Experimental and numerical investigation of the heat transfer augmentation and pressure drop in simple, dimpled and perforated dimpled louver fin banks with an in-line or staggered arrangement

Abstract

Numerical and experimental models have been developed to investigate the effect of adding an in-line and staggered arrangement of dimples and perforated dimples to multilouvered fins on the heat transfer augmentation and the pressure drop of the air flow through a multilouvered fin bank. Three-dimensional simulations of single row of louvers were conducted for the given geometries. Simulations were performed for different Reynolds numbers. The simulations revealed that the heat transfer and temperature augmentations occur due to the existence of a circulation region that is created by the dimple. Additionally, continuous temperature gradients have been observed over the louver surface with the highest temperature at the base of the louver and the lowest temperature at the middle of the louver. Additionally, the difference between these two points is more obvious with greater Reynolds numbers. Fin efficiency and fin effectiveness were calculated to assess louver performance. The air-side performance of the heat exchanger is evaluated by calculating the Colburn j factor and the Fanning friction f factor. The results demonstrate that adding dimples on the louver surface increases the j factor and the f factor. Likewise, adding perforation to the dimples results in the same increase. The present results indicate that compared with the in-line arrangement, the staggered arrangement could effectively enhance the heat transfer performance.