Experimental Investigations on Heat Transfer and Frictional Characteristics by Dimpled Surface

An experimental investigation was carried out to find the optimum dimple array pattern on flat surface. The researchers have documented theories related to dimple array pattern (i.e. inline array, staggered array, etc.) and dimple shapes (i.e. oval dimple, almond shape dimple, etc.). Protrusions like dimples are created on internal flow passage to augment the heat transfer. This project work is related to investigation of the forced convection heat transfer over dimple array. The objective of work is to find heat transfer rate and frictional characteristics from test surface and results are compared with flat surface. The dimple array pattern is in V-angled shape (60°, 90°, 120°) and pitch is 14mm & 16mm horizontally and 7mm & 8mm vertically. The Nusselt number, friction factor and thermal performance index was measured, dimples formed are spherical in shape with 10mm print diameter and 3mm depth, channel height is 25mm, test plate is having dimensions of 600 x 100 x 6mm. The Reynolds number based on hydraulic diameter was varied from 12381 to 30300. From the study it is observed that thermal performance was increasing with Reynolds number, 120° V-angled and 14mm pitch plate having higher thermal performance index of 1.82.