IJSTE - International Journal of Science Technology & Engineering | Volume 1 | Issue 9 | March 2015 ISSN (online): 2349-784X All rights reserved by www.ijste.org 56 Heat Transfer and Friction Behaviors in Rectangular Duct with two Different Ribs Sandeep Kumar Karole Ishwar Singh PG Student Lecturer Department of Mechanical Engineering Department of Mechanical Engineering Scope Collage Of Engineering Bhopal(India) Scope Collage Of Engineering Bhopal(India) Pankaj Sonkusre Lecturer Department of Mechanical Engineering Shri Balaji Engineering Collage Betul(India) Abstract Computational study was carried out to determine heat transfer and friction factors for turbulent flow through rectangular ducts with reveres pentagonal shape at same height, reveres pentagonal shape at uniformly varying height, Triangular shape at same height, Triangular shape at uniformly varying height . A commercial finite volume package ANSYS FLUENT 14.5 is used to analyze and visualize the nature of the flow across the ribbed duct. The fluid in the duct was air, and the heat transfer and friction factor were determined by measuring the overall heat transfer coefficients of the duct. To attain fully developed conditions at the entrance and exit. The walls of the air side were ribbed with an array of short ribs. The other wall of the duct was well insulated and can be considered adiabatic. The results are presented in dimensionless form, in terms of Nusselt numbers and friction factors as functions of the Reynolds number. It was found that the reveres pentagonal rib shape at same height and reveres pentagonal ribs shape at uniformly varying height increase both the heat transfer and the pressure drop compared with a smooth duct. And It was found that the Triangular shape at same height, Triangular shape at uniformly varying height increase both the heat transfer and the pressure drop compared with a smooth duct. Compare to both cases is best of the Triangular shape at uniformly varying height. Keywords: CFD, Friction Factor, Forced convection, Heat transfer, internal flow, Pressure Drop ________________________________________________________________________________________________________ I. INTRODUCTION Rectangular ducts are widely used in heat transfer devices, for instance, in compact heat exchangers, gas turbine cooling systems, cooling channels in combustion chambers and nuclear reactors. Forced turbulent heat convection in a square or rectangular duct is one of the fundamental problems in the thermal science and fluid mechanics. Since the discovery of electronic devices and computer, the technology has come a long way. Faster and smaller computers have led to the development of faster, denser and smaller circuit technologies which further has led to increased heat fluxes generating at the chip and the package level. Over the years, significant advances have been made in the application of air cooling techniques to manage increased heat fluxes. Air cooling continues to be the most widely used method of cooling electronic components because this method is easy to incorporate and is cheaply available. Repeated ribs or tabulators have been used as the promoters of turbulence to enhance the heat transfer to the flow of coolants in a channel. These roughness elements break the laminar sub-layer of the flow. The heat transfer is enhanced as well as the pressure drop, an important parameter in the analysis of the overall performance of such flows. Investigations have been conducted to predict the effect of the number of ribbed walls on heat transfer and friction characteristics. In applications such as cooling of gas turbine airfoils, rib tabulators are cast mostly on two opposite sides of the cooling channels, since the heat transfer takes place from the inner walls of the pressure and the suction sides of the blade. However, in some cases, rib tabulators are cast on one side or four sides of the cooling channels. While turbine blade internal cooling has been widely studied in the past, other applications such as electronic equipment, heat exchangers, and nuclear reactors may utilize the results of enhanced internal cooling in channels with one, two, three, or all four rib-roughened walls. The results with four-ribbed wall channel are also used to validate the assumptions made in the past to develop semi-empirical correlations for friction and heat transfer roughness functions.J.C. Han, J.S. Park, M.Y. Ibrahim.[1]- Fig. 5.1 shows the geometry of the cooling channel analyzed in this study; the channel was roughened by square ribs. The channel aspect ratio (AR =W/H) was 2.0, and the hydraulic diameter (Dh) was 34 mm. In total, 10 ribs were placed on one wall in the computational domain. The pitch-to-hydraulic diameter ratio (p/Dh) was 10.0 and the rib height-to-hydraulic diameter (h/Dh) was 0.047, which are the same as that used by Han et al.C.G. Spezial, S. Sarkar, T.B. Gatski [2]- Turbulence was analyzed using the Reynolds stress model with the Speziale–Sarkar–Gatski (SSG) pressure–strain model. The SSG model for the pressure–strain correlation terms in the transport equations for the Reynolds stress components was developed by considering the invariance with dynamical systems