Comparative Analysis of Thermal Performance in Dual-Flow Solar Air Heaters Utilizing Diverse Absorber Plates

Abstract

This study undertakes an experimental and computational evaluation of a dual-flow solar air heater (SAH) equipped with three distinct types of absorber plates: flat, trapezoidal, and U-corrugated. Experiments were conducted under actual outdoor weather conditions in Baghdad, Iraq (33.31ºN, 44.36ºE) during varying days in April and May 2022. The collector, oriented south (surface azimuth angle = zero due south) and tilted at an angle of 30º from the horizontal, was scrutinized under four different airflow rates: 0.0011, 0.0023, 0.0036, and 0.0046 kg/s. Computational simulations of the four absorber plates were performed using ANSYS Fluent software to ascertain and validate thermal efficiencies and performance characteristics. Findings indicate that at an airflow rate of 0.0046 kg/s, the thermal efficiencies of the SAHs with flat, U-corrugated, and trapezoidal plates were 43%, 51%, and 54% respectively. Additionally, a shift from parallel to anti-parallel airflow direction resulted in an increased thermal efficiency from 51% to 56%. It was determined that the optimal configuration was achieved with the U-corrugated plate in an anti-parallel airflow. The average efficiencies at the maximum airflow rate of 0.0046 kg/s were reported as 42.80% for the flat plate, 51.33% for the U-corrugated plate with parallel airflow, 54.38% for the trapezoidal plate with anti-parallel airflow, and 55.53% for the U-corrugated plate with anti-parallel airflow. Finally, a favorable alignment between the experimental and simulated results was observed, with an average discrepancy of 5.7% in thermal efficiency.