<span style="font-size:14.0pt;line-height: 115%;font-family:"Times New Roman";mso-fareast-font-family:"Times New Roman"; color:black;mso-ansi-language:EN-IN;mso-fareast-language:EN-IN;mso-bidi-language: HI" lang="EN-IN">An experimental study of convective heat transfer from flat and ribbed surfaces^†</span>

464-471Heat transfer and friction characteristics of flow in a rectangular channel with a solid rib mounted on the bottom surface of the channel have been investigated experimentally. The experiments have been carried out at Reynolds number (based on hydraulic diameter of the channel) range of 12,800 to 29,400. The skin friction coefficient, Nusselt number, velocity and temperature profile results are presented. The surface temperature images obtained with the help of liquid crystal thermography supplement the understanding of flow physics with qualitative explanation. The average Nusselt number for the ribbed flow case is higher in comparison to that for the flat surface. The increase in skin friction coefficient for the ribbed flow case is comparatively less than the Nusselt number increase, indicating the effectiveness of the ribbed surface in heat transfer enhancement applications. The liquid crystal thermography images show the flow in the downstream region of the rib to be two dimensional in nature. The recirculation and reattachment region for the ribbed flow case and their role in heat transfer effectiveness is clearly visible in the liquid crystal images.</span