Energy transformation
The principle of all light sources is to convert electric energy into visible light and heat energy, and the difference is the specific proportion.
The output of incandescent bulbs is mainly concentrated in infrared radiation, visible light only accounts for 8%. Fluorescent light sources have a higher luminous efficiency of 21%, but still emit a large number of infrared rays, ultraviolet rays, and heat.
The infrared ray generated by LED is very small, which can convert 40% of electric energy into visible light, and the rest of the energy is converted into heat, which needs to be conducted out of the LED working area, sequentially passed through the basic printed circuit board, the heat dissipation system and the housing, and finally emitted into the air.
About 60% of the energy in the LED chip is converted into heat, which needs to be dissipated by conduction and convection. If there is no efficient heat management and cooling system, the LED chip will overheat, resulting in changes in LED characteristics. The short-term effect will result in color drift and light output decrease, and the long-term effect will result in accelerated light attenuation, thus shortening the service life.
LED performance degradation
Too high junction temperature will lead to degradation of LED performance, especially service life, light color quality, and lumen output. If the rated maximum junction temperature is exceeded, the service life of the LED will decrease by 30% to 50% for every 10 degrees of increase in the operating temperature.
The last major parameter affected by the LED thermal management system is lumen output. Increasing the current can improve the lumen output of the LED, but large current will also lead to an increase in calorific value. Therefore, when determining the current value, an optimal balance must be selected between the system performance and the service life.
The light material is deformed.
In fact, we also encounter many such things in our life. For example, when an object encounters too hot a temperature, it will slightly deform, and so will the LED light source.
At present, there are two kinds of heat dissipation methods for commonly LED lights. One is active heat dissipation, i.e. air cooling, water cooling, microchannel cooling, semiconductor cooling, and other forced cooling methods.
However, active heat dissipation will increase additional power consumption, which will increase the design difficulty considering the protection level requirements.
The second is the passive heat dissipation, which is also the current mainstream heat dissipation method. It mainly relies on natural convection of air, and the heat generated by the heat source is naturally dissipated into the air through the heat sink. The heat dissipation effect of this method depends on the size of the heat sink and the material and processing of the heat sink.
Material properties
Thermal conductivity is a physical quantity used to measure thermal conductivity efficiency. The thermal conductivity of material reflects the thermal conductivity of the material. Some materials are good conductors of heat compared with other materials. For example, the thermal conductivity of pure copper is 400W/m.K, while the thermal conductivity of air is only 0.025.
Aluminum is a common material for making radiating fins, not only because of its high-cost performance but also because aluminum is easy to process, die-cast and extrude. Another more important characteristic of the heat sink is its geometry, while aluminum profiles are easy to process and form. In addition, aluminum has advantages such as light weight, corrosion resistance, and good stability. All in all, aluminum is an excellent material for making heat sinks.
For example, just like this product, the difference is not big from the front appearance but obvious from the back.
The most intuitive feeling is that the thickness is different. The thickness of the heat sink determines the strength of its heat dissipation capability.
The thickness of the heat sink of the first product is the only 28.5mm, and the thickness of the second product is 52.3mm, which is twice the difference.
Obviously, the heat dissipation performance of the first product will be much worse than that of the second product, and its service life will be shorter than that of the second product.
Therefore, when choosing LED products for oneself, the price is only a factor to consider. In addition, the heat dissipation effect and life span of LED products should also be considered.
VANTEN LED (www.vanten.co.uk）main products are LED Headlight kit, LED Fog Light, LED Interior Bulbs, LED Turn Light, LED Driving Light, LED Work Light, LED Light Bar, etc. We have our own brand VLED, and also provide OEM and ODM services.
If you have any questions about LED lights, please feel free to ask us. We will provide the most professional answers and considerate services for you.
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