Construction of a binary channel efficient cooling composites with reflective and phase-change properties

Current cooling materials are promising alternatives to electrical cooling approaches but are either inefficient or have limited capability. To achieve an optimal cooling effect, we present a binary channel cooling composite consisting of titanium dioxide (TiO₂) and paraffin. Compared with the neat High-density polyethylene (HDPE), high solar reflectance (average 69%) and the heat capacity (184.9 J/g) of paraffin allow for these composites have excellent cooling property, thereby lead to a maximum temperature decrease of about 15 °C in the daytime simulation part of high-low cycling temperature test and a decrease of about 10 °C in outdoor temperature test. The cooling performance of the binary channel cooling composites equals or surpasses those of state-of-the-art cooling materials. Besides, the nighttime simulation part of high-low cycling temperature test indicates the binary channel cooling composites also can keep the building warm by releasing the daytime absorbed heat. The maximum temperature difference between the composites and neat HDPE is about 10 °C.