{"title":"On the dynamic thermal conductivity and diffusivity observed in heat pulse experiments","authors":"Anna Fehér, Róbert Kovács","doi":"10.1515/jnet-2023-0119","DOIUrl":null,"url":null,"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.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":null,"pages":null},"PeriodicalIF":4.3000,"publicationDate":"2024-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Non-Equilibrium Thermodynamics","FirstCategoryId":"5","ListUrlMain":"https://doi.org/10.1515/jnet-2023-0119","RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MECHANICS","Score":null,"Total":0}
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.
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.
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