| Active warm clothing can take the initiative to warm the body to achieve the effect of warmth,is considered as the future development direction of the warm clothing,the research and application of electric heating clothing is the most extensive in the active warm clothing.the heating effect and the electric heating performance of the electric heating element,as the heat source in the electric heating clothing,are very important for the electric heating clothing.The object of this paper is to develop the electric heating element with,excellent electrothermal performance used in low voltage.So knitted electric fabric and flexible electric film were studied.In this paper,the strength,the maximum load current,the resistance stability and the electric heating performance of the silver-plated yarn were measured and tested.The weft knitted fabric was made by adding silver yarn row,then the resistance network model of knitted electric fabric was analyzed.The influence for the resistance stability and surface temperature uniformity of fabric on three kinds of connection modes was discussed.Then the fabric structure,the number and the spacing of conductive courses on the electric properties of knitted fabric were studied and compared to obtain the best production process.In addition,flexible electric film was produced by the way of flexible printed circuit,the effects of temperature and power on time on film resistance were studied,and the electric heating performance was tested and analyzed.The results show that,the resistivity of silver-plated yarns increases by less than 6%under low-voltage conditions with the increase of ambient temperature,and the resistance stability is good during electrification and has good electrothermal performance.The resistance of knitted fabric was minimum connected at four points,and the stability of the resistance was the best when the voltage was applied at different voltages,the surface temperature distribution was the most uniform,and the electrothermal performance was good,then the power consumption was linearly correlated with the equilibrium temperature.For three kinds of structures of the knitted fabric,the plain fabric has the lowest resistance,the balance temperature is the highest at the same voltage,and the resistance change rate is the smallest.For the knitted electrothermal fabric with the same area and the different number of rows and intervals,when the silver-plated yarn course and the polyester yarn course are knitted by one every two,the surface temperature distribution uniformity is the best,the more silver-plated yarn course and the closer the interval,the higher the equilibrium temperature at the same voltage,but the greater the rate of change in resistance during power-up.Therefore,the best process of knitted electrothermal fabric is as follows:the silver yarn courses and polyester yam courses are arranged by one every two in plain fabric.In addition,the resistance of flexible electric film is linearly related to the ambient temperature,when the temperature rises from 30?to 100 ?,the resistance increases first and then stabilizes,the power consumption of the flexible electric film is linearly related to the equilibrium temperature,the resistance has an increase of less than 5%,and the flexible electric film has good surface temperature distribution during power-on process.Two kinds of electric elements when work in low voltage have a good heating temperature and rapidly heating,high security,knitted electric fabric is soft and breathable,suitable for use in low temperature requirements,while the flexible electric film has good resistance stability and high temperature resistance property,can be used in higher temperature requirements. |
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