RESEARCH PAPERS: Natural and Mixed Convection

Effect of Aperture Geometry on Heat Transfer in Tilted Partially Open Cavities

[+] Author and Article Information
M. M. Elsayed, W. Chakroun

Mechanical Engineering Department, Kuwait University, P.O. Box 5969, Safat 13060, Kuwait

J. Heat Transfer 121(4), 819-827 (Nov 01, 1999) (9 pages) doi:10.1115/1.2826071 History: Received January 14, 1998; Revised September 22, 1998; Online December 05, 2007


Free convection from a square, tilted partially open cavity was investigated experimentally. The experiment was carried out to study the effect of the aperture geometry on the heat transfer between the cavity and the surrounding air. Four different geometrical arrangements for the opening were investigated: (1) high wall slit, (2) low wall slit, (3) centered wall slit, and (4) uniform wall slots. Each opening arrangement was studied at opening ratios (i.e., ratio of opening height to cavity height) of 0.25, 0.5, and 0.75. The average heat transfer coefficient between the cavity and the surrounding air was estimated for each geometrical arrangement for tilt angles ranging from −90 deg to +90 deg with increments of 15 deg and at a constant heat flux Grashof number of 5.5 × 108 . The results showed that for tilt angles between 90 and 75 deg, the heat transfer coefficient has a small value that is independent of the geometrical arrangement of the opening. The value of the heat transfer coefficient increases sharply with decreasing tilt angle until an angle value of zero degrees is reached. The increase in the heat transfer coefficient continues in the negative range of tilt angle but not in the same rate as in the positive range of the tilt angle. The uniform slot arrangement gave in general higher heat transfer coefficient than the other three arrangements of the opening. Large differences in the heat transfer coefficient were observed between the high and the low wall slits where the high wall slit is found to transfer more heat to the surroundings than the low wall slit. Correlations were developed to predict the average Nusselt number of the cavity in terms of the opening ratio and the cavity tilt angle for cavities with high wall slit, low wall slit, centered wall slit, and the uniform wall slots.

Copyright © 1999 by The American Society of Mechanical Engineers
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