الفهرس 
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Abstract
This thesis presents an investigation for the effect of opposed lateral and vertical eccentricity on free convection in an elliptical annulus enclosure in blunt and slender orientations. Three test specimens of elliptical cylinders having an equal radius ratio and an equal length were prepared for this purpose. The outer surface area of the inner elliptical cylinder is the same for each specimen as well as the inner surface area of the outer elliptical cylinder for each specimen. Different elliptical ratios of 0.662, 0.866 and 0.968 were investigated. The specimens were cut using the computed numerically controlled wire-cut machining. Experimental tests were performed by maintaining constant heat flux on the inner cylinder, however, the outer cylinder was exposed to approximately constant temperature (19OC-26OC) of the closed laboratory. Both ends of the annular elliptical cylinders were closed by cork to form the annular enclosure space. The experimental tests scanned the Rayleigh number (1.642×103 ≤ Ra* ≤3.849×106). The effects of the opposed vertical eccentricity and opposed lateral eccentricity on free convection for both blunt and slender orientation were investigated. Empirical correlations were deduced within an acceptable uncertainty for the experimental results. Compatible and satisfactory to the conscience agreement was found in a comparison among the results of present and previous works. It was found from this comparison that, the convective heat transfer for the opposed vertical eccentricity is greater than the convective heat transfer for the lateral opposed eccentricity in slender orientation by about 40% from concentric. The convective heat transfer for the opposed lateral eccentricity is greater than the convective heat transfer for the vertical opposed eccentricity in blunt orientation by about 30% from concentric. Slender orientation offers about 50% enhancement in free convection than the blunt situation for the same elliptical ratio.