Transfer of thermal fluctuations through the building partition formed by periodic composite material

Kula, Dorota; Wodzyński, Łukasz

doi:10.22630/aspa.2020.19.1.3

Cited by 3 publications

(3 citation statements)

References 5 publications

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“…The starting point for the analysis is the measurement results of the effective thermal conductivity performed with the use of a guarded hot plate apparatus. This parameter is commonly used in the theory of porous [2,23,24] and nonhomogeneous [25][26][27] media. To perform the measurement of the effective thermal conductivity a guarded hot plate apparatus in a one side mode was used [28,29].…”

Section: Methodsmentioning

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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Section: Methodsmentioning

confidence: 99%

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

2022

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“…Therefore, the basic thermal property of a porous charge is an effective thermal conductivity k ef . This parameter is widely used in the analysis of porous and nonhomogeneous media [20][21][22], and in contrast to the thermal conductivity of homogenous substances, it is not a material characteristic [23,24]. The value of the k ef coefficient of some granular media is a function of complex heat transfer mechanisms connected with their structure, chemical composition, and above all, with the temperature.…”

Section: Introductionmentioning

confidence: 99%

The Review of Chosen Methods Used to Investigate Heat Transfer in a Steel Porous Charge

et al. 2022

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The paper presents chosen experimental and model methods of investigating heat transfer in a steel porous charge. The results of this investigation provide information on both the qualitative and quantitative course of the analysed processes of heat exchange. The parameters which characterise the analysed phenomenon in a quantitative manner, among others, are: The effective thermal conductivity kef, the thermal contact resistance Rct and Nusselt number Nu. It has been established that it is not possible to use literature models in order to determine the kef coefficient. The authors present their own model of effective thermal conductivity. The above-mentioned parameters for a porous charge reach the values within the following ranges: kef: 1.0–8.5 W/(m×K); Rct: 0.0019–0.0057 (m2×K)/W; Nu: 1.2–7.1.

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“…It is possible to simplify this description considerably by introducing the notion of the effective thermal conductivity kef. This parameter is commonly used in the theory of porous [6][7][8] and nonhomogeneous [9][10][11] media. By using the effective thermal conductivity it is possible to describe a transient heat transfer within a bundle of bars [12].…”

Section: Introductionmentioning

confidence: 99%

Analysing the Contact Conduction Influence on the Heat Transfer Intensity in the Rectangular Steel Bars Bundle

et al. 2021

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Bundles of steel bars, besides metal foams, are an example of cellular solids. Such bundles constitute a charge during the heat treatment of bars. The paper presents a mathematical model of transient heat transfer in a bundle of rectangular steel bars based on the energy balance method. The key element of this model is the procedure of determining the effective thermal conductivity using the electrical analogy. Different mechanisms of heat transfer occurring within the analysed medium (conduction in steel and contact conduction) are assigned corresponding thermal resistances. The discussed procedure involves expressing these resistances with the use of arithmetic relationships describing their changes in the temperature function. Thermal contact resistance has been described with the use of the relationships determined experimentally. As a result of the performed calculations, the influence of contact conduction between the adjacent bars and bundle arrangement on its heating time was established. The results of the calculations show that the heating time of bundles can be lowered by 5–40% as a result of a decrease in the thermal contact resistance. This effect depends on the bar size and bundle arrangement. From the practical point of view, the analysed problem is connected with the optimization of the heat treatment processes of steel bars.

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Transfer of thermal fluctuations through the building partition formed by periodic composite material

Abstract:

Cited by 3 publications

References 5 publications

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

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

The Review of Chosen Methods Used to Investigate Heat Transfer in a Steel Porous Charge

Analysing the Contact Conduction Influence on the Heat Transfer Intensity in the Rectangular Steel Bars Bundle

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