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Tikrit Journal of Engineering Sciences (2006) 13(1) 60-87

A Theoretical Study on Natural Convection in a Concentric Vertical Annulus

Mohanned A. Al-Thaher Sami Retha  Aslan Manar S. Mahdi
Mechanical Eng. Dept., Tikrit University, Iraq

Abstract

The research include a theoretical study of natural laminar study convection heat transfer in a vertical annuls, the surfaces were at constant temperature and the inner cylinder temperature is higher than the outer cylinder temperature. The air used as a working fluid in the annulus. Rayleigh Number was( 71 page27image4116296624Ra page27image41162973125 page27image411629800010 4 ) and the radius ratio were (1.7, 2.0 and 2.3). Alternating direct implicit method (ADI) was used to solve the governing equations numerically, the governing equations were transformed into vorticity-stream function formula then transformed into algebraic equations using finite difference method. The results were declared by using contour diagrams which represent streamlines and isotherms also the results were declared by velocity and temperature distribution through the annulus and local Nusselt number along the inner cylinder.It was found in this research that heat transfer by conduction in low Rayleigh Number, also increasing the thermal boundary layer around the inner cylinder as the fluid moves up while the thermal boundary layer on the outer cylinder increases as the fluid moves down.

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KeywordsNatural Convection, Heat Transfer, Vertical Annulus, Radius Ratio.

How to cite

TJES: Al-Thaher MA., Aslan SR, Mahdi MS. A Theoretical Study on Natural Convection in a Concentric Vertical AnnulusTikrit Journal of Engineering Sciences 2006; 13(1): 60-87.
APA: Al-Thaher, M. A., Aslan, S. R., & Mahdi, M. S. (2006). A Theoretical Study on Natural Convection in a Concentric Vertical Annulus. Tikrit Journal of Engineering Sciences, 13(1), 60-87.