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    Wyświetlanie 1-6 z 6
    Tytuł:
    Correlations for the thermal conductivity of selected steel grades as a function of temperature in the range of 0–800◦C
    Autorzy:
    Wyczółkowski, Rafał
    Strychalska, Dominika
    Bagdasaryan, Vazgen
    Powiązania:
    https://bibliotekanauki.pl/articles/2134935.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    thermal conductivity
    heat transfer
    least squares method
    thermal conduction analysis
    thermal treatment of steel
    Opis:
    Reliable knowledge of thermo-physical properties of materials is essential for the interpretation of solidification behaviour, forming, heat treatment and joining of metallic systems. It is also a precondition for precise simulation calculations of technological processes. Numerical calculations usually require the knowledge of temperature dependencies of three basic thermo-physical properties: thermal conductivity, heat capacity and density. The objective of this work is to find a correlation that fits the thermal conductivity of selected steel grades as a function of temperature (within the range of 0–800◦C) and carbon content (within the range of 0.1–0.6%). The starting point for the analysis are the experimental data on thermal conductivity taken from literature. Using the method of least squares it was possible to fit an equation which allows calculating the thermal conductivity of steel depending on the temperature and carbon content. Two kinds of equations have been analyzed: a linear one (a linear model) and a second degree polynomial (a non-linear model). The thermal conductivity obtained by linear and nonlinear models varies on average from the measured values by 3% and 2.6% respectively.
    Źródło:
    Archives of Thermodynamics; 2022, 43, 3; 29--45
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An idea of a measurement system for determining thermal parameters of heat insulation materials
    Autorzy:
    Chudzik, S.
    Minkina, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/220464.pdf
    Data publikacji:
    2011
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    thermal conductivity
    artificial neural networks
    inverse heat conduction problem
    Opis:
    The article presents the prototype of a measurement system with a hot probe, designed for testing thermal parameters of heat insulation materials. The idea is to determine parameters of thermal insulation materials using a hot probe with an auxiliary thermometer and a trained artificial neural network. The network is trained on data extracted from a nonstationary two-dimensional model of heat conduction inside a sample of material with the hot probe and the auxiliary thermometer. The significant heat capacity of the probe handle is taken into account in the model. The finite element method (FEM) is applied to solve the system of partial differential equations describing the model. An artificial neural network (ANN) is used to estimate coefficients of the inverse heat conduction problem for a solid. The network determines values of the effective thermal conductivity and effective thermal diffusivity on the basis of temperature responses of the hot probe and the auxiliary thermometer. All calculations, like FEM, training and testing processes, were conducted in the MATLAB environment. Experimental results are also presented. The proposed measurement system for parameter testing is suitable for temporary measurements in a building site or factory.
    Źródło:
    Metrology and Measurement Systems; 2011, 18, 2; 261-273
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigation of non-Fourier thermal waves interaction in a solid material
    Autorzy:
    Lenarczyk, Marcin
    Domański, Roman
    Powiązania:
    https://bibliotekanauki.pl/articles/240472.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    non-Fourier equation
    heat waves
    hyperbolic heat conduction
    thermal wave interaction
    fale cieplne
    przewodzenie ciepła
    Opis:
    In this paper, effects of non-Fourier thermal wave interactions in a thin film have been investigated. The non-Fourier, hyperbolic heat conduction equation is solved, using finite difference method with an implicit scheme. Calculations have been carried out for three geometrical configurations with various film thicknesses. The boundary condition of a symmetrical temperature step-change on both sides has been used. Time history for the temperature distribution for each investigated case is presented. Processes of thermal wave propagation, temperature peak build-up and reverse wave front creation have been described. It has been shown that (i) significant temperature overshoot can appear in the film subjected to symmetric thermal load (which can be potentially dangerous for reallife application), and (ii) effect of temperature amplification decreases with increased film thickness.
    Źródło:
    Archives of Thermodynamics; 2019, 40, 1; 115-126
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Identification of the Thermal Conductivity Coefficient in the Heat Conduction Model with Fractional Derivative
    Autorzy:
    Brociek, R.
    Słota, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/382791.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    heat conduction equation
    thermal conductivity coefficient
    inverse problem
    fractional derivative
    thermal conductivity
    model przewodzenia ciepła
    współczynnik przewodzenia ciepła
    problem odwrotny
    pochodna ułamkowa
    przewodność termiczna
    Opis:
    Main goal of the paper is to present the algorithm serving to solve the heat conduction inverse problem. Authors consider the heat conduction equation with the Riemann-Liouville fractional derivative and with the second and third kind boundary conditions. This type of model with fractional derivative can be used for modelling the heat conduction in porous media. Authors deal with the heat conduction inverse problem, which, in this case, consists in identifying an unknown thermal conductivity coefficient. Measurements of temperature, in selected point of the region, are the input data for investigated inverse problem. Basing on this information, a functional describing the error of approximate solution is created. Minimizing of this functional is necessary to solve the inverse problem. In the presented approach the Ant Colony Optimization (ACO) algorithm is used for minimization.
    Źródło:
    Archives of Foundry Engineering; 2019, 3; 38-42
    1897-3310
    2299-2944
    Pojawia się w:
    Archives of Foundry Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Determination of Thermal Diffusivity of Austenitic Steel Using Pulsed Infrared Thermography
    Wyznaczanie dyfuzyjności cieplnej stali austenitycznej przy wykorzystaniu aktywnej termografii podczerwieni
    Autorzy:
    Kochanowski, K.
    Oliferuk, W.
    Płochocki, Z.
    Adamowicz, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/354398.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    thermal diffusivity
    pulsed infrared thermography
    heat conduction
    austenitic steel
    dyfuzyjność cieplna
    aktywna termografia podczerwona
    przewodzenia ciepła
    stal austenityczno-ferrytyczna
    Opis:
    The simple method of determining thermal diffusivity of solid materials at room temperature using the pulsed infrared thermography (IRT) is proposed. The theoretical basis of the method and experimental results are presented. The study was conducted on austenitic steel 316L. Theobtained results show that the thermal diffusivity value of the tested steel determined by means of pulsed infrared thermography is very approximate to the values given in the literature, obtained by using more complicated methods. The differences between these values are 0.5%.
    W niniejszej pracy przedstawiono prostą metodę wyznaczania dyfuzyjności cieplnej ciał stałych w temperaturze pokojowej przy wykorzystaniu aktywnej termografii podczerwieni. Zaprezentowane zostały teoretyczne podstawy metody oraz wyniki badań doświadczalnych. Badanie przeprowadzono dla stali austenitycznej 316L. Otrzymane rezultaty pokazują, że wyznaczona wartość dyfuzyjności cieplnej badanej stali jest bardzo bliska wartościom podanym w literaturze, otrzymanym za pomocą bardziej skomplikowanych metod. Różnica między tymi wartościami sięga zaledwie 0,5%.
    Źródło:
    Archives of Metallurgy and Materials; 2014, 59, 3; 893-897
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optimum heating of cylindrical pressure components weakened by holes
    Autorzy:
    Dzierwa, P.
    Taler, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/240098.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    kotły
    naprężenie termiczne
    normy
    odwrotne zagadnienia przewodzenia ciepła
    optymalizacja nagrzewania
    zbiorniki ciśnieniowe
    boiler standards
    heating optimization
    inverse heat conduction problem
    pressure vessels
    thermal stress
    Opis:
    A method for determining time-optimum medium temperature changes is presented. The heating of the pressure elements will be conducted so that the circumferential stress caused by pressure and fluid temperature variations at the edge of the opening at the point of stress concentration, do not exceed the allowable value. In contrast to present standards, two points at the edge of the opening are taken into consideration. The first point, P[1], is located at the cross section and the second, P[2], at the longitudinal section of the vessel. It will be shown that the optimum temperature courses should be determined with respect to the total circumferential stress at the point P[2], and not, as in the existing standards due to the stress at the point P[1]. Optimum fluid temperature changes are assumed in the form of simple time functions. For practical reasons the optimum temperature in the ramp form is preferred. It is possible to increase the fluid temperature stepwise at the beginning of the heating process and then increase the fluid temperature with the constant rate. Allowing stepwise fluid temperature increase at the beginning of heating ensures that the heating time of a thick-walled component is shorter than heating time resulting from the calculations according to EN 12952-3 European Standard. @eng
    Źródło:
    Archives of Thermodynamics; 2012, 33, 3; 111-121
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-6 z 6

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