Effect of Louver Angle in Multi-Louvered Fins at Low Reynolds Numbers

The paper studies the effect of large louver angles on the performance of large pitch multilouvered fins at low Reynolds numbers. The Reynolds number based on face velocity and louver pitch is varied between 50 and 300. Louver angles are varied from 20° to 60° for fin pitch ratios of 1.5 and 2.0. It is found that increasing louver angle has a favorable effect on flow efficiency up to a certain point, beyond which the flow efficiency decreases. The maximum flow efficiency is realized at smaller louver angles as the Reynolds number increases. The drop in flow efficiency is attributed to the development of recirculation zones which act as blockages. In spite of the decrease in flow efficiency, the heat transfer coefficient increases with louver angle for all the cases studied. It is found that as louver angle increases, impingement heat transfer at the leading surface of louvers becomes a dominant mode of heat transfer. Friction factors also increase with louver angle, primarily due to an increase in form drag.