Thermal conductivity, in porous

Much effective work have been done to research on the permeability and thermal conduction in porous media. After Darcy-Law was found, Forchhermer (Forchheimer 1901) and Brink-... 

Wang W, Li D, Tian M, Lee Y-C, Yang R (2012) Wafer-scale fabrication of silicon nanowire arrays with controllable dimensions. Appl Surf Sci 258 8649-8655 Weisse JM et al. Thermal conductivity in porous silicon nanowire arrays. Nanoscale Res Lett 7 554 Weisse JM, Lee CH, Kim DR, Zheng X (2012) Fabrication of flexible and vertical silicon nanowire electronics. Nano Lett 12 3339-3343... 

Effective Thermal Conductivities of Porous Catalysts. The effective thermal conductivity of a porous catalyst plays a key role in determining whether or not appreciable temperature gradients will exist within a given catalyst pellet. By the term effective thermal conductivity , we imply that it is a parameter characteristic of the porous solid structure that is based on the gross geometric area of the pellet perpendicular to the direction of heat transfer. For example, if one considers the radial heat flux in a spherical pellet one can say that... 

Thermal conductivities of porous oxide catalysts, which are of major practical interest, (at atmospheric pressure in air) are within the range 0.2 - 0.5 W nr K 1. The spread of values of the thermal conductivity is remarkably small for the wide range of catalysts studied by several investigators. It does not vary greatly with major differences in void fraction and pore size distribution. 

K (ris effective thermal conductivity of porous material, which takes into account thermal conductivity of the solid matrix and gas in pores and radiation in the pore system, as shown in Eq. 12 ... 

Meanwhile, the effective thermal conductivites of fabrics can be studied for varying regains. Regain is the mass of water present expressed as a percentage of the dry weight of the material. The effective thermal conductivities for porous acrylic, polypropylene, wool, and cotton is shown in Figure 1. 

The thermal conductivity of solids and fluids varies with temperature, and representative values should be selected for the temperature range of interest (Rg. 24.2). Measured thermal conductivity of porous materials is a combination of conduction and convection occurring within the pore fluids. The change in measured... 

The rate of heat penetration through the char layer is in proportion to the thermal properties and porosity of the char (43,44) since the mode of heat transfer to the unreacted lignin/char interface is by ordinary conduction through the char rather than by electron bombardment. Thus the apparent rate of devolatilization as measured by weight loss kinetics is slower (k > 1-10 min ) than one might predict from electron pseudotemperatures in the gas plasma. After an initial period, these apparent devolatilization rates are consistent with rates for conduction in porous char (44,49). 

DISTRIBUTION OF THE EFFECTIVE THERMAL CONDUCTIVITY IN A POROUS INSULATION SYSTEM SUBJECTED TO INTERNAL VAPOR CIRCULATION... 

Distribution of the Effective Thermal Conductivity in a Porous Insulation System... 

Papadakis, G., Giaglaras, P, and Kyritsis, S., A numerical method for determining thermal conductivity of porous media from in-situ measurements using a cylindrical heat source, J. Agric. Eng. Res., 45 281-293 (1990). 

This common trend can be explained considering that the total apparent thermal conductivity in micro porous materials is the sum of four physical contributions, i.e., the thermal conductivity through the solid,, the thermal conductivity through the gaseous phase, Ag, the thermal conductivity by thermal radiation, and by gas convection. A,. ... 

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