A NOVEL FAST PREDICTING TECHNIQUE FOR THE ABSORPTIVITY OF SURFACE COATING

摘要

The most common technique for a surface to have the desired thermo-physical properties or to reflect the desired optical properties is the surface coating.It is used in a wide application area from under the seas to the depths of space. In order for a surface coating to be used, it must have well-defined thermo-physical properties. These properties could be properties that are directly dependent on the material such as heat capacity, heat transfer coefficient and thermal expansion coefficient, as well as material and surface-dependent properties such as absorptivity, reflectivity and transmissivity. A bsorptivity is a very important parameter for thermal management of electronics operating under direct solar radiation. Optical methods used to measure the absorptivity are expensive and time consuming methods. In this study, obtaining the absorptivity value of a surface coating with a fast and inexpensive method is investigated. The method consists of two stages; experiment and conduction-based finite element simulation. An aluminum plate with the surface coating to be measured and an aluminum plate with well-known thermo-physical properties without any surface coating are tested in the same environment condition (wind, solar radiation etc.). In the experiment, the time-dependent temperature measurement is taken on both plates separately. Also direct solar radiation and wind speed measurement from the environment are taken. Using these measurements, the FE model is validated and the experiment condition is simulated. The absorptivity of the surface coating is obtained with the iterative solutions made as a result of the analysis test verification studies. The iterative results are presented comparatively with the maximum percent error between simulation and experiment. Consequently, unlike the known methods, the material absorptivity could be measured with a very simple, time efficient and cheap method.