Research On Heat And Mass Transfer Mechanism And Experiments Of Double-layered Heterogeneous Porous Fabric

The study of heat and moisture transfer in porous fabrics plays a crucial role in textile printing and dyeing heat setting.Currently,with the needs of daily life,multi-layer fabrics have been widely used in cold weather clothing and thermal protective clothing,which leads to a large market demand for multi-layer fabrics.To achieve better setting quality and reduced energy consumption,the process parameters must be set according to different fabric types during fabric heat setting.This paper establishes a corresponding mathematical model for the heat and mass transfer of double-layer heterogeneous porous fabric in the drying process verifies it through experiments.The main research contents and conclusions are as follows:(1)A mathematical model for the heat and mass transfer of double-layer heterogeneous porous fabric is established.Based on the one-dimensional diffusion model and combined the structural characteristics of the material itself,two internal evaporation rates are added,and the obstructing effect of moisture in the obstructing layer is considered.At the same time,the ‘moisture-heat-mass’ coupling control equation of double-layer heterogeneous porous fabric during the process of drying is established from the perspectives of energy conservation and mass conservation,and the control equation is written into the corresponding difference equation groups through the method of control volumes.(2)Using Matlab to solve the difference equations in the mathematical model of heat and mass transfer in a double-layer heterogeneous porous fabric.It can simulate the first and second constant velocity phase of the double-layer heterogeneous porous fabric and explain the reason for the occurrence of the second constant velocity phase from the model.(3)Simulations are performed for nozzle outlet temperature,fabric initial moisture content,fabric porosity,and fabric density.The simulation results show that the duration of the first constant velocity phase is mainly related to the nozzle outlet temperature,fabric initial moisture content,environmental air humidity,and the porosity and density of the fabric near the drying surface,while the duration of the second constant velocity phase is mainly related to the porosity and density of the fabric surface away from the heat source.(4)The experimental platform is designed and improved,and a real-time monitoring device for moisture content during the drying process is added.By obtaining the moisture content curve,the internal moisture transport of the fabric can be understood and the drying mechanism of the fabric can be further understood.The reliability of the model is verified through experiments.