Longitudinal finned tubes

The longitudinal finned tube is welded longitudinally along the steel pipe by high-frequency resistance welding. Fin material shall be compatible with resistance welding of steel pipe material. Before welding the fins, the external surface of the steel pipe shall be treated to ensure the welding rate of the fins. Before welding, fins shall be bent into a U-shape, cut into proper lengths, and arranged along the tube length. U-shaped finned tubes are welded in pairs, facing symmetrically and oppositely- Therefore, the total of fins is a multiple of 2. The heat transfer area of longitudinal finned tubes is 8 – 12 times higher than that of smooth tubes. As the heat transfer area increases, the volume of the heat exchanger can be greatly reduced.

♦ The heat transfer coefficient of longitudinal finned tubes is always greater than the cross-flow finned tubes because the heat transfer coefficient of longitudinal finned tubes depends on two factors, namely the internal fin effect and the external surface effect, In contrast, the cross-flow finned tube’s heat transfer coefficient only depends on its external surface effect.

♦ In addition, since the gas flows in one direction within a longitudinal finned tube, there is no need to consider pressure drop in calculating heat loss through them. This saves a lot of time and effort for engineers designing these heat exchangers.

♦ Another advantage of longitudinal finned tubes is that they can be used as both gas and liquid coolers since they have very good thermal conductivity properties as well as good mechanical strength properties, making them ideal for all types of applications that require high thermal efficiency at low cost and low-pressure drop rates.