LED Tri Proof Light have become the fourth generation of light sources and have been widely used in daily life. At present, the design of LED Tri Proof luminaires has not completely deviated from the limitations of the third-generation traditional light source design thinking, especially the heat dissipation structure needs to be optimized and improved. This time, the problem of heat dissipation of lamps and lanterns helps friends to share and exchange ideas. It is helpful, the details are as follows:
I. Summary of thermodynamics knowledge
The three laws of thermodynamics are the core of thermals. The knowledge that is closely related to the design of luminaires is three heat transfer methods: conduction, convection and radiation. For the current heat dissipation structure of lamps, the main applications are conduction and convection.
1, hot road
The heat path is the route taken by the heat. In terms of lamps, the heat path is roughly composed of a lamp bead, a lamp board and a heat sink. The LED Tri Proof Light is a heat source, and the heat of the lamp bead is conducted into the aluminum substrate, and the aluminum substrate conducts heat to the heat sink. The heat sink then transfers the heat to the surface of the radiator and the nearby air in three ways: conduction, convection and radiation. Finally, the air is convected by the air buoyancy, and the heat is transferred to the air away from the lamp, that is, the whole process of the heat dissipation of the lamp is completed.
2, thermal resistance
Thermal resistance is the resistance that heat encounters during transmission. The thermal resistance is related to the material and the rationality of the thermal circuit design. In theory, atomic and molecular crystals have the least thermal resistance (except absolute superconductivity), their thermal conductivity depends on crystal oscillators, such as diamond, corundum, high-quality jade, etc., followed by metal, and their thermal conductive carriers are electrons, such as gold, silver, copper, Aluminum, etc., non-metallic insulating materials have relatively high thermal resistance, such as plastic, wood, glass, etc., in the design of thermal circuits, try to avoid the use of thermal insulation materials.
3, heat dissipation design considerations
3.1 Thermal circuit interruption or obstruction
In the design and manufacture of LED Tri Proof Light, the common thermal circuit interruption or hindrance is easy to appear in the following parts: a floating between the lamp bead and the aluminum substrate, there is an air interlayer between the b aluminum substrate and the heat sink, and the structure of the c heat sink is unreasonable. Wait.
Air is a poor conductor of heat. When the LED Tri Proof Light bead and the aluminum substrate are suspended, the heat accumulation of the lamp bead is very fast, the junction temperature of the LED chip is too high, and the phosphor is damaged, which may be accompanied by light decay, dead light, circuit breaking, etc. .
The contact area between the aluminum substrate and the heat sink is large. During the assembly process, the fixing screws are loose or the LED Tri Proof Light board is deformed, and the light board cannot be seamlessly connected with the heat sink. The gap is filled with a large amount of air molecules, and these air molecules are like a bed of cotton. The heat conduction between the lamp board and the heat sink is hindered, resulting in a high temperature of the lamp board and the lamp body, and the body temperature of the heat sink is low, which affects the service life of the LED Tri Proof luminaires.
Some design manufacturers, lack of thermodynamic expertise, blindly pursue the appearance of the LED Tri Proof luminaires and the art, interrupted the heat. There are also some designers who consider the appearance defects of the surface of aluminum or iron sheets, or to prevent the corrosion of the LED Tri Proof luminaires in the outdoor climate environment, spraying paint and plastic powder on the surface of the radiator, because these materials are poor conductors of heat, so The heat of the obstructed heat sink is transferred to the air, which shortens the life of the lamp.
3.2, heat dissipation effectiveness
The heat sink is not as large as possible, and it is not only the larger the contact area between the surface and the air, but the various factors determine its heat dissipation performance. Factors such as good thermal conductivity, smooth heat path, and reasonable convective radiation structure determine the advantages and disadvantages of heat dissipation.
In the case of reasonable design of the heat circuit, in terms of material, the copper heat dissipation is better than the profile aluminum, the profile aluminum is better than the die-cast aluminum, and the die-cast aluminum is better than the plastic.
In terms of design structure, the same material, the larger the effective area of heat dissipation, the better, especially the effective heat dissipation area, the density of the tooth surface designed by some heat dissipation surfaces is too high, and the heat dissipation area on the surface in contact with air is large, but actually Some areas are ineffective because the heated hot air cannot be removed and still carry heat to collect in the luminaire. The heat sink is too dense, hindering the air heat exchange convection, and the black body radiates between the heat sink and the heat sink to absorb heat and reduce the efficiency of air convection.
In summary, high-quality heat sinks need to make full use of the expertise of thermodynamics, combined with the functional characteristics of the lamps themselves, as well as art, aesthetics and many other factors, designed to balance.
3.3, heat convection is blocked
Some engineers have a reasonable design of the heat sink, but do not consider the air convection heat exchange factor. A good heat sink is installed in a relatively sealed lampshade. The heat generated by the heat sink is transferred to the air on the surface, and the heated air is made. The convection motion is blocked, and the degree of freedom of air movement in the heat sink is small, resulting in a higher body temperature of the lamp.
The convection of heat convection is the most widespread problem in the current lighting industry. Designers should consider whether the air inlet of hot air and the exhaust port of hot air are smooth. Can the cold air enter the depth of the lamp body? Accurately know the proportion of convective air and convectible air, and try to reduce the proportion of convectible air.
All in all, the LED Tri Proof luminaires are a materialized thinking, using relevant professional knowledge, insight into society, will get a functional and artistic perfect product.