CFD MODELLING OF NATURAL CONVECTION HEAT AND MASS TRANSFER IN HYGROSCOPIC POROUS MEDIA

Abstract This paper presents the derivation of a model to predict heat and mass transfer in a system consisting of a turbulently flowing fluid overlying a saturated hygroscopic porous medium. Comparisons with experimental and numerical simulations have been carried out to check the accuracy of components of the model. Finally, a case study using silica gel as a representative hygroscopic porous medium is presented as an application of the model. It is shown that moisture is convected from the warm interior of a bulk of porous medium to the relatively cool periphery. This result has profound practical implications when the hygroscopic medium is stored agricultural produce as the region of high moisture content may become moldy.

[1]  C. F. Chen,et al.  Convection in superposed fluid and porous layers , 1992, Journal of Fluid Mechanics.

[2]  Ozden Turan,et al.  Impinging round jet studies in a cylindrical enclosure with and without a porous layer: Part I—Flow visualisations and simulations , 2001 .

[3]  S. Whitaker.  Diffusion and dispersion in porous media , 1967 .

[4]  Yuguo Li,et al.  High-Rayleigh-Number Natural Convection in an Enclosure Containning a Porous Layer , 1998 .

[5]  G. Neale,et al.  Practical significance of brinkman's extension of darcy's law: Coupled parallel flows within a channel and a bounding porous medium , 1974 .

[6]  S. Whitaker,et al.  Local mass and thermal equilibria in ventilated grain bulks. Part II: The development of constraints , 1992 .

[7]  Falin Chen,et al.  Experimental investigation of convective stability in a superposed fluid and porous layer when heated from below , 1989, Journal of Fluid Mechanics.

[8]  R. Viskanta,et al.  Natural convection flow and heat transfer within a rectangular enclosure containing a vertical porous layer , 1994 .

[9]  John C. Slattery,et al.  Flow of viscoelastic fluids through porous media , 1967 .

[10]  D. Poulikakos.  Buoyancy‐driven convection in a horizontal fluid layer extending over a porous substrate , 1986 .

[11]  A. J. Hunter,et al.  An isostere equation for some common seeds , 1987 .

[12]  J. W. Sutherland,et al.  Equilibrium heat and moisture transfer in air flow through grain , 1971 .

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

[14]  R.A.W.M. Henkes.  Natural-convection boundary layers , 1990 .

[15]  R. Viskanta,et al.  Natural convection in vertical enclosures containing simultaneously fluid and porous layers , 1988, Journal of Fluid Mechanics.

[16]  K. R. Blake,et al.  High Rayleigh number convection in a fluid overlaying a porous bed , 1986 .

[17]  B. Chan,et al.  Natural convection in enclosed porous media with rectangular boundaries , 1970 .

[18]  Allan Kirkpatrick,et al.  An experimental investigation of mixed cavity natural convection in the high Rayleigh number regime , 1986 .

[19]  Stanley Middleman,et al.  Flow of Viscoelastic Fluids through Porous Media , 1967 .