EXPERIMENTAL INVESTIGATION OF HEAT TRANSFER ENHANCEMENT FROM MULTIPLE DIMPLED SURFACES IN RECTANGULAR CHANNEL
The heat transfer coefficient between the plate and surrounding flowing fluid can be considerably increased by using artificial roughness. Under the present work, an experimental study has been carried out to investigate the effect of roughness and operating parameters on heat transfer and friction factor in a roughened duct provided with dimpleshape roughness geometry. Investigation carried out for two configurations (single print diameter and double print diameter dimple), having print diameter 10mm and 5mm respectively, that covered the range of Reynolds number (Re) from 4,000 to 25, 000, and relative horizontal roughness pitch (p) varied from 20, 22, and 24mm for both configurations. The ratios of dimple depth to dimple print diameter (δ/D) is kept constant 0.3. Based on the experimental data, values of Nusselt number (Nu) and friction factor (f) have been determined for different values of roughness and operating parameters. In order to determine the enhancement in heat transfer and increment in friction factor values of Nusselt number and friction factor have been compared with those of smooth duct under similar flow conditions.