Theoretical Investigation of Natural Convection Heat Transfer through Rectangular Enclosure.

Document Type : Research Studies

Authors

1 Researcher at Mechanical Power Engineering Department., Faculty of Engineering., Mansoura., Egypt.

2 Mechanical Power Engineering Department., Faculty of Engineering., Mansoura.

3 Mech. Power Eng. Dept. , Higher Technological Institute, Tenth of Ramadan City, Egypt

4 Associate Professor., Mechanical Engineering Department., University of Mansoura., CO 35516., Egypt.

Abstract

Theoretical investigations on natural convection heat transfer have been carried out inside rectangular enclosures filled with air or water. Heat transfer and fluid flow due to buoyancy forces in an enclosure are achieved. The vertical walls are insulated while the top wall is cooled and the bottom wall is heated under uniform heat flux. Steady laminar natural convection in air or water-filled, 2-D rectangular enclosure is studied numerically. The finite difference technique is used to solve the mass, momentum and energy transfer governing equations. The computational results are presented in the form of isotherm and streamline plots. Simulations are performed for several values of both the width-to-height aspect ratio of the enclosure in the range between 0.66 and 8, and the modified Rayleigh number based on the enclosure height in the range between and  whose influences upon the flow patterns, the temperature distributions, and the heat transfer rate are analyzed and discussed. The heat transfer rate from heated enclosure increases as the aspect ratio (A) increases until A=2 and then remains constant with further increase in aspect ratio. The heat transfer rate increases as the modified Rayleigh number increases. Nusselt numbers for both air or water filled enclosures are correlated with both aspect ratio (A) and modified Rayleigh number ( ). In order to validate the numerical code for the present study, present results have been compared with the benchmark results of previous researches.

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