Heat Transfer Performance Research Of Textile Composite Materials In Unsteady Environment

With the development of science and technology, as well as the appearance of all kinds of high performance fibers and composite technology, the application of textile composite insulation materials extend from the traditional clothes to various engineering fields. The internal-heat transfer of textile composite insulation materials used in outdoors is unsteady. At present, the steady-state method, which cannot veritably reflect the internal heat conduction of the material used in outdoors, is used in the test of the thermal conductivity mostly. In this paper, the agricultural textile composite insulation materials were researched. The effect of environment and structure factors on the performance of thermal conductivity of materials was tested and analyzed by the platform of non-steady testing and MATLAB numerical analysis.Deduced the temperature-time function of heat conductivity based on the unsteady heat transfer model. The thermal conductivity was obtained by MATLAB, which can process the data of the internal temperature changed over time simply and quickly.Set the unsteady heat transfer test device and analyzed the test accuracy. The thermal conductivity got by unsteady method had lower variation and better repeat-ability compared with steady method.Studied the effect of environmental factors on heat conduction performance. The increase of the environment humidity accelerated the material moisture and the heat transfer performance:The heat conduction of the material showed an increasing tendency overall with the increasing of environment temperature, but the trend was not very great. The thermal conductivity varied slightly when the initial temperature changed in a small range,otherwise it increased clearly.Studied the effect of material structure on the heat conduction performance.The heat preservation and insulation performance was the best when using polyester composite polyethylene film as coating material; the thermal conductivity decreased with the increase of porosity, when the porosity reached 82%, the thermal conductivity achieved a minimum value. With the increase of moisture regain, the thermal conductivity of materials was increased. For textile composite insulation materials with variable density structure, the thermal conductivity was minimum, when chose the structure with higher outer densityand lower internal density.