Second Law Analysis in a Partly Porous Double Pipe Heat Exchanger

A combination of the first and second laws of thermodynamics has been utilized in analyzing the performance of a double pipe heat exchanger with a porous medium attached over the inner pipe. The goal of this work is to find the best conditions that allow the lowest rate of entropy generation due to fluid friction and heat transfer with respect to the considered parameters. Results show that the minimization of the rate of entropy generation depends on the porous layer thickness, its permeability, the inlet temperature difference between the two fluids, and the effective thermal conductivity of the porous substrate. An increase in the effective thermal conductivity of the porous medium seems to be thermodynamically advantageous. Unexpectedly, the fully porous annular gap yields the best results in terms of the rate of total entropy generation.