Research Of Experimental Method Of Textile Material Performance On Unsteady-state Thermal Transfer

Following the development of textile industry,fabric is not only used in apparel,but also can be applied on other industries,including engineering heat insulation,national defense and constructional engineering field. Fabric,component with yarn and air,has the characteristics of porous,low density,good flexility,which make it easily to compound with other materials.Scholars have done many researches on textile heat transfer, mostly focus on the comfort of the body.And the text mostly did on the steady-state environment(temperature of fabric is unchanged with time), the way of heat transfer is heat convection.In this research,the text is did on the unsteady-state environment(temperature of fabric is changed with time),the way of heat transfer is heat transmit.Based on the test of time-temperature data,thermal conductivity,thermal diffusivity and volume specific heat of the fabric can be obtained by the function of heat conduction.The unsteady-state method is used to research the performance of fabric heat transfer,the primary coverage is as follows:First,according to the model of unsteady-state heat transfer,a test apparatus is been made.The details of the facilities are described including compositions,the way of data collection and data analysis.The unsteady-state test method has the merits of short-time,low heat insulation to the facilities and thermal conductivity,thermal diffusivity and volume specific heat can be obtained simultaneously.Second,the change of text parameters to the test result is analyzed. During the test,a pressure must be added upward the fabric to ensure the contact between the fabric is well;the distance between the heat source and temperature sensor is no longer than the tenth of heat side;the heat flux should be controlled under200 W/m~2 to avoid air convection.Third,the reliability of text result has been proved.For the perspex, the data between the test and reference are identical.For the fabric, unsteady-state method can be used to text fabric at different water ratio rely on its short-time merit.Forth,the discipline of fabric heat transfer at different water ratio or environmental temperature is analyzed.Thermal conductivity of fabric is increased along with the water ratio.When the environmental temperature is increased,the energy of molecule is increased which lead to the stronger vibration of crystal lattice,so the heat transfer is easier and the thermal conductivity is growing up.Fifth,the heat performance of fiber pieces is tested at different density. When the density increased,the porosity among fibers is decreased,the air ratio is also decreased,due to the higher value of fiber thermal conductivity, the thermal conductivity of fiber pieces is increased.Sixth,when two kinds of fabric are interval arranged,the effect of thermal resistance is different with the order.When the fabric with higher thermal conductivity is closer to the heat source,the thermal resistance is better.Th e discipline can guide the reasonable use of fabric.