Parametric optimization of hybrid artificial roughness used in solar air heaters using multiple criteria decision making techniques

Solar air heaters (SAHs) are widely accepted and used for drying and heating purposes. Numerous methodologies are available for augmentation of the performance of a SAH but the application of artificial roughness underside the absorber plate is reported to bean efficient one. This study aims to present the effects of using hybrid artificial roughness combining the transverse ribs along with discrete inclined ribs, on the thermo-hydraulic performance of roughened SAH. The response surface methodology (RSM) is utilized for the design of experiments to investigate the influence of relative roughness height (0.018 ≤ e/ D ≤ 0.036), relative roughness pitch (5 ≤ p/ e ≤ 15), attack angle (45° ≤ α ≤ 75°), and Reynolds number (1,900 ≤ Re ≤ 20,300) as input parameters. The empirical equations are developed for Nusselt number, friction factor, and thermo-hydraulic performance parameter based on the regression analysis. An integrated analytical hierarchy process-based weighted aggregated sum product assessment (AHP-WASPAS) method is used to evaluate an optimal parametric combination ( e/ D = 0.036, p/ e = 15, α = 75°, and Re = 20,300). The results are supported by the corresponding experimental outcomes. Also, the sensitivity analysis and rank reversal tests performed as qualitative assessment procedures for the results obtained from the proposed strategy. The proposed decision framework is reported to be very sensitive to several criteria weight fluctuations with maximum and least deviations of 15.41% and 2.56% for δWjp = +50% and δWjp = −10%, respectively. Further, the obtained results confirm the robustness of aopted decisional scheme with just one rank reversal.