On the dynamic thermal conductivity and diffusivity observed in heat pulse experiments

IF 4.3 3区工程技术 Q1 MECHANICS

Journal of Non-Equilibrium Thermodynamics Pub Date : 2024-03-11 DOI:10.1515/jnet-2023-0119

Anna Fehér, Róbert Kovács

引用次数: 0

Abstract

Determining the thermal properties of materials with complex structures is still a major engineering challenge today. The well-known heat pulse experiment can be used to determine the thermal diffusivity by measuring the temperature history as a thermal response for a fast excitation. However, the evaluation of the measurements can be challenging, especially when dealing with non-homogeneous samples. The thermal behavior of such heterogeneous materials may exhibit a response including two-time scales. Therefore, the Fourier equation is not necessarily applicable. The simplest possible alternatives are the 2-temperature models the Guyer–Krumhansl and Jeffreys heat equations. In the present paper, we focus on the interpretation of the Jeffreys heat equation; studying its analytical solution, we present a fitting method for determining the unknown parameters. We also discuss its relation with the other two heat equations, and we offer an interpretation of how to characterize the transient response of heterogeneous materials.

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热脉冲实验中观察到的动态热导率和扩散率

确定具有复杂结构的材料的热特性仍然是当今工程领域的一大挑战。众所周知的热脉冲实验可以通过测量温度历史作为快速激励的热反应来确定热扩散率。然而，对测量结果进行评估是一项挑战，尤其是在处理非均质样品时。这类异质材料的热行为可能表现出包括两个时间尺度的响应。因此，傅里叶方程并不一定适用。最简单的替代方法是 Guyer-Krumhansl 和 Jeffreys 热方程的双温模型。在本文中，我们将重点解释杰弗里斯热方程；研究其解析解，并提出一种确定未知参数的拟合方法。我们还讨论了它与其他两个热方程的关系，并就如何描述异质材料的瞬态响应提供了解释。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of Non-Equilibrium Thermodynamics 物理-力学

CiteScore

9.10

自引率

18.20%

发文量

审稿时长

1 months

期刊介绍： The Journal of Non-Equilibrium Thermodynamics serves as an international publication organ for new ideas, insights and results on non-equilibrium phenomena in science, engineering and related natural systems. The central aim of the journal is to provide a bridge between science and engineering and to promote scientific exchange on a) newly observed non-equilibrium phenomena, b) analytic or numeric modeling for their interpretation, c) vanguard methods to describe non-equilibrium phenomena. Contributions should – among others – present novel approaches to analyzing, modeling and optimizing processes of engineering relevance such as transport processes of mass, momentum and energy, separation of fluid phases, reproduction of living cells, or energy conversion. The journal is particularly interested in contributions which add to the basic understanding of non-equilibrium phenomena in science and engineering, with systems of interest ranging from the macro- to the nano-level. The Journal of Non-Equilibrium Thermodynamics　has recently expanded its scope to place new emphasis on theoretical and experimental investigations of non-equilibrium phenomena in thermophysical, chemical, biochemical and abstract model systems of engineering relevance. We are therefore pleased to invite submissions which present newly observed non-equilibrium phenomena, analytic or fuzzy models for their interpretation, or new methods for their description.