Performance enhancement of solar vortex power generator by Al2O3-in-black paint coating

Solar vortex is a clean technique for power generation. It is known for its low energy conversion efficiency. A sufficient air heating zone can enhance it to initiate and maintain a powerful swirly upward airflow. This paper presents experimental results of the performance enhancement of a solar vortex power generator by enhancing the photothermic conversion using Al2O3-in-black paint coating. Photothermic enhancement of four different 5% wt metallic powder-in-black paint was evaluated experimentally using a modified solar air heater comprising five compartments. Each compartment consisted of identical 1100 x 150 mm Aluminum absorbers tagged as an uncoated absorber, absorber coated with black enamel paint, absorber coated with Al2O3-in-black paint, absorber coated with CuO-in-black paint and absorber coated with Al2O3-CuO-in-black paint. Results show that the best solar photothermic conversion was achieved by an absorber plate coated with Al2O3-in-black paint. The mean enhancement in the thermal efficiency of the solar air heater was 51.0%, and air temperature rise was increased by 28.5%, compared with the nonpainted absorber. Since Al2O3 was the most effective coating, it has been used to enhance the performance of the solar vortex power generation system by coating the surface of the vortex generation engine. The 5%wt Al2O3-in-black paint demonstrated improvement by 17.4% in heat gain compared to the unpainted surface of the solar vortex generator.