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Proceedings of the 27th National and 5th International ISHMT-ASTFE Heat and Mass Transfer Conference December 14-17, 2023, IIT Patna, Patna-801106, Bihar, India
December, 14-17, 2023, Bihar, India

Enhancement of Free Convective Heat Transfer Inside an Enclosure with Discrete Heat Sources

Get access (open in a dialog) DOI: 10.1615/IHMTC-2023.1370
pages 847-852


The trend towards miniaturizing electronic components has compelled the electronics industry to seek improved heat-dissipation methods for optimal device performance. Natural convection, being a passive and noise-free method for heat dissipation, remains pivotal in the thermal management of such electronic devices. This study numerically investigates natural convection heat transfer within a discretely heated rectangular, vertical enclosure with an attached fin on its cold wall. The top and bottom horizontal walls of the enclosure are insulated, while the right vertical wall of the enclosure is maintained at a constant ambient temperature of 300.15K. Moreover, four discrete heaters of equal length (5mm) and spaced equidistantly (6mm) are mounted on the left wall of the enclosure, with each heater being subjected to a constant heat flux condition. The present study is limited to the laminar regime, with Rayleigh numbers ranging from 103 to 106, which is achieved using compressed gaseous nitrogen as the working fluid. Non-dimensional fin length (l/L) and fin position (h/H) are varied from 0.25 to 0.75 and 0.25 to 0.94, respectively. Results show that Nusselt Number Ratio or fin effectiveness (NNR = Nuinsert/Nunoinsert) exceeds unity at low Rayleigh numbers, owing to the dominance of fin conduction heat transfer. Furthermore, irrespective of the fin length, enclosures with a fin located at h/H of 0.5 is found to be the most effective for the investigated range of Rayleigh numbers. Consequently, NNR is found to reach its highest value of 1.54 for the non-dimensional fin position and length of 0.5 and 0.75, respectively. At high Rayleigh numbers, the effectiveness of these enclosure is significantly reduced due to the absence of any fin-boundary layer thermal interaction, with the maximum value of NNR reading a paltry 1.07 for the enclosure with an h/H of 0.94 and l/L of 0.75.