الفهرس 
INTRODUCTION AND LITERATURE SURVEYOnly 14 pages are availabe for public view
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Abstract
Experimental and numerical study on natural convection in rectangular air cavities with two discrete heaters was carried out. The numerical solution covers cases of natural convection for Prandtl number, Pr = 0.72, Rayleigh number ranging from 102 ≤ Ra ≤ 107, and cavity inclination angle, Φ from 0o to 180o with different aspect ratios, 0.5 ≤ A ≤ 50. The effects of heaters position ratios, B1 and B2, and heaters size ratio, 0.125 ≤ ε ≤ 0.375 were studied. The calculation grid used in the solution was tested to determine the best grid spacing and the effects of grid size on the numerical solution. The results are presented graphically in the form of streamline and isotherm contour plots. The experiments were performed for a range of hot wall temperatures ranging from 40°C to 90°C. The insulation material of enclosure (cavity walls) was changed three times, firstly using Styrofoam sheets, secondly using Plexy glass sheets and finally using Plexy glass cladded by Styrofoam sheets. The heat transfer characteristics, local and average Nusselt numbers are presented. The results were compared with previous results and good agreement was found. The thermal results are divided to two sub sections. One is for the different hot wall temperatures and the other one is for the different aspect ratios. Inclination angle, Ф was changed from 0o to 180o with 15o steps. The average Nusselt number changed between experimental and numerical calculation when using Styrofoam, Plexy glass and plexy glass cladded by Styrofoam sheets as insulation materials. It was decided that it is good enough to use the Plexy glass as insulation material. The numerical and experimental results were put in a correlation as a function of the different parameters. This correlation may be used in design and heat calculation in similar thermal equipment.