Double-diffusive natural convection in parallelogrammic enclosures

Double-diffusive natural convection in parallelogrammic enclosures filled with moist air is studied numerically. This geometry presents high potential for heat and/or mass transfer, since it can act as a heat and/or mass transfer promoter or as a heat and/or mass transfer inhibitor, being referred to as a heat and/or mass transfer diode. Work is concentrated on the physical modeling and on the analysis of a set of numerical results, obtained for some combinations of the dimensionless governing parameters, for two-dimensional parallelogrammic enclosures. The heat and mass transfer characteristics of the parallelogrammic enclosure are analyzed using the streamlines, heatlines and masslines. Its transfer performances are analyzed and it is explored the dependence of the global Nusselt and Sherwood numbers on the thermal Rayleigh number, aspect ratio and inclination angle, both for the situations of combined and opposite global heat and mass flows through the enclosure. Relevant information can be extracted from the presented results in what concerns the overall heat and/or mass transfer performance of the parallelogrammic enclosures, and how selected combinations of the governing parameters can lead to maximum or minimum overall transfer. The heat and/or mass transfer diode effect of this shape is also highlighted. Results clearly show the high potential of the parallelogrammic enclosures, which can be used alone or taken as the basic form to obtain, by assembly, most complete and even complex efficient heat and/or mass transfer systems. (C) 2004 Elsevier Ltd. All rights reserved.