Modeling and thermal property of multi-layer warp knitted spacer fabrics

With its unique three-dimensional structure, high porosity, and lightweight, warp-knitted spacer fabric (WKSF) is an excellent insulation material. Multilayer fabric is an effective solution for better heat control, meeting the different requirements of a wide range of applications in the field of temperature control. To know the relationship between structural parameters and heat conductivity, this study highlighted the heat transfer mechanism of multilayer WKSFs. Experimental WKSF samples were fabricated in a double needle bar warp knitting machine and had mesh and plain side layers, different thicknesses of 3 mm, 4 mm, and 4.7 mm. These samples were grouped into multilayer systems by changing thickness and contacting modes between two samples. Experimental results show that the number of layers and the type of contact between the layers affects the internal thermal convection of the multilayer system and thus has a significant effect on its thermal resistance. Also, the WKSF thickness plays a role in the thermal resistance of the multilayer system. To further clarify the heat conducting behavior from a microscopic perspective, a geometry model of multilayer WKSFs and transfer of heat physical field was constructed to perform finite element simulation by ANSYS. By comparing the simulation results with the test results, the established simulation model was practical and it was found that the heat transfer paths of multilayer WKSFs were affected by the distribution of media with different thermal conductivities. The research provides a theoretical reference for studies on thermal insulation materials.