الفهرس 
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Abstract
In this work the effect of boiling surface orientation and saturation temperature of the boiling liquid ((demineralized water) on the heat transfer coefficient during saturated nucleate pool boiling is investigated.
To meet the aforementioned needs, a test apparatus is designed, constructed and tested to achieve heat transfer measurements from aluminum alloy 6061 heating surface at different orientations. These orientations started from upward (zero degree) to downward (180 degree) with a step of 10 degrees. Demineralized water is selected to be the boiling liquid for its better thermophysical properties. This boiling liquid is tested under two saturation temperatures of 1000C and 1200C at each tested inclination angle.
A detailed analysis of the experimental results shows that the heating surface orientation has a pronounced effect on the absolute and normalized values of the heat transfer coefficient through the two investigated saturation temperatures. Also, it is found that for specific orientation , the nucleate pool boiling heat transfer coefficient is increased by increasing the saturation temperature . Furthermore, for both specific saturation temperature and heat flux; inclination angles 400 and 1400 introduced the highest nucleate pool boiling heat transfer coefficients, while angles 0.0 and 1800 gave the lowest ones.
In addition, a three parametric distribution function N® for the size of stable bubble in active nucleation sites is calculated for each inclination angle using the heat transfer measurements.
A trail has been made to correlate the distribution function`s constants (m , rst and Nmax/Awith) with the orientation.