Introduction to the heat dissipation methods of high-power LED lights

At present, the existing LED heat dissipation methods mainly include the following: natural convection heat dissipation, forced air cooling heat dissipation, liquid cooling heat dissipation, and semiconductor refrigeration heat dissipation. The characteristics of these heat dissipation methods are as follows:

1 . Natural convection heat dissipation

The natural convection heat dissipation method is the phenomenon that the fluid still relies on the temperature difference or density difference of its own force to move without external mechanical driving force, through convection heat transfer, heat conduction and radiation to make the fluid flow to produce the phenomenon of mass transfer and heat transfer. It is currently 

the most common way of heat dissipation, low cost, easy to manufacture, high-power street lights mainly in this way.

2 . Forced air cooling

The forced air cooling method uses electric power to drive fans and other mechanical equipment, and the heat sink forms an air-cooled heat sink, which forces the fluid flow of the heat source accessories, enhances the convective heat transfer coefficient, and drives the heat of the heat sink to the surrounding environment. The structure is simple and the technology is mature. At present, it is mainly used in heat sources with high heat flux density, graphics cards, and high-power lamps.

3 . Liquid cooling

Liquid cooling and heat dissipation methods include base phase liquid cooling and phase change cooling.

(1)Single-phase liquid cooling mainly involves low-temperature fluid flowing through a high-temperature heat source, and the heat is taken away by heat conduction, and the fluid does not undergo phase change.

(2)Phase change cooling mainly represents a heat pipe, that is, the evaporation end is in contact with the heat source, and the liquid phase change absorbs the heat of the heat source, condenses into liquid at the condensation end, and flows back to the evaporation end. The heat transfer between the cold and hot fluids does not require external driving. Compared with the first two heat dissipation methods, it occupies a small space, has a large heat flux per unit area, can transfer heat away from it, and has a large thermal conductivity. Suitable for high-power and high heat flux heat dissipation devices, currently in electronic products such as CPU/LED lights and other lighting fields have a wide range of applications.

4 . Semiconductor cooling

At present, the price of LEDs on the market is relatively high, which is two or three times the price of traditional light sources. In addition, LED lights need a DC drive that matches them, and cannot directly replace traditional light sources, which increases application costs and requires auxiliary heat dissipation. Equipment, these all increase the cost of LED equipment. 

Therefore, the solution to the problem of high-power LEDs can be considered in depth from two aspects. The first is to study high-quality, high-quantum-efficiency epitaxial material growth technology, improve chip luminous efficiency and brightness, and fundamentally reduce wood formation and reduce heat generation. The second is to improve the heat dissipation structure of the LED, select a reasonable heat sink, and dissipate the generated heat as soon as possible to ensure that the chip is at the normal operating temperature. In order to effectively ensure the normal operation and effective life of the LED, the research on the corresponding heat dissipation work is of great significance to the wide application of LED lights.

The heat transfer process is composed of three basic methods: heat conduction, convection, and radiation. Generally, the working environment temperature of electronic devices is -25℃~40℃, and the internal and external surface temperature of electronic devices should not exceed 150℃, and some even do not exceed 120℃. At present, electronic components driven by electricity mainly dissipate heat by means of convection and heat conduction, with the aid of radiation heat dissipation. Among them, the most widely used heat dissipation structures are active heat dissipation and passive heat dissipation. Active heat dissipation includes radiators with fans, radiators with uniform temperature plates, heat pipes and forced liquid cooling. Passive heat dissipation generally uses fins with high thermal conductivity. In the natural environment, the heat is dissipated through natural convection.