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1

Determination of the Specific Heat Flux During Boiling of the Dispersed Phase of the Emulsion

Pavlenkо Anatoliy, Koshlak Hanna, Basok Borys, Hrabova Tatiana

Rocznik Ochrona Środowiska

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2023

|

Tom 25

16--24

EN

The intensity of heat exchange between the boiling emulsion and the enclosing surfaces is associated with the physical phenomena of the formation, growth, and destruction of vapour bubbles of the low-boiling component in the liquid phase. This article presents a methodology to assess the intensity of heat exchange processes. Using this technique, it is possible to predict the energy parameters of heat exchange equipment and the degree of intensification of heat transfer processes.

2

Verification of Dead Zones Generated in Bioreactors as a Proactive Stage in Bioreactor Design

Al-Mashhadani Mahmood K. H.

Journal of Ecological Engineering

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2023

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Vol. 24, nr 6

65--74

EN

The activity and growth of microorganisms for renewable energy production are still influenced by the dead zones created in bioreactors. These areas form a nutrient and thermal gradient, causing an abundance of food in certain areas compared to famines in other areas of same bioreactor. The current study is a step in identifying those dead zones, followed by another step in improving the flow of media inside the reactor. The results indicated that the inner parts of the bioreactor may be a crucial factor in the creation and spread of such dead zones. For example, the position of the disc-type diffuser contributes to the generation of those areas at the bottom of the reactor. It was inferred from the fluid movement in reactors using the annular-type diffuser proposed in the current study. The bubble size, gas mass flux, and radiuses of fillet, as the most important factors, were examined in both bioreactors. The results revealed a noticeable improvement in these parameters in this area of the reactor when the disc diffuser was replaced by the annular diffuser. For example, the average liquid velocity was recorded in the lower part of the modernized reactor at 0.0198 m/s, while the velocity was recorded in the conventional reactor at 0.00077 m/s under same bubbles diameter used in both reactors (0.125 mm). The inclusion of the effect of the presence of microorganisms in mathematical models was also addressed in the current study. The results showed that the amount of oxygen remaining at the bottom of the reactor after bio-consumption in the presence of the annular diffuser was higher than that in the conventional reactor. This clearly emphasizes the importance of the design of the internal parts of the bioreactor.

3

Impacts of chemical reactions on inclined isothermal vertical plate

Sundar Raj M., Nagarajan G., Murugan V. P., Muthucumaraswamy R.

International Journal of Applied Mechanics and Engineering

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2023

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Vol. 28, no. 2

64--76

EN

An accurate parameterization of an irregular surge across a continuously propelled circulation through an endless isothermal inclined plate has been investigated in the presence of a first-degree uniform chemical reaction. Both the plate’s temperature and the proximal intensity are increased systematically. To evaluate non-dimensional equations, the Laplace transform is utilized. The effect of velocity components on a range of physical parameters is investigated which include Sc, Pr, Gr, Gc, α, K and t. A proportionate increase of velocity with Gr and Gc was prominent. τ and Sh were mathematically determined.

4

Analysis of heat and mass transfer in an adsorption bed using CFD methods

Janusz Szymon, Szudarek Maciej, Rudniak Leszek, Borcuch Marcin

Archives of Thermodynamics

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2023

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Vol. 44, no 2

177--194

EN

The trend of reducing electricity consumption and environmental protection has contributed to the development of refrigeration technologies based on the thermal effect of adsorption. This article proposes a methodology for conducting numerical simulations of the adsorption and desorption processes. Experimental data available in the literature were used as guidelines for building and verifying the model, and the calculations were carried out using commercial computational fluid dynamics software. The simulation results determined the amount of water vapor absorbed by the adsorbent bed and the heat generated during the adsorption process. Throughout the adsorption process, the inlet water vapor velocity, temperature, and pressure in the adsorbent bed were monitored and recorded. The results obtained were consistent with the theory in the literature and will serve as the basis for further, independent experimental studies. The validated model allowed for the analysis of the effect of cooling water temperature on the sorption capacity of the material and the effect of heating water temperature on bed regeneration. The proposed approach can be useful in analyzing adsorption processes in refrigeration applications and designing heat and mass exchangers used in adsorption systems.

5

Thermal and physical properties and heat-mass transfer processes of drying pumpkin seeds

Paziuk Vadim, Snezhkin Yurii, Dmytrenko Natalia, Ivanov Sergiu, Tokarchuk Oleksiy, Kupchuk Ihor

Przegląd Elektrotechniczny

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2022

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R. 98, nr 7

154--157

EN

We have investigated pumpkin seed heat capacity influenced by the two factors of the heat agent temperature and the moisture content of the material. The difference between the heat of evaporation when drying pumpkin seeds in a differentiated microcalorimeter DMKI 01 from the tabular value is 6%. Increasing the temperature of the heat agent from 40 to 60°C reduces the drying process by 8 times, but the most appropriate is the drying mode at 40°C, under which the germination of pumpkin seeds is 98%. The study of heat and mass transfer during drying shows that active heat up process takes place at the beginning, then there is an intensive moisture evaporation from the material as evidenced by the value of the Rehbinder test, which is close to zero.

PL

Badano pojemność cieplną pestek dyni, na którą wpływają dwa czynniki: temperatura czynnika grzewczego oraz wilgotność materiału. Różnica pomiędzy ciepłem parowania podczas suszenia pestek dyni w zróżnicowanym mikrokalorymetrze DMKI 01 od wartości tabelarycznej wynosi 6%. Podwyższenie temperatury czynnika grzewczego z 40 do 60°C skraca proces suszenia 8-krotnie, ale najbardziej odpowiedni jest tryb suszenia w 40°C, w którym kiełkowanie pestek dyni wynosi 98%. Z badań wymiany ciepła i masy podczas suszenia wynika, że na początku zachodzi proces aktywne(go nagrzewania, następnie następuje intensywne odparowywanie wilgoci z materiału, o czym świadczy bliska zeru wartość testu Rehbindera.

6

Mathematical analysis of mass and heat transfer through arterial stenosis

Hussain Azad, Sarwar Luba, Akbar Sobia, Malik M. Y.

Journal of Power Technologies

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2022

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Vol. 102, nr 3

88--95

EN

The article investigates the steady state flow of an incompressible fluid which is treated as a Williamson fluid through a stenoised region in the shape of cosine constriction. Blood is taken as a Williamson fluid. Mathematical formulation leads us to nonlinear compatibility and energy equations, which are then deciphered by the shooting technique to obtain the numerical solution. Suitable resemblance transformations are used to change partial differential equations into an embellished form of ordinary differential equations. Further, the consequences of the different parameters involved are shown by graphs and a conclusion is presented. Velocity and temperature fields are canvassed graphically for the distinct values of emerging parameters and discussed in tabular form. Skin friction and the coefficient of heat transfer are also covered in the discussion. The resulting Nusselt number curve exhibits negative deflection for variational values of λ and height of the stenosis δ.

7

Thermo-diffusion MHD convection in enclosure using heat and mass lines visualization techniques

Kushawaha Durgesh, Yadav Sushil, Singh Dwesh K., Behera Pravata Kumar

Journal of Applied Mathematics and Computational Mechanics

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2022

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Vol. 21, nr 2

63--76

EN

The numerical study of two-dimensional laminar thermo-diffusion natural convection in an exponentially heated and concentrated square enclosure of unit length in the presence of a uniform horizontal magnetic field is presented in this paper. The left and right vertical walls are assumed to have higher and lower temperatures and concentrations, respectively, and are governed by exponential functions, whereas the horizontal walls are assumed to be adiabatic and non-diffusive. The mathematical formulation of heat and mass functions has been completed, and heat and mass line contours have been drawn based on these functions to investigate the behavior of heat and mass in the cavity. The flow governing equations were solved using a finite difference method in conjunction with the Successive Over-Relaxation (SOR) technique and then converted to a vorticity-stream function form. A detailed comparison of isotherms with heatlines and isosolutes with masslines has been performed. Furthermore, the reduction for lower Rayleigh numbers Ra surpassing the reduction for higher values of Ra. The maximum reduction in overall heat and mass transfer has been observed for higher Hartmann (Ha = 8).

8

Heat and mass transfer in a vertical channel flow through a porous medium in the presence of radiation

Guria M.

International Journal of Applied Mechanics and Engineering

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2022

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Vol. 27, no. 3

63--78

EN

An analysis is made of heat and mass transfer in a three dimensional flow between two vertical porous plates through a porous medium. Analytical solutions have been obtained using the perturbation technique. The effect of non-dimensional parameters on velocity, temperature and concentration field are shown graphically. It is seen that the main flow velocity decreases with an increase in both the radiation parameter and Schmidt number but increases with an increase in the thermal Grashoff number, mass Grashoff number as well as the permeability parameter. Variations of the shear stress at the left plate are given in a tabular form. It is seen that the shear stress due to the primary flow at the left plate increases with an increase in the Reynolds number but decrease with an increase in the Schmidt number. With the increase of both the radiation parameter and Reynolds number the temperature decreases. The concentration field also decreases with an increase of the Schmidt number. Variations of mass flux at the left plate are given in tabular form. It is seen that the mass flux at the left plate increases with increase in both Schmidt number or Reynolds number.

9

Application of chromatographic plate theory on the weathered crust elution-deposited rare earth ore with carboxylate

Zhang Zhenyue, Wang Guangshuai, Li Chunhua, Chi Ruan, Long Fei, Chen Zhuo, Chi Xiao Wang, Liu Defeng

Physicochemical Problems of Mineral Processing

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2021

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Vol. 57, iss. 4

48--62

EN

To improve the leaching process of rare earth and reduce the impurities in the leachate, the carboxylate ammonium, such as ammonium acetate, ammonium citrate and ammonium tartrate, were selected as lixiviant to compare the effects of concentration, flow rate, pH and temperature on leaching mass process of rare earth and aluminum. Meanwhile, the leaching behaviors of rare earth and aluminum leached by three kinds of carboxylate ammonium were analyzed by chromatographic plate theory. The relationship between the flow rate and height equivalent (HETP) could fit well with the Van Deemter equation and there was an optimal flow rate (uopt) for the leaching of the rare earth and aluminum. Besides, the conditions of carboxylate ammonium lixiviant were optimized. The optimum concentrations of ammonium acetate, ammonium tartrate and ammonium citrate were 15 g/L, 25 g/L and 5 g/L respectively, the leaching flow rate was 0.50 mL/min, the pH value was approximatively 7.00 and the leaching temperature was 293 K to 303 K. At these conditions, the mass transfer efficiencies of three ammonium carboxylates for rare earth and aluminum was in the order of ammonium acetate > ammonium tartrate > ammonium citrate. Moreover, the ammonium acetate could commendably inhibit aluminum ions entering the lixivium.

10

Review on the numerical investigations of mass transfer from drug eluting stent

Song Jianfei, Kouidri Smaine, Bakir Farid

Biocybernetics and Biomedical Engineering

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2021

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Vol. 41, no. 3

1057--1070

EN

Drug-eluting stent (DES) as the newly developed treatment for the cardiovascular disease has been the preferred treatment option for most of the patients with significant reduction of restenosis incidents. However, the follow-up complications such as late thrombosis after stent implantation limit the further widespread use of DES which has caused extensive attention from the researchers. Numerical method has been widely employed to predict the DES performance in human body during the past decades, contributing to the stent design optimization and a better understanding of drug release mechanisms in a cost-effective way compared to the experiments. Among the existing numerical investigations, different modelling methods of DES inside artery can be found to study the drug transport process, and adopting the proper models physically and mathematically plays a key role to obtain the results well fitting with the practical case. Therefore, in this review article, the existing numerical researches regarding DES mainly in the last two decades have been focused and summarized including the established modeling methods and the controlling parameters investigations related to drug release from DES. In addition, the common results obtained have been discussed collectively aiming to guide the following researches.

11

Preparation of a solid product with high water content and water retention properties

Cvijić Marko, Golob Janvit

Polish Journal of Chemical Technology

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2020

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Vol. 22, nr 3

17--23

EN

This work presents the development of a solid product with a high water content (99.08%) and water retention properties. Water was chosen as a potential carrier of a volatile active substance and water retaining properties of material were studied at a temperatures and relative air humidity values with the support of the theory of drying. The study first confirmed the role of Gibbs’ phase rule in the research of solid-gas phase equilibrium, and second presented drying kinetics developed from Fick’s second law and expressed with the first term of the Fourier equation. Solutions of equations for phase equilibrium and mass transfer enabled the calculation of Luikov’s parameters, which are important for equilibrium relations and for the diffusivity of water in a solid for mass transfer prediction. The obtained thermodynamic and kinetic parameters enabled product characterisation that may be important for the prediction of retention times.

12

Influence of chemical reaction on the heat and mass transfer of nanofluid flow over a nonlinear stretching sheet: a numerical study

Misra Santoshi, Govardhan K.

International Journal of Applied Mechanics and Engineering

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2020

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Vol. 25, no. 2

103--121

EN

A numerical study on a steady, laminar, boundary layer flow of a nanofluid with the influence of chemical reaction resulting in the heat and mass transfer variation is made. The non-linear governing equations with related boundary conditions are solved using Adam’s predictor corrector method with the effect of a Brownian motion and thermophoresis being incorporated as a model for the nanofluid, using similarity transformations. Validation of the current numerical results has been made in comparison to the existing results in the absence of chemical reaction on MHD flows. The numerical solutions obtained for the velocity, temperature and concentration profiles for the choice of various parameters are represented graphically. Variations of heat and mass transfer across a Brownian motion and thermophoresis are studied and analyzed.

13

Mass transfer analysis of two-phase flow in a suspension of microorganisms

Mamatha S.U., Ramesh Babu, K., Durga Prasad Putta, Raju C.S.K., Varma S.V.K.

Archives of Thermodynamics

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2020

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Vol. 41, no 1

175--192

EN

The aim of present work is to investigate the mass transfer of steady incompressible hydromagnetic fluid near the stagnation point with deferment of dust particles over a stretching surface. Most researchers tried to improve the mass transfer by inclusion of cross-diffusion or dust particles due to their vast applications in industrial processes, extrusion process, chemical processing, manufacturing of various types of liquid drinks and in various engineering treatments. To encourage the mass transport phenomena in this study we incorporated dust with microorganisms. Conservation of mass, momentum, concentration and density of microorganisms are used in relevant flow equations. The arising system of nonlinear partial differential equations is transformed into nonlinear ordinary differential equations. The numerical solutions are obtained by the Runge-Kutta based shooting technique and the local Sherwood number is computed for various values of the physical governing parameters (Lewis number, Peclet number, Eckert number). An important finding of present work is that larger values of these parameters encourage the mass transfer rate, and the motile organisms density profiles are augmented with the larger values of fluid particle interaction parameter with reference to bioconvection, bioconvection Lewis number, and dust particle concentration parameter..

14

Investigation of the mechanism of moisture absorption in colloidal museum materials in order to improve the safety of exhibits and improve the hygiene of museum rooms

Dovhaliuk Volodymyr, Ujma Adam, Chovniuk Yurii

System Safety : Human - Technical Facility - Environment

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2019

|

Vol. 1, nr 1

805--809

EN

Moisture sorption is one of the most important destruction factors for colloidal capillary-porous exhibits in museums (painting, clothing etc.), which is dependent on microclimate in museum rooms. The analysis of moisture sorption properties, kinetics of sorption and swelling of textile museum exhibits is carried out. Isotherms of desorption of viscose and woollen yarns and fabrics of different density (and threads of them) are identical. The analysis of the isotherms of fabrics of various fibre cloths and threads of them shows that they all are similar in shape to the curves and have the form typical for leading capillary-porous bodies. The hysteresis loop for almost all tissues is observed throughout the range of relative humidity of the medium. In this work, the characteristics of the hysteresis loop (area, limited by it, length of the loop), which are of informational significance in the description of the processes of isothermal sorption-desorption of the materials mentioned above, are indicated. The research results allow optimizing of microclimate control in museum rooms for elimination of destruction of exhibits, improve the safety of storage and ensure the hygiene of the air indoor environmental.

15

Algorytm obliczania współczynników dyfuzji Maxwella i Stefana w wieloskładnikowych mieszaninach gazów gęstych

Tabiś B.

Przemysł Chemiczny

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2018

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T. 97, nr 1

132--135

PL

Przedstawiono metodę obliczania współczynników dyfuzji Maxwella i Stefana w wieloskładnikowych mieszaninach gazowych pod wysokimi ciśnieniami, zwanych gazami gęstymi. W takich warunkach współczynniki aktywności ciśnieniowej składników są różne od jedności. Do określenia objętości molowej gazów przyjęto równanie stanu Penga i Robinsona. Binarne współczynniki dyfuzji Maxwella i Stefana w roztworach nieskończenie rozcieńczonych wyznaczono na podstawie uogólnionej metody empirycznej. Zaproponowano algorytm obliczeń, który może być zastosowany do tworzenia kodów programowych. Przedstawiono reprezentatywne wyniki obliczeń otrzymane na podstawie tego algorytmu.

EN

Maxwell-Stefan diffusion coeff. were detd. in multicomponent gaseous mixts. under elevated pressure (dense gases). Under such conditions, fugacity coeff. of the components differed from unity. To det. the molar vol. of gases, the Peng-Robinson equation of state was used. Binary Maxwell-Stefan diffusion coeff. in infinite diln. were detd. by an unified empirical method. An efficient algorithm for numerical computations was also developed to prepare numerical codes.

16

Mass transfer process of leaching weathered crust elution-deposited rare earth ore with magnesium salts

Chen Z., Zhang Z., He Z., Chi R.

Physicochemical Problems of Mineral Processing

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2018

|

Vol. 54, iss. 3

1004--1013

EN

In order to optimize the leaching process of weathered crust elution-deposited rare earth ore with magnesium salts, the influence of different flow rate, concentration of magnesium ions, initial pH of magnesium salts solution and experimental temperature on the mass transfer process of rare earth and aluminum was investigated in the case of using magnesium salts as leaching agent. The relationship between the flow rate μ and the HETP (Height Equivalent of Theoretical Plate) is in accordance with the Van Deemter equation when magnesium salts were used as leaching agent. The optimum condition for rare earth and aluminum were 0.4 cm3/min of flow rate and 0.2 mol/dm3 of magnesium ion concentration of magnesium sulfate, magnesium chloride and magnesium nitrate respectively. Under this condition the mass transfer efficiency of rare earth and aluminum with three kinds of magnesium salts follow the order of Mg(NO3)2>Mg(Cl)2>MgSO4. High temperature contributes to improving the mass transfer efficiency of rare earth and aluminum. Magnesium nitrate as the leaching agent can get the highest leaching mass transfer efficiency of rare earth and magnesium sulfate as the leaching agent can make the impurity leaching and mass transfer efficiency of Al is the lowest.

17

Wymiana masy w układach rozproszonych do zastosowań biomedycznych

Metera A., Markowska-Radomska A., Dłuska E.

Inżynieria i Aparatura Chemiczna

|

2018

|

Nr 3

71--72

PL

Badano uwalnianie doksorubicyny przy pH 7,4 (środowisko komórek zdrowych) oraz 6,3 (środowisko komórek nowotworowych) zemulsji o różnych rozmiarach kropel. W fazie zewnętrznej emulsji wykorzystano biopolimer, którego lepkość zmienia się w zależności od pH środowiska, co pozwoliło na selektywne uwalnianie chemoterapeutyku. Uzyskano szybsze uwalnianie składnika w warunkach kwaśnego pH oraz z emulsji o mniejszych rozmiarach kropel.

EN

The release of doxorubicin at pH 7.4 (normal cells) and 6.3 (tumor cells) from emulsions with different drop sizes was tested. In the emulsion external phase a biopolymer of viscosity depending on the environmental pH was used allowing for the selective release of chemotherapeutics. A faster release of the component was obtained under acidic pH and from emulsions with smaller drop sizes.

18

Mieszanie gaz-ciecz w mieszalniku z asymetrycznym mieszadłem BT-6

Frankiewicz S., Woziwodzki S.

Inżynieria i Aparatura Chemiczna

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2018

|

Nr 3

59--60

PL

Przedstawiono badania mieszania układu ciecz-gaz w mieszalniku zaopatrzonym w zmodyfikowane mieszadło BT-6. Analizowano zapotrzebowanie mocy mieszania, stopień zatrzymania gazu oraz objętościowy współczynnik wnikania masy. Dla układów gaz-ciecz przebieg zmian względnej mocy mieszania był porównywalny z mieszadłem BT-6, jednakże spadek mocy mieszania był większy. W pracy zaproponowano również równania korelacyjne opisujące zmiany stopnia zatrzymania gazu oraz objętościowego współczynnika wnikania masy.

EN

The paper presents study results of gas-liquid mixing in a standard vessel equipped with the asymmetric BT-6 impeller. The power requirements, gas hold-up and volumetric mass transfer coefficient were examined. The results indicate that the relative power demand as a function of gas flow number is similar to the BT-6 impeller, although the power drop is greater. The new equations for gas holdup and volumetric mass transfer coefficient were proposed.

19

Badanie deformacji kropel z wymianą masy w prostym przepływie ścinającym

Jasińska M., Mańkowski M.

Inżynieria i Aparatura Chemiczna

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2018

|

Nr 5

131--132

PL

Przedstawiono symulacje numeryczne deformacji kropli w prostym przepływie ścinającym. Obliczenia wykonano dla liczb kapilarnych mniejszych od wartości krytycznych gwarantujących deformację kropli bez jej rozpadu. W pracy badano zachowanie się kropli w przypadku obecności ścianek ograniczających układ, a wyniki symulacji porównano z wynikami doświadczalnymi opublikowanymi w literaturze. Wykonane symulacje pozwoliły również na określenie współczynników transportowych dla wymiany masy. Wartości tych współczynników zweryfikowano z wykorzystaniem modelu Favelukisa i Lavrentevej.

EN

In this work the numerical simulation of drop deformation in a simple shear flow is presented. Calculations were made for capillary numbers smaller than critical, providing a pure deformation of droplet and excluding possibility of its breakage. The deformation of droplet in a confined system was investigated and compared with experimental data published in literature. The performed simulations allowed also the estimation of mass transfer coefficients. Their values were verified using the Favelukis and Lavrenteva model.

20

Experimental evaluation of a helical laboratory photobioreactor for cultivation of thermophilic cyanobacteria – hydrodynamics and mass transfer studies

Gluszcz P., Klepacz-Smółka A., Ledakowicz S.

Chemical and Process Engineering

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2018

|

Vol. 39, nr 4

457-–473

EN

The aim of the paper is to present the hydrodynamic, mass transfer and illumination characteristics of a laboratory helical-tube photobioreactor Biostat PBR-2S, commercially available and used in many laboratories in Poland and worldwide. The investigated hydrodynamics parameters were: mean liquid circulation rate, liquid velocity/residence time in the tubular part of the apparatus and mixing time, measured in the wide range of rotary speed of the circulation pump. The influence of the aeration intensity on these parameters was also checked. The volumetric oxygen and carbon dioxide transfer coefficients in the liquid phase and their dependency on the liquid circulation rate and gas inflow rate were determined. The experiments were performed in tap water and then in a real three-phase cultivation broth at the end of thermophilic cyanobacteria T. synechococus growth. For the final evaluation of the tested PBR there were series of test cultivations run under different conditions of illumination. The highest final concentration of the biomass of tested cyanobacteria reached the relatively high value of 4.38 g/dm3 of the dry biomass, although the process conditions were not fully optimized. The laboratory photobioreactor PBR-2S proved to be a good tool for investigations of microalgae cultivation processes. The presented results and practical observations may help to analyze and understand the mutual influence of the specific process parameters in the described PBR, especially during autotrophic organism cultivations.