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Advances in Materials Science and Engineering
Volume 2013 (2013), Article ID 125267, 7 pages
http://dx.doi.org/10.1155/2013/125267
Research Article

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

Merchant Marine College, Shanghai Maritime University, Shanghai 201306, China

Received 6 March 2013; Revised 13 September 2013; Accepted 19 November 2013

Academic Editor: Martha Guerrero

Copyright © 2013 Kan Ankang and Han Houde. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

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.