Numerical prediction of flow and heat transfer in a channel in the presence of a built-in circular tube with and without an integral wake splitter

A numerical investigation was carried out to study the heat transfer behavior of a circular tube in cross-flow configuration with a longitudinal fin attached at the rear of the tube. The investigated configuration is intended to model either an element of a cross-flow heat exchanger or an element of the array of pin fins. The longitudinal finning of a circular tube is assumed to be in a configuration where the fin is attached at the back of the circular tube. The longitudinal fins, built-in with the tubes, are called integral splitter plates. The splitter plate creates a streamlined extension of the circular tube. It brings about enhancement of heat transfer from the tube surface. A reduction in the size of the wake zone in comparison with the wake of a circular tube is observed. Narrowing of the wake zone reduced convective heat transfer from the tube surface but the splitter plate itself generated an extra fin area for conduction. Overall, there is an improvement in heat transfer past the circular tube with an integral splitter plate compared with the case of flow past a circular tube without a splitter plate. Flow and heat transfer results are presented for three different chord lengths of the splitter plate and three different values of the Reynolds numbers (500, 1000 and 1500). The heat transfer enhancement obtained by finning was compared with that obtained by increasing the diameter of the unfinned tubes.