The effect of particles size distribution on aesthetic and thermal performances of polydisperse TiO_2 pigmented coatings: Comparison between numerical and experimental results

摘要

A new approach in designing pigmented coatings considering both visual and thermal concerns was introduced by authors in previous works. The objective was to design a pigmented coating with dark appearance which can stay cool while exposed to sunlight. This behavior can be achieved by coating a typical black substrate with a pigmented coating with controlled size and concentration of particles and coating thickness. In present work, the spectral behaviour of polydisperse TiO_2 pigmented coatings was studied. The radiative properties of polydisperse TiO_2 powders were evaluated and the radiative transfer in the pigmented coating was modelled using the radiation element method by ray emission model (REM 2). The effects of particles size distribution on spectral reflectivity, optimization parameter, and color coordinates were discussed. The results of numerical calculation were validated by experimental reflectivity measurements of several TiO_2 pigmented coating samples made from two different TiO_2 powders with different size distributions of particles. The results show that our model can reasonably predict the spectral reflectivity of TiO_2 pigmented coating samples. Moreover, the results of optimized monodisperse TiO_2 pigmented coatings were again validated.