Journal ArticleDOI
Natural Convection in a Horizontal Cylinder with Partial Heating: Energy Efficiency Analysis
TLDR
In this article, a numerical analysis of free convection of air in an isothermal horizontal cylinder, cooled and heated at different wall locations is presented. And the effect of Rayleigh number on heat transfer and fluid flow characteristics within the cavity is investigated.Abstract:
The current study reports a numerical analysis of free convection of air in an isothermal horizontal cylinder, cooled and heated at different wall locations. Three heater sizes are discussed in this study. The first heated zone is spread across one-quarter of the sidewall; the second is uniformly distributed over the half of the wall and the third active wall covers three-quarters of the cylinder. Five various locations are considered and examined for each active zone of the sidewall. The computation is carried out for Rayleigh number ranging from 102 to 106. Numerical results characterizing heat transfer and flow features are achieved using an iterative model developed in COMSOL Multiphysics. The effect of Rayleigh number on heat transfer and fluid flow characteristics within the cavity are investigated. Particular attention is paid to the influence of heater location and heater size on energy efficiency. It is found that the mean Nusselt number and dimensionless velocity increase when increasing the Rayleigh number. Moreover, the optimal level of energy efficiency is achieved if the heating zone is centered at the upper part of the cylinder, regardless of the heater size. It is also shown that the optimal configuration providing higher energy efficiency is obtained when three-quarters of the sidewall are locally heated, and more precisely, if the active zone is centered at the top of the cylinder.read more
Citations
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Journal ArticleDOI
Interaction of mixed convection with non-gray gas radiation in a partially heated horizontal pipe: entropy generation analysis
Journal ArticleDOI
Natural convection from a horizontal cylinder placed in a square enclosure: CFD simulations
Journal ArticleDOI
Simulation of mass and heat transfer of Quercus leaf particles during hydrothermal extraction
Xiangyu Gao,Chensi Guo,Junying Chen,Lijun Wang,Xiao-Dong Zhao,Chun Chang,Xiuli Han,Jiande Song +7 more
TL;DR: In this article , the authors developed a mass and heat transfer model of Quercus leaf particles during hydrothermal extraction, and the results showed that the average particle size was 116.7 μm, and after soaking in water for 24 hours, the particle size increased to 127.3 μm.
Journal ArticleDOI
Improved Energy Efficiency of Mixed Convection Heating Process in Eccentric Annulus
TL;DR: In this paper, a numerical study of mixed convection heat transfer in horizontal eccentric annulus is presented, where the inner cylinder is supposed to be hot and rotating, however the outer one is kept cold and mo...
References
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Journal ArticleDOI
Natural convection in enclosures with localized heating from below and symmetrical cooling from sides
Orhan Aydin,Wen-Jei Yang +1 more
TL;DR: In this paper, a two-dimensional, rectangular enclosure with localized heating from below and symmetrical cooling from the sides has been numerically investigated and the results showed that the average Nusselt number at the heated part of the lower wall, \overline Nu, was shown to increase with an increase the Rayleigh number, Ra, or of the non-dimensional heat source thickness.
Journal ArticleDOI
Numerical study of natural convection in an enclosure with localized heating from below—creeping flow to the onset of laminar instability
K. E. Torrance,J. A. Rockett +1 more
TL;DR: Torrance, Orloff & Rockett as discussed by the authors made an analytical study of the natural convection induced in an enclosure by a small hot spot centrally located on the floor, and solved the equations of fluid flow in axisymmetric cylindrical coordinates with the Boussinesq approximation.
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Numerical investigation of natural convection phenomena in a uniformly heated circular cylinder immersed in square enclosure filled with air at different vertical locations
Salam Hadi Hussain,Ahmed Hussein +1 more
TL;DR: In this paper, a numerical study of two dimensional steady natural convection is performed for a uniform heat source applied on the inner circular cylinder in a square air (Pr ǫ = 0.7) filled enclosure in which all boundaries are assumed to be isothermal.
Journal ArticleDOI
Mixed convection heat transfer in a differentially heated square enclosure with a conductive rotating circular cylinder at different vertical locations
Salam Hadi Hussain,Ahmed Hussein +1 more
TL;DR: In this paper, a numerical simulation using a finite volume scheme is carried out for a laminar steady mixed convection problem in a two-dimensional square enclosure of width and height (L), with a rotating circular cylinder of radius (R = 0.2L) enclosed inside it.
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Numerical study of natural convection in a vertical porous annulus with discrete heating
TL;DR: In this article, the relative importance of discrete heating on natural convection in a vertical annulus filled with a fluid-saturated porous medium has been investigated when the inner wall is subject to discrete heating, and the analysis is carried out for a wide range of modified Rayleigh and Darcy numbers for different heat source lengths and locations.