| In recent years, many researchers have devoted to the study of textile comfort, and have achieved good results. Therefore, how to improve the thermal comfort of textiles is still a hot direction in the modern textile industry. Throughout nearly ten years, the research of the textile thermal comfort is very active, and the research category is also quite widely. At the same time, the evaluation of fabric thermal comfort index and evaluation system are put forward, and the main scope of the research is divided as the following several aspects:the first one is fabric heat transfer performance, the heat transfer mechanism and test principle, test methods, and the second is the research and development of woven material heat transfer performance test device.It is well known that the structure determines the performance, so the difference of the heat transfer performance of the fabric is definitely caused by the difference of the fabric structure. In the past studies, there is more development by studying the relationship in qualitative description than in quantitative description between the structure and the properties of the fabrics. This is very strict in terms of a science. Although the relationship between fabrics’geometry structure and their heat transfer performance is studied, and many researchers have described the influence of the macroscopic parameters, such as the thickness, bulk density and cover coefficient, on the heat transfer performance of the fabrics, however, the specific fabric geometrical parameters (such as high flexural wave, buckling length) is how to influence the fabric of heat transfer performance, it has rarely been studied. So, it is urgent to make a quantitative study on the influence of geometrical parameters on the heat transfer performance of fabrics.In this paper, we study the relationship between the stability and the dynamic heat transfer performance of the fabric and the geometrical parameters of the fabric, based on the basic test of the structure parameters of the fabric and the steady state and dynamic heat transfer performance. We has selected 23 kinds of winter common woven fabrics, focusing on analysis of the fabric structures parameters and the heat transfer performance, and fabric thermal resistance and transient temperature time curve and the related indexes are used as the description index of static thermal comfort and fabric transient thermal comfort.The result shows that all the fabrics’heat transfer performance is not the same.This paper mainly studies the relationship between the geometric structure and their static and dynamic heat transmitting properties with the perspective of quantitative, and the main contents of the research include the following aspects:(1)The test of fabric geometry structure parameters the fabric material slicing to observe the fabric warp and weft to cut the surface morphology measurement of fabric of the geometric structure parameters. (2) the study of the relationship between specific geometric structural parameters and the steady-state heat transfer performance We test the steady heat transfer performance of the textile using the YG606 LF flat plate type insulation tester, and thermal resistance, CLO value and other indicators are used to characterize the fabric of steady-state thermal comfort. The influences of fabric structure, yarn count, yarn density, thickness and bulk density on the thermal resistance of fabrics are also analyzed. At the same time, the influence of geometrical parameters on the thermal resistance of fabric is analyzed by means of the method of multiple regression analysis. (3)The study on fabric dynamic heat transfer properties To simulate the dynamic process that winter garments contact human skin in very cold conditions at a moment,which results in changes in the dynamic process of human skin temperature, YG406 LF type flat plate type insulation is used to record the dynamic process of heat transfer test plate temperature along with the time change, the plate test (equivalent to human skin) temperature versus time curve, and puts forward the five indicators to characterization of the dynamic heat transfer process. At the same time, analyze the relationship between geometrical parameters and dynamic heat transfer performance of fabrics.Through the analysis, we can draw the following conclusions:(1) fabric geometry structure parameters change will cause the fabric structure, thus affecting the fabric heat transfer performance; (2) steady state heat transfer performance of heat resistance of fabrics, and it is affected by fabric, yarn linear density, yarn density, thickness and density of the effects of the different fabric structure under the thermal resistance of the size of the order for the plain weave> 2/1 Twill> 2/2 twill> 3/1 Twill> 3/2 twill> 5 gold 2 flying weft satin; thermal resistance with the yarn linear density, bulk density increases and decreases with the warp density, thickness increases first increased and then decreased. (3) The structure determines the performance, and the steady-state heat transfer performance of the fabric has a great relationship with the geometrical parameters of the structure. Through multiple regression analysis, there is a relationship equation among thermal resistance、yarn density, warp density and other parameters: R= 4.636437-0.079031Tt+0.007937Pj+7.97498t-0.009196σ. From this equation can be seen in these parameters, thickness of fabric thermal resistance, impact is the biggest, followed by the line density, warp density and bulk density. (4) From the fabric geometry structure phase structure parameters of quantitative analysis of the fabric geometry structure affect the thermal resistance of the fabric using multiple regression analysis method, get the fabric thermal resistance and fabric geometry structure phase parameters of the equation R=-0.0177+1.7lj+4.7×10-5lw+0.0021hj/hw-5.2 × 10-5 xj+7.2×10-6xw+0.0329dj/dw From the relationship equation can be seen, weaving weft yarn diameter ratio dj/dw and weft buckling wave height ratio of h/hw namely fabric geometric characteristic parameters of fabric thermal resistance effect is significant, followed by the warp and weft length, an organizational cycle width. (5) characterization of the fabric dynamic heat transfer test index maximum temperature drop delta T1, temperature drop time delta T1, cooling down rate k is reduced, return to the starting temperature required time delta t2 and heating rate k liters. Through the multiple regression and analysis of 5 large dynamic heat transfer index and fabric geometry structure parameters, five regression equations, and this equation analysis shows, fabric geometry structure parameters of fabric dynamic heat transfer performance of quantization effects. In addition, through the analysis, it is found that the dynamic heat transfer performance of the fabric is mainly related to the effective contact area of the fabric. The larger the effective contact area is, the shorter the time of the dynamic heat transfer process is, the greater the cooling rate and the rate of return of the fabric. At the end of this paper, the future research direction is prospected. |
PDF Full Text Request