Effects of Attaching Baffles onto the Inclined Walls of Attic Frames for Purposes of Energy Conservation

This article addresses the buoyant air circulation inside attic spaces of houses and buildings with sloped roofs and horizontally suspended ceilings. In order to counteract the excessive heat transmission through the roof that takes place during the wintertime, when the attic is heated at the base, this study attached an array of baffles onto the top inclined walls to alter the flow characteristics of the buoyant air. To perform the computational analysis, the finite volume method is the vehicle for the discretization of the conservation equations. The Boussinesq approximation is not invoked, and all thermophysical properties are considered as temperature-dependent. Simulations are performed for several values of baffles length and the Rayleigh number. The influence of these parameters upon the flow and temperature patterns is analyzed and discussed. A comparison of the thermal performance between baffled attics and non-baffled attics is presented. The results show that the presence of baffles provides an important energy savings for heating and helps keep the attic at a desired temperature.

[1]  Kenneth S. Ball,et al.  Laminar Natural Convection in Isosceles Triangular Enclosures Heated From Below and Symmetrically Cooled From Above , 1998, Heat Transfer: Volume 1 — Heat Transfer in Flowing Systems.

[2]  George N. Facas Natural convection in a cavity with fins attached to both vertical walls , 1993 .

[3]  V. A. Akinsete,et al.  Heat transfer by steady laminar free convection in triangular enclosures , 1982 .

[4]  Dimos Poulikakos,et al.  The fluid dynamics of an attic space , 1983, Journal of Fluid Mechanics.

[5]  S. M. Bajorek,et al.  Experimental Investigation of Natural Convection in Partitioned Enclosures , 1982 .

[6]  Nishimura Tatsuo,et al.  Natural convection in horizontal enclosures with multiple partitions , 1989 .

[7]  M. Sen,et al.  ANALYSIS OF LAMINAR NATURAL CONVECTION IN A TRIANGULAR ENCLOSURE , 1988 .

[8]  Antonio Campo,et al.  EXPERIMENTAL-BASED CORRELATIONS FOR THE CHARACTERIZATION OF FREE CONVECTION OF AIR INSIDE ISOSCELES TRIANGULAR CAVITIES WITH VARIABLE APEX ANGLES , 2005 .

[9]  R. D. Flack,et al.  The Experimental Measurement of Natural Convection Heat Transfer in Triangular Enclosures Heated or Cooled from Below , 1980 .

[10]  Tassos G. Karayiannis,et al.  Natural convection heat transfer in a partially—or completely—partitioned vertical rectangular enclosure , 1991 .

[11]  S. Patankar Numerical Heat Transfer and Fluid Flow , 2018, Lecture Notes in Mechanical Engineering.

[12]  Haydee Salmun,et al.  Convection patterns in a triangular domain , 1995 .

[13]  L. Namli,et al.  Laminar natural convection in a pitched roof of triangular cross-section: summer day boundary conditions , 2000 .

[14]  M. Teubner,et al.  Heat exchange in an attic space , 2002 .

[15]  Adrian Bejan,et al.  Natural convection in a partially divided enclosure , 1983 .

[16]  Tassos G. Karayiannis,et al.  On Natural Convection in a Single and Two Zone Rectangular Enclosure , 1992 .

[17]  G. D. Davis Natural convection of air in a square cavity: A bench mark numerical solution , 1983 .

[18]  Y. S. Sun,et al.  Effects of wall conduction, internal heat sources and an internal baffle on natural convection heat transfer in a rectangular enclosure , 1997 .