Natural convection heat transfer and fluid flow in a thermal chimney with multiple horizontally-aligned cylinders

To address the scarcity of natural convection research for tube array with three or more columns horizontally-aligned cylinders, this paper conducts RANS/URANS simulations multiple cylinder in one two rows, validated by particle-image velocimetry and heat transfer measurements. Parametric study varying horizontal vertical pitches is implemented RANS transition SST model. Key findings are then substantiated examined URANS. It found that pitch influences balance between chimney effect blockage effect, thus has an optimum respect to draft velocity. For all distances computed two-row thermal model, flow pattern stays a plume-dominant mode at large chimney-dominant small pitch. Interestingly, intermediate (pitch/diameter?2.5), switches from over minor increase (from 4.5 6 diameters), leading significant augmentation velocity on surfaces. This distinct thermo-flow behavior, identified first time authors’ knowledge, may be harnessed improve performance passive exchangers.