LED Heat Dissipation Technology (1) : Heat Dissipation Method

Writer：Jane Time：2021-06-24 Browse：176

Heat dissipation is one of the main factors affecting the illumination intensity of LED lamps. LED lamps are 80 percent more energy efficient than traditional incandescent bulbs, but their LED components and driver circuits dissipate a lot of heat. If this heat is not properly vented, the luminosity and life of LED lighting fixtures will decrease dramatically.

The heat sink can solve the heat dissipation problem of low illumination LED lamps. Lamp manufacturers can produce 40W LED replacement lights as well as 60W LED replacement lights. High illumination LED lighting fixtures will encounter heat dissipation problems. A heat sink cannot solve the heat dissipation problem of 75W or 100W LED lighting fixtures. The need for high brightness bulbs is obvious, with 75W and 100W bulbs accounting for a large share of the lighting market. The market is eager to take advantage of the energy conservation and maintenance advantages inherent in LED lighting. The U.S. Energy Independence and Security Act of 2007 required the use of more efficient lighting starting in 2012. These new requirements have prompted consumers to seek alternatives to existing incandescent lamps with good lighting quality, long life, and strong illumination.

In order to achieve the desired lighting intensity, active cooling technology must be used to address the heat released by the LED lamp assembly. Some active cooling solutions such as fans do not have as long life as LED lighting fixtures. In order to provide a practical active cooling solution for high brightness LED lighting fixtures, the cooling technology must be low energy consumption; And can be applied to small lamps and lanterns; Its life should be similar to or higher than the lamp source.

Generally speaking, according to the way of taking heat from the radiator, the radiator can be divided into active heat dissipation and passive heat dissipation. Passive cooling, refers to the LED light source through the radiator heat source as natural heat into the air, the heat dissipation effect is proportional to the size of heat sink, but because it is a natural send out quantity of heat, the effect of course, is often used in those without the requirements of the equipment to the space, or used to heat small parts of heat, Such as part of the popular motherboard in the north bridge also take passive heat dissipation, the vast majority of active heat dissipation, active heat dissipation is through the fan and other heat dissipation equipment will be forced to take away the heat from the heat sink, which is characterized by high heat dissipation efficiency, and small equipment volume.

Active heat dissipation can be divided into air cooling, liquid cooling, heat pipe cooling, semiconductor refrigeration, chemical refrigeration and so on. Air-cooled cooling is the most common way of cooling, and comparatively speaking, it is also a cheaper way. In essence, air cooling is to use the fan to take away the heat absorbed by the radiator. It has the advantages of relatively low price and convenient installation. But the environmental dependence is relatively high, such as temperature rise and overclocking when its heat dissipation performance will be greatly affected.

Surface

The liquid cooling heat dissipation is through the liquid in the pump driven by the forced circulation to take away the heat of the radiator, compared with air cooling, has the advantages of quiet, stable cooling, small dependence on the environment and so on. The price of liquid cooling is relatively high, and the installation is relatively troublesome. At the same time, as far as possible in accordance with the instructions of the installation method to obtain the best heat dissipation effect. Due to the consideration of cost and ease of use, water is usually used as the heat conduction liquid for liquid cooling, so liquid cooling radiator is often called water cooling radiator.

Heat pipe

Heat pipe belongs to a kind of heat transfer element, it makes full use of the heat transfer principle and rapid heat transfer properties of cooling medium, through the liquid evaporation and condensation in the vacuum tube to transmit heat, high thermal conductivity, excellent isothermal property, heat and cold on both sides of the heat transfer area can be arbitrary change, which can be heat transfer and temperature can be controlled at a series of advantages, And the heat exchanger composed of heat pipes has the advantages of high heat transfer efficiency, compact structure, small fluid resistance loss and so on. Its thermal conductivity far exceeds that of any known metal.

Semiconductor refrigeration

Semiconductor refrigeration is the use of a special semiconductor refrigeration chip in the power generation of temperature difference to refrigeration, as long as the heat at the high temperature end can be effectively dissipated, the low temperature end is constantly cooled. A temperature difference is generated on each semiconductor particle, and a cooling sheet consists of dozens of such particles connected in series, thus creating a temperature difference on the two surfaces of the cooling sheet. Using this temperature difference phenomenon, with air cooling/water cooling to cool the high temperature end, can get excellent heat dissipation effect. Semiconductor refrigeration has the advantages of low refrigeration temperature and high reliability. The cold surface temperature can reach below minus 10℃, but the cost is too high, and it may cause short circuit because the temperature is too low. And now the process of semiconductor refrigeration sheet is not mature, and it is not practical.

Chemical refrigeration

Chemical refrigeration is the use of ultra-cold chemicals that absorb large amounts of heat as they melt to lower the temperature. The use of dry ice and liquid nitrogen is more common in this regard. For example, dry ice can be used to get the temperature below -20 ° C, while more "geeky" players can use liquid nitrogen to get the CPU temperature below -100 ° C (in theory), although due to its high cost and short duration, this method is often used in LABS or by extreme overclocking enthusiasts.