Study On Comprehensive Measurement Method Of Infrared Emissivity And Photothermal Absorptivity Of Fabric

As the materials that contact with human body the most closely,fabrics and clothing made of them play an important role in maintaining normal body temperature and thermal comfort of human body.Thermal radiation is an important form of energy exchange between human body and the environment,and fabric plays an adjusting role in energy exchange.Infrared emissivity and photothermal absorptivity are two radiation performance indexes with high correlation in the study of human thermal comfort.However,in the actual research,the measurement of these two indexes has been limited.Although the spectrometer can be used to measure them,they are limited by the spectrum response range of the photosensitive sensor,and the conventional measurement methods cause errors to the measurement results because of the characteristics of the fabric which is not a good conductor and porous material.Therefore,based on the characteristics of fabrics,this study explores a new method to synchronously measure the infrared emissivity and photothermal absorptivity of fabrics under conventional experimental conditions.In this study,the measurement method is based on the fact that the fabric absorbs photothermal radiation energy and radiates infrared energy outward to maintain the heat balance.According to the theory of dry heat transfer and thermal radiation,the infrared energy radiated by the fabric is studied,and the measurement principle of infrared emissivity and photothermal absorption rate of the fabric is deduced.According to the measurement principle,a set of samples were measured and analyzed by a device.The results show that this method can measure effectively,and the infrared emissivity is mostly distributed in 0.80-0.95,and the photothermal absorptivity is distributed in 30 %-90 %.Radiation power has no significant influence on infrared emissivity and photothermal absorptivity.According to the validity of the test results of the same group of samples by spectrometer and spectrophotometer,it is found that the infrared emissivity measured by selfbuilt device is basically consistent with the results of spectrometer,and the measurement results of most fabrics by self-built device are accurate.The distribution trend of photothermal absorptivity measured by self-built device is similar to that of spectrophotometer,which can reflect the absorption of light and heat energy by fabric,but the more accurate results need to be corrected by more accurate measurement of blackbody temperature.Through the exploration of infrared emissivity and photothermal absorptivity of fabric,the measurement method under conventional experimental conditions is obtained,which can be used as the experimental inquiry process with infrared emissivity and photothermal absorptivity as parameters,and provide objective basis and research ideas for the future research of human thermal comfort.