First, the problem of LED cooling industry
LED lighting is recognized as the next lighting technology due to its power saving, environmental protection and long life. However, more than 70% of the LED's electrical energy is converted into heat and must be dissipated. Although LED lighting technology has developed rapidly, there are reports of 200 lm per watt of light, but LED cooling is a very headache in LED lighting, and has become a roadblock on the road of universal development of LED lighting.
The biggest problem that hinders the popularity of LED lighting applications is the high price of LED lamps, which are caused by heat problems. Due to the heat problem, the current LED street lamp development is walking on the edge of death.
Humans have been studying heat transfer for hundreds of years. Heat transfer technology and technology are very mature. It is like a mature fruit. It falls to the ground and is covered by leaves. It is not seen by the people now, so that when it comes to the electronics industry, The main reason is that when the CPU heat in the computer suddenly increases, people do not pull out the leaves on the ground, pick up the ripe fruits, and transplant the mature heat transfer knowledge into the electronics industry. Instead, it has created a number of new terms: "active cooling", "passive cooling", "heat sinking", etc. It doesn't sound like what it means. English "Sink" is also a very rare term in heat transfer technology and technology.
From the perspective of heat transfer and technology, LED heat dissipation is not complicated. It only involves a very small part of heat transfer—heat conduction heat transfer and convection heat transfer (mainly air natural convection heat transfer), in which heat conduction heat transfer can be utilized. The ready-made heat transfer computer software gets a very accurate solution, such as analyzing the temperature distribution inside the LED package chip (heat transfer process); analyzing the internal temperature distribution from the LED chip to the heat dissipation fin. However, it should be noted that for convective heat transfer, where air flow is involved, it must be studied through a large number of experiments, and computer software calculations have only academic significance and no practical engineering significance, because the error is too large.
The reasons for the simple problem of LED heat dissipation are: knowledge faults, people with mature heat transfer knowledge are involved in the research of LED heat dissipation, and lack of professional LED heat research institutions to give clear guidance to the industry.
At present, many professional thermal technicians in the industry are transferred from the heat dissipation of computers. Naturally, the commonly used technologies and business activities are brought over. For example, heat pipe technology is widely applied to high-power LED lighting (such as In the streetlights, new business opportunities have been created for heat pipe manufacturers that originally served computer chip heatsinks, and even reflow heat pipes have been proposed.
If the heat dissipation of the LED lamp uses a general heat pipe like a chicken to kill a pig knife, then the use of a reflux heat pipe is like killing a chicken and lifting the knife. A company in Taiwan invented the "Liquid Immersion Heat Dissipation Technology", which lacked the knowledge of basic convection heat transfer and actually won the Gold Award for the International Invention Exhibition. These inventors inspired by the car's water tank are not sure why the car's engine uses water (liquid) cooling technology, and the role of water in the heat dissipation process.
Second, the current LED street light problem
The LED street lamp shown in Figure 1 is the most typical and most commonly used structure: the heat sink is bare, the large aluminum substrate with the LED light source chip is mounted on the heat sink substrate (below), and the front transparent shield is added. . This structural design has the following problems:
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