Thermohydraulic performance enhancement of a solar air heater integrating jet impingement and semi-cylindrical side-wall modification within a dual-chamber configuration: a combined experimental and numerical investigation

This work introduces a novel hybrid solar air heater (SAH) architecture that combines jet impingement and semi-cylindrical side-wall geometry modifications within a dual-chamber duct to simultaneously exploit active and passive augmentation mechanisms. A systematic parametric study was conducted across a range of jet diameters and row configurations using three-dimensional computational fluid dynamics (CFD) simulations carried out in ANSYS Fluent, with the solar load model (SLM) and the re-normalisation group (RNG) k-ε turbulence model employed for realistic boundary representation. Experimental measurements, conducted under controlled laboratory conditions using a calibrated solar simulator, provided the validation dataset against which numerical predictions were benchmarked. The analysis identified two optimal configurations: a three-row jet plate with 20 mm perforations and a four-row jet plate with 15 mm perforations, yielding thermohydraulic efficiencies of 85.89% and 79.6%, respectively, with corresponding maximum thermal efficiencies of 88.86% and 88.1%. A comprehensive 4E assessment encompassing energy, exergy, economic, and environmental dimensions revealed peak exergy efficiency of 4.1%, annual CO 2 mitigation up to 0.43 ton per year, and an energy-based payback period ranging from 2 to 6.6 months. Flow visualisation from CFD demonstrated that the synergistic coupling of curved sidewalls with impinging jets intensifies secondary vortex formation, suppresses near-wall dead zones, and redistributes heat flux more uniformly over the absorber plate. These findings establish the complementary value of combining geometric modification with jet-driven turbulence promotion in the design of high-efficiency solar thermal systems.