LED explosion-proof lights floodlights / floodlights cooling principle

LED fever problem

As with conventional light sources, semiconductor light-emitting diodes (LED explosion-proof lamps) also generate heat during operation, depending on the overall luminous efficiency. Under the action of external electric energy, electrons and holes are radiated and recombined to generate electroluminescence, and the light radiated from the vicinity of the PN junction must pass through the semiconductor medium and packaging medium of the LED explosion-proof lamp chip to reach the outside (air). . Integrated current injection efficiency, radiative luminescence quantum efficiency, external light extraction efficiency, etc., eventually only about 30-40% of the input electrical energy is converted into light energy, and the remaining 60-70% of the energy is mainly generated by the non-radiative composite lattice vibration. Form LED explosion-proof lamps convert heat energy.

LED heat on the impact of life In general, LED lights work is stable, good or bad, and the lamp body itself is essential for heat dissipation, the market's high-brightness LED lamp heat dissipation, often using natural heat, the effect is not ideal. The LED luminaire creates LED luminaires that consist of LEDs, heat sinks, actuators, and lenses. Therefore, LED explosion-proof lamps are also an important part of heat dissipation. If the LEDs do not cool well, their lifetime will be affected.

Thermal management is a major issue in high-brightness LED applications

Since the p-type doping of Group III nitrides is limited by the solubility of Mg acceptors and the higher startup energy of holes, heat is particularly easily generated in the p-type region, and this heat must be dissipated on the heat sink through the entire structure; The heat dissipation paths of LED explosion-proof lamps are mainly heat conduction and thermal convection; the low thermal conductivity of Sapphire substrate materials leads to an increase in the thermal resistance of the device, resulting in a serious self-heating effect, which has a devastating effect on the performance and reliability of the device.

The effect of heat on high-brightness LEDs

The heat is concentrated in a very small chip. The temperature of the chip rises, causing a non-uniform distribution of thermal stress, chip emission efficiency, and lasing efficiency of the phosphor powder. When the temperature exceeds a certain value, the device failure rate increases exponentially. Statistics show that for every 2°C increase in component temperature, the reliability drops by 10%. When multiple LEDs are densely arranged to form an LED explosion-proof lamp lighting system, the heat dissipation problem is more serious. Solving the thermal management problem has become a prerequisite for the application of high-brightness LED explosion-proof lamps.

The relationship between chip size and heat dissipation

The most direct way to increase the brightness of the power LED explosion-proof lamp is to increase the input power, and in order to prevent the saturation of the active layer, the size of the pn junction must be increased accordingly; the increase in the input power of the LED explosion-proof lamp must increase the junction temperature. Reduce quantum efficiency. The increase of single-tube power of the LED explosion-proof lamp depends on the ability of the device to derive heat from the pn junction, increase the size of the chip alone while maintaining the current chip material, structure, packaging process, constant current density on the chip, and equivalent heat dissipation conditions. , the junction temperature will continue to rise

LED heat dissipation method

Aluminum heat sink fins

This is the most common way to dissipate heat, using aluminum heat sink fins as part of the housing to increase the heat sink area.

Thermal plastic shell

The use of LED explosion-proof lamp insulation heat-displacement plastic instead of aluminum alloy heat sink, can greatly improve the heat radiation ability.

Radiant heat treatment

The surface of the lamp shell is radiated and heat-dissipated. The simple method is to apply radiant heat-dissipating paint, which can remove heat from the surface of the lamp shell by radiation.

Air Fluid Mechanics

With the shape of the lamp housing, convection air is created, which is the least costly way to enhance heat dissipation.

fan

The interior of the lamp shell is enhanced with long-lived high-efficiency fans, and the cost is low and the effect is good. However, changing the fan is more troublesome and it is not suitable for outdoor use. This kind of design is rare.

Heat pipe

The use of heat pipe technology, the heat from the LED explosion-proof light chip leads to the shell heat sink fins. Large lamps, such as street lamps, are common designs.

Liquid bulb

Using liquid bubble encapsulation technology, the transparent liquid with a higher thermal conductivity is filled into the lamp bulb. This is in addition to the principle of light reflection, the only use of LED chips out of the heat transfer surface, heat dissipation technology.

The use of lamp caps

In home-type, lower-power LED explosion-proof lights, the interior of the lamp head is often used to place part or all of the heat-generating drive circuit. In this way, it is possible to dissipate heat from a lamp with a large metal surface, such as a screw base lamp, because the lamp head is in intimate contact with the lamp holder metal electrode and the power cord. Therefore, a part of the heat can be derived therefrom.

Thermal Conduction and Heat Dissipation Integration--Application of High Thermal Conductive Ceramics

The purpose of the heat dissipation of the lamp shell is to reduce the operating temperature of the LED explosion-proof lamp chip. Because the chip expansion coefficient of the LED explosion-proof lamp and our commonly used metal thermal conductivity and thermal expansion material expansion coefficient greatly differ, it is impossible to directly solder the LED chip to avoid high and low temperature thermal stress. Destroy the LED chip. The latest high thermal conductivity ceramic material has a thermal conductivity close to that of aluminum, and the expansion system can be adjusted to synchronize with the LED chip. In this way, heat conduction and heat dissipation can be integrated to reduce the intermediate heat conduction.

10.PVC modified material

Thermally conductive, secondary package

Cooling technology breakthrough

Most existing ceiling lamps use finned aluminum as a heat sink. The heat dissipation effect of this LED explosion-proof lamp radiator is unsatisfactory, and the radiator usually reaches a higher temperature.

1. Break through the problem of unsatisfactory cooling effect of existing finned aluminum radiators

Most of the existing ceiling lamp uses finned aluminum as a radiator. This type of radiator has a poor cooling effect, and the radiator usually reaches a higher temperature.

2. Use insulated heat-dissipating plastic instead of aluminum alloy to create heat sink

In 2009, Korea had developed an LED explosion-proof lamp-insulated, heat-dissipating plastic that maintains its heat-dissipation capability while keeping the level of aluminum alloy flat. At the same time, the heat radiation capability has been increased by 4-8 times. The LED explosion-proof lamp heat sink made of this heat-dissipating material can greatly increase the overall heat dissipation effect.

3. Using the principle of liquid convection to provide a ceiling lamp with good heat dissipation performance

The LED explosion-proof lamp utilizes the heat absorbed from the lampshade by the coolant in the liquid tank installed on the lampshade, and utilizes the natural convection of the coolant between two liquid tanks with different heights to absorb the coolant from the lampshade. The heat is emitted so that the shade of the ceiling lamp is well cooled.

4 can be flexible rotation, easy to install

Because the coolant convection pipe connected between the two liquid storage tanks of the LED explosion-proof lamp has a bellows structure, and the bellows structure can be stretched and bent, it does not hinder the flexible rotation of the lampshade, and the LED explosion-proof lamp is also easy to install.