Analysis of Heat Transfer and Pressure Drop according to the Installation Location and Arrangement of Vortex Generators in a Finned Air Channel of a Solar Air Collector

The solar-air collector is a renewable energy system that recovers solar thermal energy using air.Unlike liquid-type solar collectors, they can obtain thermal energy without requiring large-scale equipment.However, its thermal efficiency must be improved due to the low thermal conductivity of the air.In this study, the heat transfer and pressure drop in a solar-air collector with a finned air channel were evaluated when vortex generators were attached to the fin surfaces.Six configurations were analyzed based on installation location and vortex generator arrangement at Reynolds numbers ranging from 3,000 to 15,000.The results confirmed that the vortex generator improved the heat transfer performance by up to 2.36 times.However, the friction factor increased by up to 4.11 times.Hence, the thermal-hydraulic performance was assessed by considering both improvements in heat transfer and increases in pressure drop.The best performance was achieved when the vortex generators were attached only to the vertical surface of the fins, in an arrangement that expanded the area along the airflow direction.These results are expected to provide valuable information for the further development of air heaters.