Abstract
The development of insulation materials with low effective thermal conductivity is essential for energy savings in various applications, including buildings, food services, pipe insulation, and refrigeration. Such materials can be developed by using micro-or nanoporous structures, as well as low–thermal conductivity gases and/or reduced pressure. A va-riety of effective medium approximation (EMA) models have been developed to study thermal transport through solid in porous structures. However, in many cases, the impacts of porosity on solid conduction are not well predicted by EMA models because of the assumptions made for simplification. Furthermore, the results can vary by a factor of up to 1.5, depending on the morphology of the pores. Hence, proper guidance is needed to choose the appropriate EMA model for a given morphology. This work presents a finite element method study using COMSOL Multiphysics software for various geometries, including hollow cubes, overlapping hollow spheres (normally stacked and tightly packed), and Voronoi structures, and compares the results to those obtained from various EMA models. Simulation results for the hollow cubes and Voronoi structures matched well with the Maxwell-Eucken and Russell model. The results for hollow spheres closely matched the Bauer model and the Glicksman model with fitting parameters. This work provides guidance on analyzing and designing insulation materials for energy savings in the future.
| Original language | English |
|---|---|
| Pages (from-to) | 19-32 |
| Number of pages | 14 |
| Journal | Computational Thermal Sciences |
| Volume | 13 |
| Issue number | 6 |
| DOIs | |
| State | Published - 2021 |
Funding
This work is supported by the project entitled, “Models to Evaluate and Guide the Development of Low Thermal Conductivity Materials for Building Envelopes,” funded by the Building Technologies Office, Office of Energy Efficiency and Renewable Energy, of the U.S. Department of Energy. This work is supported by the project entitled, “Models to Evaluate and Guide the Development of Low Thermal Conductivity Materials for Building Envelopes,” funded by the Building Technologies Office, Office of Energy Efficiency and Renewable Energy, of the U.S. Department of Energy. This paper has been authored by UT-Battelle, LLC, under contract with the U.S. Department of Energy (DOE). The U.S. Government retains and the publisher, by accepting the paper for publication, acknowledges that the U.S. Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this paper or allow others to do so, for U.S. Government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads /doe-public-access-plan).
| Funders | Funder number |
|---|---|
| DOE Public Access Plan | |
| Development of Low Thermal Conductivity Materials for Building Envelopes | |
| U.S. Government | |
| U.S. Department of Energy | |
| Office of Energy Efficiency and Renewable Energy | |
| Building Technologies Office |
Keywords
- conduction heat transfer in porous materials
- effective medium approximations
- finite element method
- low thermal conductivity
