Performance of the LED array panel in a confined enclosure

This study performs an experimental study concerning performance of an LED array under natural convection. A total of 270 1-W LEDs having an efficiency of 75% are used to simulate a large LED panel. The size of the cooling heat sink is 348 mm × 558 mm having vertical plate fin configuration with a fin spacing of 9.33 mm. The effect of shrouding, including shrouding above the heat sink and the blockages being placed at the entrance and exit are investigated. For the shrouding effect above heat sink, the heat transfer coefficient is first slightly increased with the rise of shroud distance and peaks at a shroud distance of 20 mm, followed by a marginal decrease of heat transfer coefficient with the shroud distance. On the other hand, a continuous but a very small increase of the heat transfer coefficients with the inlet or outlet blockage distance is seen, yet no plateau is seen as opposed to the effect of shroud distance above heat sink. For the same blockage distance, normally the heat transfer coefficient for those being blocked at the exit is slightly higher than that of inlet blockage. The maximum temperature within the heat sink does not take place at the central position; rather it peaks at the quarter position of the heat sink due to edge effect and likely higher air flow at the center position. The average heat transfer coefficient reaches 6 W/m K as the upper shield is removed.