應用於電子晶片冷卻之強制鰭流熱傳研究

Heat Transfer of Forced Convective Fin Flow with Cooling Applications to Electronic Chipset

The detailed heat transfer measurements over three smooth-walled rectangular channels with open boundaries on their two side profiles and a sealed-bottom end, simulating a cooling passage in the fan-fin type heat sink of CPU cooling unit performed. The interactive effects of side-profile leakage flow and streamwise coolant stream are functionally related with Reynolds number and channel length-to-gap ratio, which demonstrate considerable influences on local and spatially averaged heat transfers over the fin surfaces Heat transfer modifications caused by varying Reynolds number (Re) and length-to-gap ratio of channel (L/B) over the ranges of 500≤Re≤3000 and 5.89≤L/B≤21.33 are disclosed by examining the detailed heat transfer distributions over the fin surfaces. In conformity with the experimentally revealed heat transfer physics, a regression-type analysis is performed to develop the correlation of spatially-averaged Nusselt number over fin surface, which permits the individual and interactive effect of Re and L/B on heat transfers to be evaluated. A criterion for selecting the optimal length-to-gap ratio of a confined fin channel that provides the maximum convective heat flux from fin surface is formulated. 本論文量測三組平滑壁面的矩形通道熱傳詳細分佈，此矩形通道由三面平滑面組成，兩側面呈開式邊界，其底端封閉，藉以模擬風扇──鰭狀式之電腦CPU冷卻單元的一組冷卻通道。沿著側邊洩漏之冷卻流體與流向流場間之交互作用為雷諾數（Re）和通道長度／深度比（L/B）之函數式。此種交互作用對於局部和鰭面平均熱傳產生顯著之影響。藉由檢視平滑鰭面熱傳係數分佈之情形，闡示因改變雷諾數和通道的長度／深度比對平滑面鰭流熱傳性能所產生之影響。雷諾數及通道的長度／深度兩項參數之變化範圍分別是500≤Re≤3300以及5.89≤L/B≤21.33。與實驗結果顯示之熱傳物理現象一致，本研究利用回歸分析的方式，推導出計算鰭面熱傳平均值之實驗公式，據以評估雷諾數和通道長度／深度比之單獨及偶合效應對平滑面鰭流熱傳性能所產生之影響。本實驗研究亦推導出一項選擇此類鰭流場最佳鰭片長度／深度比之設計規範，藉以提供最高之鰭流場對流熱通量。