In this paper, the thermal and hydrodynamic behavior of alternating elliptical tubes in a double-pipe heat exchanger has been introduced and examined. Additionally, the effect of pitch length and degree of flattening on the rate of forced convective heat transfer and pressure drop in alternating elliptical tubes has been studied and compared with the results of circular tubes. The experiments were conducted in the Reynolds range of 200 to 1200, and the results were calculated using the statistical method of the confidence interval with 95 percent accuracy. The fluid tested was water and oil as the heat transfer base. Experimental results show that the heat transfer rate and pressure drop of alternating elliptical tubes are higher than those of circular tubes, and with a decrease in pitch length and an increase in flattening at a constant tube length, both heat transfer and pressure drop increase. It was also determined that the heat transfer rate of the alternating elliptical tube with the same flatness and a pitch of 120 millimeters is approximately 1.05 and the pressure drop is approximately 1.03 times that of the alternating elliptical tube with a pitch of 280 millimeters. Additionally, the heat transfer rate of the alternating elliptical tube with the same pitch and a flatness of 10 mm was approximately 1.15, and the pressure drop was approximately 1.11 times that of the alternating elliptical tube with a flatness of 12 mm. Finally, it was concluded that the heat transfer rate of the alternating elliptical tube with pitch and flattening of 10-120 mm, 10-280 mm, and 12-120 mm is approximately 2.30, 2.20, and 2 times, respectively, and the pressure drop is 1.33, 1.29, and 1.2 times that of the circular tube. Subsequently, by comparing and examining the criterion for the increase in efficiency ratio for elliptical and circular tubes, it was determined that the performance coefficient of the elliptical tubes is higher than that of the circular tubes. Among them, the elliptical tube with a pitch and flattening of 10-120 mm has the best performance.