Solar Light LED Heat Dissipation

Solar Light LED heat dissipation

1. Metal thermal conductivity table (W/mK)
The thermal conductivity coefficient is defined as: per unit length, per K, how much energy can be delivered in W, the unit is W/mK. Among them: "W" refers to the unit of thermal power, "m" refers to the unit of length, meter, and "K" refers to the unit of absolute temperature. The larger the value, the better the thermal conductivity.

The following is a table of the thermal conductivity of several conventional metals:

2. Heat transfer method
Heat transfer is achieved through three ways: heat conduction, convection and heat radiation. In the process of realizing heat transfer, these three methods are often not carried out separately.
Heat conduction: It is the process by which a large number of molecules, atoms, etc. collide with each other to transfer the internal energy of an object from a higher temperature part to a lower part. Heat conduction is the main way of heat transfer in solids. In gases and liquids, heat conduction is often carried out at the same time as convection. Various materials have different heat conduction properties, metal is better, glass, feathers, fur, etc. are poor.
Thermal convection: It is a process in which the internal energy is transferred from the higher temperature part to the lower part by the flow of liquid or gas. Convection is the main way of heat transfer between liquid and gas, and the convection of gas is more obvious than that of liquid.
Thermal radiation: It is a process in which an object directly emits energy and transmits it to other objects without relying on the medium. Thermal radiation is the main way to transfer energy over long distances. For example, solar energy is transmitted to the earth through space in the form of thermal radiation.

3. Solar LED light heat dissipation
The heat dissipation of LED lights mainly relies on a good heat conduction path to transfer the heat of the LED to the shell, and then rely on the air convection around the shell to dissipate heat, and directly radiate a part of the heat to the outside. LED lights require good heat dissipation in order to reduce the junction temperature of the LED light beads and increase the life of the LED light beads.

(1) The junction temperature of the LED refers to the temperature of the LED chip. In practical applications, the junction temperature is difficult to measure. We generally control the temperature of the LED pin (anode). Generally, the temperature of the 2835 and 5730 light bead pins is controlled below 60 degrees; the pin temperature of high-power 1WLED is controlled below 80 degrees, and the surface temperature of high-power lights is controlled below 60 degrees. Relatively speaking, the lower the junction temperature, the longer the life of the LED light bead.

(2) Ways to reduce LED junction temperature
a. Reduce the thermal resistance of the LED itself; b. Good secondary heat dissipation mechanism; c. Reduce the thermal resistance between the LED and the installation interface of the secondary heat dissipation mechanism; d. Control the rated input power; e. Reduce the ambient temperature.

(3) Heat dissipation method of lights and lanterns
a. Light material selection: LED lamps generally use aluminum and aluminum alloy with good thermal conductivity as the main structural components, which can quickly conduct the heat generated by the LED light beads to the surface of the light.

b. Structural form: LED lights are made into straight trough heat dissipation fins to facilitate air convection and take away the heat from the surface of the lights. At the same time, the surface area of ​​the lights is increased, which is conducive to the radiant heat dissipation of the lights. The larger the exposed area of ​​the light, the better the heat dissipation effect.

c. Reduce the thermal resistance of the installation interface: the LED light beads and the aluminum substrate, and the aluminum substrate and the structural parts should be tightly combined. In order to reduce the thermal resistance, add heat dissipation paste or thermal silica gel between them. There must be no gaps in the connection between the structural parts.

d. Surface spraying also has a certain impact on the heat dissipation of LED lights. Aluminum alloys generally use surface spray paint. Because the spray paint coating is thin, it has little effect on heat dissipation, and the powder coating is thicker, which is not conducive to heat dissipation.

Analysis of main parameters of lights:
1. Light size: shell size of the light
2. Light power: refers to the maximum power when the light is on
3. Input voltage/current: the power supply voltage/current of the light.
4. IP rating: the waterproof and dustproof rating of the light, the outdoor light is IP65, the underwater light is IP68, and the underground light is IP67. (Note: Please refer to the introduction on the product information for the protection effect corresponding to the IP level)
5. Light-emitting angle: refers to the angle of the light from the light, which is the comprehensive effect of the primary light distribution of the LED particles, the secondary light distribution of the lens, and the third light distribution of the light-emitting surface of the light.
6. Color/color temperature: the final light color or color temperature of the light.