ojme.02.2017.11.15

In the present study a non-Newtonian fluid flowing in an annulus pipe, has been simulated numerically. The considered geometry is an annulus pipe equipped with some fins. Heat transfer and entropy generation for some different fin geometries have been characterized through a written computer program. The written code is based on finite element method using Hermitian weight functions. Using first order Hermitian weight function, keeps all derivations continuous in the integrating domain, while improving convergence rate and also the accuracy of the solution. The geometry of fins is optimized using “Entropy Generation Minimization”, in order to reach maximum heat transfer rate. Increasing length of a fin, improves heat transfer while increasing pressure drop of the flow which in turn decrease heat transfer; therefore the optimizing method should simultaneously consider the two mentioned effects. In the present work, simulation of the non- Newtonian fluid has been accomplished using Power Law for modeling of non-Newtonian flow, while continuity, mass and energy reservation laws have been considered. Entropy generation rate is then obtained using second law of thermodynamics. Different fin geometries and arrangements are compared in order to find the optimum condition..