Numerical investigation of heat transfer and flow characteristics of in-line and staggered circular and ellipti̇cal tube bank

In this study, 18 different cases are determined for an in-line and staggered arrangement of circular and elliptical tube banks and their heat and flow characteristics are investigated numerically depending on different S_L^* and S_T^* values. The dimensionless pitch ratios (S_L^* and S_T^*) are determined as 1.6, 2 and 2.5, and the ratio of the horizontal radius to the vertical radius (a/b) of the elliptical tubes is determined as 0.75 and 1.5. The flow is assumed to be incompressible, steady, two-dimensional and turbulent. The heat transfer surface areas are assumed to be equal for the circular and elliptical tube banks and the equivalent diameter (D_e) is taken as 12.7 mm. A total of 16 tubes are used, with the number of vertical tubes being N_T and longitudinal tubes being N_L. Numerical studies are performed using ANSYS Fluent with RNG k - ɛ turbulence model. The average inlet air velocity values were determined as 2 m/s, 4 m/s, 6 m/s, and 8 m/s, respectively. According to the results obtained, the highest thermal efficiency was achieved for the in-line tube bank at the Reynolds number of 6520 in case 8, with a numerical value of 136.80, and for the staggered tube bank at the same Reynolds number in case 18, with a numerical value of 157.67.