Prediction of the Global Performance of a Finned Tube Air Cooler and Effect of Radial Slits on Its Fin Surface

Abstract

In the present work, numerical modeling was used to study the local behavior of flow and energy variables to understand the underlying physics in a Finned Tube Cooler. The cooler under consideration is a single circular-fin air cooler tube confined in a duct. The optimizations of fin pitch and fin clearance as predicted by Rangan et al. (2003) have been elucidated based on the underlying physical principles involved. The model was further applied to study the augmentation of heat transfer and suppression of pumping power due to symmetric radial slits on the fin surface. Reversal of heat transfer direction is seen in the wake of the tube in the case of an unserrated fin. Radial slits reduce this region by aiding mixing of the flow. The heat transfer performance of the fin is enhanced by 5% by placing symmetric radial slits at the onset of flow separation in comparison against an unserrated heat exchanger. But the pumping power requirements also increase at a similar rate. Nomenclature Mass flow rate in fin space Nusselt number (hDf/k) Reynolds number (pU <JVj«) Approach velocity Fin space Clearance space between fin and duct