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130322

Investigation of Natural Convection in Enclosed Concentric Cylindrical Annuli.

Article

Last updated: 04 Jan 2025

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Subjects

-

Tags

Mechanical Power Engineering

Abstract

An experimental study of natural convection in a cylindrical enclosed annulus filled with air has been carried out to investigate the effect of diameter ratio and the angle of inclination on the rate of heat exchanged across it. In different case studies the inner cylinder surface is heated up at a uniform heat flux, surrounding atmospheric dir convectively cools the outer cylinder The annulus is long with respect to the gap width (L/8>>1). The experiments are performed in the horizontal case for modified Rayleigh number (R α. S)α ranging from 5 to 105 and diameter ratio of 1.15 /DoDi2.3. Heat transfer results are also given for the annulus of Do/Di=2.88 all different inclination angles. For the horizontal case, the average heat transfer coefficient is found to be strongly dependent on flow regime. Over the lower range R α . S 1.3x103, the effect of both Rayleigh number and the diameter ratio is diminished. For the higher range 1.3x103≤ R α . S≤ 105, the average heat transfer coefficient is strongly affected by Rayleigh number as well as the diameter ratio. The results also show that the increase of inclination angle of the annulus axis causes an increase in the rate of convective heat transfer, while the effect of Rayleigh number diminishes for 0>60" Empirical correlations are given for the average Nusselt number as a function of the modified Rayleigh number and comparisons are made with the available literature.

DOI

10.21608/bfemu.2020.130322

Keywords

Natural convection, Horizontal annulus, Inclined annulus, Uniform heat flux, Air gap insulation

Authors

First Name

Elsayed

Last Name

Elshafei

MiddleName

A. M.

Affiliation

Mechanical Power Engineering Department., Faculty of Engineering., El-Mansoura University., Mansoura., Egypt.

Email

eelshafei@mans.edu.eg

City

Mansoura

Orcid

-

Volume

30

Article Issue

1

Related Issue

19434

Issue Date

2005-03-01

Receive Date

2005-01-11

Publish Date

2020-12-16

Page Start

11

Page End

23

Print ISSN

1110-0923

Online ISSN

2735-4202

Article File

BFEMU_Volume 30_Issue 1_Pages 11-23.pdf

PDF . 436.7kB

Link

https://bfemu.journals.ekb.eg/article_130322.html

Detail API

https://bfemu.journals.ekb.eg/service?article_code=130322

Order

7

Type

Research Studies

Type Code

1,205

Publication Type

Journal

Publication Title

MEJ. Mansoura Engineering Journal

Publication Link

https://bfemu.journals.ekb.eg/

MainTitle

Investigation of Natural Convection in Enclosed Concentric Cylindrical Annuli.

Details

Type

Article

Created At

22 Jan 2023