ENHANCEMENT OF HEAT TRANSFER IN A PASSIVE COOLED HEAT EXCHANGER USING POROUS MATERIAL

Document Type : Original Article

Authors

1 Mechanical Department, Faculty of Engineering, Al-Azhar University, Cairo, Egypt

2 Mechanical Power Engineering Department, Faculty of Engineering, Ain Shams University, Cairo, Egypt

10.21608/auej.2023.249114.1475

Abstract

The airside of air-cooled heat exchangers causes poor thermal characteristics resulting in a low heat transfer coefficient (HTC). To overcome this issue, extended surfaces are widely used to improve both thermal performance and HTC. This research presents a numerical investigation of passive cooling by using copper foam porous material as an extended surface to increase the heat transfer area, for laminar flow, on a heat exchanger consisting of a vertical down-faced V-shape porous media attached to a vertical heat source for augmentation of the heat transfer rate in the heat exchanger. The hydraulic and thermal characteristics of passive cooling were studied to evaluate the thermal performance by the overall HTC and Nusselt number. The finite Element Method (FEM) is used to conduct this research by employing the COMSOL software. The study was carried out for different V-shape angles of 30, 60, 90, and 180 degrees and porous insert thicknesses from 0.1-100 mm. The effect of porosities of 50%, 75%, and 95% were investigated. The results show that the hydraulic and thermal characteristics were changed with changing the porous insert height and slightly changed with changing the angles and porous insert thicknesses. The porous insert height was changed from 1-100 mm, and the results indicate that beyond 4 mm height, the performance is almost unchanged, and the effectiveness decreases significantly with increasing the height. Angle 14 degrees gives the best buoyancy and pumping power. Also, porosity 50% gives the best HTC. Accordingly, a fin thickness of 2 mm and a porous insert height of 4 mm were adopted.
 
Special Issue of AEIC 2024 (Mechanical & Chemical and Material Engineering  Session)

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Journal of Al-Azhar University Engineering Sector
Volume 19, Issue 72
Special Issue for Al-Azhar Engineering 16th. International Conference (AEIC 2024)
July 2024
Pages 37-55

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