High-power LED is superior to the common miniwatt LED in the field of cooling performance. The electricity channel and the hot channel are separated, its LED chips are connected in a metal chip, and the cooling performance has been greatly improved.
However, high-power LED is used for the special lamps, or used for the lamps in the severe environment, the protection degrees of these lamps is above IP65 ( IP level ),if the shell is nonmetal materials (such as the plastic), even though LED has been connected t o the aluminous base board (MCPCB). If the heat on the aluminous base board can not effectively conduct to the shell surface, the heat gathered will make the temperature of the aluminous base board greatly rise. The excessive temperature may increase the possibility of the disabled LED and cause fast LED lumens ( Luminous Flux Maintenance Meter ) depreciation and life loss
Theoretically, it is difficult to calculate the situation of heat dissipation of lamps. The major difficulty is that conduction and convection affects the heat conduction at the same time. However, the convection is in the closed cavity, the boundary condition is very complex, the conduction has to go though multilayer thermal conductive materials and multilayer interface, the sectional area is usually unequal, which has caused the difficulties to analyze the heat flow line distribution before calculation.
Because the lamps began to warm up after switching on, and finally arrive at the thermal stable state. The temperature of each point is the highest in the stable state, in other words, the temperature of each point is the highest in the thermal stale state, therefore, the thermal calculation of the lamps usually only considers the steady state, the transient temperature distribution is not so much important.
Because the lamps structure has a variety of medium, in the practical calculation, we must solve each medium. It is difficult and unnecessary to calculate the temperature field distribution inside the lamps. In fact, what we care about is whether the temperature of some parts can be within the tolerant temperature range. We only need to figure out the temperature when these parts are in the stable state.
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