Abstract
Effects of using nanoliquid and double porous elliptic objects on the flow separation and convective heat transfer control for flow over multiple heated blocks in channel are numerically investigated by using finite element method. Spherical, brick, blade and cylindrical shaped alumina particles are used in water up to solid volume fraction of 2%. Impacts of Reynolds number (50 <= Re <= 500), permeability of the porous ellipses (10(-5)<= Da(1)<= 5 x 10(-2) and 10(-5)<= Da(2)<= 5 x 10(-2)), aspect ratio of the ellipses (0.25 <= AR(1)<= 1.5, 0.25 <= AR(2)<= 1.5), distance between the ellipses (0.2H <= sx <= 1.6H) and distance of the first ellipse from inlet (-H <= mx <= H) on the hydro-thermal performance are explored. The highest performance improvement is obtained by using the cylindrical shaped particles in the base heat transfer fluid at the highest solid volume fraction and the amount of heat transfer enhancement are 33% and 40.5% for hot blocks while negligible pressure drop is observed. Varying the aspect ratio of the ellipses in the perpendicular direction to the flow, up to 25% and 30% heat transfer increment are obtained for hot block with slight rise of pressure coefficient. However, when varying the horizontal location of the porous ellipses in the channel and permeability of them, there is considerable rise of pressure drop. Variation of the average heat transfer from the hot blocks with varying permeability of the ellipses are obtained as 32% and 25%. Successful hydro-thermal performance estimation results are achieved by using artificial neural networks with feed-forward network architecture of 1 hidden layer and 17 neurons. (C) 2021 Beihang University. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd.