Parametric study on flow characteristics and heat transfer in rectangular channels with strip slits in ribs on one wall.

• Twelve slit ribs with various rib heights and open-area ratios are evaluated. • Flow structures and resulted heat transfer behaviors are analyzed and discussed. • Creating a slit in high-height ribs can improve the heat transfer performance. Augmentation of heat transfer must always be judged against an additional pressure loss. To this context, this paper explores slitted ribs on the turbulent flow and heat transfer characteristics in rectangular cooling channels with an aspect ratio of 4:1. A verified v2f turbulence model is applied in the present numerical simulations in the Reynolds number range from 20,000 to 80,000. The flow and thermal performance of various geometrical structures for the ratios of slit-length-to-rib-length (R l = 0, 0.20, 0.35 and 0.50) and the rib heights (e = 10 mm, 15 mm and 20 mm) are comprehensively compared and evaluated. Special thermal behaviors are carefully observed and analyzed with slits on ribs of different height. It is found that strip slits in low-height ribs provide both lower Nusselt number and friction factors than the corresponding solid ribs, while an opposite effect is captured for strip slits on high-height ribs. The present results suggest that introducing a short-length strip slit in ribs could be a beneficial way to enhance heat transfer of cooling channels with high-height ribs. [ABSTRACT FROM AUTHOR]