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Wyświetlanie 1-15 z 46
Tytuł:
Optimization of heat transfer oriented surfaces by thermovision and using CFD method
Autorzy:
Kapjor, A.
Smatanová, H.
Hužvár, J.
Greššak, T.
Jandačka, J.
Powiązania:
https://bibliotekanauki.pl/articles/402248.pdf
Data publikacji:
2013
Wydawca:
Politechnika Świętokrzyska w Kielcach. Wydawnictwo PŚw
Tematy:
heat transfer
natural convection
CFD method
Opis:
The paper presents applications of infrared measurements. It discusses the use of thermovision and CFD method in the analysis of heat transfer in experimental measurement with natural convection.
Źródło:
Structure and Environment; 2013, 5, 4; 41-44
2081-1500
Pojawia się w:
Structure and Environment
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Entropy production due to conjugate natural convection in a nanofluid-filled enclosure with a stepped wall
Autorzy:
Bouchoucha, Abd el
Oztop, Hakan F.
Bessaih, Rachid
Abu-Hamdeh, Nidal
Powiązania:
https://bibliotekanauki.pl/articles/38894787.pdf
Data publikacji:
2023
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Tematy:
entropy generation
natural convection
nanofluids
cavity
wall
Opis:
The main aim of this paper is to improve the heat transfer in a square cavity with a body at the left wall filled with a Al2O3/water nanofluid for different geometries. Numerous simulation experiments are conducted. A relative temperature is maintained at the vertical and top horizontal walls while the bottom wall is warm. The finite volume approach is considered to resolve the equations governing the thermal transfer flow in the physical domain based on the SIMPLER algorithm. In this study, different values of the following parameters are considered: Rayleigh number (104 ≤ Ra ≤ 105) and solid volume fraction (0 ≤ φ ≤ 0.1) of nanoparticles (NPs). Parameters, such as the Rayleigh (Ra) and Bejan (Be) numbers, thermal conductivity, body’s dimensions, and NPs volume fraction, which directly affect the entropy generation and heat transfer rate, are studied in a particular way. The obtained results show that entropy generation goes ahead with the Ra increase and inverse to the solid volume fraction increase. One can notice that the heat transfer has a proportional relation with φ and Ra.
Źródło:
Engineering Transactions; 2023, 71, 2; 161-183
0867-888X
Pojawia się w:
Engineering Transactions
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Natural and mixed convection of a nanofluid in porous cavities: critical analysis using buongiorno’s model
Autorzy:
Zahmatkesh, Iman
Habibi, Mohammad Reza
Powiązania:
https://bibliotekanauki.pl/articles/279435.pdf
Data publikacji:
2019
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
natural convection
mixed convection
nanofluid
porous media
Buongiorno’s model
Opis:
In this paper, Buongiorno’s mathematical model is adopted to simulate both natural convection and mixed convection of a nanofluid in square porous cavities. The model takes into account the Brownian diffusion and thermophoresis effects. Both constant and variable temperatures are prescribed at the side walls while the remaining walls are maintained adiabatic. Moreover, all boundaries are assumed to be impermeable to the base fluid and the nanoparticles. The governing equations are transformed to a form of dimensionless equations and then solved numerically using the finite-volume method. Thereafter, effects of the Brownian diffusion parameter, the thermophoresis number, and the buoyancy ratio on the flow strength and the average Nusselt number as well as distributions of isocontours of the stream function, temperature, and nanoparticles fraction are presented and discussed.
Źródło:
Journal of Theoretical and Applied Mechanics; 2019, 57, 1; 221-233
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical modelling and analysis of cooling system of electrical transformer dipped into polymerised resin
Autorzy:
Smołka, J.
Nowak, A. J.
Wrobel, L. C.
Powiązania:
https://bibliotekanauki.pl/articles/1955729.pdf
Data publikacji:
2003
Wydawca:
Politechnika Gdańska
Tematy:
dry electrical transformer
heat transfer
natural convection
coupled analysis
Opis:
This paper discusses a numerical model of the heat dissipation processes in an electrical transformer dipped into polymerised resin. The transformer is cooled by both natural convection (via the ambient air) and forced convection (via the water cooling system attached to one of the transformer casing walls). Two cases have been compared, i.e. the cooler connected to the bottom or the top wall of the transformer container, respectively. In order to improve the modelling of the natural convection problem, an independent geometrical model of the surrounding air was created and considered separately. The continuity of temperature and heat flux along the interface between the transformer and air was enforced by an iterative procedure. This procedure allowed one to calculate and then prescribe local heat fluxes to the external walls of the transformer. The numerical results obtained in this project have yielded information on the efficiency of the analysed cooling system.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2003, 7, 3; 439-448
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mathematical modeling of large floating roof reservoir temperature arena
Autorzy:
Liu, Y.
Fan, J.
Cheng, Q.
Powiązania:
https://bibliotekanauki.pl/articles/778000.pdf
Data publikacji:
2018
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
floating roof tank
temperature field
natural convection
numerical simulation
Opis:
The current study is a simplification of related components of large floating roof tank and modeling for three dimensional temperature field of large floating roof tank. The heat transfer involves its transfer between the hot fluid in the oil tank, between the hot fluid and the tank wall and between the tank wall and the external environment. The mathematical model of heat transfer and flow of oil in the tank simulates the temperature field of oil in tank. Oil temperature field of large floating roof tank is obtained by numerical simulation, map the curve of central temperature dynamics with time and analyze axial and radial temperature of storage tank. It determines the distribution of low temperature storage tank location based on the thickness of the reservoir temperature. Finally, it compared the calculated results and the field test data; eventually validated the calculated results based on the experimental results.
Źródło:
Polish Journal of Chemical Technology; 2018, 20, 1; 67-74
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of radial fins on natural convection between horizontal circular and square cylinders
Autorzy:
Jafari, I.
Mahdavy-Moghadam, H.
Taeibi-Rahni, M.
Dayyan, M.
Seyyedi, S. M.
Powiązania:
https://bibliotekanauki.pl/articles/279844.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
radial fins
natural convection
lattice Boltzmann method
horizontal annulus
Opis:
In this paper, the effects of the number and arrangement of radial fins on laminar natural co- nvection between horizontal circular and square cylinders has been investigated numerically with the lattice Boltzmann method. The Rayleigh number is varied from Ra = 10³ − 10⁶), the number of fins (N = 2 − 8) and the Prandtl number (Pr = 0.7). The local Nusselt number profiles over the outer and inner cylinders and the average Nusselt number over the top, bottom and side walls of the outer cold square cylinder are obtained. The temperature and streamline contours are also depicted to investigate the heat and fluid flow behavior inside the computational domain.
Źródło:
Journal of Theoretical and Applied Mechanics; 2014, 52, 3; 827-837
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Natural convection in a partially heated cylinder: A numerical study
Autorzy:
Núñez, José
Beltrán, Alberto
Rivero, Michel
Powiązania:
https://bibliotekanauki.pl/articles/2055060.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
bifurcations
natural convection
partially heated cylinder
switching modes solutions
Opis:
This work presents a numerical study on a natural convective flow in a cylindrical container heated from below, cooled from above, and partially heated from the lateral wall. Mass, momentum and energy equations were solved with a developed hybrid Fourier-finite volume code and validated with the commercial software COMSOL Multiphysics for steady-state solutions. The primary solutions correspond to steady-states Cm with azimuthal wavenumbers m. The results show mode competition between different states leading to many flow solutions including steady axisymmetric, steady non-axisymmetric, time-dependent pulsating wave solutions, and other flow states with a variety of spatiotemporal symmetries.
Źródło:
Journal of Theoretical and Applied Mechanics; 2021, 59, 4; 623--636
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Natural convection from four circular cylinders in across arrangement within horizontal annular space
Autorzy:
Laidoudi, Houssem
Powiązania:
https://bibliotekanauki.pl/articles/387589.pdf
Data publikacji:
2020
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
natural convection
multiple cylinders
annular space
heat transfer
numerical simulation
Opis:
Numerical investigation is accomplished to study the roles of governing parameters of natural convection on the fluid motion and heat transfer rate of four heated circular cylinders placed inside a circular enclosure of cold surface. The cylinders are positioned in across arrangement. The representative results are obtained within the ranges of initial conditions as: Prandtl number (Pr = 7.1 to 1000) and Rayleigh number (Ra = 103 to 105). The average Nusselt number of each inner cylinder is computed. The effects of thermal buoyancy strength on the fluid motion and temperature are also illustrated. It was found that the heat transfer rate of cylinders depends significantly on the position inside the enclosure. Moreover, the role of Prandtl number on flow and thermal patterns is negligible. The values of Nusselt number are also given, which can be useful for some engineering applications.
Źródło:
Acta Mechanica et Automatica; 2020, 14, 2; 98-102
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Badanie konwekcji swobodnej z powierzchni pionowego walca w środowisku hiperbarycznym
Experimental investigation of natural convection from vertical cylinder in the hyperbaric environment
Autorzy:
Majchrzycka, A.
Powiązania:
https://bibliotekanauki.pl/articles/366405.pdf
Data publikacji:
2010
Wydawca:
Polskie Towarzystwo Medycyny i Techniki Hiperbarycznej
Tematy:
konwekcja swobodna
pionowy walec
hel
natural convection
vertical cylinder
helium
Opis:
W pracy przedstawiono badania, dotyczące konwekcji swobodnej z powierzchni pionowego walca odwzorowującego sylwetkę nurka o zmiennym wydatku energetycznym. Badania wykonano w helu o ciśnieniu p = 0,5-5MPa, a wyniki przedstawiono postaci równania kryterialnego Nu = f(Ra) oraz korelacji, która umożliwia obliczenie współczynnika przejmowania ciepła w funkcji ciśnienia gazu i symulowanego wydatku energetycznego nurka.
The paper reports experimental investigation of natural convection from vertical cylinder that simulates the diver’s body of the different activity level. Experiments were carried out in the hyperbaric helium at absolute pressure range of p=0,5-5 MPa. The results are given as the correlation Nu = f(Ra) and correlation between convective heat transfer coefficient from the outer surface of vertical cylinder, pressure and simulated activity level.
Źródło:
Polish Hyperbaric Research; 2010, 1(30); 13-24
1734-7009
2084-0535
Pojawia się w:
Polish Hyperbaric Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Natural convection flow in semi-trapezoidal porous enclosure filled with alumina-water nanofluid using Tiwari and Das’ nanofluid model
Autorzy:
Vedavathi, Nallapati
Venkatadri, Kothuru
Fazuruddin, Syed
Raju, G. Sankara Sekhar
Powiązania:
https://bibliotekanauki.pl/articles/38889212.pdf
Data publikacji:
2022
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Tematy:
natural convection
laminar flow
porous medium
nanofluid
semi-trapezoidal enclosure
Opis:
Nowadays, optimal parameters are necessary for heat transfer enhancement in different practical applications. A numerical simulation of natural convection in a semi-trapezoidal enclosure embedded with porous medium is presented. Stream function and temperature using the Darcy–Boussinesq approximation and Tiwari and Das’ nanofluid model with new more realistic empirical correlations for the physical properties of the nanofluids are formulated. The developed partial differential equations are employed with the help of the stream function approach. The in-house developed computational MATLAB code is validated with the previously published work. The impact of a wide range of governing parameters on fluid flow patterns and temperature gradient variations is presented. The thermal Rayleigh number (Ra) can be a control key parameter for heat and convective flow. Thermal dispersion effects are also examined in this study. An increase in the Rayleigh number leads to an increase in heat transfer, where one can find a reduction of convective heat transfer with φ.
Źródło:
Engineering Transactions; 2022, 70, 4; 303-318
0867-888X
Pojawia się w:
Engineering Transactions
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Badanie procesu suszenia konwekcyjnego pietruszki korzeniowej
Testing the convective-drying process of parsley root
Autorzy:
Skorupska, E.
Powiązania:
https://bibliotekanauki.pl/articles/291036.pdf
Data publikacji:
2005
Wydawca:
Polskie Towarzystwo Inżynierii Rolniczej
Tematy:
suszenie
konwekcja naturalna
pietruszka korzeniowa
drying
natural convection
root parsley
Opis:
Badano wpływ temperatury czynnika suszącego 50, 60 i 70°C i kształtu cząstek pietruszki korzeniowej na kinetykę procesu suszenia w warunkach konwekcji naturalnej. Doświadczalne krzywe suszenia i szybkości suszenia kinetyki suszenia pietruszki w cienkiej warstwie podzielono na dwa etapy, z których końcowy opisano modelem. Określono zakres zmian szybkości suszenia i średnią wartość szybkości suszenia w funkcji zawartości wody.
An influence of the drying-medium temperature 50, 60, 70°C and the shape of the parsley-root particles on the kinetics of the drying process under the conditions of natural convection was investigated. Experimental curves of drying and drying rate kinetics of parsley in a thin layer were divided into two stages, where the final one was determined using a model. The scope of changes in drying and the average drying rate were determined as a function of water content.
Źródło:
Inżynieria Rolnicza; 2005, R. 9, nr 9, 9; 313-320
1429-7264
Pojawia się w:
Inżynieria Rolnicza
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Artificial neural network to predict the natural convection from vertical and inclined arrays of horizontal cylinders
Autorzy:
Amiri, A.
Karami, A.
Yousefi, T.
Zanjani, M.
Powiązania:
https://bibliotekanauki.pl/articles/779019.pdf
Data publikacji:
2012
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
natural convection
Inclined Array
Vertical Array
modeling
artificial neural network
Opis:
The main focus of the present study is to utilize the artifi cial neural network (ANN) in predicting the natural convection from horizontal isothermal cylinders arranged in vertical and inclined arrays. The effects of the vertical separation spacing to the cylinder diameter ratio (Py/d), horizontal separation spacing to the cylinder diameter ratio (Px/d) and Rayleigh number (Ra) variation on the average heat transfer from the arrays are considered via this prediction. The training data for optimizing the ANN structure is based on available experimental data. The Levenberg-Marquardt back propagation algorithm is used for ANN training. The proposed ANN is developed using MATLAB functions. For the best ANN structure obtained in this investigation, the mean relative errors of 0.027% and 0.482% were reached for the training and test data, respectively. The results show that the predicted values are very close to the experimental ones.
Źródło:
Polish Journal of Chemical Technology; 2012, 14, 4; 46-52
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The modified XFEM for solving problems of a phase change with natural convection
Autorzy:
Stąpór, Paweł
Powiązania:
https://bibliotekanauki.pl/articles/139838.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
phase change
natural convection
extended finite element method
level set method
Opis:
This paper presents an extended finite element method applied to solve phase change problems taking into account natural convection in the liquid phase. It is assumed that the transition from one state to another, e.g., during the solidification of pure metals, is discontinuous and that the physical properties of the phases vary across the interface. According to the classical Stefan condition, the location, topology and rate of the interface changes are determined by the jump in the heat flux. The incompressible Navier–Stokes equations with the Boussinesq approximation of the natural convection flow are solved for the liquid phase. The no-slip condition for velocity and the melting/freezing condition for temperature are imposed on the interface using penalty method. The fractional four-step method is employed for analysing conjugate heat transfer and unsteady viscous flow. The phase interface is tracked by the level set method defined on the same finite element mesh. A new combination of extended basis functions is proposed to approximate the discontinuity in the derivative of the temperature, velocity and the pressure fields. The single-mesh approach is demonstrated using three two-dimensional benchmark problems. The results are compared with the numerical and experimental data obtained by other authors.
Źródło:
Archive of Mechanical Engineering; 2019, LXVI, 3; 273-294
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Charakterystyka suszarnicza owoców bzu czarnego
Drying characteristics for elder fruits
Autorzy:
Peroń, S.
Surma, M.
Zdrojewski, Z.
Powiązania:
https://bibliotekanauki.pl/articles/290090.pdf
Data publikacji:
2010
Wydawca:
Polskie Towarzystwo Inżynierii Rolniczej
Tematy:
suszenie
owoc
bez czarny
konwekcja naturalna
drying
elder
fruit
natural convection
Opis:
Badano wpływ temperatury suszenia na dynamikę narastania temperatury wnętrza owoców bzu czarnego, szybkość ich wysychania a także ich skurcz suszarniczy i zdolność do rehydracji. Suszenie prowadzono w warunkach konwekcji naturalnej w temperaturach 50, 60, 70°C przy początkowej wilgotności surowca około 75%. Wyniki przedstawiono w postaci wykresów oraz równań korelacyjnych.
The research involved examination of drying temperature impact on the dynamics of temperature rise inside elder fruits, drying rate, and their drying shrinkage and ability to rehydration. Drying was carried out in natural convection conditions at temperatures: 50, 60, 70°C at initial material humidity.
Źródło:
Inżynieria Rolnicza; 2010, R. 14, nr 2, 2; 117-123
1429-7264
Pojawia się w:
Inżynieria Rolnicza
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The natural convection inside a 3D triangular cross section cavity filled with nanofluid and included cylinder with different arrangements
Autorzy:
Ghoben, Zainab Kareem
Hussein, Ahmed Kadhim
Powiązania:
https://bibliotekanauki.pl/articles/2096184.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
Tematy:
natural convection
triangular cavity
inner cylinder
nanofluid
3D
konwekcja naturalna
Opis:
In this paper the laminar unsteady natural convection heat transfer of (Al2O3-water) nanofluid inside 3D triangular cross section cavity was investigated. The cavity was heated differentially, the vertical walls were kept at different constant temperatures. The left hot and the right cold. The effect of the solid volume fraction was examined for two values and compared with the pure water results. The (Ra) range studied was (103≤Ra≤106). Inserting cylindrical body inside the cavity also investigated in three cases. One concentric cylinder has radius (15%) of the cavity side length. The other cases were of two cylinders having radius (7.5%) of the cavity side length, aligned vertically or nonaligned. The results show that the higher solid volume fraction gives the maximum enhancement of the average (Nu) and this enhancement increases with (Ra) increase. For the cases with inner cylinders, the average (Nu) enhanced for the case of double cylinders over single cylinder. On other hand, the nonaligned position of the cylinders giving more enhancement than other position. As like as, the location of maximum horizontal or vertical velocities were varied with the cylinders position while (Ra) has no effect.
Źródło:
Diagnostyka; 2022, 23, 2; no. art. 2022205
1641-6414
2449-5220
Pojawia się w:
Diagnostyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 46

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