Mixed convection in rectangular enclosures with adiabatic fins attached on the heated wall

Abstract

The investigation of heat transfer and fluid flow by mixed convection in a vertical rectangular cavity containing adiabatic partitions attached to the heated wall is numerically studied. The parameters governing this problem are the Rayleigh number (103≤Ra≤4×105), the Reynolds number (5≤Re≤100), the aspect ratio of the cavity (2.5≤A≤15), the partitions length (0.1≤B≤0.95), the aspect ratio of the micro cavities (0.33≤C≤0.66) and the Prandtl number (Pr=0.72). The results obtained indicate that the heat exchange between the system and the external medium, through the cold wall and the upper vent, are considerably affected by the presence of the partitions and for all the values of A and Ra considered. However, the quantity of heat released by the higher opening remains insensitive to the presence of the partitions; it depends only on the intensity of the forced flow. Moreover, it is shown that for critical values of Re and Ra, these rates of heat transfer pass by maxima of which the value is independent of A when this parameter is equal to or higher than 10. For high Reynolds numbers, the flow is dominated by forced convection for low values of Ra and high values of B. Finally, the competition between natural and forced convection occurs when Ra≥104. The heat transfer is correlated with the main parameters and presented for an eventual utilization in design.