Study on air permeability and thermal resistance of textiles under heat convection

Convective heat transfer plays a very important role in thermal resistance of textiles due to its porous structure, and the thermal resistance of textiles will be quite different when they are investigated under different testing standards and conditions. Nowadays, however, there is still no commercial instrument for evaluating the thermal resistance of textiles under convective heat transfer. Besides, there is no report about the influence of pore structure (pore size and the ratio of a pore's cross-sectional area to the total cross-sectional area of fabric) on thermal resistance of textiles. Therefore, in this work, one newly designed device has been developed for evaluating the thermal resistance of textiles with different parameters in terms of porosity, pore size and pore cross-sectional area under heat convection. The results showed that with the increase of the pore size and the ratio of pore area to total area of fabric, the air permeability increases and the thermal resistance of fabric decreases; the pore size and the ratio of pore area have more significant influence compared to the influence of porosity; and the thermal resistance decreases with the increase of air permeability.