Study On The Performance Of The Heat Dissipation For Power-Type LED

Light emitting diode (abbr. LED) has advantages in the following aspects:small size, light quality, environment friendliness, low cost of power, quick response, long service life and so on. Because of its prominent performance compared with the tradition light source, various countries and regions in the word have been attracted to positively research and develop the LED, and it is called the third revolution in the lighting domain. However, as the power of LED constantly increases, the cooling problem becomes more and more important, and the heat dissipation problem restricts the further development of LED.In this paper, the fluent has been used to study on the heat dissipation performance of power-type LED, mainly including in the following aspects:(1) For the five different structure radiators of the single chip LED, according to the principle of minimum in junction temperature and convenience of making, a radiator which fins are perpendicular to its plat with90°angle is chosen. And then the optimization design for the radiator chosen has been carried out. At last, one effective structure has been obtained.(2) The flow field and temperature field for the rectangle fin type air cooling radiator of the integrated high-power LED under air forced convection has been investigated as well. The air flows into the radiator uniformly. The flow velocity in the middle area gradually decreases, especially where beneath the chip under the effect of frictional drag and the pressure difference. The fluid flows out of the radiator in the form of jet flow and the velocity near to the exit area gradually increases because the pressure in the middle area is higher than the both side exits. The flow velocity gradually decreases under the effect of ambient air drag after outflowing the radiator. The two side temperature of the radiator fins maintains about302K, and the middle part is about305K. The temperature in two sides is lower than that in the middle part, and the maximal temperature is from303k to305K in the axial direction. The minimum temperature keeps about300K, and the difference in temperature is larger in the upside fins, quantity of heat is accumulated. The fin temperature is the highest which is straightly beneath the chip.(3) Air cooling radiators in the three types of rectangle type, nail column type and mixture type have been devised. By contrasting their flow field and temperature field, we could obtain the following conclusions:flow disturbance and frictional drag of nail column type radiator is larger and the velocity is the lowest, and the junction temperature is the highest, which is309K, and the temperature gradient is larger than that of others, so the heat dissipation effect is the worst. The flow of the mixture type radiator is the best, and the temperature gradient is more uniform than that of others, which is helpful for extending its service life. Therefore, the heat dissipation effect of the mixture type radiator is the best, and the rectangle type radiator is secondary.