Experimental study on forced convection in tubes with internal wave-like longitudinal fins

The characteristics of turbulent flow and heat transfer in tubes with three kinds of inside wave fins were investigated experimentally. The corresponding correlation for the friction factors and Nusselt numbers vs. the Reynolds numbers for the fin-tubes were obtained. The results of the above fin-tubes were compared with that of the smooth tubes. It was found that the fin-tubes with blocked inner tubes can significantly enhance the heat transfer among the three kinds of the fin-tubes due to the increase of fluid velocity in the tubes.