Enhancing Mixed Convection Heat Transfer from Multiple Protruding Heat Sources Using Inclined Obstacles.

Awad, Mahmoud M.; Sultan, Gamal Ebrahim; A. El-Awady, Waleed

doi:10.21608/bfemu.2021.206159

Enhancing Mixed Convection Heat Transfer from Multiple Protruding Heat Sources Using Inclined Obstacles.

Document Type : Research Studies

Authors

¹ Mechanical Power Engineering Department, Faculty of E Engineering, Mansoura 35516 University, Mansoura 35516, Egypt.

² Professor of Mechanical Power Engineering Department, Mansoura University, Mansoura 35516, Egypt

10.21608/bfemu.2021.206159

Abstract

Experimental and numerical investigations are conducted to study the heat transfer enhancement of electronic components by re-directing the air flow to the surfaces of the heat sources and cavities between them. The study simulates the electronic components as a three heat sources which are mounted in a horizontal rectangular channel.
The flow is re-directed to the heat sources using three inclined obstacles above the heat sources in order to orient the flow to both the closed cavity regions and heat sources surfaces. The numerical investigation is conducted using a commercial package "FLUENT 6.1". The heat sources dimensions are 15 cm width. 4 cm length, and 5.8 cm while the obstacles inclination angles are 26.5^o, 36.9^o, 45^o, and 51.3^o. The Reynolds number is range from 856 to 8340 and Grashof number is fixed at about 2.0 x 10⁷. The study is extended to investigate the effect of channel height at fixed inclined obstacle angle of 36.9^o on heat transfer characteristics while the heat sources height is constant. The pressure drop due to heat sources protrusion and the inclined obstacles is also investigated. The results show that, as obstacle angle increases or channel height decrease (height ratio increases) the heat transfer for the three heat sources increases and gives an enhancement in the average Nusselt number up to 153.4%. It is noticed that, as the obstacle inclination angle increases the second heat sources towards to have the highest heat transfer coefficient. As obstacle angle or height ratio increases, the pressure drop increases sharply. The results also show that, the enhancement of the average Nusselt number due to using obstacles angles is more than that due to increasing Reynolds number for the same consumed pumping power. Two empirical correlations for average Nusselt number as a function of Richardson number and obstacle inclination angle or height ratio are obtained for each heat source.

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