鰭片表面應用於滴淋蒸發式電子散熱系統之研究

A Study of Falling Film Evaporation on Finned Surfaces in Electronic Cooling System

吳東旅(Tung-Lu Wu)

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(2008年)

https://doi.org/10.6841/NTUT.2008.00568

摘要

近年來電子晶片規格不斷微小化，密集度上升，所產生之熱量亦隨之增加，因此需要一套高效率的散熱系統以維持效能。本研究模擬中央處理器(CPU)之發熱條件，以飽和溫度50℃之核沸騰與滴淋蒸發實驗，探討其熱傳性能。實驗中以介電液FC-72作為工作流體並改變光滑與蝕刻表面參數為主，包括粗糙度0.25 μm光滑表面，以及鰭片間距、高度與寬度均為100 μm之針狀表面，鰭片高、寬均為100 μm或400 μm的兩種槽道表面。由此四種表面進行滴淋蒸發與核沸騰實驗；滴淋裝置有五個滴淋孔，孔徑可分為0.17、0.23、與0.41 mm；流量為24.5 ~ 99.1 ml/min；滴淋孔與測試表面距離為10與30 mm；發熱量為10 ~ 150 W。實驗結果得知，在核沸騰實驗中以鰭片高、寬均為400 μm的槽道表面所呈現之熱傳性能為最佳，平均較光滑表面增加約65.7%，在80 ~ 100 W之加熱量下，其熱阻值約為0.15 K/W。滴淋蒸發實驗中孔徑參數部份以0.23 mm所呈現之整體性能為最佳，低熱通量下呈現衝擊對流效應之優勢，高熱通量下維持其熱傳性能。滴淋高度為10 mm時，低熱通量下性能較佳；高度30 mm則在高熱通量下性能較佳。實驗中則以鰭片高、寬均為400 μm槽道表面所呈現之性能為最佳；流量為99.1 ml/min較光滑表面增加約55.5 %。

關鍵字

核沸騰 ； 滴淋蒸發 ； 蝕刻表面 ； 介電液FC-72

並列摘要

Recently, the manufacture technology of computer chips has advanced toward reducing size and increase densities of circuit and power. Therefore, an efficient cooling system is required for maintaining the performance of chips. This study simulates a heat source of central processing unit (CPU), and uses dielectric fluid FC-72 as the working fluid for a liquid cooling device. Experiments of pool boiling and falling film evaporation have been conducted at 50℃ saturation temperature, and the effects of test parameters on the heat transfer performance are discussed. The tested surface are: a smooth surface of 0.25 μm roughness；a pin-finned surface of 100 μm fin height, thickness and gap width; two straight finned surfaces of 100 μm or 400 μm fin height. In the falling film evaporation experiments, the orifices hole diameter of the fluid spraying device is 0.17, 0.23 or 0.41 mm, and the distance from the orifices to surface is 10 or 30 mm. The flow rate varies from 24.5 to 99.1 ml/min, and the heat input power varies between 10 and 150 W.
The result shows that the straight finned surface of 400 μm fin height yields the best performance in pool boiling, which is 65.7% greater than the smooth surface in average. This surface also shows the best performance in falling film evaporation tests, about 55.5% greater than the smooth surface at a fixed flow rate (99.1 ml/min). In the falling film evaporation, the 0.23 mm orifice diameter yields the best overall performance, which results from significant impinging convection effect at low heat fluxes the fluid and maintaining sufficient liquid flow at high heat fluxes. At low heat flux, the shorter distance between the orifice and test surface (10 mm) results in the better performance than that of 30 mm, but contrary results are found at high heat flux.

並列關鍵字

Dieletric fluid FC-72 ； Pool boiling ； Falling film evaporation ； Etch

參考文獻

2005 “Thermal performance and key challenges for future CPU cooling

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