CFD analysis has been done to predict the heat transfer and fluid flow characteristics of smooth, internally finned and ribbed tubes for various flow conditions to compute the wall temperature, outlet temperature and Nusselt number. Wall temperature and Nusselt number as a function of optimum fin height, fin numbers, fin shape, duct shape and rib shape have been predicted to obtain maximum heat transfer to air flowing inside the tube. Experimental models have been made to validate the CFD analysis which could predict the wall temperature and Nusselt number. The results obtained from the computations could be used to predict the heat transfer and fluid flow characteristics of an internal finned tube specifically used in chemical and power plants.