Optimization of fin numbers in an external extended finned tube heat exchanger is the main subject of this work. For this purpose an experimental apparatus was constructed and available data such as temperature distribution along the heat exchanger surface at fixed Reynolds and different Rayleigh numbers were recorded and used as a verification tool for corresponding numerical results. Numerical results which are responsible for heat transfer rate, average fin Nusselt number and temperature distribution were reported. According to numerical results optimized fin numbers for maximum heat transfer were obtained for a given conditions. Also the rate of entropy generation has been calculated and consequences to the same results for optimum fin numbers. Finally to estimate the average fin Nusselt number, characteristic length scale S is introduced and used in new obtained correlation for current heat exchanger.
