LAUSR

Abstract This current research is focused on sensitivity analysis and surrogate-based optimization of solar air heater channel-types with three rows delta winglet pairs arranged in both Common-Flow-Down and Common-Flow-Up orientations at Reynolds numbers of 5,000 and 10,000. The performance of the channel is investigated by considering the variation of nine input parameters related to chord, height and angle of attack of each row of delta winglet pairs, in which the rows of the vortex generators are independent from each other. Sensitivity analysis is carried out by means of Morris, FAST and PAWN indices. From sensitivity analysis, it is highlighted that the friction factor is much more sensitive to the design variables than Nusselt number. The optimization procedure consists on the combination of the Anisotropic Kriging model and Non-dominated Sorting Genetic Algorithm (NSGA-II). The optimized solutions indicated the highest performances of the channel are achieved when the vortex generators are not periodically distributed along the channel. With regard to net power ratio, Common-Flow-Up array performs better than Common-Flow-Down arrays, and further enhancement of this parameter is noted when the Reynolds number is increased. The main vortices generated by delta winglet pairs at Re = 10,000 propagate downstream closer to the absorber plate, and the corner vortices are weak and rapidly dissipated along the main flow direction, for both Common-Flow-Up and Common-Flow-Down arrangements.