U.S. Department of Energy Office of Scientific and Technical Information
Thermal conductivity of two-dimensional disordered fibrous materials defined by interfiber thermal contact conductance and intrinsic conductivity of fibers
A general framework for the theoretical analysis and numerical calculations of the effective thermal conductivity of two-dimensional homogeneous and isotropic disordered fibrous materials is developed in this work based on the model of random contacts between soft-core spherocylinders. The analysis accounts for the interfiber contact conductance and intrinsic conductivity of fibers and is performed in a wide space of governing parameters that includes the fiber aspect ratio, Biot number calculated for a single thermal contact between fibers, and material density ranging from values corresponding to the percolation threshold up to those characteristic of dense fiber networks. For dense networks, exact theoretical equations for the thermal conductivity of materials composed of spherocylinders with an arbitrary aspect ratio and Biot number are derived. The effect of the intrinsic conductivity of fibers on the thermal transport in fibrous materials is found to depend on the density of contacts and can be significant in sufficiently dense fiber networks even if the Biot number for a single thermal contact is small. Semiempirical corrections to the theoretical equations are derived for small and moderate fiber densities. The power law exponent describing the approximate dependence of the conductivity on the density parameter is found to vary from values close to 1 up to values exceeding 2 when evaluated within different finite ranges of the density parameter. This finding explains the variability of scaling laws for thermal conductivity of fibrous materials suggested in the literature based on numerical simulations performed in different regions of the space of material parameters.
Volkov, Alexey N. and Zhigilei, Leonid V.. "Thermal conductivity of two-dimensional disordered fibrous materials defined by interfiber thermal contact conductance and intrinsic conductivity of fibers." Journal of Applied Physics, vol. 127, no. 6, Feb. 2020. https://doi.org/10.1063/1.5136238
Volkov, Alexey N., & Zhigilei, Leonid V. (2020). Thermal conductivity of two-dimensional disordered fibrous materials defined by interfiber thermal contact conductance and intrinsic conductivity of fibers. Journal of Applied Physics, 127(6). https://doi.org/10.1063/1.5136238
Volkov, Alexey N., and Zhigilei, Leonid V., "Thermal conductivity of two-dimensional disordered fibrous materials defined by interfiber thermal contact conductance and intrinsic conductivity of fibers," Journal of Applied Physics 127, no. 6 (2020), https://doi.org/10.1063/1.5136238
@article{osti_1608704,
author = {Volkov, Alexey N. and Zhigilei, Leonid V.},
title = {Thermal conductivity of two-dimensional disordered fibrous materials defined by interfiber thermal contact conductance and intrinsic conductivity of fibers},
annote = {A general framework for the theoretical analysis and numerical calculations of the effective thermal conductivity of two-dimensional homogeneous and isotropic disordered fibrous materials is developed in this work based on the model of random contacts between soft-core spherocylinders. The analysis accounts for the interfiber contact conductance and intrinsic conductivity of fibers and is performed in a wide space of governing parameters that includes the fiber aspect ratio, Biot number calculated for a single thermal contact between fibers, and material density ranging from values corresponding to the percolation threshold up to those characteristic of dense fiber networks. For dense networks, exact theoretical equations for the thermal conductivity of materials composed of spherocylinders with an arbitrary aspect ratio and Biot number are derived. The effect of the intrinsic conductivity of fibers on the thermal transport in fibrous materials is found to depend on the density of contacts and can be significant in sufficiently dense fiber networks even if the Biot number for a single thermal contact is small. Semiempirical corrections to the theoretical equations are derived for small and moderate fiber densities. The power law exponent describing the approximate dependence of the conductivity on the density parameter is found to vary from values close to 1 up to values exceeding 2 when evaluated within different finite ranges of the density parameter. This finding explains the variability of scaling laws for thermal conductivity of fibrous materials suggested in the literature based on numerical simulations performed in different regions of the space of material parameters.},
doi = {10.1063/1.5136238},
url = {https://www.osti.gov/biblio/1608704},
journal = {Journal of Applied Physics},
issn = {ISSN 0021-8979},
number = {6},
volume = {127},
place = {United States},
publisher = {American Institute of Physics (AIP)},
year = {2020},
month = {02}}
Univ. of Virginia, Charlottesville, VA (United States)
Sponsoring Organization:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V); National Aeronautics and Space Administration (NASA); National Science Foundation (NSF)
Grant/Contract Number:
EE0008195
OSTI ID:
1608704
Alternate ID(s):
OSTI ID: 1598737
Journal Information:
Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 6 Vol. 127; ISSN 0021-8979
ASME 2009 International Mechanical Engineering Congress and Exposition, Volume 12: Micro and Nano Systems, Parts A and Bhttps://doi.org/10.1115/IMECE2009-11282