Numerical study has been carried out to investigate heat transfer and pressure drop characteristics for streamlined shape tubes. The flow and thermal fields are investigated with varying diameter ratio of the tube ranging from 0.4 to 2.5 and Reynolds number ranging from 10,000 to 30,000. The results show that heat transfer per unit fan power is maximum at $D_2/D_1=0.8$. Furthermore, the heat transfer per unit fan power of streamlined shape tubes was compared with circular tube. The heat transfer per unit fan power of streamlined shape tube was larger than that of circular tube.