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|Title:||Heat transfer from flat and ribbed surfaces with interrupted heating|
|Source:||Low, K.W.,Yap, C. (2001). Heat transfer from flat and ribbed surfaces with interrupted heating. Advances in Electronic Packaging 2 : 989-996. ScholarBank@NUS Repository.|
|Abstract:||The heat dissipation due to flat and ribbed surfaces is extensively studied mainly with uniform temperature or uniform heat flux conditions. It is known that when the boundary layer is interrupted, the heat transfer coefficient can increase significantly. In view of the increase of heat flux in devices and applications, a computational study of interrupted heating with flat and ribbed surfaces is conducted. The findings of the study can provide useful insight into enhancing the forced convection cooling by air in various applications. An example would be the cooling of printed circuit boards in electronic packaging. The dissipation of heat generated is a key limiting factor to further miniaturization of electronic circuits. Forced convection cooling of these circuits is an economical and efficient technique used in many applications such as in micro, mini and mainframe computers. Computations were conducted using the commercial Computational Fluid Dynamics code FLUENT. The Renormalised Group (RNG) k-ε turbulence model with non-equilibrium wall functions is used to model the turbulent flows. The results for the flat surface with uniform heat flux are used as a base case for comparison. The local heat transfer coefficient is found to be slightly higher (by 5 to 12%) on the flat surface with interrupted heating. This is due to the interruption of the thermal boundary layer. At each insulated section the thermal boundary layer redevelops and hence local heat transfer is enhanced. The ribbed surface model also has a higher heat transfer coefficient due to the re-developing thermal boundary layers. The effect on the heat transfer is especially significant (in the order of 35%) at the leading edge of each module. However, this enhancement comes with a penalty of a higher pressure drop of about 70%. The pressure drop for the flat surface with an interrupted heating model is the same as that for the base case, as there is no change in the geometry.|
|Source Title:||Advances in Electronic Packaging|
|Appears in Collections:||Staff Publications|
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