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Wyszukujesz frazę "Rayleigh Number" wg kryterium: Temat


Wyświetlanie 1-4 z 4
Tytuł:
Experimental tests for the occurence of convective heat transfer within the bed of rectangular steel profiles
Autorzy:
Wyczółkowski, R.
Musiał, D.
Powiązania:
https://bibliotekanauki.pl/articles/239990.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
konwekcja swobodna
liczbia Rayleigha
free convection
Rayleigh number
rectangular sections
Opis:
The paper describes tests intended to examine the occurrence of natural convection within the space occupied by 40x20 mm rectangular steel sections. Within these tests the bed of four layers of section was heated by the electric palate heater. Depending on the manner in which the heater was positioned, the tests were divided into two series. In the case of heating from above, the heat flowing through the bed is transferred only by conduction and radiation. When heating the bed from below, in addition to conduction and radiation, also a convective heat transfer will occur. Should this be the case, it will result in the intensification of the heat exchange. The results of measurements carried out have not demonstrated that the occurrence of any possible natural convection would influence the development of a temperature field in this type of charge.
Źródło:
Archives of Thermodynamics; 2012, 33, 3; 89-100
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The heat transfer and flow structure analyses of low concentration copper nanofluids in a strong magnetic field
Autorzy:
Roszko, A.
Fornalik-Wajs, E.
Powiązania:
https://bibliotekanauki.pl/articles/175547.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
nanofluids
heat transfer
flow structure
fast Fourier transform
Nusselt number ratio
thermomagnetic Rayleigh number
Opis:
Main aim of this paper was to analyze the influence of strong magnetic field on the enhancement or suppression of nanofluids transport processes. The second objective was to determine how the flow structure changed under the influence of a magnetic field. Analyzed diamagnetic nanofluids composed of distilled water and the copper nanoparticles of 40–60 nm size in three different concentrations (50, 500, and 1000 ppm). The experimental enclosure position in the magnet test section caused the most intricate interaction of the acting forces: the gravitational and magnetic buoyancy ones, and made the interpretation of results very difficult. The Nusselt number ratio and the thermomagnetic Rayleigh number were determined for heat transfer analysis, while the fast Fourier transform was performed for the nanofluid flow structure analysis. Spectral analysis for all examined nanofluids was presented. Influence of nanoparticles concentration was clearly visible, while the direct impact of magnetic field on the heat transfer and flow structure should be still investigated.
Źródło:
Transactions of the Institute of Fluid-Flow Machinery; 2015, 128; 29-42
0079-3205
Pojawia się w:
Transactions of the Institute of Fluid-Flow Machinery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of aspect ratio of enclosure on free convection from horizontal cylinders in Bingham plastic fluids
Autorzy:
Baranwal, Ashok Kumar
Gupta, Anoop Kumar
Tiwari, Anurag Kumar
Melnik, Roderick
Powiązania:
https://bibliotekanauki.pl/articles/2173430.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Bingham plastic fluids
aspect ratio
Rayleigh number
Nusselt number
natural convection
płyn plastikowy Bingham
współczynnik proporcji
liczba Rayleigha
liczba Nusselta
naturalna konwekcja
Opis:
Heat transfer in steady free convection from differentially heated cylinders enclosed in a rectangular duct filled with Bingham plastic fluids has been solved numerically for the ranges of the dimensionless groups as, Rayleigh number, 102 Ra 106; Prandtl number, 10 Pr 100 and, Bingham number, 0 Bn 50 for aspect ratios AR = 05, 0.6, 0.7, 0.8, 0.9 and 2. The streamlines, isotherm contours, yield surfaces, local and average Nusselt numbers were analysed and discussed. It is found that as the aspect ratio of the enclosure increases from 0.5 to 0.9, the average Nusselt number on the surface of the hot cylinder increases as a larger amount of fluid takes part in convection. Moreover, at sufficiently large Bingham numbers, yield stress forces dominate over buoyancy causing the flow to cease and thus the Nusselt number approaches its conduction limit. Finally, the Nusselt number approaches its conduction limit once the maximum Bingham number is reached.
Źródło:
Chemical and Process Engineering; 2022, 43, 2; 271--277
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of components effecting free convection intensity in steel rectangular sections
Autorzy:
Wyczółkowski, R.
Powiązania:
https://bibliotekanauki.pl/articles/240388.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
free convection
Rayleigh number
section bundles
effective thermal conductivity
heat treatment
konwekcja swobodna
liczbia Rayleigha
efektywna przewodność cieplna
obróbka cieplna
Opis:
Free convection is one of the heat transfer modes which occurs within the heat-treated bundles of steel rectangular section. A comprehensive study of this phenomenon is necessary for optimizing the heating process of this type of charge. The free convection intensity is represented by the Rayleigh number Ra. The value of this criterion depends on the following parameters: the mean section temperature, temperature difference within the section, kinematic coefficient of viscosity, volume expansion coefficient and the Prandtl number. The paper presents the analysis of the impact of these factors on free convection in steel rectangular sections. The starting point for this analysis were the results of experimental examinations. It was found that the highest intensity of this process occurs for the temperature of 100°C. This is mainly caused by changes in the temperature difference observed in the area of sections and changes in kinematic coefficient of viscosity of air. The increase in the value of the Rayleigh number criterion at the initial stage is attributable to changes in the parameter of temperature difference within the section. After exceeding 100°C, the main effect on convection is from changes in air viscosity. Thus, with further increase in temperature, the Rayleigh number starts to decline rapidly despite further rise in the difference in temperature.
Źródło:
Archives of Thermodynamics; 2015, 36, 3; 105-121
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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