The paper deals with an experimental study of the influence of conical rings with internal fins inserts on heat transfer and friction characteristics in a circular tube. In the present work, the conical rings with internal fins are placed in the test tube section with five different diameter ratios of the ring to tube diameter (d/D = 0.5, 0.6, 0.7) and for each ratio, the rings are placed with three different arrangements, converging conical ring, CR array, diverging conical ring, DR array and converging-diverging conical ring, CDR array. In the experiment, cold air at ambient condition is passed through the uniform heat flux circular tube for Reynolds numbers in a range of 8000 to 32464. The results indicate that the effect of the reverse flows, ring to tube diameter ratio and the ring arrays can improve the heat transfer rate in the tube. Also, the experimental results demonstrate that the use of conical ring with internal fins inserts leads to a higher heat transfer rate than that of the plain surface tube, and the diverging conical ring array yields a better heat transfer than the others. The results are also correlated in the form of Nusselt number and friction factor as a function of Reynolds number, and diameter ratio.