بررسي همزمان انتقال حرارت و رطوبت در منسوجات متخلخل به همراه جذب رطوبت در الياف

چكيده انگليسي :

Investigation of Coupled heat and Moisture Transfer in Porous Textiles with Moisture Sorption in Fibers Zeinab Kabiri Narjeskabiri64@gmail com February 25 2012 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisor Dr Mohsen Davazdah Emami mohsen@cc iut ac ir Dr Ahmadreza Pishevar apishe@cc iut ac ir AbstractDevelopment in the textile industry expands executive boundaries to produce industrial clothing and textiles Betterunderstanding of transport phenomena in textiles could help in optimizing aspects of the making textiles process anddevelopment of new textile with special applications The coupled heat and mass transfer mechanism in poroustextiles is complicated Heat and moisture transfer in textile is coupled with the sorption of water vapor in the fibersand the associated energy change within The heat transfer mechanism in porous textiles includes conduction by thesolid material of the fibers conduction by intervening air radiation and convection Meanwhile the moisturetransfer mechanisms include vapor diffusion in the void spaces moisture sorption by the fibers capillary effects andevaporation condensation The water vapor diffuses in the void spaces of porous fibrous media due to the differencein the water vapor concentration The moisture sorption by the fibers takes place because of the water vapor sinternal chemical compositions and structures Until now the study of transport phenomena spent much time andenergy but nowadays with the advancement of numerical methods and tools like Computational Fluid Dynamics CFD accurate simulation of textiles and fibers and adsorption in fibers is possible In the present study usingthese tools the fabric will be simulated with two methods The first approach is to consider fabric as a porous media The second approach is to simulate fabric as a structure composed from large number of fibers Textiles ability inthe excess heat and moisture transfer from the body are studied in this project For this purpose the diffusion of heatand mass from the body skin into the fabric and its surrounding media is simulated The moisture of the skin bydiffusion through the fabric is transferred from lower layers of fabric adjacent to the skin to the fabric surface andthen to the surrounding environment Therefore in this study the governing heat and mass transfer equations andstructural relationships are presented and solved using CFD The first approach modeling is performed to model afabric as a porous media for two cases of PAN fibers and wool fibers The effect of physical variables is consideredon transfer properties of textiles To verify the results the experimental data is used for comparing the predictions ofPAN fibers The second approach which takes into account the water vapor sorption mechanisms in fibers isdeveloped to describe and predict the coupled heat and moisture diffusion in porous textile The model is based onthe energy and moisture conservation equations during the transportation for textiles made from PAN fibers Thismodel takes the geometrical characters of the fiber into account It allows the study of the direct sorption in fibersand the influence between the fibers The presence of moisture in textiles heavily affects its performance In thismodel absorption of water vapor in the air within the fibers by suitable boundary conditions is simulated In order todetermine the boundary conditions on the fibers surface appropriate subprograms are developed and implementedinto the present CFD code The processes of water vapor transfer in the void space between fibers sorption in fibersand their interaction with heat transfer are illustrated The effects of porosity of the fabric on heat and mass transferare also discussed Key Words Coupled Heat and Moisture Transfer Moisture Sorption Porous Textiles

كبيري، زينب

بررسي همزمان انتقال حرارت و رطوبت در منسوجات متخلخل به همراه جذب رطوبت در الياف

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