Orientation effects on heat dissipation performance of plate-fin heat sink for LED application

The plate-fin heat sink is widely used in LED lamp for application of multi-angle illumination. According to the key structures of a LED projection lamp, the orientation effects on heat dissipation performance of plate-fin heat sink with natural convection cooling were researched under 3 driving currents and 7 inclination angles between illumination direction and gravity direction. Based on the validity and accuracy of numerical simulation verified by experimental results, the thermal mechanisms with respect to maximum excess temperature and temperature uniformity were investigated through analyzing temperature and flow data derived from numerical simulation. The obvious differences of air velocity distribution in the flow channel of fins are found among inclination angles, these differences are the main reason of sensitive orientation effect about maximum excess temperature and temperature uniformity. In addition, air velocity difference between upstream and downstream around the measuring point with maximum temperature can be used to quantitatively interpret the variation trend of temperature uniformity in different inclination angles. Furthermore, the effects of inclination angle and fin spacing on the maximum excess temperature were analyzed. The results show that the heat dissipation performance of plate-fin heat sink with optimal fin spacing has high orientation sensitivity, so the study of orientation effects on the air flow and heat transfer of plate-fin heat sinks is an indispensable task in the thermal design of LED with multi-angle illumination function.