الفهرس 
Chapter one scope and aim of studyOnly 14 pages are availabe for public view
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Abstract
The topic of boiling heat transfer in porous media has drawn broad attention worldwide. This attention because the pool and flow boiling processes in porous media are encountered in many important practical engineering areas. In other side, heat transfer enhancement with pool and flow boiling is possible by the use of a porosity medium with a high surface-to-volume ratio, leading to a high heat transfer area in a small volume. In the present study experimental investigation was carried out on the forced convection boiling heat transfer in uniformly heated vertical annular tube filled with a porous medium of beads. The study is concerned mainly with the effect of beads species, beads size, and annular gab thickness of the tube on the boiling heat transfer process. The experimental tests were carried out with three different species of beads (stainless steel beads of 8, 6 and 4mm mean diameter gravel beads of diameter 8 mm, and polymer beads of diameter 8mm,), and three different sizes of the annular gab of the tube (10, 20- and 30-mm gab thickness). The experimental results were compared with the case without a porous medium. The results show that, the heat transfer is enhanced by the porous medium specially in the region of low heat flux, and this enhanced effect depends on the species and size of the beads. Beads that have thermal conductivity (stainless steel beads) have enhancing effect greater than beads that have low conductivity (gravel., and polymer beads). Also, the heat transfer enhancing effect has increased with decreasing the beads size and the annular gap size of the tube. However, there exist optimal size of beads corresponding to the most effective enhanced heat transfer.