Technology丨How to do outdoor LED display heat dissipation

2,106 views admin 2020-05-04

With the advent of summer, it is inevitable that everyone is extremely hot, and the LED display is also more prone to heat. The high temperature will cause the failure probability of electronic components to increase rapidly, resulting in a decline in the reliability of the LED display. In order to control the temperature of the electronic components inside the led display, so that it does not exceed the maximum allowable temperature specified under the working environment conditions in which the led display is located, a heat dissipation design of the led display is required. The heat dissipation design of led display screen, how can low cost, high quality, is the content of this article.

There are three basic ways of transferring heat: heat conduction, convection and radiation.

Heat conduction: Gas heat conduction is the result of gas molecules colliding with each other when they move irregularly. The heat conduction in the metal conductor is mainly completed by the movement of free electrons. Heat conduction in non-conductive solids is achieved by vibration of the lattice structure. The heat conduction mechanism in liquid mainly depends on the action of elastic waves.

Convection: refers to the heat transfer process caused by the relative displacement between the various parts of the fluid. Convection only occurs in fluids and is necessarily accompanied by thermal conduction. The heat exchange process that occurs when a fluid flows over the surface of an object is called convective heat transfer. The convection caused by the different density of the cold and hot parts of the fluid is called natural convection. If the movement of the fluid is caused by external forces (fan, etc.), it is called forced convection.

Radiation: The process by which an object transfers its ability in the form of electromagnetic waves is called thermal radiation. Radiant energy transfers energy in a vacuum, and there is energy conversion, that is, thermal energy is converted into radiant energy and radiant energy is converted into thermal energy.

When selecting the heat dissipation method, the following factors should be considered: heat flux density, volume power density, total power consumption, surface area, volume, working environment conditions (temperature, humidity, air pressure, dust, etc.) of the LED display screen. According to the heat transfer mechanism, there are natural cooling, forced air cooling, direct liquid cooling; evaporative cooling; thermoelectric cooling; heat pipe heat transfer and other heat dissipation methods.

LED screen heat dissipation design method

The heat exchange area between the hot electronic component and the cold wind, and the temperature difference between the hot electronic component and the cold wind directly affect the heat dissipation effect. This involves the design of the air volume into the led display box and the design of the air duct. When designing ventilation ducts, try to use straight ducts to transport the air, and avoid sharp bends and bends. Ventilation ducts should avoid sudden expansion or contraction. The expansion angle should not exceed 20 °, and the contraction angle should not exceed 60 °. Ventilation ducts should be sealed as much as possible, and all overlaps should follow the direction of flow.

When designing the led display cabinet, there are a few points to note:

The vent hole should be located near the upper side of the box. The air intake hole should be set on the lower side of the box, but not too low to prevent dirt and water from entering the box installed on the ground.

The design should be such that natural convection contributes to forced convection. The air should circulate from the bottom to the top of the box, and a dedicated air inlet or exhaust hole should be used. Cooling air should flow through the heat-generating electronic components, and at the same time, air flow short circuit must be prevented. Filter screens should be installed at the air inlet and air outlet to prevent debris from entering the cabinet.

When designing, make sure that the air inlet and exhaust are far away. To avoid repeated use of cooling air.

To ensure that the direction of the radiator slot is parallel to the wind direction, the radiator slot cannot block the wind path.

The fan is installed in the system. Due to structural limitations, the air inlet and air outlet are often blocked by various kinds, and their performance curves will change. According to practical experience, the inlet and outlet of the fan should be at least 40mm away from the obstruction. If there is space limitation, it should be at least 20mm.