Number：

103B_ME1_002

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Name：

Titles：

Author：

鄭澤明、曾憲中、王潮熏

Tzer-Ming Jeng，Sheng-Cgung Tzeng，Chao-Xun Wang

Paper name：

垂直通氣孔道數目與長度對主動式LED鰭片散熱座整體熱傳特性之影響

Effects of Vertical Flow Duct，Number and Length on Heat Transfer Characteristics of the

Active LED Finned Heat Sink

Name of activity：

2014能源與冷凍空調學術研討會

Keywords：鰭片散熱座、混合對流、垂直孔道、熱傳、LED

Finned heat sink，mixed heat transfer，vertical flow ducts，heat Transfer，LED.

Abstract：

本研究以實驗方法探討「具垂直通氣孔道之主動式逕向鰭片散熱座」的整體熱傳特性，散熱座以鋁合金製成，其基本構型為中空圓柱體具24個輻射排列竟向鰭片。鋁合金散熱座圓柱體還型壁上則有多個垂直通氣孔連通外界與散熱座的中空腔體。本研究以多根塑膠管連通多個垂直通氣道，其中相鄰的半數塑膠管併聯為壓縮空氣入口、另外一半的塑膠管併聯為壓縮空氣出口，以空壓機提供額定流量的空氣通過散熱座內部。以此來模擬散熱座內建馬達風扇時驅動的氣流，此時，散熱座內部將具有強制對流、而外部則具有自然對流的混合對流冷卻效果。本研究有系統的探討垂直通氣孔道數目、長度與空氣流率等因素對整體對流熱傳特性的影響，實驗結果指出，導入強制氣流的散熱座確實能增強整體熱傳，在空氣流率=3-13 L/min 的測試範圍內，導入空氣可以使純自然對流熱傳的散熱座的整體熱阻(R)再降低約25~50%；而在較小的空氣流率下，具24個垂直通氣孔道的散熱座的R略低於只有12個通氣孔道的，但當空氣流率持續升高，通氣孔道數目對整體熱阻的影響就變得不明顯；在目前的測試中，並未發現垂直通氣孔道的長度對整體熱阻有值得注意的影響；最後，本研究也發現垂直通氣孔道的數目對整體壓降影響不大，但通氣孔道的長度對整體壓降則有可觀的影響。

This work experimentally investigated the overall heat transfer characteristics of aNovel active LED finned heat sink with multiple vertical flow ducts. The configuration of the heat ink，made of aluminum alloy，is a hollow circular cylinder with 24 radial plate fins. There are ultiple vertical flow ducts in the circular vertical wall of the heat sink. These vertical ducts onnect the ambient and the internal chamber of the heat sink. This work used the air compresser o supply air flow through the heat sink to simulate the air flow driven by the built-in motor fan. It can obtain the additional forced convection heat transfer to improve the original free convection heat transfer of the passive finned heat sink. This work explored the effects of the ertical ducts’number and length as well as the air flow rate on the overall cooling performance f the heat sink. Experimental results indicate that the air flow through the heat sink did strengthen the overall heat transfer. Within the range of the present air flow rate(3-13 L/min)， he air flow reduced the total thermal resistance(R)about by 25~50% by comparing with the heat sink without forced air flow through. At smaller air flow rate，the thermal resistance of the eat with 24 flow ducts was somewhat lower than that with 12 flow ducts. However，when the air flow rate increased continuously，the effect of the flow ducts’number on the total thermal resistance was insignificant. For the present all tests，there was no noteable influence of flow ucts’length on the overall heat transfer. Finally,the work also demonstrates that the pressure rop increased with increasing the length of the flow ducts，but did not vary obviously with number of the flow ducts.