整合噴嘴之微渠道散熱器於晶片冷卻之研究

A Study of Micro Channels Integrated with Multiple Jet for Chip Cooling

劉瀚陽(Han-Yang Liu)

指導教授 ： 簡良翰

國立臺北科技大學/機電學院/能源與冷凍空調工程系碩士班/碩士(2011年)

https://doi.org/10.6841/NTUT.2011.00210

摘要

近年來電子運算晶片密集度越來越高，使其平均發熱量高達200 W/cm2，需要發展出更高效率的散熱系統。本研究整合噴擊冷卻與微渠道冷卻兩種散熱型式，設計出噴嘴與微渠道一體成型之散熱結構，期望能達到較佳之熱傳性能。在投影面積為12×12 mm2 的散熱器中，共有十一條微渠道，渠道高0.8 mm，寬0.6 mm，渠道長度為12 mm，每條渠道設置3 或5 個噴嘴，噴嘴孔徑為0.24 與0.4 mm，噴嘴間距為1.5 ~ 3 mm，以非導電液FC-72 作為工作流體，噴擊流量設定為100 ~ 810ml/min，並維持系統飽和溫度為30 與50℃，進行實驗分析。實驗結果顯示，單相熱傳時，熱傳性能會隨著噴擊流量增大而線性上升；而當產生對流沸騰後，流量增加至一定範圍以上，對熱傳性能之影響便開始降低。在雙相熱傳狀態下，且飽和溫度30℃時，因為氣體密度較小，使得渠道內氣體所佔之比例較高，進而干擾渠道內之流場及後續噴擊出之液體；相較於相同條件下之飽和溫度50℃之測試結果，其表面過熱度高出約13.48 ~ 24.72％。在相同噴擊流速下，噴嘴較靠近微渠道出口之表面，可縮短液體流經渠道之長度，故熱傳性能較佳；當每條微渠道所配置之噴嘴數量增加，可有效降低渠道內溫度邊界層厚度，進而達到最佳的對流沸騰熱傳配置，但過快之噴擊速度，會造成噴嘴間相互干擾，產生較多停滯渦流，造成渠道內壓力與阻抗增加。每個測試表面之熱阻抗，皆隨著加熱量或噴擊流量
增加而下降，其中以三個0.4 mm 之噴淋孔，將微渠道均分成四段之表面性能最佳，最低熱阻可達到0.0611 K/W，適用於晶片散熱之條件。而除了低流量(100 ml/min)狀態外，熱傳性能皆隨著s/d 值增加而上升。經迴歸及疊代計算，可分別歸納出單相與雙相熱傳之經驗式，其誤差範圍為± 25％及± 30％以內。

關鍵字

噴擊冷卻 ； 微渠道 ； 非導電液FC-72 ； 單相熱傳 ； 雙相熱傳

並列摘要

As chip power densities in electronic equipment increasing to more then 200W/cm2, an effective cooling system is required for computer chips. In this study,A heat sink integrating micro-channels with multiple jets was designed to achieve better heat transfer performance for chip cooling. This study used dielectric fluid FC-72 as working fluid. The cooling fluid was introduced to a 12×12 mm2
heated surface, which had 11 micro-channels, each channel was 0.8 mm high, 0.6 mm wide,and 12 mm in length. There were 3 or 5 nozzles install on each micro-channel. The
nozzle diameters were 0.24 or 0.4 mm, and the nozzles spacing varied from 1.5 to 3 mm.
In the tests, the saturation temperature of cooling device system was set at 30 and50℃, and the volume flow rate varied from 100 to 810 ml/min.The experimental result showed that heat transfer performance increased with
increasing flow rate for single phase heat transfer. However, in two phase heat transfer regime, the influence of the flow rate diminished when it passed a certain limit. For two phase convection, because that the vapor density at 30℃ was almost an half of that at 50℃, the excess vapor interfered the flow within micro-channels. Hence, the superheat temperature of the heat sink at saturation temperature 30℃ was greater than that at 50℃
by about 13.48 ~ 24.72%. For the same flow rate, the surfaces whose nozzles located near the micro- channels exit yielded better heat transfer performance by shortening thetraveling distance of the liquid in the channels. The thermal boundary thickness reduced as the number of nozzles per channel increased, and thus greater boiling convective heat transfer efficiency was achieved. However, when the jet velocity was too fast, jet streams would interfere with each other, resulting in more stagnant eddy current, larger
thermal resistance and pressure drop. Except for low flow rate (100 ml/min), the heat transfer performance increased with increasing (s/d) ratios. The thermal resistance
decreased with increasing impingement flow rate or increasing input power of every test surface. The best surface had three nozzles of 0.4 mm diameter, which equally divided micro-channels into four segments. It had lowest thermal resistance about 0.0611 K / W. This new cooling device is found to be a promising chip cooling solution for its low thermal resistance for the practical application of electronic cooling. Correlations of heat transfer coefficient of the single-phase and two-phase heat transfer of the micro-channel/jet cooling integrated device have been developed. Compared with the single phase and two phase data, the prediction uncertainties are within ± 25% and ±30%, respectively.

並列關鍵字

Jet cooling ； Micro Channels ； Dielectric fluid FC-72 ； Single Phase Heat Transfer ； Two Phase Heat Transfer

參考文獻

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[23] 張秦耀、簡良翰，「非導電流體之兩相噴擊冷卻實驗研究」，碩士論文，國立臺北科技大學能源系，台北，2009。

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