Numerical analysis of heat transfer by conduction and natural convection in loose-fill fiberglass insulation--effects of convection on thermal performance
A two-dimensional code for solving equations of convective heat transfer in porous media is used to analyze heat transfer by conduction and convection in the attic insulation configuration. The particular cases treated correspond to loose-fill fiberglass insulation, which is characterized by high porosity and air permeability. The effects of natural convection on the thermal performance of the insulation are analyzed for various densities, permeabilities, and thicknesses of insulation. With convection increasing the total heat transfer through the insulation, the thermal resistance was found to decrease as the temperature difference across the insulating material increases. The predicted results for the thermal resistance are compared with data obtained in the large-scale climate simulator at the Roof Research Center using the attic test module, where the same phenomenon has already been observed. The way the wood joists within the insulation influence the start of convection is studied for differing thermophysical and dynamic properties of the insulating material. The presence of wood joists induces convection at a lower temperature difference.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 5342143
- Report Number(s):
- ORNL/CON-338; ON: DE92014938
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
FIBERGLASS
HEAT TRANSFER
NUMERICAL ANALYSIS
THERMAL INSULATION
DENSITY
NATURAL CONVECTION
PERFORMANCE
PERMEABILITY
POROSITY
STRUCTURAL BEAMS
THERMAL CONDUCTION
THICKNESS
WOOD
COMPOSITE MATERIALS
CONVECTION
DIMENSIONS
ENERGY TRANSFER
MASS TRANSFER
MATERIALS
MATHEMATICS
PHYSICAL PROPERTIES
320107* - Energy Conservation
Consumption
& Utilization- Building Systems- (1987-)
360606 - Other Materials- Physical Properties- (1992-)