Numerical Analysis of Solar Air Heater Roughened with B-Shape and D-Shape Roughness Geometry

A 2-D computational analysis of heat transfer augmentation and fluid flow characteristics with B-shaped and D-shaped artificial roughness has been carried out under the Reynolds number (Re) range from 4000-20000. Comparing the predictions of different turbulence models with experimental results available in the literature, the renormalization group k-Ɛ (RNG) turbulence model is selected for the present study. A detailed analysis of heat transfer variation was done using various geometrical parameters such as four different pitch (P) values of 10, 15, 20, and 25 mm corresponding to pitch ratio (P/e) of 11.111, 16.666, 22.222, and 27.777 respectively, at constant height (e) of 0.9 mm. The highest value of Nusselt number (Nu) improvement reached up to 2.264 times and 21.91 times at P/e of 11.111 for B-shape and D-shape roughness respectively for Re of 20000 as compared to the smooth channel. A significant enhancement of heat transfer is predicted in the present simulation and the maximum Thermohydraulic Performance Parameter (THPP) attained up to 1.47 for B-shaped roughness. The novelty of the proposed model appears as present numerical findings offer better performance compared to existing research.