Computational Model of Effective Thermal Conductivity of Green Insulating Fibrous Media
Modelling effective thermal properties is crucial for optimizing the thermal performance of materials such as new green insulating fibrous media. In this study, a numerical model is proposed to calculate the effective thermal conductivity of these materials. The fibers are considered to be non-overl...
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MDPI AG
2024-01-01
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| Online Access: | https://www.mdpi.com/1996-1944/17/1/252 |
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| author | Hamidou Sankara Dominique Baillis Ousmane Coulibaly Rémi Coquard Naïm Naouar Zahia Saghrouni |
| author_facet | Hamidou Sankara Dominique Baillis Ousmane Coulibaly Rémi Coquard Naïm Naouar Zahia Saghrouni |
| author_sort | Hamidou Sankara |
| collection | DOAJ |
| description | Modelling effective thermal properties is crucial for optimizing the thermal performance of materials such as new green insulating fibrous media. In this study, a numerical model is proposed to calculate the effective thermal conductivity of these materials. The fibers are considered to be non-overlapping and randomly oriented in space. The numerical model is based on the finite element method. Particular attention is paid to the accuracy of the results and the influence of the choice of the representative elementary volume (REV) for calculation (cubic or rectangular parallelepiped slice). The calculated effective thermal conductivity of fibrous media under different boundary conditions is also investigated. A set of usual mixed boundary conditions is considered, alongside the uniform temperature gradient conditions. The REV rectangular slice and uniform temperature gradient boundary conditions provide a more accurate estimate of the effective thermal conductivity and are therefore recommended for use in place of the usual cubic representative elementary volume and the usual mixed boundary conditions. This robust model represents a principal novelty of the work. The results are compared with experimental and analytical data previously obtained in the literature for juncus maritimus fibrous media, for different fiber volume fractions, with small relative deviations of 7%. Analytical laws are generally based on simplified assumptions such as infinitely long fibers, and may neglect heat transfer between different phases. Both short and long fiber cases are considered in numerical calculations. |
| first_indexed | 2024-03-08T15:02:32Z |
| format | Article |
| id | doaj.art-84b4b13d4ce247e1932893eabe52cf83 |
| institution | Directory Open Access Journal |
| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-08T15:02:32Z |
| publishDate | 2024-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Materials |
| spelling | doaj.art-84b4b13d4ce247e1932893eabe52cf832024-01-10T15:03:09ZengMDPI AGMaterials1996-19442024-01-0117125210.3390/ma17010252Computational Model of Effective Thermal Conductivity of Green Insulating Fibrous MediaHamidou Sankara0Dominique Baillis1Ousmane Coulibaly2Rémi Coquard3Naïm Naouar4Zahia Saghrouni5LaMCoS, INSA-Lyon, CNRS UMR 5259, Université de Lyon, 69621 Villeurbanne, FranceLaMCoS, INSA-Lyon, CNRS UMR 5259, Université de Lyon, 69621 Villeurbanne, FranceLaboratoire de Physique et de Chimie de l’Environnement (ED-ST/LPCE), Université Joseph KI-ZERBO, Ouagadougou 03 BP 7021, Burkina FasoEC2 Modélisation Campus Lyon Tech, 69603 Villeurbanne, FranceLaMCoS, INSA-Lyon, CNRS UMR 5259, Université de Lyon, 69621 Villeurbanne, FranceLaboratory of Thermal and Energetic Systems Studies (LESTE), National Engineering School of Monastir, University of Monastir, 5019 Monastir, TunisiaModelling effective thermal properties is crucial for optimizing the thermal performance of materials such as new green insulating fibrous media. In this study, a numerical model is proposed to calculate the effective thermal conductivity of these materials. The fibers are considered to be non-overlapping and randomly oriented in space. The numerical model is based on the finite element method. Particular attention is paid to the accuracy of the results and the influence of the choice of the representative elementary volume (REV) for calculation (cubic or rectangular parallelepiped slice). The calculated effective thermal conductivity of fibrous media under different boundary conditions is also investigated. A set of usual mixed boundary conditions is considered, alongside the uniform temperature gradient conditions. The REV rectangular slice and uniform temperature gradient boundary conditions provide a more accurate estimate of the effective thermal conductivity and are therefore recommended for use in place of the usual cubic representative elementary volume and the usual mixed boundary conditions. This robust model represents a principal novelty of the work. The results are compared with experimental and analytical data previously obtained in the literature for juncus maritimus fibrous media, for different fiber volume fractions, with small relative deviations of 7%. Analytical laws are generally based on simplified assumptions such as infinitely long fibers, and may neglect heat transfer between different phases. Both short and long fiber cases are considered in numerical calculations.https://www.mdpi.com/1996-1944/17/1/252effective thermal conductivitythermal insulationnumerical modelhomogenizationfibrous media |
| spellingShingle | Hamidou Sankara Dominique Baillis Ousmane Coulibaly Rémi Coquard Naïm Naouar Zahia Saghrouni Computational Model of Effective Thermal Conductivity of Green Insulating Fibrous Media Materials effective thermal conductivity thermal insulation numerical model homogenization fibrous media |
| title | Computational Model of Effective Thermal Conductivity of Green Insulating Fibrous Media |
| title_full | Computational Model of Effective Thermal Conductivity of Green Insulating Fibrous Media |
| title_fullStr | Computational Model of Effective Thermal Conductivity of Green Insulating Fibrous Media |
| title_full_unstemmed | Computational Model of Effective Thermal Conductivity of Green Insulating Fibrous Media |
| title_short | Computational Model of Effective Thermal Conductivity of Green Insulating Fibrous Media |
| title_sort | computational model of effective thermal conductivity of green insulating fibrous media |
| topic | effective thermal conductivity thermal insulation numerical model homogenization fibrous media |
| url | https://www.mdpi.com/1996-1944/17/1/252 |
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