Abstract :
[en] Phase change material (PCM) featured with high latent heat thermal energy storage capacity and isothermal phase transition is employed in building walls decorated with radiative cooling (RC) coating, to modify the cooling effect on building thermal performance. Numerical analysis indicates that the RC coating causes the exterior temperature of P-RC walls to be lower than the ambient temperature, achieving a maximum exterior temperature drop of 13.63 ℃. The thermal buffer effect of PCM enables to shaving of the temperature peak and shift of the temperature valley, inducing the exterior temperature of the P-RC wall to fluctuate slightly in comparison to the RC wall. The interior temperature of the P-RC wall is found to approach to target temperature tightly. PCM located closer to the outside completes the phase transition more rapidly, which is beneficial to leveling radiative cooling of RC coating. The exterior temperature of P-RC walls increases with the augment of solar radiation intensity, ambient temperature, and indoor temperature. Augment of PCM thickness, ambient temperature, or indoor temperature is conducive to interior temperature. Latent heat thermal energy storage of PCM enlarges the effective thermal capacity of walls, which is favorable to maintaining interior temperature within the target temperature. In conclusion, studied results highlight that radiation cooling can be improved by PCM, with substantial benefits to develop passive cooling available to building energy conservation.
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