Heat dissipation is a key issue that LED street lights need to solve. As we all know, LED is a photovoltaic device, in which only 15% to 25% of the electrical energy is converted into light energy, and the rest of the electrical energy is almost converted into thermal energy, so that the temperature of the LED rises. In high-power LEDs, heat dissipation is a big problem. For example, if a 10W white LED has a photoelectric conversion efficiency of 20%, 8W of electric energy is converted into thermal energy.
If no heat dissipation measures are taken, the core temperature of the high-power LED will rise rapidly, when its junction temperature (TJ) When the temperature rises above the maximum allowable temperature (typically 150 ° C), high power LEDs may be damaged by overheating. Therefore, in the design of high-power LED lamps, the most important design work is the heat dissipation design. Due to the high brightness requirements of LED street lamps, the use environment is harsh. If the heat dissipation is not well solved, the LED will be aging quickly and the stability will be reduced. As soon as the street lamp with 250W high-pressure sodium lamp is used, the heat dissipation control is very good.
Even if it works for 5,000 hours, the light decay is still very small. High-power LED street lights under the same conditions, if the heat dissipation is not good, the light decay will be great. The cooling methods of LED street lamps mainly include: natural convection heat dissipation, added fan forced heat dissipation, heat pipe, loop heat pipe heat dissipation and temperature equalization plate heat dissipation. Adding a fan to force the heat dissipation system is complicated and has low reliability, and the heat pipe and the temperature equalization plate have a high cost.
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