Abstract
Optimum configurations of a finned annulus with longitudinal fins of triangular cross-section have been investigated numerically for the enhancement of overall (hydraulic and thermal) performance so that optimum use of energy and saving of cost may be achieved. A steady, laminar and incompressible flow is considered in the fully-developed region of the finned annulus subjected to the thermal boundary condition of constant heat transfer rate per unit axial length. Optimization has been carried out by using genetic algorithm. Finite element method is employed to perform the numerical simulation of the flow and provide function values to the optimizer Using surface flow area goodness factor as the objective function, various optimum configurations have been proposed depending on practical and industrial requirements. A comparison of the present optimum configurations has been carried out with those based on the Nusselt number as an objective function. The results indicate that the present objective function gives, in many cases, cost- and weight-efficient optimum configurations with considerable reduction in pressure loss and provides optimum use of energy along with saving of the cost. Relative performance measures recommend the use of at least 18 fins to have trade off between the gain in heat transfer coefficient and loss in the pressure gradient.