A numerical study of laminar free convection heat transfer between inner sphere and outer vertical cylinder |
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| Affiliation: | 1. Université Paris Ouest, Laboratoire Thermique Interfaces Environnement, LTIE-GTE EA 4415, 50, Rue de Sèvres, F-92410 Ville d’Avray, France;2. Universidad Politécnica de Madrid, Departamento de Física Aplicada, Ronda de Valencia 3, E-28012 Madrid, Spain;1. Materials Innovation Institute (M2i), Mekelweg 2, 2628 CD, Delft, The Netherlands;2. Delft Institute of Microsystems and Nanoelectronics (Dimes), Delft University of Technology, Mekelweg 6, 2628 CD, Delft, The Netherlands;3. Research and Development Center for Semiconductor Lighting, Institute of Semiconductors, Chinese Academy of Sciences, Haidian, Beijing 100086, China;4. State Key Laboratory of Solid-State Lighting, Haidian, Beijing 100086, China;1. Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad 91775-1111, Iran;2. Department of Mechanical Engineering, Semnan Branch, Islamic Azad University, Semnan, Iran;1. Department of Mechanical Engineering, National Chiao Tung University, Hsinchu 300, Taiwan;2. Department of Mechanical Engineering, Yuan Ze University, Taoyuan, Taiwan;1. Key Laboratory of Railway Vehicle Thermal Engineering of MOE, Lanzhou Jiaotong University, Lanzhou, Gansu 730070, PR China;2. School of Mechanical Engineering, Lanzhou Jiaotong University, Lanzhou, Gansu 730070, PR China;3. School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou, Gansu 730070, PR China |
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| Abstract: | The effects of height and radius ratio with a Newtonian fluid have been investigated numerically to determine heat transfer by natural convection between the sphere and vertical cylinder with isothermal boundary conditions. The inner sphere and outer vertical cylinder were heated and cooled in a steady change of temperature. Calculations were carried out systematically for a range of the Rayleigh numbers to determine the average Nusslet numbers which are affected by the geometric ratio parameters (HR and RR) on the flow and temperature fields. The governing equations, in terms of vorticity, stream function and temperature are expressed in a spherical polar coordinate system. Results of the parametric study conducted further reveal that the heat and flow fields are primarily dependent on the Rayleigh number and height and radius ratio, for a Prandtl number of 0.7, with the Rayleigh number ranging from 103 to 106, and the height and radius ratio varying from 1.2 to 5.0. Above all, the specification of different convective configurations has a significant effect on the average heat transfer rate across the composite annulus gap. |
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