Asphalt solar collectors: A literature review

Highlights: ► Solar energy can be harnessed by asphalt pavements. ► Research on asphalt thermal behavior and asphalt solar collectors is reviewed. ► Asphalt temperature is very sensitive to the variation of absortivity. ► Asphalt solar collector efficiency depends on flow rate and geometrical parameters. -- Abstract: Asphalt pavements subject to solar radiation can reach high temperatures causing not only environmental problems such as the heat island effect on cities but also structural damage due to rutting or hardening as a result of thermal cycles. Asphalt solar collectors are doubly effective active systems: as they solve the previously mentioned problems and, moreover, they can harness energy to be used in different applications. The main findings of the existing research on asphalt solar collectors are gathered together in this review paper. Firstly, the main heat transfer mechanisms involved in the solar energy collection process are identified and the most important parameters and variables are presented. After analyzing the theoretical foundations of the heat transfer process, this review focuses on the types of studies carried out so far on asphalt's thermal behavior, different methodologies employed by other authors to study asphalt solar collectors and influence of the variables involved in thermal energy harvesting.