Heat transfer enhancement in inserted extruded aluminum finned tubes

Heat transfer enhancement in tubes is widely applied in various industrial processes. The traditional method of heat transfer enhancement is to insert radial fins to expand the internal surface area and destroy the flow. However, there is a flue gas corridor in the central area of the tube, and the cost of expanding the inner fin is high. A centrally symmetrical bent extruded aluminum fin was developed to enhance the heat transfer in the tube. An experimental platform was constructed to test the performance of inner finned tubes and explore the process of combining extruded aluminum inner fin with steel tube. The bent extruded aluminum fins with two side fins extending to the central axis possesses the best comprehensive heat transfer performance. The heat transfer correlation of the optimal fin structure is Nu = 0.864Re0.4275Pry0.3818(Pry/Prw)?0.1004. With low cost and strong heat transfer performance, the bent extruded aluminum inner fin tube will gain wide applications in the engineering field.