Detailed and simplified models for evaluation of effective thermal conductivity of open-cell porous foams at high temperatures in presence of thermal radiation

2014 ◽  
Vol 68 ◽  
pp. 612-624 ◽  
Author(s):  
Miguel A.A. Mendes ◽  
Prabal Talukdar ◽  
Subhashis Ray ◽  
Dimosthenis Trimis
Keyword(s):  
Thermal Conductivity ◽  
Thermal Radiation ◽  
Effective Thermal Conductivity ◽  
High Temperatures ◽  
Simplified Models ◽  
Open Cell

scholarly journals Effective Thermal Conductivity of Open Cell Polyurethane Foam Based on the Fractal Theory

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Kan Ankang ◽  
Han Houde
Keyword(s):  
Thermal Conductivity ◽  
Fractal Dimension ◽  
Effective Thermal Conductivity ◽  
Polyurethane Foam ◽  
Solid Phase ◽  
Fractal Theory ◽  
Heat Radiation ◽  
Total Thermal Conductivity ◽  
Equivalent Thermal Conductivity ◽  
Open Cell

Based on the fractal theory, the geometric structure inside an open cell polyurethane foam, which is widely used as adiabatic material, is illustrated. A simplified cell fractal model is created. In the model, the method of calculating the equivalent thermal conductivity of the porous foam is described and the fractal dimension is calculated. The mathematical formulas for the fractal equivalent thermal conductivity combined with gas and solid phase, for heat radiation equivalent thermal conductivity and for the total thermal conductivity, are deduced. However, the total effective heat flux is the summation of the heat conduction by the solid phase and the gas in pores, the radiation, and the convection between gas and solid phase. Fractal mathematical equation of effective thermal conductivity is derived with fractal dimension and vacancy porosity in the cell body. The calculated results have good agreement with the experimental data, and the difference is less than 5%. The main influencing factors are summarized. The research work is useful for the enhancement of adiabatic performance of foam materials and development of new materials.

Effective thermal conductivity and internal thermal radiation in burning black liquor particles

2003 ◽  
Vol 175 (5) ◽  
pp. 873-900 ◽  
Author(s):  
M. P. Järvinen* ◽  
R. Zevenhoven ◽  
E. K. Vakkilainen ◽  
M. Forssén
Keyword(s):  
Thermal Conductivity ◽  
Thermal Radiation ◽  
Effective Thermal Conductivity ◽  
Black Liquor

Convective Heat Transfer Analysis of Open Cell Metal Foam for Solar Air Heaters

Solar Energy ◽  
2003 ◽  
Author(s):  
Nihad Dukhan ◽  
Pablo D. Quinones
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Metal Foam ◽  
Heat Transfer Analysis ◽  
Transfer Model ◽  
Aluminum Foams ◽  
Maximum Heat ◽  
Open Cell ◽  
Maximum Heat Transfer

A one-dimensional heat transfer model for open-cell metal foam is presented. Three aluminum foams having different areas, relative densities, ligament diameters, and number of pores per inch were analyzed. The effective thermal conductivity and the heat transfer increased with the number of pores per inch. The effective thermal conductivity of the foams can be up to four times higher than that of solid aluminum. The resulting improvement in heat transfer can be as high as 50 percent. The maximum heat transfer for the aluminum foams occurs at a pore Reynolds number of 52. The heat transfer, in addition, becomes insensitive to the flow regime for pore Reynolds numbers beyond 200.

An Analytical Unit Cell Model for the Effective Thermal Conductivity of High Porosity Open-Cell Metal Foams

2014 ◽  
Vol 102 (3) ◽  
pp. 403-426 ◽  
Author(s):  
Xiao Hu Yang ◽  
Jia Xi Bai ◽  
Hong Bin Yan ◽  
Jiu Jie Kuang ◽  
Tian Jian Lu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Cell Model ◽  
Metal Foams ◽  
Unit Cell ◽  
High Porosity ◽  
Unit Cell Model ◽  
Open Cell

Experimental and numerical investigation on the effective thermal conductivity of stochastic structure

2019 ◽  
Vol 9 (8) ◽  
pp. 861-871
Author(s):  
Milad Saljooghi ◽  
Younes Bakhshan ◽  
Saeid Niazi ◽  
Jamshid Khorshidi
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Metal Foam ◽  
Metal Foams ◽  
Open Cell ◽  
Geometrical Properties ◽  
Copper Aluminum ◽  
Thermo Physical Properties ◽  
Modern Technologies

The Conception of thermo-physical properties of porous materials is a challenging task for scientists to conquer. The open cell metal foam increases heat transfer while energy dissipation, dimension and density of them which are constraints for modern technologies significantly reduce. In the present study, the open cell metal foams with four kinds of structures have been investigated numerically and experimentally and the effective thermal conductivity (ETC) of them have been extracted with using different base fluids such as water, air and paraffin. Also, various metals have been considered copper, aluminum, nickel and silver. Finally, a validated correlation for calculation of ETC of open cell metal foams has been developed which is function of thermal conductivity of fluid and metal, porosity and geometrical properties of pore that is applicable for all open cell metal foam approximately. The results show, good agreements between the modeling results and experimental data.

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