Numerical analysis of heat and flow transfer in porous textiles - Influence of wind velocity and air permeability

Abstract

A three-dimensional model was proposed to solve the conjugate problem of heat and flow transfer through porous textiles in the present work. The natural and forced convection between textile surface and external environment as well as inside the porous structure were considered by allowing ambient air flow to penetrate the textiles using a computational fluid dynamic approach. The proposed model was validated by the high consistency between the experimental and simulating results, with the maximum difference less than 9.3% in thermal resistance. Detailed numerical parametric study was further conducted to clarify the influence of parameters including ambient wind velocity, textile permeability and interior air movement on heat transfer through textiles. Results demonstrated that the thermal insulation of textiles were significantly decreased with higher ambient wind velocity, since the interior forced convection was enhanced. In addition, the reduction of textile permeability is beneficial to decrease the inner air transportation and minimize the heat taken away by forced convection. The effect of convection on the heat transmission was less prominent for lower permeable textiles which generally exhibited better thermal insulation than high permeable textiles under windy environment.