HEAT TRANSFER AND FRICTION FACTORS OF HIGH PRANDTL NUMBER LAMINAR FLOW THROUGH AN ANNULUS WITH CIRCUMFERENTIAL FINS
An experimental investigation was performed to predict heat transfer and friction factors for high Prandtl number flow through a concentric annulus with roughness. This roughness consisted of circumferential fins of both conductive and non-conductive material. The inner tube of the horizontal annulus had fins whose heights were varied during each test. The outer tube was insulated while constant heat was applied from inside of the inner tube. The results indicated that heat transfer increased with the increase in (i) number of fins, (ii) height of fins and (iii) Reynolds number. The friction factor increased with the (i) increase in number of fins, (ii) increase in fin height and (iii) decrease in Reynolds number. It was observed that the conductive fins transferred 30% and 110% more heat than non-conductive fins with 2.54 cm and 1.27 cm spacings, respectively, based on the same Reynolds number. An uncertainty analysis was performed to ascertain the uncertainty associated with the experimental data.