Entropy generation for unsteady natural convection and thermal radiation inside a porous enclosure

Abstract

Entropy generation problem for unsteady natural convection and thermal radiation in a vertical porous enclosure, submitted to a uniform hot walls temperature and filled with a fluid saturated porous medium, has been performed. A time–space variations study is presented for fluid flow, heat transfer and radiative transfer irreversibilities, local entropy generation Sgen and modified Bejan number Bem. A sensitivity study shows that Bem increases, particularly near the boundaries, due to an increase in N or Br values and it decreases as τD or R values increase. For the cases of ε and ω, an inversion phenomenon is observed. Furthermore, Sgen and the total entropy generation Egen values rise when there is an increase in ε, τD, R or Br values. In opposition, Sgen and Egen values decrease with the increase of ω or N values.