This paper introduces experimental tests to investigate the hydrothermal characteristics of align-complete circular tube (CCT) or semicircular tube (SCT) banks at a wide range of airflow across the tubes. The tests considered several gap ratios between the bases (0.126    0.378) of pairs of SCTs with different pitch ratios in transversal/longitudinal directions. The findings declare that the SCT is a helpful passive tool for supplementing the air-cooling load, while it also leads to raising the airflow resistance, when compared with systematic shape. Moreover, the ¯Nu_o and f_o are increased by expanding the space between the flat bases and decreasing the spacing between the tubes in both directions. Besides, the hydrothermal performance approach (HTPA) is affected by varying SCT geometrical parameters. It is increased by increasing the gap between the flat SCTs-bases in addition to the transversal pitch and decreasing the longitudinal pitch. It is recorded that the maximum value of HTPA through this study is 2.25.