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Optimization Design of Radiator Structure for High Power Light Emitting Diode

Author: JiShengTao
Tutor: LiJing；MaoJiSen
School: South China University of Technology
Course: Chemical Engineering
Keywords: high power LED CPSEFR integral gravity heat pipe radiator enhance heat transfer numerical simulation
CLC: TK124
Type: Master's thesis
Year: 2011
Downloads: 154
Quote: 0
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Abstract

LED(Light-emitting diode)is an injection luminescent diode component, has the characterizes of high efficiency, environment protection, long life, strong orientation and good quality of color rendering, which has been widely used in the fields such as color rendering, decorations, roads and special lightings. Its photoelectric conversion efficiency is only about 10%~25%, while 75%~90% of the energy is conversed to heat, in this artic the photoelectric conversion efficiency is 20%. As it develops into high integration, heat generates and chip temperature linearly rise, so that the performance of light source lost. Therefore, heat dissipation is one of the key technical bottlenecks as LED develops. This thesis mainly focus on the design radiator of high power LED, which single-chip power higher than 0.5W, study the effects of different parameters of radiator on its performance; furthermore, optimize the structure of radiator and improve its performance of heat dissipation and solve the problem of heat dissipation of high power LED at last.A Fin-type Radiator with Cover Plate which has Stack Effect (Cover Plate Stack Effect Fin-type Radiator, CPSEFR) and an integrated gravity heat pipe radiator were designed for high power LED in this thesis. Firstly, study the performance of CPSEFR by experimental and numerical methods; secondly, designs models focus on integrated gravity heat pipe radiator and gives theoretical analysis and calculations of the models.The chip temperature of LED can be controlled under 48.3℃and 66.5℃respectively when injected power are 56W and 126W by using the new type structure radiator; the temperature of lamps in different places have a good uniformity; the temperature of different components increase linearly when the injected power increase, the linear fitting function can be got as y=33.611+14.523x for chip temperature increasing when injected power increased; thermal resistance between air and chip heat source, between air and substrate first reduce and then tend to be flattened when inject power increase from 56W to 126W, reducing about 0.06℃/ W while that reduce about 0.009℃/ W between substrate and chip.Numerical study finds that fluid flow in z-direction flow channel and side parts slot in x-direction present to be exponential curve; furthermore the side parts slot increase the chaos degree and enhance convection heat transfer which are the key measures for improving performance of heat sinks. Compared simulation results with experimental results about new type heat sink, they are closed to each other and the maximum error is within 5.96%, which proved the exactness and practicality of simulation results. The heat dissipation capability of heat sink first increase then tend to be flattened when distance between fins increase; With the quantity of fins increase, the heat transfer capacity increase first, and then decrease; The size of substrate has little effect on its heat dissipation capability but side parts slot can enhance heat dissipation.Both theoretical analysis and calculation find that the maximum heat dissipation of integrated gravity heat pipe heat sink is 0.355W/cm2 and it can control chip temperature under 36.42℃when the injected power is 28 W.Research finds can be applied to engineering practices which also are meaningful for new radiator design for high power LED, improving the heat dissipation performance of LED and prompting the development of illuminating industry.

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CLC: > Industrial Technology > Energy and Power Engineering > Thermal engineering, heat > Thermal Engineering Theory > Heat Transfer
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