Numerical simulation of 2D turbulent natural convection of humid air in a cavity filled with solid objects.

Iyi, Draco; Hasan, Reaz; Penlington, Roger

Abstract

Natural convection flow in enclosures containing solid objects is important in the design of a wide range of industrial and engineering applications. Numerical calculations were performed for low turbulence double-diffusion convection for humid air inside a rectangular cavity with an aspect ratio of 2:1(height/width) and partially filled with disconnected solid cylindrical objects occupying 15% of the total cavity volume. The vertical walls are maintained at 1.2 and 21 °C and a Rayleigh number of the fluid mixture based on the height of the vertical wall is 1.45 × 109. In the computations, turbulent fluxes of momentum, heat and mass were modelled by a low-Re (Launder-Sharma) κ-□ eddy diffusivity model. Radiation equation was discretised using the discrete ordinate method. Detailed analysis was performed on the flow and heat transfer and on the turbulence quantities within the cavity. The effect of 2D simplification of inherently 3D radiation modelling was carefully scrutinised and calculations carried out with an equivalent emissivity. Variations of average Nusselt number and buoyancy flux are analysed. Profiles of turbulent kinetic energy and turbulent viscosity are studied in detail to observe the net effect on the intensity of turbulence caused by the interactions of radiation with double-diffusive natural convection heat and mass transfer. Particular emphasis was placed on quantifying the proximity of the solid objects to the active walls. It has been found that turbulence is suppressed as the objects get closer to the walls.

Citation

IYI, D., HASAN, R. and PENLINGTON, R. 2013. Numerical simulation of 2D turbulent natural convection of humid air in a cavity filled with solid objects. Procedia engineering [online], 56: proceedings of 5th Bangladesh Society of Mechanical Engineers (BSME) International conference on thermal engineering 2012 (ICTE 2012), held during 21-23 December 2012, Dhaka, Bangladesh, pages 538-543. Available from: https://doi.org/10.1016/j.proeng.2013.03.157

• Journal Article Type: Conference Paper
• Conference Name: 5th Bangladesh Society of Mechanical Engineers (BSME) International conference on thermal engineering 2012 (ICTE 2012)
• Conference Location: Dhaka, Bangladesh
• Acceptance Date: May 7, 2013
• Online Publication Date: May 7, 2013
• Publication Date: May 31, 2013
• Deposit Date: Dec 23, 2016
• Publicly Available Date: Dec 23, 2016
• Journal: Procedia engineering
• Print ISSN: 1877-7058
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 56
• Pages: 538-543
• DOI: https://doi.org/10.1016/j.proeng.2013.03.157
• Keywords: Double diffusive heat and mass transfer; Natural convection; Emissivity
• Public URL: http://hdl.handle.net/10059/2064