Thermal and hydraulic performance for laminar flow over a fin and flat tube heat exchanger with various aspect ratios studied numerically. The parameters studied were inlet air velocity and flat-tube aspect ratio. The inlet air velocity was changed within the range of 0.5–3.5 m/s, and the aspect ratio of the flat-tubes has been changed in the range of 0.33–1. To do this study, a three-dimensional numerical model was implemented to investigate the airside performance using the commercial CFD software ANSYS FLUENT 17.2. The numerical model consists of 4 tubes in a staggered arrangement, to simulate a dry cooling process in a heat exchanger. The numerical model has been validated by comparing the pressure drop and the heat transfer coefficient with the experimental published data. A good agreement was observed between the present and experimental published data. In the current study, pressure drop (ΔP), heat transfer coefficient (h), area goodness factor (j/f), and heat transfer per unit fan power (Q/P_f) were determined and illustrated graphically. The results indicated that the flat-tube aspect ratio has a significant effect on the pressure drop and the heat transfer per unit fan power. Decreasing the flat tube aspect ratio from 1 (circular tube) to 0.33 the pressure drop reduced by 33.7% and 57.3% with an air inlet velocity of 0.5 and 3.5 m/s respectively. Also, decreasing the flat tube aspect ratio from 1 to 0.33, the Q/P_f is enhanced by 52.9% and 111.5% with an air inlet velocity of 0.5 and 3.5 m/s respectively. Finally, it is concluded that the flat-tube with the lowest aspect ratio has the highest overall performance of the heat exchanger, and thus it is recommended to reduce the energy consumption.

数值研究了不同长宽比的翅片和扁平管式换热器层流的热和水力性能。研究的参数是进气速度和扁管纵横比。进气速度在0.5-3.5 m / s的范围内变化，扁管的纵横比在0.33-1的范围内变化。为了进行这项研究，使用商业CFD软件ANSYS FLUENT 17.2实施了三维数值模型来研究空侧性能。数值模型由交错排列的4个管组成，以模拟热交换器中的干式冷却过程。通过将压降和传热系数与实验公布的数据进行比较，验证了该数值模型的有效性。在目前的和实验的公开数据之间观察到很好的一致性。在当前的研究中，压降（ΔP），传热系数（h），面积优度因子（j / f）和每单位风扇功率的传热（Q / P）_f）已确定并以图形方式说明。结果表明，扁平管的长宽比对单位风扇功率的压降和传热有显着影响。将扁平管的长宽比从1（圆形管）降低到0.33时，压降分别降低了33.7％和57.3％，进气速度分别为0.5和3.5 m / s。同样，将扁管的宽高比从1降低到0.33，Q / P _f分别以5和3.5 m / s的进气速度提高了52.9％和111.5％。最后，得出结论，纵横比最低的扁平管具有最高的热交换器整体性能，因此建议降低能耗。