Abstract:

                     This research presents the results of numerical study of heat transfer and pressure drop in a heat exchanger that is designed with different shape fins. The heat exchanger used for this research consists of a rectangular duct fitted with different shape fins (pin fins as well as thin plate fin), and is heated from the lower plate. The fin shape and the heat exchanger (HE) configuration were numerically studied to maximize the convective heat transfer rate and minimize the pressure drop across the heat exchanger & also along the heat sink. For analysis a three dimensional finite volume based numerical model using CFD tool ANSYS FLUENT 14.0 was used. The simulation applied to estimate convection heat transfer rate of fin surface and pressure drop in duct due to shape change at  two different Reynolds number (Re 5000 & 50000)  with different pin fins & a thin plate fin in turbulent forced convection conditions. Different fin configuration includes tear drop, elliptical & rectangular cross section fins along with a thin rectangular plate fin, all having constant total surface area and pin height ratio having different fin material has been studied. The data and conclusions of this study can be applied to the optimization of different heat exchangers which are used in industry. It can also be used in the design of Heat sink having internal fins, Charge air-cooler tubes with internal fins, vertical tubes & pipes & also for external fins of air cooled I.C engines, compressors, electric motors, turbine blade cooling, space industry. The results obtained from the different simulations shows that convective heat transfer rate increases with increase in Reynolds number. Hence turbulent flow conditions of (Re=5000) are applied for the first simulation over all fin configurations & results shows that thin rectangular plate fin dissipates maximum heat transfer rate & posses minimum pressure drop along duct geometry, this result also represents that under less turbulent forced conditions thin plate fin is better  than pin fins. While at much higher Reynolds number (Re=50000) elliptical pin fins have the maximum heat transfer rate & even minimum pressure drop as compared to all pin fin configurations. The research work also shows that material having higher thermal conductivity posses higher convective heat transfer rate. Despite having the same total surface area thin rectangular plate fin has the minimum volume which is beneficial from weight point of view.

Key words:  CFD, FLUENT, Simulation, Optimization, Turbulence