Experimentation on Optimal Configuration and Size of Thin Cylinders in Natural Convection

Ali Riaz (Department of Mechanical Engineering, Pakistan Institute of Engineering and Applied Sciences, Islamabad, 45650, Pakistan)
Adnan Ibrahim (School of Engineering Science, University of Science and Technology of China, Hefei, 230027, China)
Muhammad Sohail Bashir (Hefei National Laboratory for Physical Sciences at the Microscale, CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui, 230026, China.)
Masroor Asghar (Department of Information Technology, University of Southern Queensland, Toowoomba, 4350, Queensland, Australia)
Muhammad Abdullah (Department of Mechanical Engineering, Pakistan Institute of Engineering and Applied Sciences, Islamabad, 45650, Pakistan)
Ajmal Shah (Department of Mechanical Engineering, Pakistan Institute of Engineering and Applied Sciences, Islamabad, 45650, Pakistan)

Article ID: 4720

Abstract


In this paper, an experimental study of laminar, steady state natural convection heat transfer from heated thin cylinders in an infinite air medium has been reported. Two electrically heated cylinders having the same slenderness ratio (L/D) i.e. 6.1 but different diameters i.e. 3.8 cm and 5.08 cm were used. 105 experiments were carried out to study the effect of diameter and inclination angle of thin cylinder on natural convection heat transfer. After mandatory corrections of radiation and endcap heat losses, convective heat transfer results were presented in the form of local and average dimensionless numbers. For vertical configuration of thin cylinder, Nusselt number was varied from 52.99 to 95.10 corresponding to 1.28×108≤Ra*L≤1.08×1010. While for horizontal configuration,Nusselt number was varied from 10.74 to 17.78 corresponding to 9.42×104≤Ra*D≤8.17×106. Results were compared with the published data and found satisfactory as the maximum percentage difference was only 3.09%. The essence of research is that the heat transfer coefficient increases with decrease in diameter and increase in inclination angle. Smoke flow visualization was done to capture patterns of fluid flow. Finally, comparison was made to quantify increase in Nusselt number from slender cylinder as compared to the flat plate.


Keywords


Natural convection; Thin cylinders; Flat plate; Nusselt number

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References


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DOI: https://doi.org/10.30564/ssid.v4i2.4720

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