液体直接散热型LED室内灯研究

发布时间：2018-02-21 12:07

本文关键词： LED 室内灯散热液体可靠性　出处：《重庆大学》2014年硕士论文　论文类型：学位论文

【摘要】：LED工作时70%~80%的能量转换为热量，导致结温升高，性能下降。随着功率的提升，热量带来的问题愈加突出，因此对照明产品进行散热设计意义重大。功率不超过10W LED室内灯的散热设计以金属散热器方式为主，称之为球泡灯。而外加的金属散热器却增加了球泡灯的成本，导致其价格高于传统灯具，用户难以接受；而金属散热器与铝基板之间的导热硅脂层也影响了灯具的散热效果。针对以上问题，国内外研究人员提出了一种可能替代金属散热器方式的液体直接散热方式，并展开了一些工作，主要包括对产品宣传及专利的布局方面，而对产品的散热性能及可靠性缺乏深入的研究，产品推广受到了很大的阻碍。因此，论文分别从理论、实验及仿真三个方面对液体直接散热型LED室内灯的散热性能及可靠性进行了深入研究，以期能够为产品的推广提供可靠依据。 ①基于基本传热理论，分析了金属散热器LED球泡灯及液体直接散热LED室内灯的结构特点，建立了两种灯具的热阻模型并进行了热学仿真，证明了液冷方式的可行性。 ②设计了恒温加热实验系统，对比了高温浸没实验前后散热液体的透光性及光源的光谱变化，确定了可用的散热液体及光源。结果发现，变压器油实验后的透过率曲线严重衰变，而硅油实验前后透光率无明显变化，透过率均大于90%；硅油浸没过的灯珠光谱分布及强度均无明显变化。因此硅油可以作为LED的散热介质。此外，通过对灯珠外观的观察，发现鸿利E系列环氧树脂封装灯珠透镜脱离，不能用作实验光源，其他灯珠表面完好，可以用作实验光源。 ③基于正向电压法测量结温的原理，搭建了实验系统，，分别标定了两种灯具所用LED光源的电压温度系数，并测量了不同电流下两种灯具的稳态温度，与仿真结果进行了对比，证明了液体散热方式的实际可行性及仿真的正确性。通过实验发现，液体直接散热方式的LED结温、铝基板温度及外部壳体温度均低于金属散热器方式，而仿真结果与实验结果的误差均在6.4%以内。 ④模拟了单因素变化对液体直接散热型LED灯散热效果的影响，确定了主要影响因素；通过正交方法研究了主要影响因素对散热效果影响的主次顺序，对液体散热结构进行了优化。仿真发现，灯壳外径、液面高度及铝基板直径是影响散热效果的主要因素，而对应的最终优化结果为45mm、30mm及16mm。同时，研究了不同灯壳外径、液面高度及铝基板直径下结温随功率的变化，可以发现。结温随功率的变化线性变化，且液体直接散热方式一般适用于功率不超过10W的室内照明LED灯具的散热。 ⑤搭建了光衰测试系统，测量了不同电流下的光衰情况，推算出了不同电流对应的寿命。结果发现，电流在700mA以下时，LED灯具的寿命不低于25000小时；而900mA时，灯具的功率不足3.5W，而寿命仅6000多小时，虽与Cree公司给出的实际测量寿命严重不符，但已经能满足照明需求。同时对比了液体直接散热型及金属散热器型LED室内灯的性能价格发现，液体直接散热方式可以降低灯具成本，提高初始光通量，提升性价比。
[Abstract]:In light of the above problems , the heat dissipation performance and the reliability of the LED indoor lamp with the power of not more than 10 W have been studied deeply . Therefore , the paper studies the heat dissipation performance and reliability of the liquid direct heat dissipation LED indoor lamp from three aspects : theory , experiment and simulation , with a view to providing reliable basis for the popularization of the product . ( 1 ) Based on the theory of basic heat transfer , the structural characteristics of LED bulb and liquid direct heat dissipation LED indoor lamp are analyzed . The thermal resistance model of two lamps is established and the thermal simulation is carried out to prove the feasibility of liquid cooling mode . The experiment system of constant temperature heating was designed to compare the light transmittance of the heat radiating liquid before and after the high temperature immersion test and the spectral change of the light source . The results show that the transmittance curve after the oil experiment of the transformer is seriously decayed , and the transmittance is more than 90 % . ( 3 ) Based on the principle of measuring junction temperature based on forward voltage method , the voltage temperature coefficient of LED light source used in two lamps is set up , and the steady state temperature of two lamps under different current is measured and compared with the simulation results . The results show that the LED junction temperature , the temperature of the aluminum substrate and the temperature of the outer shell are lower than that of the metal radiator , and the error of the simulation results and the experimental results is within 6.4 % . The influence of single factor on the heat dissipation effect of liquid direct heat dissipation LED lamp is simulated . The main influencing factors are determined . The main factors influencing the heat dissipation effect are studied by orthogonal method . The results show that the outer diameter , the height of the liquid surface and the diameter of the aluminum substrate are the main factors which influence the heat dissipation effect . The results show that when the current is below 700mA , the service life of the LED lamp is not less than 25,000 hours ; when 900 mA , the power of the lamp is less than 3.5W , and the service life is only 6000 hours .

【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM923.34

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