Research On Measurement Method Of Material Emissivity At Near Ambient Temperature

The emissivity is an important parameter of material’s thermal radiation characteristics. The result of emissivity will be different if an object is measured by different methods. The complexity of its influencing factors makes the diversity of emissivity measurement technology. Currently, many measurement systems are expensive and have high standards of test conditions. So it is necessary to research an appropriate method to measure the emissivity of object for the practical engineering.This paper proposes the concepts of effective radiation, effective brightness temperature and effective emissivity. And a new emissivity measurement method based on infrared thermometer is proposed. The whole system mainly includes a sample heating chamber, an emissivity tunable infrared thermometer and a surface thermocouple thermometer. The infrared thermometer’s emissivity is adjusted to match the emissivity of sample itself, when the measurement temperature equals to the real temperature, then the sample’s emissivity is directly obtained. Several typical coatings and far-infrared textile samples are measured within the wavelength range of 8~14μm by this systems under room temperature to 200℃, the change of emissivity with measurement temperature near ambient temperature is analyzed. Another experimental platforms of emissivity measurement based on energy method is established, it includes a sample heating chamber, reference blackbody and infrared thermometer. The results of two methods are compared and found it can be matched well. At last, the emissivity properties of each samples is analyzed.The method based on infrared thermometer can be used in the practical enginee ring and has the advantages of high speed and low cost.