Numerical analysis of the effects of changeable transverse and longitudinal pitches and porous media inserts on heat transfer from an elliptic tube bundle

In this paper, effects of changeable transverse and longitudinal pitches and porous media inserts on overall heat transfer from an elliptic tube bundle are studied numerically. Governing equations used for the analysis of fluid flow inside the porous media inserts are Darcy-Brinkman-Forchheimer equations, and for the fluid flow without porous inserts are classical Navier-Stokes equations. A finite volume code is used to solve the governing equations. The tube bundle consists of 10 rows of elliptical tubes 3.17 cm in major diameter and 1.4 cm in minor diameter in a staggered arrangement. Aluminum foams are used as porous media inserts between the tubes with three different porosities. It is shown that the use of the aluminum foam enhances heat transfer significantly (more than 50% in some cases). However, the pressure drop increases as the Reynolds number grows. The differences among various cases are also discussed. Finally, it is shown that the overall heat transfer efficiency increases more effectively by increasing the transverse pitch with respect to the longitudinal and diagonal pitches while the flow regime remains laminar.