Comparision of Heat Transfer Coefficients in Free and Forced Convection Using Circular annular Finned Tubes

ABSTRACT In this study, heat transfer coefficients in both free and forced convection heat transferusing vertical circular annular finned tubes were investigatedexperimentally. For this purpose three types of metals were used, namely,Aluminum, Copper, and Iron. These metals differ from each other intheir specific weight,cost and thermal conductivities which are 204 W/m.K for Aluminum, 386 W/m.K for Copper and 73 W/m.K for iron.Surface temperature employed during experiments varied between 40and 60 Co at 10 Co intervals. The spacing between fins is 1cm. It was found that the heat transfer coefficient increases with increasing air speed from (1to 3) m/s, and there is anoticeable increase in heat transfer coefficientwhen using Copper metal to manufacture the tube and the fins as compared to Aluminum and Ironmetals.