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Title: Natural convective heat transfer from square cylinder

Abstract

This article is concerned with natural convective heat transfer from square cylinder mounted on a plane adiabatic base, the cylinders having an exposed cylinder surface according to different horizontal angle. The cylinder receives heat from a radiating heater which results in a buoyant flow. There are many industrial applications, including refrigeration, ventilation and the cooling of electrical components, for which the present study may be applicable.

Authors:
; ;  [1]
  1. University of Žilina, Faculty of Mechanical Engineering, Department of Power Engineering, Univerzitná 1, 010 26 Žilina (Slovakia)
Publication Date:
OSTI Identifier:
22608635
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1745; Journal Issue: 1; Conference: 20. International scientific conference on the application of experimental and numerical methods in fluid mechanics and energy 2016, Terchova (Slovakia), 27-29 Apr 2016; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CYLINDERS; HEAT; HEAT TRANSFER; HEATERS; REFRIGERATION; SIMULATION; SURFACES

Citation Formats

Novomestský, Marcel, E-mail: marcel.novomestsky@fstroj.uniza.sk, Smatanová, Helena, E-mail: helena.smatanova@fstroj.uniza.sk, and Kapjor, Andrej, E-mail: andrej.kapjor@fstroj.uniza.sk. Natural convective heat transfer from square cylinder. United States: N. p., 2016. Web. doi:10.1063/1.4953732.
Novomestský, Marcel, E-mail: marcel.novomestsky@fstroj.uniza.sk, Smatanová, Helena, E-mail: helena.smatanova@fstroj.uniza.sk, & Kapjor, Andrej, E-mail: andrej.kapjor@fstroj.uniza.sk. Natural convective heat transfer from square cylinder. United States. doi:10.1063/1.4953732.
Novomestský, Marcel, E-mail: marcel.novomestsky@fstroj.uniza.sk, Smatanová, Helena, E-mail: helena.smatanova@fstroj.uniza.sk, and Kapjor, Andrej, E-mail: andrej.kapjor@fstroj.uniza.sk. 2016. "Natural convective heat transfer from square cylinder". United States. doi:10.1063/1.4953732.
@article{osti_22608635,
title = {Natural convective heat transfer from square cylinder},
author = {Novomestský, Marcel, E-mail: marcel.novomestsky@fstroj.uniza.sk and Smatanová, Helena, E-mail: helena.smatanova@fstroj.uniza.sk and Kapjor, Andrej, E-mail: andrej.kapjor@fstroj.uniza.sk},
abstractNote = {This article is concerned with natural convective heat transfer from square cylinder mounted on a plane adiabatic base, the cylinders having an exposed cylinder surface according to different horizontal angle. The cylinder receives heat from a radiating heater which results in a buoyant flow. There are many industrial applications, including refrigeration, ventilation and the cooling of electrical components, for which the present study may be applicable.},
doi = {10.1063/1.4953732},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1745,
place = {United States},
year = 2016,
month = 6
}
  • Experimental data are presented on heat transfer from a horizontal cylinder 0.126 mm in diameter under conditions of free convection of helium with large temperature heads (the dimensionless temperature head, equal to the ratio of the temperature difference to the absolute temperature of the gas, ranged from 0 to 50). An empirical relation is used which reliably describes the experimental data. A condition is found for ignoring convection compared to conduction when evaluating heat transfer from small-diameter cylinders.
  • Steady laminar natural convection heat transfer in a two-dimensional, partially or fully open square cavity with three equally heated walls and various inclination angles is analyzed numerically. The overall average Nusselt number for a fully open cavity is approximately half the previously obtained average Nusselt number for a cavity with a heated back wall and insulated top and bottom walls for the same Rayleigh number. The dimensionless flow rate through the cavity is about twice the flow rate through the cavity with a heated back wall and two insulated walls. The effects of an aperture and cavity orientation, with respectmore » to the direction of gravity, on natural convection heat transfer in the cavity are clarified.« less
  • Heat transfer from a cylinder placed on the vertical center-line of a square enclosure that is partly filled with a porous medium that is saturated with a fluid has been numerically studied. The cylinder is buried in the porous medium. The horizontal upper surface of the porous medium is separated from the rest of the enclosure by a horizontal impermeable barrier that is assumed to offer negligible resistance to heat transfer. The gap between the barrier and the top of the enclosure is filled with the same fluid as that with which the porous medium is saturated. The surface ofmore » the cylinder has been assumed to be kept at a uniform high temperature. The bottom and sides of the enclosure are assumed to be adiabatic while the horizontal upper surface of the enclosure is assumed to be kept at a uniform low temperature. The natural convective flows that occur in the porous medium and in the fluid layer above the barrier have been assumed to be steady, laminar, two-dimensional and symmetrical about the vertical center-line of the enclosure. Fluid properties have been assumed constant except for the density change with temperature which gives rise to the buoyancy forces. The governing equations have been expressed in dimensionless form and solved using a finite element procedure. Results have been obtained for a Prandtl number of 0.7 for a wide range of the governing parameters. The main aim of the study was to determine how the mean heat transfer rate from the cylinder is affected by the size of the fluid gap at the top of the enclosure. The effect of this gap size has been related to changes in the flow pattern in the porous and fluid regions. The results have application in situations where the heat transfer has to be reduced but cost considerations require that as little insulation material as possible be used.« less
  • A thin-layer approximation is applied to the laminar momentum and energy equations governing the natural convection above an isothermal heat disk in air. Using the Bousssinesq assumption the equations are nondimensionalized in terms of a stream function, pressure and temperature difference. The variables are expanded in a series solution and the resulting set of equations are solved numerically. The solution is cast in terms of the nondimensional radial position and the disk Grashof number. These two parameters are shown to define the outer boundary conditions which are uniquely determined from a point source solution. The outer velocity boundary condition ismore » shown to decrease in relative magnitude as the disk Rayleigh number increases. Beyond a Rayleigh number of approximately 10{sup 6} the outer flow may be ignored in calculating the disk transfer rate. The radial variation of the outer flow is to the {minus}1/5 power measured inward from the leading edge. This is a result of the scaling difference of thin layer flow, and the outer, plume entrainment flow. The local heat transfer rate is increased by including the entrainment effects on the outer flow and varies as the Grashof number to the power (1/5 {epsilon}), where {epsilon} is a decreasing function of inward radial distance.« less
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