Numerical Analysis on the Optimization of Evaporative Cooling Performance for Permeable Pavements

Abstract

The phenomenon of urban heat islands is mainly caused by the increase of artificially hardened surfaces in cities, and it can be alleviated by using permeable pavements to dissipate latent heat. There are many disagreements on the cooling effect of permeable pavements, and at present, it still needs more tests and modeling to prove this view. This paper proposes a 3-D transient model based on the heat transfer theory of porous media to accurately evaluate the cooling performance of permeable pavements. The influences of surface thermal parameters, storage depths, and spraying schemes on the cooling performance of permeable pavements are analyzed. The results show that compared with the peak temperature in the dry state, saturated permeable pavements can be significantly reduced. It is also found that the reflectivity of permeable pavements is positively correlated with the magnitude of temperature reduction and it has the most significant effect on the surface temperature among the discussed thermal parameters. A water storage layer with a thickness of 15 cm is recommended to balance economic costs and the cooling performance of permeable pavements. Based on the calculation results of the temperature reduction and cooling time, the optimal quantity of water spray is given innovatively. The proposed model can help improve the material components, structures, and maintenance methods of permeable pavements.