Investigation of Experimental and Numerical Study of the Effect of Artificial Roughness on Single‐Pass Solar Air Heater

ABSTRACT An experimental and numerical study has investigated the heat transfer (HT) and friction characteristics of a solar air heater (SAH) duct roughened using a rectangular S‐shaped artificial roughness arrangement (inline and staggered). The thermal performance of SAH is studied with design variables such as the length of the relative roughness ( d/H = 1.33), the height of the relative roughness ( e/H = 0.271), and the distance between S ( b / H = 0.667) remaining constant as the Reynolds number ( Re ) ranges from 3000 to 10,000 and the angle of attack 60°. Relative roughness of pitch range p/H (1.667, 3.33, 5, and 6.667) for inline with relative roughness of length ( l/H ) (0.8335, 1.666, 2.5, and 3.335) for staggered. A three‐dimensional computational fluid dynamics (CFD) simulation is carried out using the CFD code, ANSYS Fluent, and the renormalization group k – ε turbulence model for solving turbulence terms in governing equations. It has been found that HT enhancement can be achieved by using an artificial roughness staggered arrangement at l/H = 0.8335 and e/D = 0.271 with an angle of attack ( α ) of 60°. Also offers the best thermal performance factor for the investigated range of 3.12.