Abstract
Asphalt materials commonly have high absorption coefficients, and their surface temperature reaches as high as 80 oC during daytime hours since their surfaces are exposed to solar radiation for long periods. Hence, asphalt pavements can easily be converted to solar air heaters (SAHs) to collect solar energy. Even though asphalt materials have low thermal conductivity, resulting in a weak convection heat exchange rate between the flowing air and asphalt surface. The current experimental study analyzes utilizing aluminum shavings as asphalt coating materials to improve SAHs’ thermal performance. To this aim, a serpentine SAH prototype was constructed, and several sensors were utilized to monitor its dynamic thermal response. Black-painted aluminum shavings were utilized as coating materials to improve the convective heat exchange rate and increase the roughness of the absorber surface. Two scenarios were considered, including the uncoated absorber plate and coated one with 0.2 kg aluminum shavings. The experiments were carried out for two air mass flow rates of 0.02 kg/s and 0.03 kg/s under field conditions. Based on the air mass flow rate, the coated absorber reaches higher temperatures, approximately 5 oC to 9 oC, than the uncoated one. The acquired results illustrate that the coated SAH has nearly 4 oC to 5 oC higher maximum exhaust air temperature; hence, the coating strategy improves the thermal efficiency by 24.75% and 44% in two air mass flow rates of 0.02 kg/s and 0.03 kg/s, respectively.
Highlights
Asphalt materials commonly have high absorption coefficients, and their surface temperature reaches as high as 80 oC during daytime hours since their surfaces are exposed to solar radiation for long periods
The acquired results illustrate that the coated solar air heaters (SAHs) has nearly 4 oC to 5 oC higher maximum exhaust air temperature; the coating strategy improves the thermal efficiency by 24.75% and 44% in two air mass flow rates of 0.02 kg/s and 0.03 kg/s, respectively
Pavements are exposed to solar radiation for a long time during daytime hours, and their surface temperature can reach nearly to 80 oC; pavements can serve as affordable heat absorbers [3]
Summary
Asphalt materials commonly have high absorption coefficients, and their surface temperature reaches as high as 80 oC during daytime hours since their surfaces are exposed to solar radiation for long periods. The acquired results illustrate that the coated SAH has nearly 4 oC to 5 oC higher maximum exhaust air temperature; the coating strategy improves the thermal efficiency by 24.75% and 44% in two air mass flow rates of 0.02 kg/s and 0.03 kg/s, respectively. Numerous literature investigated SAHs’ performance due to their simple structure, easy construction and maintenance, and low-cost operation [4, 5] These studies assessed simple, effective, and affordable techniques such as artificial roughness, corrugations, and coating strategies to improve the performance of solar air heaters [6, 7]. Abdelkader et al [12, 13] used CNTs/CuO black paint as coating materials in a flat plate solar air heater using ribs roughness Using these methods caused thermal performance to increase by 18.8% compared to a conventional SAH. The used sands simultaneously acted as coating and thermal storage units and improved performance by nearly 39% higher performance than the SAH using the aluminum absorber
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
