Nauki Techniczne

Chemical and Process Engineering

Zawartość

Chemical and Process Engineering | 2019 | vol. 40 | No 1

Abstrakt

The quantitative description of an airlift bioreactor, in which aerobic biodegradation limited by carbonaceous substrate and oxygen dissolved in a liquid takes place, is presented. This process is described by the double-substrate kinetics. Mathematical models based on the assumption of plug flow and dispersion flow of liquid through the riser and the downcomer in the reactor were proposed. Calculations were performed for two representative hydrodynamic regimes of reactor operation, i.e. with the presence of gas bubbles only within the riser and for complete gas circulation. The analysis aimed at how the choice of a mathematical model of the process would enable detecting the theoretical occurrence of oxygen deficiency in the airlift reactor. It was demonstrated that the simplification of numerical calculations by assuming the “plug flow” model instead of dispersion with high Péclet numbers posed a risk of improper evaluation of the presence of oxygen deficiency zones. Conclusions related to apparatusmodelling and process design were drawn on the basis of the results obtained. The paper is a continuation of an earlier publication (Grzywacz, 2012a) where an analysis of single-substrate models of the airlift reactor was presented.

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Autorzy i Afiliacje

Robert Grzywacz

Abstrakt

The paper focuses on the modelling of bromate formation. An axial dispersion model was proposed to integrate the non-ideal mixing, mass-transfer and a kinetic model that links ozone decomposition reactions fromthe Tomiyasu, Fukutomi and Gordon (TFG) ozone decaymodelwith direct and indirect bromide oxidation reactions, oxidation of natural organicmatter and its reactionswith aqueous bromine. To elucidate the role of ammonia an additional set of reactions leading to bromamine formation, oxidation and disproportionation was incorporated in the kinetic model. Sensitivity analysis was conducted to obtain information on reliability of the reaction rate constants used and to simplify the model.

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Autorzy i Afiliacje

Urszula Olsińska

Abstrakt

Validation results of a theoretical model that describes the formation of bromate during ozonation of bromide-containing natural waters are presented. An axial dispersion model integrating the nonideal mixing, mass-transfer and a kinetic model that links ozone decomposition reactions from the Tomiyasu, Fukutomi and Gordon ozone decay model with direct and indirect bromide oxidation reactions, oxidation of natural organicmatter and reactions of dissolved organics and aqueous bromine was verified. Themodel was successfully validated with results obtained both at a laboratory and a full scale. Its applicability to different water supply systems was approved.

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Autorzy i Afiliacje

Urszula Olsińska

Abstrakt

The flow structure around rising single air bubbles in water and their characteristics, such as equivalent diameter, rising velocity and shape, was investigated using Particle Image Velocimetry (PIV) and Shadowgraphy in a transparent apparatus with a volume of 120 mL. The effect of different volumetric gas flow rates, ranging from 4 μL/min to 2 mL/min on the liquid velocity was studied. Ellipsoidal bubbleswere observedwith a rising velocity of 0.25–0.29m/s. It was found that a Kármán vortex street existed behind the rising bubbles. Furthermore, the wake region expanded with increasing volumetric gas flow rate as well as the number and size of the vortices.

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Autorzy i Afiliacje

Björn Lewandowski
Michał Fertig
Georg Krekel
Mathias Ulbricht

Abstrakt

The paper presents the experimental study of a novel unsteady-statemembrane gas separation approach for recovery of a slow-permeant component in the membrane module with periodical retentate withdrawals. The case study consisted in the separation of binary test mixtures based on the fast-permeant main component (N2O, C2H2) and the slow-permeant impurity (1%vol. of N2) using a radial countercurrent membrane module. The novel semi-batch withdrawal technique was shown to intensify the separation process and provide up to 40% increase in separation efficiency compared to a steady-state operation of the same productivity.

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Autorzy i Afiliacje

Stanislav V. Battalov
Maxim M. Trubyanov
Egor S. Puzanov
Tatyana S. Sazanova
Pavel N. Drozdov
Ilya V. Vorotyntsev

Abstrakt

The research was focused on the selection of the best conditions for the lactic acid production. As the organic source diluted waste whey was used. Two facultative anaerobic bacteria strains were examined: Lactobacillus rhamnosus and Lactococcus lactis. The neeed of anaerobic conditions as well as mineral supplementation of cultivationwere investigated. It turned out that the oxidationwas not the key parameter, but cultivationmediumneeded a supplementation for higher process efficiency. Finally, Lactobacillus rhamnosus strain was selected, for which LA production was app. 45% higher than for Lc. lactis. On the other hand, Lactobacillus rhamnosus was active at higher lactose concentration, thus waste whey needed to be less diluted. Additionally, high values of product/substrate yield coefficient make the process very efficient.

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Autorzy i Afiliacje

Magdalena Lech
Anna Trusek

Abstrakt

The paper presents modeling and simulation results of the operation of a three-phase fluidized bed bioreactorwith partial recirculation of biomass. The proposed quantitative description of the bioreactor takes into account biomass growth on inert carriers, microorganisms decay and interphase biomass transfer. Stationary characteristics of the bioreactor and local stability of steady-stateswere determined. The influence of microbiological growth kinetics on the multiplicity of steady-states was discussed. The relationship between biofilm growth and boundaries of fluidized bed existence was shown.

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Autorzy i Afiliacje

Szymon Skoneczny
Bolesław Tabiś

Abstrakt

CFD modelling of momentum and heat transfer using the Large Eddy Simulation (LES) approach has been presented for a Kenics static mixer. The simulations were performed with the commercial code ANSYS Fluent 15 for turbulent flow of three values of Reynolds number, Re = 5 000, 10 000 and 18 000. The numerical modelling began in the RANS model, where standard k−ε turbulence model and wall functions were used. Then the LES iterations started from the initial velocity and temperature fields obtained in RANS. In LES, the Smagorinsky–Lilly model was used for the sub-grid scale fluctuations along with wall functions for prediction of flow and heat transfer in the near-wall region. The performed numerical study in a Kenics static mixer resulted in highly fluctuating fields of both velocity and temperature. Simulation results were presented and analysed in the form of velocity and temperature contours. In addition, the surface-averaged heat transfer coefficient values for the whole insert length were computed and compared with the literature experimental data. Good compliance of the LES simulation results with the experimental correlation was obtained.

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Autorzy i Afiliacje

Halina Murasiewicz
Barbara Zakrzewska

Abstrakt

Helical coil heat exchangers are widely used in a variety of industry applications such as refrigeration systems, process plants and heat recovery. In this study, the effect of Reynolds number and the operating temperature on heat transfer coefficients and pressure drop for laminar flow conditions was investigated. Experiments were carried out in a shell and tube heat exchanger with a copper coiled pipe (4 mm ID, length of 1.7 m and coil pitch of 7.5 mm) in the temperature range from 243 to 273 K. Air – propan-2-ol vapor mixture and coolant (methylsilicone oil) flowed inside and around the coil, respectively. The fluid flow in the shell-side was kept constant, while in the coil it was varied from 6.6 to 26.6 m/s (the Reynolds number below the critical value of 7600). Results showed that the helical pipe provided higher heat transfer performance than a straight pipe with the same dimensions. The convective coefficients were determined using theWilson method. The values for the coiled pipe were in the range of 3–40 W/m2 ·K. They increased with increasing the gas flow rate and decreasing the coolant temperature.

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Autorzy i Afiliacje

Krzysztof Kowalski
Dorota Downarowicz

Abstrakt

Biocomposite foam scaffolds of poly(ε-caprolactone) (PCL) with different porogenes were produced with batch foaming technique using supercritical carbon dioxide (scCO2) as a blowing agent. In performed experiments composites were prepared from graphene-oxide (nGO), nano-hydroxyapatite (nHA) and nano-cellulose (nC), with various concentrations. The objective of the study was to explore the effects of porogen concentration and foaming process parameters on the morphology and mechanical properties of three-dimensional porous structures that can be used as temporary scaffolds in tissue engineering. The structures were manufactured using scCO2 as a blowing agent, at two various foaming pressures (9 MPa and 18 MPa), at three different temperatures (323 K, 343 K and 373 K) for different saturation times (0.5 h, 1 h and 4 h). In order to examine the utility of porogenes, a number of tests, such as static compression tests, thermal analysis and scanning electron microscopy, have been performed. Analysis of experimental results showed that the investigated materials demonstrated high mechanical strength and a wide range of pore sizes. The obtained results suggest that PCL porous structures are useful as biodegradable and biocompatible scaffolds for tissue engineering.

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Autorzy i Afiliacje

Katarzyna Sawicka
Katarzyna Kosowska
Marek Henczka

Abstrakt

Knowledge of the temperature distribution in subsurface layers of the ground is important in the design, modelling and exploitation of ground heat exchangers. In this work a mathematical model of heat transfer in the ground is presented. The model is based on the solution of the equation of transient heat transfer in a semi-infinite medium. In the boundary condition on the surface of the ground radiation fluxes (short- and long-wave), convective heat flux and evaporative heat flux are taken into account. Based on the developed model, calculations were carried out to determine the impact of climatic conditions and the physical properties of the ground on the parameters of the Carslaw-Jeager equation. Example results of calculated yearly courses of the daily average temperature of the surface of the ground and the amount of particular heat fluxes on the ground surface are presented. The compatibility of ground temperature measurements at different depths with the results obtained from the Carslaw–Jaeger equation is evaluated. It was found that the temperature distribution in the ground and its variability in time can be calculated with good accuracy.

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Autorzy i Afiliacje

Barbara Larwa
Krzysztof Kupiec

Instrukcja dla autorów

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 have to comply with the main topics of the journal, i.e. discuss at least one of the four main areas, namely:
• New Advanced (Nano) Materials
• Environment & Water Processing (including circular economy)
• Biochemical & Biomedical Engineering (including pharmaceuticals)
• Climate & Energy (including energy conversion & storage, electrification, decarbonization)

Chemical and Process Engineering publishes: i) experimental and theoretical research papers, ii) short communications, iii) critical reviews, and iv) perspective articles. Each publication form is peer-reviewed by at least two independent referees.

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Manuscripts are submitted for publication via Editorial System. When writing a manuscript, you may choose to submit it as a single Word file to be used in the refereeing process. The manuscript needs to be written in a clear way. The minimum requirements are:
• Please use clear fonts, at least 12 points large, with at least 1.5-line spacing.
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• Use Simple Past to talk about your experiment and your results as they were finished before you wrote the paper. Use Simple Past to describe what you did.
Example: Two samples were taken. Temperature increased to 200K at the end of the process.
• Use Simple Present to refer to figures and tables.
Example: Table 2 shows nitrogen concentration changes in the process.
• Use Simple Present to talk about your conclusions. You move here from describing your results to stating what is generally true.
Example: The process is caused by changes of nitrogen concentration.
• Capitalise words like ‘Table 2’, ‘Equation 11’.
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e. Tables should be made according to the format shown in the template.
f. All figures and tables should be numbered and provided with an appropriate caption and legend, if necessary. They have to be properly referenced to and commented in the text of the manuscript.

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6. Acknowledgements may be included before the list of literature references

7. 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 in alphabetical order of surnames of the first author. It is obligatory to indicate the DOI number of those literature items, whose numbers have already been assigned. Journal titles should be specified by typing their right abbreviations or, when in doubts, according to the Science and Engineering Journal Abbreviations.

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.



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