Expert: LED luminaire thermal coating applications

About LED luminaires heating and cooling coating applications according to
China Paints Onlineexperts
introduction: With the LED technology as a new generation of lighting technology has been widely concerned in recent years, LED power increased, cooling issues are more and more attention. Long-term observation by researchers of Chisheng Weihua thermal coatings has found that this is because the light decay of LEDs or their lifespan is directly related to their knot temperature, the heat dissipation is not good knot temperature on the high life is short. Unlike incandescent and fluorescent lamps used in the past, their energy loss is large, but most of the energy is directly radiated through infrared light, light sources have less heat, and LEDs, in addition to the energy consumed as visual light, other energy is converted into heat. Also because in recent years, electronic products gradually to high density, high integration development, LED products are no exception, so to solve the LED cooling problem has become today to improve LED performance, the development of LED industry's main problems.
led heating is because not all of the added electrical energy is converted into light energy, but part of it into heat energy. LED light efficiency is currently only 100lm/W, its electro-optical conversion efficiency is only about 20 to 30%. This means that about 70% of the electricity is turned into heat. Specifically, LED knot temperature is caused by two factors: the internal quantum efficiency is not high, that is, when electrons and cavities are composited, and not 100% of photons are produced, often referred to as "current leakage" and the PN region of the compound rate of the carriers reduced. The leakage current multiplied by the voltage is this part of the power, that is, converted to thermal energy, but this part does not account for the main component, because the internal photon efficiency is now close to 90%. Internally produced photons cannot all be ejaculation to the outside of the chip and eventually converted to heat, which is the main part, as this so-called external quantum efficiency is only about 30%, most of which is converted into heat.
As mentioned earlier, although the light efficiency of incandescent lamps is very low, only about 15lm/W, but it converts almost all the electrical energy into light energy and radiation out, because most of the radiation energy is infrared, so the light efficiency is very low, but it eliminates the problem of cooling. LED thermal solution: to solve the LED cooling, mainly from two aspects, before and after the package, can be understood as LED chip cooling and LED luminaire cooling. Led chip cooling is mainly related to substrate and circuit selection and process, this paper does not elaborate. This article mainly introduces the cooling of led luminaires, because any LED will be made into lamps, so the LED chip generated heat is always eventually scattered through the housing of the lamp into the air. If the heat dissipation is not good, because the LED chip's thermal capacity is very small, a little heat accumulation will make the chip's knot temperature increase rapidly, if the long-term operation at high temperature state, its life will be shortened very quickly.
, however, there are many ways in which these heats can really guide the chip to the outside air. Specifically, the heat generated by the LED chip comes out of its metal cooling block, first through the solder to the PCB of the aluminum substrate, and then through the thermal adhesive to the aluminum radiator. So the heat dissipation of LED luminaires actually includes two parts: thermal conductivity and cooling. However, LED lamp shell cooling according to the power size and place of use, there will be different choices. There are now several main cooling methods: aluminum cooling fins: this is the most common way to dissipate heat, using aluminum cooling fins as part of the shell to increase the cooling area. Thermal plastic shell: Fill the thermal material when the plastic shell is molded, increasing the thermal conductivity and cooling capacity of the plastic shell. Air fluid mechanics uses the shape of the lamp shell to create tsyring air, which is the lowest cost of enhanced cooling.
other fan lamp shell inside with longevity and high efficiency fan to enhance heat dissipation, low cost, good results. However, to change the fan is a bit of trouble, nor is it suitable for outdoors, this kind of design is relatively rare. Using heat-conducting tube technology, the heat transfer pipe is directed from the LED chip to the shell cooling fin. In large lamps, such as street lamps, this is a common design. Surface radiation cooling treatment lamp shell surface to do radiation cooling treatment, simply is to apply Zhisheng Weihua radiation cooling paint, heat can be taken away from the lamp shell surface by radiation. The following new type of thermal coating: ZS-411 radiation cooling coating, coating coating with high thermal conductivity and a large cooling surface area, while a considerable wide wavelength range (1-20 m) with a high radiation rate, can significantly improve the comprehensive performance including conduction, convex, radiation cooling.
This coating uses a high-performance thermal solution, the thermal solution has a high visible and near-infrared light reflectivity, high thermal infrared emission and stability and other special properties, but also has good physical performance, chemical performance and good construction of a variety of compounds, the thermal solution works by the inorgic collosome particles (less than 100 nanometers) condensation and produce binding force. The addition of nanotubes and other materials with high thermal conductivity and emission in the coating solution can make the coating surface appear macro-glossy micro-rough appearance of nanomaterial components, which can greatly increase the contact area between the cooling device and the outside world, and significantly enhance the cooling effect. At the same time, a large number of e-jumped by a variety of sharpstones as a composite infrared radiation, not only increased the impurity energy level, improve the infrared radiation coefficient, but also maintain the corresponding thermal stability, heat resistance. On the whole, the luminous efficiency of LED is still relatively low, which causes the knot temperature to increase and the life to decrease. In order to reduce the knot temperature to improve life, we must pay great attention to the problem of cooling.
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