自然對流增強散熱模組應用於高功率LED燈之研究

Enhancement of Natural Convection Thermal Module Applied to High-Power LEDs

黃翔聖(Hsiang-Sheng Huang)

指導教授 ： 陳希立

國立臺灣大學/工學院/機械工程學研究所/博士(2009年)

https://doi.org/10.6342/NTU.2009.10064

摘要

本文主要目的是開發出新型的自然對流增強散熱模組應用於高功率LED燈之研究，分別提出平板型與燈罩型蒸氣腔體散熱模組以及熱電散熱模組。由實驗的結果可知，平板型蒸氣腔體模組於加熱功率為30W以及熱源面積為225mm2時，相較於銅板與鋁板模組之擴散熱阻可分別降低26%與36%；其熱源表面溫度則可分別降低4.8oC與6.8oC。另外，燈罩型蒸氣腔體模組於LED輸入功率為15W時，其擴散熱阻比值相較於銅板與鋁板模組可分別降低27%與32%；其總熱阻比值可分別降低8%與12%；熱源表面溫度可分別降低4.1oC與5.7oC。本研究所提出的蒸氣腔體散熱模組於自然對流下，其熱傳能力依然優越且能有效解決擴散熱阻的問題與降低LED晶片溫度。另外，蒸氣腔體之燈罩型結構的設計可搭配實際照明燈具的造型，這有助於在LED散熱技術領域上提供前瞻的發展技術與改進方向。
本文亦提出將熱電冷卻器整合於傳統鰭片熱沈應用於高功率LED燈之散熱，並以理論與實驗分析建立一適用於此熱電模組之熱性能理論分析模式，以及定義一熱性能指標用以來評估其熱電散熱模組的性能表現。研究結果顯示其最佳操作電流為0.5A，並且在其有效操作範圍內，熱電冷卻器確實能有效降低熱源溫度。最後，本研究建構出一模擬預測軟體程式，不僅可預測平板型蒸氣腔體模組以及熱電散熱模組之熱傳性能，亦可用來進行系統最佳化分析。本研究將模擬預測的結果與實驗值進行比較，其蒸氣腔體模組之最大誤差為±6%；熱電散熱模組之平均誤差為±15.8%。此外，本研究亦針對這兩種散熱模組進行最佳化分析，並以分析結果來設計最佳化鰭片熱沈，以提昇散熱模組之整體性能。原本的熱電散熱模組相較於傳統散熱模組(未搭配熱電冷卻器)最大可降低其熱源表面溫度4oC；當熱沈進行最佳化設計後，其最佳熱電散熱模組之有效加熱功率極限值可從16W提昇至41W，且相較於搭配最佳化熱沈之傳統散熱模組最大可降低熱源表面溫度9.3oC。

關鍵字

平板型 ； 燈罩型 ； 蒸氣腔體 ； 熱電冷卻器 ； 有效加熱功率極限值

並列摘要

This article provides the novel thermal modules to solve the heat dissipation of the high-power light-emitting diodes (LEDs) in natural convection. The study can be divided into two parts. In the first part, the flat-plate-type and the lamp-type vapor chamber modules are applied to the high-power LEDs. The experimental results show that the spreading resistance and the heater temperature of the flat-plate-type vapor chamber at 30 W are lower than those of the copper plate by 26 % and 4.8 oC, respectively, and are lower than those of the aluminum plate by 36 % and 6.8 oC, respectively.
Compared with the copper and the aluminum plates, the lamp-type vapor chamber at 15 W is reduced about 8 % and 12 % for the ratio of total thermal resistance, respectively. Besides, it is also about 4.1 oC and 5.7 oC lower for the central wall temperature of the lighting side, respectively. This study proves that the vapor chamber can effectively lower the spreading resistance and diminish the hotspot effect. When compared with the solid metal spreaders, the vapor chamber provides a better choice as a heat spreader for LED cooling with high-power consumption.
In the second part, the present study proposes the thermoelectric air-cooling module, which integrates a thermoelectric cooler (TEC) and a flat-plate fin heat sink, for high-power LEDs cooling. The influences of the heating power and the thermoelectric cooler's current on the thermal performance of the thermoelectric module are experimentally and theoretically determined. The experimental results indicate that when heating power increases from 5 W to 15 W, the optimal electric current is 0.5 A. This study verifies the effective operating region where the cooling performance of the conventional module can be effectively enhanced by integrating it with the thermoelectric cooler.
In addition, this study develops a novel analytical model of thermal analogy network to predict the thermal capabilities of the flat-plate-type vapor chamber and the thermoelectric modules. The model's prediction result agrees well with the experimental data. Because the geometric dimensions of the heat sink influence the thermal performance of the thermoelectric module, the presented study does a series of optimum analysis for each geometry parameter. Based on the results of the optimum analysis, the maximal effective heating power increases from 16 W to 41 W. Compared with the conventional module (without TEC), the heater temperatue can be reduced about 9.3 oC in this study.

並列關鍵字

Flat-plate-type ； Lamp-type ； Vapor chamber ； Thermoelectric cooler ； Maximal effective heating power

參考文獻

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