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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

Numerical Study on Solar Reflection Performance of Cool Painting and the Optimization

Get access (open in a dialog) DOI: 10.1615/IHTC15.rad.009357
pages 7181-7190

Аннотация

Recently air temperature in urban areas increases in comparison with that of suburban or rural area. One of the countermeasures to mitigate the urban heat island is coating surfaces of buildings by painted layer with higher solar reflectance so-called cool painting. It is important to evaluate the solar reflectance on developing and constructing the painting. Though the solar reflectance can be measured by a spectrophotometer with integrating sphere, accurate numerical prediction of reflective properties of the painted layer including arbitrary pigment can be contributed to the development of cool paint material. The effect of the diffuse reflection in the painted layer is bigger than that of specular reflection on the paint surface. It is important to evaluate the scattering properties of pigment which is related to the reflection performance. For evaluation of the scattering of the pigment in the medium, anisotropic scattering should be considered. In this paper, the radiation method is applied for predicting the solar reflectance of painted layer. It is intended that the accuracy of the evaluation is improved by taking into account the anisotropy of the scattering medium. The hemispherical spectral reflectance of the painted layer including TiO2 or ZnO is evaluated. It is resulted that spectral reflectance of paint film having arbitrary values of particle size, volume fraction of pigment, and coating thickness can be calculated by this method. And the validity of the numerical method is evaluated by comparison with the reflective property of actual painted layer by means of spectrophotometry.