Feasibility study on using asphalt pavements as heat absorbers and sensible heat storage materials in solar air heaters: An experimental study

Asphalt pavements are affordable infrastructures exposed to solar irradiation for a long time a day, and they experience considerable high temperatures. Due to high thermal capacity, asphalt pavements can store high sensible thermal energy during daytime hours and release it when solar irradiation is negligible or absent. The current study investigates the heat dynamics and thermal efficiency of asphalt solar air heaters (SAHs) utilizing asphalt materials that function as both heat absorbers and sensible heat storage units. To this aim, a 1.2 m(2) single-glazed baffled SAH prototype was constructed, and its heat dynamics were monitored on cold and mild winter days at two different air mass flow rates of 0.02 kg/s and 0.03 kg/s. The constructed SAH uses black stainless-steel baffles to produce a serpentine air passageway and improve turbulence and heat exchange rates. The acquired data illustrates that the maximum intake and exhaust air temperature difference reaches up to 14 degrees C and 24 degrees C on cold and mild winter days, respectively. When the solar irradiation was negligible in the evening, the asphalt pavement serves as sensible heat storage and heats the passing airflow up to 8 degrees C and 12 degrees C at sunset on cold and mild winter days, respectively. This issue causes the collector thermal efficiency to reach as high as 80%. Therefore, using asphalt materials is a feasible approach to simultaneously serve as heat absorber and sensible heat storage.