LED thermal technology and thermal materials
Heat dissipation is a major factor affecting the lighting intensity of LED lamps. The heat sink extrusion can solve the heat dissipation problem of low-illuminance LED lamps. but a extruded heat sink cannot solve the heat dissipation problem of 75W or 100W LED lamps.
In order to achieve the ideal lighting intensity, active cooling technology must be used to resolve the heat released by the LED lighting components. Some active cooling solutions such as fans have less lifespan than LED lamps. In order to provide a practical active cooling solution for high-brightness LED lamps, the thermal cooling technology must be low energy consumption; and can be applied to small lamps; its life span should be similar to or higher than the lamp source.
Cooling method
Generally speaking, according to the way the heat is taken away from the radiator, the radiator can be divided into active cooling and passive cooling. The so-called passive heat dissipation means that the heat of the heat source LED light source is naturally dissipated into the air through the heat sink. The heat dissipation effect is proportional to the size of the heat sink, but because the heat is naturally dissipated, the effect is of course greatly reduced. In equipment that is not required, or used to dissipate heat for components that do not generate much heat. For example, some popular motherboards also adopt passive heat dissipation on the north bridge. Most of them adopt active heat dissipation. Active heat dissipation is forced by cooling devices such as fans. It is characterized by high heat dissipation efficiency and small size of the equipment.
Active heat dissipation, subdivided in terms of heat dissipation, can be clarified into air cooling, liquid cooling, heat pipe cooling, semiconductor cooling, chemical cooling, and so on.
Air-cooling is the most common way of thermal cooling, and in comparison, it is also a cheaper way. Air cooling is essentially the use of a fan to take away the heat absorbed by the radiator. It has the advantages of relatively low price and convenient installation. However, it is highly dependent on the environment, for example, the thermal performance will be greatly affected when the temperature rises and overclocking.
Liquid cooling
Liquid cooling is the forced circulation of the liquid under the drive of the pump to take away the heat of the radiator. Compared with air cooling, it has the advantages of quietness, stable cooling, and less dependence on the environment. The price of liquid cooling is relatively high, and installation is relatively complicated. At the same time, try to install in accordance with the instructions in the manual to get the best heat dissipation effect. For cost and ease of use considerations, liquid-cooled heat dissipation usually uses water as the heat-conducting liquid, so liquid-cooled radiators are often referred to as water-cooled radiators.
Heat pipe
The heat pipe is a kind of heat transfer element. It makes full use of the principle of heat conduction and the fast heat transfer properties of the refrigerant. It transfers heat through the evaporation and condensation of the liquid in the fully enclosed vacuum tube. It has extremely high thermal conductivity and good isothermal properties. The heat transfer area on both sides of the cold and heat can be changed arbitrarily, heat can be transferred over a long distance, temperature can be controlled, and a series of advantages, and the heat exchanger composed of heat pipes has high heat transfer efficiency, compact structure, small fluid resistance, etc. advantage. Its thermal conductivity has far exceeded the thermal conductivity of any known metal.
Semiconductor refrigeration
Semiconductor refrigeration is to use a special type of semiconductor refrigeration chip to produce a temperature difference when it is energized. As long as the heat of the high temperature end can be effectively dissipated, the low temperature end will be continuously cooled. A temperature difference is generated on each semiconductor particle, and a refrigeration sheet is formed by connecting dozens of such particles in series, thereby forming a temperature difference on the two surfaces of the refrigeration sheet. Using this temperature difference phenomenon, combined with air cooling/water cooling to cool the high temperature end, excellent heat dissipation effect can be obtained. Semiconductor refrigeration has the advantages of low cooling temperature and high reliability. The cold surface temperature can reach below minus 10, but the cost is too high, and it may cause short circuits due to the low temperature, and the current semiconductor refrigeration technology is not mature and not practical enough .
Chemical refrigeration
The so-called chemical refrigeration is to use some ultra-low temperature chemical substances, and use them to absorb a lot of heat when they melt to reduce the temperature. In this regard, the use of dry ice and liquid nitrogen is more common. For example, using dry ice can reduce the temperature to below minus 20, and some more'perverted' players use liquid nitrogen to lower the CPU temperature below minus 100 (theoretically). Of course, due to the high price and the short duration, this method is often used. Seen in the laboratory or extreme overclocking enthusiasts.
