Wyniki wyszukiwania - BazTech

1

The CO2 capture system with a swing temperature moving bed

Kozak-Jagieła Ewa, Rerak Monika, Zima Wiesław, Cebula Artur, Grądziel Sławomir, Mondino Giorgia, Blom Richard, Nord Lars O., Skjervold Vidar T.

Acta Mechanica et Automatica

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2024

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Vol. 18, no. 1

93--100

EN

The reduction in CO2 emissions is now a very popular topic. According to the International Energy Agency, CO2 emitted in 2021 was 6% more than that emitted in 2020. Carbon capture and storage (CCS) is gaining popularity as a possible solution to climate change. Experts estimate that industry and power plants will be responsible for 19% of total CO2 emissions by 2050. This paper presents the design of a semi-industrial-scale system for CO2 capture based on the moving bed temperature swing adsorption technology. According to the results of laboratory tests conducted by the SINTEF industry, this technology demonstrates high capture efficiency (>85%). The CO2 capture medium involved in adsorption is activated carbon passing through individual sections (cooling, heating, adsorption), where CO2 is bonded and then released. The heat and mass transfer processes are realised on the developed stand. The heat exchangers use steam and water as the heating/cooling medium. The paper reviews the existing solutions and describes the developed in-house design of heat exchangers that will ensure heat transfer conditions being a trade-off between economic and efficiency-related issues of the CO2 capture process. The designed test stand will be installed in a Polish power plant and is expected to meet the method energy intensity target, set at ≤ 2.7 MJ/kg CO2, with a capture efficiency exceeding 85%. The aim of the work was to develop and solve technical problems that would lead to the construction of a CO2 capture station with parameters mentioned above. This stand uses an innovative method where CO2 is captured by contacting the fluid (gases) with solid particles. The heat exchange associated with the heating and cooling of the adsorbent had to be solved. For this purpose, heat exchangers were designed with high thermal efficiency and to prevent the formation of mounds.

2

Potential of Indirect Regenerative Evaporative Cooling System (M-Cycle) for Electronic Applications

Olbrycht Robert, Kałuża Marcin, Felczak Mariusz, Levchenko Dmytro, Więcek Bogusław

Pomiary Automatyka Robotyka

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2023

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R. 27, nr 3

19--25

EN

The article presents a simple prototype system based on the concept of indirect regenerative evaporative cooling (IREC) thermodynamic cycle for electronics applications. The key problem of selecting porous capillary material is discussed and preliminary experimental results are presented using IR thermography. The presented research is an initial step towards the development of a laboratory-validated, fully operational IREC system for high-power electronics.

PL

W artykule przedstawiono prototypowy układ chłodzenia oparty na koncepcji cyklu termodynamicznego pośredniego regeneracyjnego chłodzenia wyparnego (IREC) do zastosowań w elektronice. Omówiono kluczowy problem doboru porowatego materiału kapilarnego i przedstawiono wstępne wyniki eksperymentów z wykorzystaniem termografii w podczerwieni. Przedstawione badania stanowią wstępny krok w kierunku opracowania zweryfikowanego laboratoryjnie, w pełni funkcjonalnego systemu IREC do odprowadzania ciepła w systemach elektronicznych dużej mocy.

3

Przegląd zastosowania nanopłynów oraz materiałów porowatych w pośrednim chłodzeniu wyparnym

Stefaniak Łukasz, Rajski Krzysztof, Danielewicz Jan

Ciepłownictwo, Ogrzewnictwo, Wentylacja

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2023

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T. 54, nr 12

33--40

PL

Pośrednie chłodzenie wyparne staje się coraz bardziej popularne ze względu na wykorzystanie przyjaznych dla środowiska czynników chłodniczych: powietrza (R-729) i wody (R-718). Istotą procesu jest wymiana ciepła i masy, która zachodzi w wymienniku. Opracowania zagraniczne szeroko opisują nowoczesne technologie wspomagające ten proces, podczas gdy polskojęzyczna literatura nie porusza zagadnienia niemalże w ogóle. W artykule skupiono się na dwóch głównych innowacjach wynikających z przeglądu literatury (od 2010 roku): wprowadzeniu nanopłynów opartych na wodzie oraz zastosowaniu materiałów porowatych na powierzchni kanału mokrego. Przeanalizowano kluczowe parametry stosowane do opisu urządzeń do chłodzenia wyparnego takie jak sprawności: termometru mokrego, punktu rosy oraz egzergetyczną, wydajność chłodniczą, EER oraz COP. Przedstawiono wyniki badań nanopłynów jedno-, dwu- i trzyskładnikowych. Analiza wykazała poprawę parametrów charakteryzujących pośrednie urządzenia wyparne wynoszące od kilku do kilkudziesięciu procent przy zastosowaniu nanopłynów w zależności od temperatury powietrza na wlocie. Dokonano przeglądu stosowanych materiałów porowatych stanowiących powierzchnie kanału mokrego. Wydzielono cztery główne typy stosowanych materiałów: porowate ceramiczne oraz włókna naturalne, polimerowe i tekstylne. Zestawiono wady oraz zalety stosowania tych materiałów w wymiennikach pośrednich w celu ułatwienia wyboru rodzaju materiału. Określono, że spośród dwóch omawianych modyfikacji w pierwszej kolejności należy skupić się na aplikacji materiałów porowatych, jako że są one związane bezpośrednio z konstrukcją wymiennika. Natomiast nanopłyny można zastosować w urządzeniach istniejących. W podsumowaniu stwierdzono, że rozwój technologii pośredniego chłodzenia wyparnego może stanowić istotne oraz ekologiczne uzupełnienie obecnie stosowanych sprężarkowych systemów chłodzenia.

EN

Indirect evaporative cooling is becoming increasingly popular due to the use of environmentally friendly refrigerants: air (R-729) and water (R-718). The main idea of the process is the heat and mass transfer that takes place in the exchanger. Foreign studies extensively describe modern technologies supporting this process, while the Polish-language literature does not cover the issue almost at all. The article focuses on two main innovations resulting from the literature review (as of 2010): the introduction of water-based nanofluids and the use of porous materials on the surface of the wet channel. Main parameters used to describe evaporative cooling devices include wet thermometer, dew point, and exergetic efficiencies, cooling capacity, EER, and COP. Results for single-, two-, and three-component nanofluids are presented. The analysis showed performance improvements for indirect evaporative units of several to tens of percent with nanofluids, depending on the inlet air temperature. The applied porous materials used on the surface of the wet channel were reviewed. Four main types of materials used have been distinguished: porous ceramic and natural fibers, polymer fibers, and fabric fibers. The advantages and disadvantages of using these materials in indirect heat exchangers were summarized to facilitate the choice of material type. It was determined that of the two modifications discussed, the application of porous materials should be focused on first, since they are directly related to the construction of the heat exchanger. In contrast, nanofluids can be applied to existing devices. Eventually, it was pointed out that the development of indirect evaporative cooling technology can be an important and ecological complement to the currently used compressor systems.

4

Assessment of heat and mass transfer processes in vapor bubbles under conditions of metastable equilibrium of liquids

Koshlak Hanna

Archives of Thermodynamics

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2023

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Vol. 44, no 4

483--506

EN

This paper proposes a mathematical model that allows expanding the scope of research into the mechanism of heat transfer during explosive boiling, cavitation and boiling of multicomponent liquids, identifying the most influential factors and optimizing technological processes. The proposed model takes into account the processes of heat accumulation in the high-boiling part of liquid mixtures (for example, emulsions) and the use of this energy in the process of boiling their thermolabile part, as well as for superheating the resulting steam in steam bubbles. This effect can also be used to evaluate the effects of liquid boiling in thermodynamically unstable regions of liquid media.

5

Agitation efficiency of different physical systems

Karcz Joanna, Szoplik Jolanta, Major-Godlewska Marta, Cudak Magdalena, Kiełbus-Rąpała Anna

Chemical and Process Engineering

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2021

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Vol. 42, nr 2

139–-156

EN

Efficiency of agitation was considered for different physical systems on the basis of our own experimental studies on homogenisation, heat and mass transfer as well as gas hold-up. Measurements were performed for different physical systems: Newtonian liquids of low and higher viscosity, pseudoplastic liquid, gas–liquid and gas–solid–liquid systems agitated in vessels of the working volume from 0.02 m3 to 0.2 m3. Agitated vessels of different design were equipped with a high-speed impeller (10 impellers were tested). Comparative analysis of the experimental results proved that energy inputs (power consumption) should be taken into account as a very important factor when agitation efficiency is evaluated in order to select a proper type of equipment. When this factor is neglected in the analysis, intensification of the process can be estimated only.

6

The four-sided lid driven square cavity using stream function-vorticity formulation

Bagai Shobha, Kumar Manoj, Patel Arvind

Journal of Applied Mathematics and Computational Mechanics

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2020

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Vol. 19, nr 2

17--30

EN

In this paper, an unsteady 2-D incompressible fluid flow with heat and mass transfer in a four-sided lid driven square cavity is investigated numerically. The top, bottom, left, and right walls of the square cavity move to the right, left, downward and upward respectively. All four sides of the cavity move with a uniform velocity. The flow variables are simulated below the critical Reynolds numbers with isothermal and mass-transfer conditions in the square cavity. We have used a streamfunction-vorticity (ψ - ξ) formulation to investigate the fluid flow in terms of flow variables ψ, ξ, T and C at low Reynolds numbers (Re). The Prandtl number (Pr) and Schmidt number (Sc) have been chosen as 6:62 and 10, 50, 100, 150 respectively, in order to calculate the numerical solutions of T and C. The matrix method has been used to evaluate the stability and convergence of the numerical scheme. The conditions obtained from the matrix method have been used to arrive at the numerical solutions with desired accuracy.

7

Effects of radiation and Eckert number on MHD flow with heat transfer rate near a stagnation point over a non-linear vertical stretching sheet

Fenuga O. J., Hassan A. R., Olanrewaju P. O.

International Journal of Applied Mechanics and Engineering

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2020

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Vol. 25, no. 1

27--36

EN

This work investigates the effects of radiation and Eckert number on an MHD flow with heat transfer rate near a stagnation-point region over a nonlinear vertical stretching sheet. Using a similarity transformation, the governing equations are transformed into a system of ordinary differential equations which are solved numerically using the sixth order Runge-Kutta method with shooting technique. Tabular and graphical results are provided to examine the physical nature of the problem. Heat transfer rate at the surface decreases with radiation, Eckert number and as radiation increases, the flow temperature also increases for velocity ratio parameters […].

8

Analysis of magnetohydrodynamic (MHD) nanofluid flow with heat and mass transfer over a porous stretching sheet

Odesola A. S., Abiala I. O., Akinpelu F. O., Fenuga O. J.

International Journal of Applied Mechanics and Engineering

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2020

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Vol. 25, no. 4

162--174

EN

This work investigates a three-dimensional Magnetohydrodynamic (MHD) nanofluid flow with heat and mass transfer over a porous stretching sheet. Firstly, partial differential equations are transformed into coupled non-linear ordinary differential equations through a similarity variables transformation and solved by Galerkin Finite Element Methods (FEM). The effects of thermal radiation, viscous dissipation and chemical reaction on the fluid flow are considered. The behaviour and properties of pertinent flow parameters on the velocity, temperature and concentration profiles are presented and discussed graphically. The effects of the friction coefficient parameter, Nusselt and Sherhood numbers are also shown and considered using tables. The work is in good agreement in comparison with the recent work in literature.

9

Heat and mass transfer mechanism on three-dimensional flow of inclined magneto Carreau nanofluid with chemical reaction

Rao B. Madhusudhana, Gopal Degavath, Kishan Naikoti, Ahmed Saad, Prasad Putta Durga

Archives of Thermodynamics

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2020

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Vol. 41, no 2

223--238

EN

The characteristic of nano sized particles mass flux conditions are engaged in this investigation. Here we assume that the nano sized particle flux is zero and the nano sized particle fraction arranged itself on the boundary layer. With this convincing and revised relation, the features of Buongiorno relation on three-dimensional flow of Carreau fluid can be applied in a more efficient way. The governing partial differential equations of continuity, momentum, energy and concentration equations which are transmitted into set of pair of nonlinear ordinary differential equations utilizing similar transformations. The numeric solutions are acquired by engaging the bvp4c scheme, which is a finite-difference code for solving boundary value problems. A parametric study is accomplished to demonstrate the impact of Prandtl number, Weissenberg numbers, radiation parameter, chemical reaction parameter, thermophoresis parameter, Brownian motion parameter and Lewis number on the fluid velocity, temperature and concentration profiles as well skin friction coefficient, Nusselt number and Sherwood number within the boundary layer. From this we find the way in which magnetic parameter contributes to the increase in local skin fraction, and the decrease in the Nusselt and Sherwood numbers in these cases. The effects of the velocity temperature and concentration profile are obtained and presented graphically.

10

The improvement of the rheological model for controlling the stress-strain state and humidity in the materials of museum pieces: zener thermodiffusion model for capillary-porous bodies

Dovhaliuk V. B., Chovnyuk Y. V., Ivanov E. A., Shyshyna M. O.

Zeszyty Naukowe. Quality. Production. Improvement

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2019

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No. 2 (11)

51--71

EN

The drying and humidifying processes of capillary-porous (colloid) bodies occur during the production of various materials for the consumer goods industry, building materials, storage of museum pieces, etc. It is known that the main linkage forms of the moisture and colloid capillary-porous bodies (CCPBs), namely adsorption, capillary condensation and capillary linkage of the free moisture in the cavities of the above bodies, depend on the temperature and relative humidity of drying/humidifying agent. It means that the CCPBs behave in a peculiar way depending on the temperature and humidity fields. The problems of CCPBs drying (or humidifying) process include the issue of the heat and humidity transfer both in the middle of the body and in the boundary layer on the interface of phases “body (object of drying/humidifying process) – environment”. The drying/humidifying intensity is at its maximum when the possibilities of the heat and mass transfer in the boundary layer correspond to the possibilities of moisture and heat moving inside the object of drying/humidifying process. The properties of the CCPB as material possessing specific elastic-viscous properties are described within the framework of O.Y. Ishlinskiy - O.R. Rzhanitsin generalized elastic-viscous body theory. A comparative analysis of the above mentioned CCPB’s properties from the point of view of Zener thermodiffusion theory is conducted. The mechanism of moisture transferring from the CCPBs’ central layers (as object of drying/humidifying process) up to their surfaces is developed. The theoretical researches examined the drying/humidifying phenomena for both the entire volume of the CCPB and three structural directions. It is noted that drying/humidifying of CCPBs is a complicated heat and mass transfer process accompanied by mechanisms of molecular nature determining the kinetics of their running. It is shown that the appropriate equations’ solution of molecular-molar heat and moisture transfer under the appropriate boundary (limit) conditions allows to describe the fields, i.e. the distribution of transfer potentials (the temperature and moisture content in the CCPB as object of drying/humidifying) at any time of the appropriate process. The drying/humidifying curves (“drying/humidifying rate versus CCPB humidity”) and the temperature curves (“CCPB temperatures versus CCPB humidity”) reflect the nature of the drying/humidifying processes. In the framework of the proposed generalized rheological model of CCPB, the residual deformations of bodies for various load types (the time-varying stress applied to the CCPB) is estimated.

11

Calculation of processes of melting metal particles (inoculator) in a one-dimensional problem statement

Pavlenko Anastasiia

Journal of New Technologies in Environmental Science

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2019

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Vol. 3, nr 3

149--152

EN

The article presents the results of research of thermophysical peculiarities obtaining volumetric amorphous structures in metals and alloys. This technology differs mainly the realization internal heat removal by means of local heat sink (inoculator). A mathematical model of melting inoculator in melts for optimizing the process of obtaining massive amorphous structures, which allows to reduce time of experimental research and material resources to create massive amorphous structures. Mathematical modeling of processes heat and mass transfer inoculator in melts allows you to identify peculiarities of the technological process, and establish influence inoculator on the degree of amorphization melt. The results provide an effective assessment of the intensity of heat transfer during the casting process, which makes it possible to estimate and predict the ability of alloys to the amorphization of the structure.

12

Unsteady MHD thermal diffusive and radiative fluid flow past a vertical porous plate with chemical reaction in slip flow regime

Ravi Kumar D., Jayarami Reddy K., Raju M. C.

International Journal of Applied Mechanics and Engineering

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2019

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Vol. 24, no. 1

117--129

EN

An analytical solution of an MHD free convective thermal diffusive flow of a viscous, incompressible, electrically conducting and heat-absorbing fluid past a infinite vertical permeable porous plate in the presence of radiation and chemical reaction is presented. The flow is considered under the influence of a magnetic field applied normal to the flow. The plate is assumed to move with a constant velocity in the direction of fluid flow in slip flow regime, while free stream velocity is assumed to follow the exponentially increasing small perturbation law. The velocity, temperature, concentration, skin friction, Nusselt number and Sherwood number distributions are derived and have shown through graphs and tables by using the simple perturbation technique.

13

Analysis of a chemically reactive MHD flow with heat and mass transfer over a permeable surface

Fenuga O. J., Aroloye S. J., Popoola A. O.

International Journal of Applied Mechanics and Engineering

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2019

|

Vol. 24, no. 1

53--66

EN

This paper investigates a chemically reactive Magnetohydrodynamics fluid flow with heat and mass transfer over a permeable surface taking into consideration the buoyancy force, injection/suction, heat source/sink and thermal radiation. The governing momentum, energy and concentration balance equations are transformed into a set of ordinary differential equations by method of similarity transformation and solved numerically by Runge- Kutta method based on Shooting technique. The influence of various pertinent parameters on the velocity, temperature, concentration fields are discussed graphically. Comparison of this work with previously published works on special cases of the problem was carried out and the results are in excellent agreement. Results also show that the thermo physical parameters in the momentum boundary layer equations increase the skin friction coefficient but decrease the momentum boundary layer. Fluid suction/injection and Prandtl number increase the rate of heat transfer. The order of chemical reaction is quite significant and there is a faster rate of mass transfer when the reaction rate and Schmidt number are increased.

14

The thermophysical peculiarities heat and mass transfer inoculators in melts metals

Koshlak H.

Journal of New Technologies in Environmental Science

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2018

|

Vol. 2, nr 4

183--186

EN

The article presents the results of research of thermophysical peculiarities obtaining volumetric amorphous structures in metals and alloys. This technology differs mainly the realization internal heat removal by means of local heat sink (inoculator). A mathematical model of melting inoculator in melts for optimizing the process of obtaining massive amorphous structures, which allows to reduce time of experimental research and material resources to create massive amorphous structures. Mathematical modeling of processes heat and mass transfer inoculator in melts allows you to identify peculiarities of the technological process, and establish influence inoculator on the degree of amorphization melt. The results provide an effective assessment of the intensity of heat transfer during the casting process, which makes it possible to estimate and predict the ability of alloys to the amorphization of the structure.

15

A numerical method for viscous flow in a driven cavity with heat and concentration sources placed on its side wall

Ambethkar V., Basumatary L. R.

Journal of Applied Mathematics and Computational Mechanics

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2018

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Vol. 17, nr 3

17--30

EN

This paper proposes a method to numerically study viscous incompressible two-dimensional steady flow in a driven square cavity with heat and concentration sources placed on its side wall. The method proposed here is based on streamfunction-vorticity (Ψ-ξ) formulation. We have modified this formulation in such a way that it suits to solve the continuity, x and y-momentum, energy and mass transfer equations which are the governing equations of the problem under investigation in this study. No-slip and slip wall boundary conditions for velocity, temperature and concentration are defined on walls of a driven square cavity. In order to numerically compute the streamfunction Ψ, vorticityfunction ξ , temperature θ, concentration C and pressure P at different low, moderate and high Reynolds numbers, a general algorithm was proposed. The sequence of steps involved in this general algorithm are executed in a computer code, developed and run in a C compiler. We propose that, with the help of this code, one can easily compute the numerical solutions of the flow variables such as velocity, pressure, temperature, concentration, streamfunction, vorticityfunction and thereby depict and analyze streamlines, vortex lines, isotherms and isobars, in the driven square cavity for low, moderate and high Reynolds numbers. We have chosen suitable Prandtl and Schmidt numbers that enables us to define the average Nusselt and Sherwood numbers to study the heat ad mass transfer rates from the left wall of the cavity. The stability criterion of the numerical method used for solving the Poisson, vorticity transportation, energy and mass transfer has been given. Based on this criterion, we ought to choose appropriate time and space steps in numerical computations and thereby, we may obtain the desired accurate numerical solutions. The nature of the steady state solutions of the flow variables along the horizontal and vertical lines through the geometric center of the square cavity has been discussed and analyzed. To check the validity of the computer code used and corresponding numerical solutions of the flow variables obtained from this study, we have to compare these with established steady state solutions existing in the literature and they have to be found in good agreement.

16

Methodology for experimental research of heat and mass transfer processes during inhalation of e-cigarettes aerosols

Odziomek M.

Inżynieria i Aparatura Chemiczna

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2018

|

Nr 5

144--145

EN

This work is focused on the development and validation of experimental method for testing EC-aerosols under simulated conditions of human respiratory tract with variable aerosol residence time in the physiologically humid environment associated with the inhalation pattern. Initial results obtained using the laser diffractometry indicate the usefulness and applicability of developed method for EC-aerosol testing for a deeper understanding of simultaneous heat and mass transfer processes during EC-aerosol formation, inhalation and movement in the human respiratory tract.

PL

Praca koncentruje się na opracowaniu i walidacji metodyki badań doświadczalnych aerozoli uwalnianych z e-papierosów do środowiska odzwierciedlającego pod względem panującej wilgotności, temperatury oraz czasu przebywania aerozolu drogi oddechowe człowieka. Wstępne wyniki uzyskane przy użyciu dyfraktometru laserowego wskazują na przydatność zaproponowanej metody badania aerozoli do głębszego zrozumienia roli procesów wymiany ciepła oraz masy w trybie ich powstawania, inhalacji oraz transportu w drogach oddechowych.

17

Role of slip velocity in a magneto-micropolar fluid flow from a radiative surface with variable permeability: a numerical study

Sharma B. K., Tailor V., Goyal M.

International Journal of Applied Mechanics and Engineering

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2017

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Vol. 22, no. 3

637--651

EN

An analysis is presented to describe the hydromagnetic mixed convection flow of an electrically conducting micropolar fluid past a vertical plate through a porous medium with radiation and slip flow regime. A uniform magnetic field has been considered in the study which absorbs the micropolar fluid with a varying suction velocity and acts perpendicular to the porous surface of the above plate. The governing non-linear partial differential equations have been transformed into linear partial differential equations, which are solved numerically by applying the explicit finite difference method. The numerical results are presented graphically in the form of velocity, micro-rotation, concentration and temperature profiles, the skin-friction coefficient, the couple stress coefficient, the rate of heat and mass transfers at the wall for different material parameters.

18

Transfer effects on an unsteady MHD mixed convective flow past a vertical plate with chemical reaction

Raju R. S.

Engineering Transactions

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2017

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Vol. 65, iss. 2

221--249

EN

An attempt is made to study the effects of chemical reaction and combined buoyancy effects on an unsteady MHD mixed convective flow along an infinite vertical porous plate in the presence of hall current. A uniform magnetic field is applied in a direction normal to the porous plate. The governing coupled non-linear partial differential equations are solved using an efficient Galerkin finite element method. With the help of graphs, the effects of the various important parameters entering into the problem on the velocity, temperature, and concentration fields within the boundary layer are discussed. Also the effects of the pertinent parameters on the skin-friction coefficient and rates of heat and mass transfer in terms of the Nusselt number and Sherwood number are presented numerically in a tabular form. The results obtained show that the velocity, temperature, and concentration fields are appreciably influenced by the presence of chemical reaction, hall current, heat, and mass transfer. It is observed that the effect of Schmidt number and chemical reaction parameter is to decrease the velocity and concentration profiles in the boundary layer while the velocity profiles are increasing with increasing of hall parameter, Grashof numbers for heat and mass transfer. There is also considerable effect of hall current and chemical reaction on skin-friction coefficient and Nusselt number. In the present analysis various comparisons with previously published work are performed and the results are found to be in a good agreement.

19

Walidacja modelu przepływu ciepła i wilgoci przez ubiór ochronny

Łapka P., Furmański P., Bugaj M. A., Cieślikiewicz Ł., Pietrak K., Kubiś M., Wiśniewski T. S.

Zeszyty Naukowe SGSP / Szkoła Główna Służby Pożarniczej

|

2016

|

Nr 58 (tom 2) (2)

231--251

PL

W artykule przedstawiono zaawansowany model matematyczny i numeryczny transportu ciepła i masy w wielowarstwowych ubraniach ochronnych, które były poddane działaniu wysokiej temperatury otoczenia lub dużych radiacyjnych strumieni ciepła emitowanych przez gorące ciała. Zaproponowany model uwzględniał przewodzenie ciepła i promieniowanie cieplne w warstwach tkaniny o spektralnych właściwościach optycznych i w szczelinach powietrznych oraz transport energii związany z dyfuzją wilgoci przez ubranie ochronne oraz z procesami sorpcji i desorpcji wody w włóknach tkaniny. Dodatkowo do modelu włączono złożone warunki bilansu energii i masy oraz warunki optyczne na granicach warstw tkaniny. Do rozwiązania równań modelowych opracowano autorski iteracyjny algorytm numeryczny, który bazował na metodzie objętości kontrolnych. Następnie przeprowadzono analizę walidacyjną zaproponowanego modelu obliczeniowego poprzez porównanie otrzymanych wyników z wynikami pomiarów eksperymentalnych dla wybranego pakietu ubrania ochronnego ogrzewanego przez krótki czas radiacyjnym strumieniem ciepła emitowanym przez promiennik podczerwieni, a następnie chłodzonego w otoczeniu. Otrzymano dobrą zgodność czasowych przebiegów temperatury, co potwierdziło wiarygodność zaproponowanego modelu.

EN

An advanced mathematical and numerical model of heat and mass transfer in the multi-layer protective clothing, which was exposed to either high temperature environment or to high incident radiative heat flux emitted by hot objects was presented in this paper. The developed model accounted for heat conduction and thermal radiation in a non -grey layers of the protective garment. Additionally, heat transport associated with water vapour diffusion through the protective clothing and with sorption and desorption of liquid water in the fabric fibres were included. Complex energy and mass balances as well as optical conditions at the external and internal interfaces between clothing layers were formulated and incorporated into the model. A novel iterative numerical algorithm which was based on the Finite Volume Method was developed to solve the system of governing equations. Finally, the validation analysis of the model was carried out for selected multi-layer clothing which was exposed for a short time to radiative heat flux emitted by an infrared emitter and then cooled down in the surroundings. The simulated and experimentally measured time variations of temperatures were in good agreement, therefore the accuracy of the proposed model was validated.

20

On problems of heat and mass transfer in concrete structures

Kowalik M., Poński M.

Zeszyty Naukowe Politechniki Częstochowskiej. Budownictwo

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2016

|

Z. 22 (172)

171-183

EN

A stochastic finite difference approach based on stochastic finite elements is proposed for heat and mass transfer modeling. Porous structure with random material properties is investigated. The theoretical formulation of the problem is described. A system of partial differential equations is obtained and solved for first two probabilistic moments of the random temperature field. Example of stochastic thermal analysis in concrete structure with random material parameters are given.

PL

W artykule zastosowano metodę stochastycznych różnic skończonych do analizy problemów przepływu ciepła i ruchu wilgoci. Przedstawiono sformułowanie teoretyczne problemu. Badano porowatą strukturę z losowymi parametrami materiałowymi. Do rozwiązania zagadnienia zastosowano metodę perturbacyjną.