Numerical Simulation of Heat Transfer Enhancement in a Heat Exchanger Using Porous Material

This paper investigates numerically, the effect of porous inserts on forced convection in a circular pipe. Two different configurations are considered (i) porous material is inserted at the core of the pipe and (ii) an annulus porous material is attached to the inner wall. The flow inside the porousmaterial is modeled using the Darcy-Brinkman-Forchheimer model. The effect of several parameters mainly, porous layer thickness (Rr), Darcy number (Da) and thermal conductivity (ke), on the Nusselt number (Nu) and pressure drop are investigated. In the first configuration, the valueof Rr which maximizes Nu varies linearly from 0.8 to 0.95 as the value of Da decreases from 10-3to 10-6, While previous investigation reported a fixed value of 0.8 for Rr. In the secondconfiguration, for low value of ke, increasing Rr decreases Nusselt number, and the porous thickness to achieve lowest Nu, varies linearly from 0.6 to 0.85 as the value of Da decreases from 10-3 to 10-6 and the fully porous pipe configuration, yields the maximum Nu. But for high value of ke, increasing Rr increases Nu. At the expense of reasonable pressure drop, the optimum thickness of porous material is Rr=0.6, maximizes Nu in first configuration and minimizes it in secondconfiguration

Keywords:

Enhancement , forced convection , porous media