Thermohydraulic Performance Due to Turbulators of Multiple Hemi-Circular Geometries in Solar Thermal Collector

The use of solar energy, a substantial and environmentally sustainable form of renewable energy, is advantageous for a variety of purposes, encompassing heating, cooling, electricity production, and drying techniques. Solar air heaters (SAHs) have demonstrated significant efficiency in harnessing solar energy for various thermal applications, such as heating and drying processes. Despite the promise of solar air heaters (SAHs), their actual use is typically limited due to restricted convective heat transfer produced by the smooth absorber walls. The primary aim of this study is to enhance the thermal efficiency of a solar air heater (SAH) by including a set of carefully designed hemispherical turbulators in a strategic manner. The turbulators were built with meticulous attention to dimensional parameters, encompassing a range of width ratios (w/e) from 1.0 to 2.0. The relative height (e/H) was determined to be 0.5, and the relative pitch (p/e) was systematically defined at 10. A comprehensive series of experimental experiments was done, encompassing a wide range of Reynolds numbers, spanning from 2000 to 16,000. The primary focus of this comprehensive assessment was on key performance metrics, specifically the Nusselt number, friction factor, and overall thermohydraulic efficiency. Significant enhancements were noted in the Nusselt number and the friction factor, with peak values of 2.85 and 5.75, respectively, observed under specific parametric conditions of w/e = 1.6, e/H = 0.5, and p/e = 10, as well as w/e = 1.2, e/H = 0.5, and p/e = 10.