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Wyszukujesz frazę "wspolczynnik przenikania ciepla" wg kryterium: Temat


Wyświetlanie 1-4 z 4
Tytuł:
Measurement of heat flux density and heat transfer coefficient
Autorzy:
Taler, D.
Taler, J.
Grądziel, S.
Powiązania:
https://bibliotekanauki.pl/articles/240288.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
pomiar temperatury
strumień ciepła
współczynnik przenikania ciepła
zagadnienie odwrotne
heat flux
heat transfer coefficient
inverse problem
temperature measurement
Opis:
The paper presents the solution to a problem of determining the heat flux density and the heat transfer coefficient, on the basis of temperature measurement at three locations in the flat sensor, with the assumption that the heat conductivity of the sensor material is temperature dependent. Three different methods for determining the heat flux and heat transfer coefficient, with their practical applications, are presented. The uncertainties in the determined values are also estimated.
Źródło:
Archives of Thermodynamics; 2010, 31, 3; 3-18
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative study of heat transfer and pressure drop during flow boiling and flow condensation in minichannels
Autorzy:
Mikielewicz, D.
Andrzejczyk, R.
Jakubowska, B.
Mikielewicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/240815.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
two-phase pressure drops
heat transfer coefficient
boiling
condensation
dwufazowy spadek ciśnienia
współczynnik przenikania ciepła
wrzenie
kondensacja
Opis:
In the paper a method developed earlier by authors is applied to calculations of pressure drop and heat transfer coefficient for flow boiling and also flow condensation for some recent data collected from literature for such fluids as R404a, R600a, R290, R32,R134a, R1234yf and other. The modification of interface shear stresses between flow boiling and flow condensation in annular flow structure are considered through incorporation of the so called blowing parameter. The shear stress between vapor phase and liquid phase is generally a function of nonisothermal effects. The mechanism of modification of shear stresses at the vapor-liquid interface has been presented in detail. In case of annular flow it contributes to thickening and thinning of the liquid film, which corresponds to condensation and boiling respectively. There is also a different influence of heat flux on the modification of shear stress in the bubbly flow structure, where it affects bubble nucleation. In that case the effect of applied heat flux is considered. As a result a modified form of the two-phase flow multiplier is obtained, in which the nonadiabatic effect is clearly pronounced.
Źródło:
Archives of Thermodynamics; 2014, 35, 3; 17-37
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of temperature and thermal stresses distribution in power boiler elements with use inverse heat conduction method
Autorzy:
Grądziel, S.
Powiązania:
https://bibliotekanauki.pl/articles/240169.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
metoda inwersji
propagacja nacisków
szybkozmienna temperatura
współczynnik przenikania ciepła
heat transfer coefficient
inverse method
stress distribution
transient temperature
Opis:
The following paper presents the method for solving one-dimensional inverse boundary heat conduction problems. The method is used to estimate the unknown thermal boundary condition on inner surface of a thick-walled Y-branch. Solution is based on measured temperature transients at two points inside the element's wall thickness. Y-branch is installed in a fresh steam pipeline in a power plant in Poland. Determination of an unknown boundary condition allows for the calculation of transient temperature distribution in the whole element. Next, stresses caused by non-uniform transient temperature distribution and by steam pressure inside a Y-branch are calculated using the finite element method. The proposed algorithm can be used for thermal-strength state monitoring in similar elements, when it is not possible to determine a 3-D thermal boundary condition. The calculated temperature and stress transients can be used for the calculation of element durability. More accurate temperature and stress monitoring will contribute to a substantial decrease of maximal stresses that occur during transient start-up and shut-down processes.
Źródło:
Archives of Thermodynamics; 2011, 32, 3; 191-200
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of flue gas recirculation on heat transfer in a supercritical circulating fluidized bed combustor
Autorzy:
Błaszczuk, A.
Powiązania:
https://bibliotekanauki.pl/articles/240532.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
heat transfer coefficient
cluster renewal approach
flue gas recirculation
circulating fluidized bed
współczynnik przenikania ciepła
recyrkulacja spalin
cyrkulacyjna warstwa fluidalna
Opis:
This paper focuses on assessment of the effect of flue gas recirculation (FGR) on heat transfer behavior in 1296t/h supercritical coal-fired circulating fluidized bed (CFB) combustor. The performance test in supercritical CFB combustor with capacity 966 MWth was performed with the low level of flue gas recirculation rate 6.9% into furnace chamber, for 80% unit load at the bed pressure of 7.7 kPa and the ratio of secondary air to the primary air SA/PA = 0.33. Heat transfer behavior in a supercritical CFB furnace between the active heat transfer surfaces (membrane wall and superheater) and bed material has been analyzed for Geldart B particle with Sauter mean diameters of 0.219 and 0.246 mm. Bed material used in the heat transfer experiments had particle density of 2700 kg/m3. A mechanistic heat transfer model based on cluster renewal approach was used in this work. A heat transfer analysis of CFB combustion system with detailed consideration of bed-to-wall heat transfer coefficient distributions along furnace height is investigated. Heat transfer data for FGR test were compared with the data obtained for representative conditions without recycled flue gases back to the furnace through star-up burners.
Źródło:
Archives of Thermodynamics; 2015, 36, 3; 61-83
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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