碩士 / 國立臺北科技大學 / 能源與冷凍空調工程系碩士班 / 96 / 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.
| Identifer | oai:union.ndltd.org:TW/096TIT05703064 |
| Date | January 2008 |
| Creators | Tung-Lu Wu, 吳東旅 |
| Contributors | 簡良翰 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 93 |
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