Analysis of effective thermal conductivity for circular tubes made with porous media based on fractal theory

Heat Transfer ◽  
2021 ◽  
Author(s):  
Di Yu ◽  
Shihong Qi ◽  
Baolian Niu ◽  
Yinglin Li
Keyword(s):  
Thermal Conductivity ◽  
Porous Media ◽  
Effective Thermal Conductivity ◽  
Fractal Theory ◽  
Circular Tubes

PREDICTION OF EFFECTIVE THERMAL CONDUCTIVITY OF POROUS MEDIA WITH FRACTAL-MONTE CARLO SIMULATIONS

Fractals ◽  
2014 ◽  
Vol 22 (03) ◽  
pp. 1440004 ◽  
Author(s):  
YOUSHENG XU ◽  
YOUQU ZHENG ◽  
JIANLONG KOU
Keyword(s):  
Thermal Conductivity ◽  
Porous Media ◽  
Monte Carlo ◽  
Fractal Dimension ◽  
Effective Thermal Conductivity ◽  
Scaling Laws ◽  
Volume Fraction ◽  
Probability Model ◽  
Fractal Theory ◽  
Monte Carlo Simulation Technique

On the basis of the fractal scaling laws of pore distribution in natural porous media, a probability model is developed for thermal conductivity in porous media by combining fractal theory and Monte Carlo technique. The current numerical model, which was validated by comparison with the existing experimental data, shows that the thermal conductivity of porous media is a function of the thermal conductivities of volume fraction, pore area fractal dimension, tortuosity fractal dimension and random number. The effect of microstructure parameters on the effective thermal conductivity of porous media is studied. The proposed fractal Monte Carlo simulation technique has advantages compared with conventional numerical methods and may have the potential in analyzing other transport properties of porous media.

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.

Fractal Model for Thermal Conductivity of Wetting, Fibrous Porous Media

2012 ◽  
Vol 496 ◽  
pp. 12-16
Author(s):  
Fang Long Zhu ◽  
De Hong Xia ◽  
Yu Zhou
Keyword(s):  
Thermal Conductivity ◽  
Porous Media ◽  
Fractal Dimension ◽  
Effective Thermal Conductivity ◽  
Fractal Model ◽  
Self Similarity ◽  
Conductivity Model ◽  
Electrical Analogy ◽  
Fibrous Porous Media ◽  
Thermal Conductivity Model

The current paper deals with the fractal effective thermal conductivity model for fibrous porous media containing unsaturated water moisture. The model is based on the thermal-electrical analogy and statistical self-similarity of porous media. The fractal effective thermal conductivity model can be expressed as a function of the pore structure (fractal dimension) and architectural parameters of porous media. It is expected that the model will be helpful in the evaluation of thermal comfort for textiles in the whole range of porosity.

Experimental and Numerical Research on Effective Thermal Conductivity of Granular Porous Media

2011 ◽  
Vol 320 ◽  
pp. 353-358
Author(s):  
Yu Feng Shi ◽  
Wen Ce Sun ◽  
Li Hua Shi ◽  
Jing Cui
Keyword(s):  
Thermal Conductivity ◽  
Porous Media ◽  
Effective Thermal Conductivity ◽  
Experimental System ◽  
Two Dimensional ◽  
Infinite Body ◽  
Fractal Method ◽  
Granular Porous Media ◽  
Unsteady Heat Conduction ◽  
Numerical Research

Effective thermal conductivity of granular porous media is investigated by experimental and numerical methods. Using the unsteady heat conduction formula of semi-infinite body, effective thermal conductivity is obtained by measuring temperature field of the experimental system. In this experiment, solid particle is pebble and pore fluid is water or brine with salinity of 20.2%. Granular porous media is not applicable for fractal method, therefore based on structural character of granular porous media; two-dimensional cylinder model is used to calculate effective thermal conductivity of granular porous media in this paper. The simulation results correspond well with the experimental results. This proves that calculating effective thermal conductivity of granular porous media by using this two-dimensional model is accurate. This model could be extrapolated to unsaturated porous media. Research shows that effective thermal conductivity increases logarithmically with the increasing of saturation.

scholarly journals Permeability and effective thermal conductivity of bisized porous media

2007 ◽  
Vol 50 (7-8) ◽  
pp. 1295-1301 ◽  
Author(s):  
Ricardo P. Dias ◽  
Carla S. Fernandes ◽  
Manuel Mota ◽  
José A. Teixeira ◽  
Alexander Yelshin
Keyword(s):  
Thermal Conductivity ◽  
Porous Media ◽  
Effective Thermal Conductivity
Sign in / Sign up

Export Citation Format

Share Document