Study On Heat Dissipation Of LED Devices Under Natural Convection

The density of electronic devices integration is now growing faster and faster, following the Moore’s law in the semiconductor industry. On this background, the heat flux of electronic devices is also increasing at the same pace. The technology on heat dissipation is now the hotspot of heat transfer field. LED is considered as the4th generation energy-saving lighting source, which is widely concerned. The thermal problem of LED has been confusing the optical engineers all the time. It is now one of most stubborn obstacles placed in front of the popularization of high power LED.Natural convection is a passive way of heat dissipation, which is of the highest reliability. Compared with the positive ways of heat dissipation, it does not need any additional energy supply, and no moving part is included. Thus, it is a maintenance free way, suitable for the long life LED applications. Rectangular fin heat sink is the most common one. However, the rectangular fin heat sink is orientation-dependent. The orientation effects of rectangular fin heat sink need to be further revealed.In this thesis, theoretical and experimental analysis is done aiming at the LED application. The following researches have been performed,1、The building of numerical model on rectangular fin heat sink under natural convection. By the commercial computational fluid dynamics software Fluent, a3D model was built according to the experiment setup. The validity is well verified by the experiment. Taking advantage of the model, the flow status in several orientations is analyzed. Also, two factors on the deterioration of natural convection are revealed.2-. The development of natural convection test equipment for orientation effect research. The test equipment is a revolvable frame which can hang the object in air, and sustain the fixed orientation. Since the object is hung instead of held, the test can achieve a more idealized natural convection status.3^Omni-orientation natural convection experimental research on rectangular fin heat sink. The performances of rectangular fin heat sink in8orientations are yielded. The influence induced by heat load, fin spacing and orientation effect is concluded. An orientation factor η was proposed. The variation rules of ηwith orientation angles are obtained.