Enhancement of Natural Convection Thermal Module Applied to High-Power LEDs
Date Issued
2009
Date
2009
Author(s)
Huang, Hsiang-Sheng
Abstract
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. ompared 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.n 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.n 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.
Subjects
Flat-plate-type
Lamp-type
Vapor chamber
Thermoelectric cooler
Maximal effective heating power
Type
thesis
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