Spectral Emissivity Meaurement Facitily For Solar Absorbing Coating Based On Integrating-Sphere Reflectoetry

Solar selective absorbing coating is a key material in solar thermal conversion. Many nations are paying more and more attention on the utilization of solar. In order to enhance the solar use efficiency and reduce the cost of exploring solar, the measurement based on the optical property such as emissivity and absorption rate is of great signifance. However, emissivity is a multivariate function, which involves not only the surface state, components and temperature of the material but also the radiation wavelength and radiation direction. Developing measuring equipment which uses the spectral emissivity of coating is very necessary.After analyzing the solar selective absorbing coating and summarizing the available methods of spectral emissivity measurement, we choose the integrating-sphere reflectometry as the research method to the measuring equipment, upon which develop the measurement system on coating spectrum emissivity. The main contributions are the follows.First, a simple survey about the available methods of measurement of emissivity is made. With the help of the three laws of radiation, we obtain the mathematical model of the emissivity measurement system, which based on the integrating-sphere reflectometry.Second, based on the built mathematical model, we build the hardware system, which includes the design of source subsystem, beam splitting subsystem, heating and temperature controlling system, integrating-sphere system, and vacuum chamber system. According to the requirement of spectrum data acquisition system, USB-2810A is chosen as the date collecting card to the measuring system. In light of the algorithm and program flow diagram, we complete the software to the spectrum data collecting system of the measurement system, which uses LabVIEW8.60.Finally, based on the date analysis of emissivity, we test the error, accuracy, repeatability and stability of the system, and the design result of the measurement system on coating spectrum emissivity meets the requirements and technical specification, not only on theory but also on practice.