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Enhancement of Free Convection Heat Transfer Coefficient by Cavity making in Horizontal Surfaces of Electronic Elements | ||
| Al-Ma'mon College Journal | ||
| Article 1, Volume 0, Issue 19, 2018, Pages 207-227 | ||
| Authors | ||
| Ammar T. Ahmad; Q. M. Wadi; Hikmat N.Abdul Karem | ||
| Abstract | ||
| A natural convection heat transfer from horizontal flat square surfaces with square cavities was studied experimentally. The inner length of the cavity is equivalent to (0.5, 0.75) of the outer length of the square surface, (Lo= 96mm). Two models made of aluminum have been used to study the distribution of air temperature above the surfaces after being heated towards the top at constant temperature. A mathematical relationship was developed after analyzing the results to calculate the convective heat transfer coefficient from these surfaces and compared the results with the mathematical relations derived for the horizontal flat surfaces, square and square with a hollow square cavity with length ratio of (0.25) of the original outer length [1], and mathematical equations derived for the disk and three rings had inner to outer diameter ratios of (0.25, 0.5, 0.75) [2]. It has been found that; increasing the proportion of the cavity leads to increases in the heat transfer coefficients (local, average), Nuselt number (local, average) and the average value of the constant (c), while the local heat transmitted is reduced because of the reduction of the heat transfer area compared with the research [1] and the results show differences from [2] because of using the outer diameter (do) of the disk and rings as the characteristic lengths. While research [1] and the current search used the distance (Lo-Li) as the characteristic length of the flow and Grashof number between (105-106). | ||
| Keywords | ||
| Convection Heat; Transfer Coefficient; Electronic Elements | ||
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