An Investigation of Radiative Heat Transfer in Fibrous Thin Sheets

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Title: An Investigation of Radiative Heat Transfer in Fibrous Thin Sheets
Author: Qashou, ImadMohammed
Advisors: BEHNAM POURDEYHIMI, Committee Chair
HOOMAN TAFRESHI, Committee Co-Chair
MARTIN HUBBE, Committee Member
PETER HAUSER, Committee Member
Abstract: Fibrous materials possess desirable heat transfer characteristics and are used in many thermal applications including thermal insulations. Radiant heat transfer thru such materials is very important even at moderate temperatures. Thus, a fundamental understanding of the radiative heat transfer through such materials is necessary and allows better evaluation of its insulation capabilities. Due to the complex mathematical formulation of the theory of radiative heat transfer, the solution of its equations is consequently as complicated. Computational fluid dynamics (CFD) simulations provide a practical method to understand the response of fibrous media to this electromagnetic irradiation. In this study, for the first time, the Surface-to-Surface model is used to investigate the response of fibrous materials to radiative heat transfer. The unsteady state heat transfer equations are solved for the temperature and heat flux in and around the fibers that constitute a nonwoven fibrous media. Of particular interest here is the effect of fiber diameter, fiber conductivity, and material's Solid Volume Fraction (SVF) in heat transfer through the material. For a fixed fiber diameter, it is shown that the larger the solid volume fraction, the lower is the material's temperature. It is also shown that the fiber conductivity has a significant influence on the radiative heat transfer in nonwoven materials. Our simulation results indicate that the average fiber temperature is directly influenced by SVF, fiber conductivity, and fiber diameter. However, SVF has been observed to have the greatest influence followed by the fiber conductivity, and lastly fiber diameter. The web thickness effect was also simulated. The material's average temperature decreased with increasing thickness for fixed SVF and fiber diameter. Experimental work has also been conducted to verify the simulation results. Comparison between curve fitting of simulation and experimental data showed a relatively good correlation
Date: 2009-05-27
Degree: PhD
Discipline: Fiber and Polymer Science
URI: http://www.lib.ncsu.edu/resolver/1840.16/5563


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