Effective thermal conductivity for anisotropic granular porous media using fractal concepts

Conference · Tue Jul 01 04:00:00 EDT 1997

OSTI ID:20014429

Sabau, A S; Tao, Y X; Liu, G; Vidhuvalavan, G

The use of granular porous media in chemical processes, thermal insulation, heat exchangers, and nuclear reactor fuel rods has led to the development of correlations for thermophysical properties, such as thermal conductivity. These correlations are essential in the prediction of heat and mass transfer involving porous media. Analytical correlations are derived for the effective thermal conductivity of anisotropic, Granular Porous Media (GPM). The correlations proposed, which can be apply in general to any porous media material, are used to determine the effective thermal conductivity of GPM that are formed by semi-cylindrical ice particles. Pictures of the cross-section of GPM provide digital data for measuring local fractal dimensions. Local fractal dimensions are used to determine an equivalent three-dimensional Representative Unit Cell (RUC) for the GPM considered. A simplified analysis of heat conduction at the RUC level provide an analytical expression for the effective heat transfer coefficient. Estimates for the effective thermal conductivity by the use of the models are discussed and compared with various models known in literature. Finally, results for anisotropic thermal conductivities, which are obtained by the use of fractal correlations, are discussed.

• Research Organization: Tennessee State Univ., Nashville, TN (US)
• Sponsoring Organization: National Aeronautics and Space Administration
• OSTI ID: 20014429
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
42 ENGINEERING
ANISOTROPY
CORRELATIONS
FRACTALS
GRANULAR MATERIALS
HEAT TRANSFER
MASS TRANSFER
POROUS MATERIALS
THEORETICAL DATA
THERMAL CONDUCTIVITY