Computational Model of Heat Conduction in the Steel Round Bar Bundle

lkowski, R. Wyczó; La, Martynov; Boryca, J.

doi:10.12693/aphyspola.136.1001

Cited by 4 publications

(4 citation statements)

References 6 publications

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“…Below approximately 500 °C, the key heat exchange process, in terms of intensity, is conductive heat transfer. However, as previously demonstrated by the authors in their earlier publications [11,38,41,44], above 500 °C, the most significant influence on the heating process of the bundle is thermal radiation. Thus, the analysis of conductive heat transfer within the temperature range chosen by the authors, i.e., from 20 to 600 °C, is highly justified.…”

Section: Resultsmentioning

confidence: 56%

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Experimental and Theoretical Studies of the Thermal Contact Conductance for Bundles of Round Steel Bars

Wyczółkowski,

Bagdasaryan,

Strycharska

2023

Materials

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The paper presents investigations devoted to the analysis of the thermal contact conduction in a bundle of round steel bars. The phenomenon can be expressed quantitatively with the use of thermal contact conductance (hct). The starting points for the presented analysis were the results of the experimental measurements of the effective thermal conductivity. The measurements were performed for samples of a medium in the form of flat packed beds of bars with three different arrangements: staggered, in-line, and crossed and four bar diameters: 10, 20, 30, and 40 mm. Next, a mathematical model was developed, thanks to which the values of the hct coefficient were calculated for the analyzed cases. This approach consists in analyzing thermal resistances in the medium model, which is defined with an elementary cell. It was established that the value of the hct coefficient in the temperature range of 50–600 °C changes within the range of 50–175 W/(m2·K), and it decreases with an increase in the bar diameter. The final effect of the present study was to develop generalized approximation equations describing changes in thermal contact conductance in the heated bar bundle simultaneously in the temperature and bar diameter function.

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Section: Resultsmentioning

confidence: 56%

“…The method of calculating the resistances R br and R gs has been described in the work [41]. These resistances take into consideration the thermal conductivity of bar material k br and gas k gs , which fills the voids.…”

Section: Analytical Modelmentioning

confidence: 99%

Experimental and Theoretical Studies of the Thermal Contact Conductance for Bundles of Round Steel Bars

Wyczółkowski,

Bagdasaryan,

Strycharska

2023

Materials

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“…Energies 2021, 14, x FOR PEER REVIEW The method of determining the thermal conduction resistances for all ele the cell (these resistances in Figure 3 are shown in gray) is described in detai When calculating these resistances, one should take into account that the bar conductivity ks and the gas thermal conductivity kg vary with temperature chang case analyzed, it was assumed that the material of the bars is low-carbon steel S with a maximum carbon content of 0.2% [18], whereas the gas phase is amb Thermal conductivity ks of the assumed grade of steel and thermal conductivi are identified with Equations ( 10) and (11) [19]: The method of determining the thermal conduction resistances for all elements in the cell (these resistances in Figure 3 are shown in gray) is described in detail in [17]. When calculating these resistances, one should take into account that the bar thermal conductivity k s and the gas thermal conductivity k g vary with temperature change.…”

Section: Methodsmentioning

confidence: 99%

Determination of the Radiation Exchange Factor in the Bundle of Steel Round Bars

et al. 2021

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A method to obtain a radiation exchange factor FR in the bundle of steel round bars is presented. This parameter is required for determination of the radiative thermal conductivity krd, which is one of the basic thermal properties of the bar bundles. In the presented approach, the analyzed parameter is calculated indirectly. The initial point for calculations is the geometric model of the medium defined as a unit cell. Then, for the elements present in this cell, the thermal resistance of both conduction and radiation is determined. The radiation resistance is calculated from the radiosity balance of the surfaces enclosing the analyzed system. On this basis, the radiation thermal conductivity krd is calculated. Next, taking into account the bar diameter, the value of parameter FR is also determined. The analysis is performed at the process temperature range of 200 to 800 °C for three bar diameters: 10, 20 and 30 mm, and for the three porosities of the bundle. Different emissivity of bars in the range of 0.5 to 0.9 was also taken into account. Finally, a relationship that allows calculating the FR factor correlated with the emissivity of the bars and the bundle porosity was established. The krd obtained from the methodology presented and compared with the values calculated directly do not exceed 9%; however, after averaging over the entire temperature range of the process, the difference does not exceed 0.2%.

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“…The problem of heat transfer in round bar bundles has been widely analysed by the authors. The works published in this field concerned: determination of the effective thermal conductivity [13][14][15], heat conduction [16], thermal radiation [17][18][19] and free convection [20]. The present article is concerned with the problem of heat transfer in a bundle of flat bars.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Thermal Contact Conductance in a Bundle of Flat Steel Bars

2022

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The phenomenon of thermal contact conduction in two-phase (fluid-solid) media determines many technological processes. An example of such a process is heat treatment of steel bars, when a heated charge has a form of a packed bundle. In order to determine the optimal heating curve it is necessary to have knowledge about the intensity of transfer through contact areas of the bars. This phenomenon is quantified by the thermal contact conductance hct. The article describes the methodology of determining the hct coefficient for bundles of flat steel bars. The starting point for the analysis is the measurement of the effective thermal conductivity kef performed for 5 × 20 mm and 10 × 20 mm bars. Individual samples of the same bars differed in arrangement. The analytical investigation used the concept of an elementary cell. This approach consisted in analysing resistances for individual heat transfer types: conduction, contact conduction and radiation. Based on the performed calculations it has been established that the value of the hct coefficient for the analysed samples is within the range 128–472 W/(m2 K). Changes of the hct coefficient in the temperature range 25–700 °C can be described with a second degree polynomial. It has been established that hct assumes maximum values in the temperature range from 300 °C to 400 °C.

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Computational Model of Heat Conduction in the Steel Round Bar Bundle

Cited by 4 publications

References 6 publications

Experimental and Theoretical Studies of the Thermal Contact Conductance for Bundles of Round Steel Bars

Experimental and Theoretical Studies of the Thermal Contact Conductance for Bundles of Round Steel Bars

Determination of the Radiation Exchange Factor in the Bundle of Steel Round Bars

Experimental Investigation of Thermal Contact Conductance in a Bundle of Flat Steel Bars

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