Heat and Moisture Transfer Through Nonwoven Fabrics

Abstract

A theoretical model is demonstrated that provides a reliable prediction of thermal transmission through nonwoven structures. The validity of the model is confirmed in experiments that measure the thermal conductivity of various nonwoven barrier fabrics. The model is used to characterize the relative contribution of heat transfer mechanisms to the total heat transmission. It also provides a good explanation of the roles played by fiber and fabric variables in determining the thermal insulation of nonwoven barrier materials.

Microbial barrier permeability and thermophysiological and mechanical properties of static dissipative woven fabric system

“…A lower water vapour resistance is the better the possible evaporation of moisture (sweat) from the wearer's or sleeper's body. The textile having the water vapour resistance up to 5 m 2 Pa W -1 is, according to the literature, a material with very good physiological properties [10,11]. It can be concluded that the static dissipative woven fabric before and after finishing have very good physiological properties and thus great wearing and feeling comfort.…”

Heat and Moisture Transfer Through Nonwoven Fabrics

“…Using an analogy with our thermal conductivity model (Equation 1, Part I of this series [ 3 ] ), assuming a vapor pressure gradient across the fabric thickness, and allowing for vapor diffusion through fibers and air interstices, we write a, water vapor diffusion model as follows:…”

“…where In this model, D, is the diffusion coefficient of water vapor in air and Djll and Dil represent the diffusion I coefficient along the fiber axis and perpendicular to it, Xj is the fiber volume fraction, a is the anisotropy factor (ratio of the number of filaments in the machine and cross machine directions), 4 is the polar orientation angle ( Figure 10 [ 3 ] ), L is the fabric thickness, and d is the fiber diameter. A detailed derivation of this model and the underlying assumptions are given in Appendix A of Part I [3].…”

A simple simulation method for designing fibrous insulation materials

“…However, in some applications involving high temperatures, steel fibers, alumina fibers, and/or other similar temperature-resistance materials have also been used for insulation [1,2]. Heat transfer in a fibrous insulation material occurs through conduction, convection, and radiation.…”

“…Convection heat transfer can often be neglected since the friction between the fibers and the interstitial fluid may suppress convective motions inside the media. While radiative heat transfer is generally important in high-temperature applications (see [3,4] for instance), conductive heat transfer is often the mechanism by which heat transfers through fibrous materials in temperatures near or below room temperature [2].…”