Title: Entropy generation for unsteady natural convection and thermal radiation inside a porous enclosure
Authors: Abdesslem Jbara; Khalifa Slimi; Abdallah Mhimid
Addresses: The National Engineering School, University of Monastir, Monastir 5019, Tunisia ' The Higher Institute of Transportation and Logistics, University of Sousse, Sousse 4000, Tunisia ' The National Engineering School, University of Monastir, Monastir 5019, Tunisia
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.
Keywords: entropy generation; porous enclosures; thermal radiation; unsteady natural convection; finite volume method; fluid flow; heat transfer; radiative transfer irreversibilities.
International Journal of Exergy, 2013 Vol.12 No.4, pp.522 - 551
Received: 29 Mar 2012
Accepted: 09 Aug 2012
Published online: 15 Jul 2013 *