Thermal performance improvement of artificially roughened solar air heater

Solar air heaters are useful because they can lessen the need for fossil fuel–powered electricity, thereby lowering emissions and cutting down on energy costs. Experiments were conducted to inspect the thermal performance of a solar air heater with combined ribs and delta-winglet in a single-pass solar air heater. The present goal was boost the thermal performance of a solar air collector. A constant relative roughness height ratio of 0.6 was used to organize eight delta-winglets and seven rectangular ribs on the absorber duct's bottom surface. The attack angles for both winglets and ribs were maintained at 60° and 90°, respectively. The winglet vortex generators were set in a common flow-down configuration with a pitch ratio of 10. This experimental investigation was performed at a mass flow rate of 0.022 kg/s with typical ranges of solar irradiance from 330 W/m2 to 850 W/m2. Results show that the useful energy and thermal efficiency were enhanced by 19.2% and 21.2%, respectively, at maximum solar irradiance compared to a smooth duct. The considered compound ribs and vortex generators affect the temperature of the outlet air, resulting in a considerable improvement in the heat transfer convective rate.