests different shapes of pellets were considered. Both the numerical tests as well as our own experimental results showed that the approximate model provides results that are in good agreement with the exact solution. In the experimental part of this work adsorption of p-nitrophenol and acetic acid from aqueous solutions on cylindrical pellets of activated carbon was conducted.

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Abstract

The aim of this work was to achieve a deeper understanding of the heat transfer in a microtubular Solid Oxide Fuel Cell (mSOFC) stack based on the results obtained by means of a Computational Fluid Dynamics tool. Stack performance predictions were based on simulations for a 16 anodesupported mSOFCs sub-stack, which was a component of the overall stack containing 64 fuel cells. The emphasis of the paper was put on steady-state modelling, which enabled identification of heat transfer between the fuel cells and air flow cooling the stack and estimation of the influence of stack heat losses. Analysis of processes for different heat losses and the impact of the mSOFC reaction heat flux profile on the temperature distribution in the mSOFC stack were carried out. Both radiative and convective heat transfer were taken into account in the analysis. Two different levels of the inlet air velocity and three different values of the heat losses were considered. Good agreement of the CFD model results with experimental data allowed to predict the operation trends, which will be a reliable tool for optimisation of the working setup and ensure sufficient cooling of the mSOFC stack.

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Abstract

Widely used CFD codes enable modelling of PC boilers operation. One of the areas where these numerical simulations are especially promising is predicting deposition on heat transfer surfaces, mostly superheaters. The basic goal of all simulations is to determine trajectories of ash particles in the vicinity of superheater tubes. It results in finding where on the surface the tube will be hit by particles, and what diameter and mass flow of the particles are. This paper presents results of CFD simulations for a single tube and a bundle of in-line tubes as well. It has been shown that available parameters like ash particle density, shape factor, reflection coefficients affect the trajectories in a different way. All the simulations were carried out with Fluent code of Ansys software.

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Abstract

The article is focused onthe energetical balance of a technical system for the conversion of crushed tyres by pyrolysis. Process temperatures were set in the range from 500 to 650°C. Mass input of the material was 30 kg per hour. The aim of the article is to answer the following questions as regards the individual products: Under which process conditions can the highest quality of the individual products related to energy be reached? How does the thermal efficiency of the system change in reaction to various conditions of the process?

On the basis of the experimental measurements and calculations, apart from other things, it was discovered that the pyrolysis liquid reaches the highest energetic value, i.e. 42.7 MJ.kg-1, out of all the individual products of the pyrolysis process. Generated pyrolysis gas disposes of the highest lower calorific value 37.1 MJ.kg-1 and the pyrolysis coke disposes of the maximum 30.9 MJ kg-1. From the energetic balance, the thermal efficiency of the experimental unit under the stated operational modes ranging from about 52 % to 56 % has been estimated. Individual findings are elaborated on detail in the article.

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Abstract

The main topic of this study is the mathematical modelling of bubble size distributions in an aerated stirred tank using the population balance method. The air-water system consisted of a fully baffled vessel with a diameter of 0.29 m, which was equipped with a six-bladed Rushton turbine. The secondary phase was introduced through a ring sparger situated under the impeller. Calculations were performed with the CFD software CFX 14.5. The turbulent quantities were predicted using the standard k-ε turbulence model. Coalescence and breakup of bubbles were modelled using the MUSIG method with 24 bubble size groups. For the bubble size distribution modelling, the breakup model by Luo and Svendsen (1996) typically has been used in the past. However, this breakup model was thoroughly reviewed and its practical applicability was questioned. Therefore, three different breakup models by Martínez-Bazán et al. (1999a, b), Lehr et al. (2002) and Alopaeus et al. (2002) were implemented in the CFD solver and applied to the system. The resulting Sauter mean diameters and local bubble size distributions were compared with experimental data.

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Abstract

The paper presents the dynamic characteristics of a continuous tank bioreactor for microbiological process, with a developed predator-prey food chain. The presence of the predator microorganism considerably influences the position and stability character of steady-states. There appears to exist a wide range of unstable steady-states and high-amplitude oscillations of state variables. Without automatic control, the system can operate only in unsteady conditions. From technological point of view, this circumstance is unfavorable. It was shown that oscillations can be removed by employing automatic control with continuous P or PI controllers. Moreover, the use of a controller with integrating element causes removal of the predator from the bioreactor. The paper discusses an application of this phenomenon for practical purposes.

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Abstract

Any complete CFD model of pulverised coal-fired boiler needs to consider ash deposition phenomena. Wall boundary conditions (temperature and emissivity) should be temporally corrected to account for the effects of deposit growth on the combustion conditions. At present voluminous publications concerning ash related problems are available. The current paper presents development of an engineering tool integrating deposit formation models with the CFD code. It was then applied to two tangentially-fired boilers. The developed numerical tool was validated by comparing it with boiler evaporator power variation based on the on-line diagnostic system with the results from the full CFD simulation.

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Abstract

The numerical investigation of the mixing process in complex geometry micromixers, as a function of various inlet conditions and various micromixer vibrations, was performed. The examined devices were two-dimensional (2D) and three-dimensional (3D) types of serpentine micromixers with two inlets. Entering fluids were perturbed with a wide range of the frequency (0 - 50 Hz) of pulsations. Additionally, mixing fluids also entered in the same or opposite phase of pulsations. The performed numerical calculations were 3D to capture the proximity of all the walls, which has a substantial influence on microchannel flow. The geometry of the 3D type serpentine micromixer corresponded to the physically existing device, characterised by excellent mixing properties but also a challenging production process (Malecha et al., 2009). It was shown that low-frequency perturbations could improve the average mixing efficiency of the 2D micromixer by only about 2% and additionally led to a disadvantageously non-uniform mixture quality in time. It was also shown that high-frequency mixing could level these fluctuations and more significantly improve the mixing quality. In the second part of the paper a faster and simplified method of evaluation of mixing quality was introduced. This method was based on calculating the length of the contact interface between mixing fluids. It was used to evaluate the 2D type serpentine micromixer performance under various types of vibrations and under a wide range of vibration frequencies.

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Abstract

To stabilise the periodic operation of a chemical reactor the oscillation period should be determined precisely in real time. The method discussed in the paper is based on adaptive sampling of the state variable with the use of chaotic mapping to itself. It enables precise determination of the oscillation period in real time and could be used for a proper control system, that can successfully control the process of chemical reaction and maintain the oscillation period at a set level. The method was applied to a tank reactor and tubular reactor with recycle.

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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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