Combined heat and moisture convective transport in a partial enclosure with multiple free ports

Abstract

a b s t r a c tCombined heat and moisture transport in an enclosure with free ports has been investigated numerically. Enclosed moist air interacts with the surrounding air through these free-vented ports. The governing conservation equations were solved numerically using a control volume-based finite difference technique. Appropriate velocity boundary conditions at each ports are imposed to achieve overall mass conservation across this system. Air, heat and moisture transport structures are visualized respectively by streamlines, heatlines and masslines. Effects of buoyancy ratio, thermal Rayleigh number on convective heat/moisture transfer rate and flow rate across each free-vented port are discussed. Particularly, Numerical results demonstrate that the convective heat and moisture transport patterns and transport rates on horizontal ports greatly depend on properties of porous medium, while the air exchange rate on vertical port is almost unaffected by the buoyancy ratios for most situations.

Passive heat and moisture removal from a natural vented enclosure with a massive wall

“…The simulated results have been compared with those of extended domain method, which demonstrates that the present boundary assumptions are valid particularly as opening sizes are less than 1/2 [3,14]. Detailed numerical comparisons with benchmark results will also be presented in the following sections.…”

“…For liquid solutions, thermal diffusivity is considerably higher than mass diffusivity, and this is one of the causes of many remarkable patterns of these flows, like convective cells separated by sharp interfaces [13,14]. For air mixtures, however, Beghein et al [17] pointed out that the Lewis numbers of different kinds of pollutants mixed with air might vary between 0.2 and 5 (25 C and 1 atm).…”

“…One of these quantities can be pollutant concentration within the fluid. Such a phenomenon, combining temperature and concentration buoyancy forces, is called multi-component flow or double diffusion [13,14]. Taking essentially the building construction elements as an example, the convection motion of moist air results from the different levels of temperature and moisture concentration, thus giving rise to a double diffusive free convective fluid flow.…”

“…Additionally, visualization of the heat and moisture convective transports, using streamlines, heatlines and masslines [17,18,20e29], would be conducted, such that the transport paths of fluid, heat and moisture in the fluid cavity and walls would be presented clearly and vividly. Problems relevant to multiple solutions or oscillatory solutions [14,21,23] are not analyzed; the corresponding combinations of the dimensionless governing parameters and boundary conditions leading to such phenomena are intentionally avoided.…”

Influence of thermal radiation on non-Darcian natural convection in a square cavity filled with fluid saturated porous medium of uniform porosity

“…The buoyancy effect on free convection in a vertical cavity was analyzed by Tong and Subramanian [15] and Lauriat and Prasad [16]. Li Tang et al [17] studied combined heat and moisture convective transport in a partial enclosure with multiple free ports. Later Fu-Yun Zhao et al [18] investigated free heat and mass transfer in a porous enclosure with side vents.…”