基于热管散热的人功率LED热特性测量与分析

提出了一种新型结构的同路热管,建立了回路热管性能测试试验装置.在相同的测试条件下,研究了热负荷、倾角等对回路热管的起动特性和均温特性、热阻等传热性能的影响.试验结果表明,热管散热器的热阻在0.21 K/W～2.6 K/W之间,且整个散热器具有均匀的温度分布.与当前的LED散热器相比,这种结构的热管散热器具有散热效率高、结构紧凑、加工方便、热阻小、重量轻、成本低等特点,可以满足大功率LED散热的要求.     

大功率LED冷却用平板热管散热器的实验研究

对一种新型平板热管散热器冷却大功率LED芯片阵列进行实验研究。在自然对流冷却条件下,分析了平板热管散热器的启动特性、均温特性以及通电电流、倾角对其传热性能的影响。利用热电转换方法得到LED芯片的结温变化。实验结果表明:平板热管散热器的总热阻在0.3053～0.3425℃/W间,且散热器整体温度分布均匀合理,具有很强的散热能力;LED结温在47.9～59.0℃间,远低于110℃。     

一种回路热管对大功率LED散热的研究

针对大功率LED散热能力较其它照明灯具差这一问题,研制了一种应用在多芯片大功率LED散热上的回路热管装置,并研究了热负荷、倾角等对热管的起动性、均温性和热阻等的影响。试验结果表明,所设计的热管散热器的热阻在0.48～1.47K/W之间;在蒸发器倾斜角为0°和30°时,蒸发器的均温性分别被控制在1.5℃和4.3℃以内。因此,将这种结构的热管应用在大功率LED散热系统中时,首先应该对蒸发器倾斜角度对系统散热性能的影响进行测试评估。     

LED简灯热管散热器的试验研究及性能评价

为获得基于自然对流的异型热管散热器用于LED筒灯的工作性能,研制了热管散热器试验件,并进行了试验研究。结果表明：热管散热器启动性能良好,启动时间约为33min;散热器具有较好的均温性能,40W时蒸发面最大温差为4．7℃;在试验条件下,热源表面最高温度不超过70℃;加热功率对接触热阻、扩散热阻和热管热阻基本无影响,而翅片换热热阻随加热功率的增加而减小。基于试验所得结果,并通过热阻网络分析,论证了异型热管散热器可满足LED筒灯散热的需求。     

用于大功率LED冷却的热管散热器的实验研究

提出了一种将大功率发光二极管(LED)散热和热管传热相结合的用于大功率LED冷却的热管散热器新概念,并对设计出的热管散热器的传热性能和整体的均温性进行了试验研究.试验结果表明,热管散热器的热阻在0.21～2.6 K/W,且整个散热器具有均匀的温度分布.与当前的LED散热器相比,这种结构的热管散热器具有散热效率高、结构紧凑、热阻小、重量轻、成本低等特点,可以满足未来大功率LED散热的要求.     

应用于大功率LED器件的回路热管散热研究

为解决大功率LED的散热问题,提出一种应用于大功率LED散热的微型回路热管,研究了充液率和倾斜角度对热管冷却大功率LED的启动性能、结温和热阻等特性的影响.研究结果表明:热管的最佳充液率为60％,系统的总热阻为7.5 K/W,此时对应的热管的热阻为1.6 K/W;热管的启动时间约为6.5 min,LED的结点温度被控制在42℃以下,很好地满足了大功率LED的结温稳定性要求.     

并行多通道大功率LED回路热管散热器

为解决大功率LED散热问题,构造了一种一体化并 行多通道大功率LED回路热管散热器。利用水作为工质,在不同加热功率、不同倾斜角以及 不同充液比条件下对该新结构热管散热器的热性 能进行了研究。结果表明,这种新结构热管散热器不仅能使散热器上下底板处于均温状态, 而且当芯片加 热功率达到200W时,芯片加热面中心最高温度不超过71.8℃;倾斜角度对热管换热性能影响不大;在一 定加热功率范围内,新结构热管散热器的热阻随加热功率的增大而减小,当芯片加热功率达 到240W时, 热阻最小,最小可达0.19K/W。构造的一体化并行多通道大功率LED 回路热管散热器具有很好的传热性能,并提高了承载高热流密度的能力。     

基于平板热管的大功率LED散热系统模拟及优化

为解决大功率LED的散热问题,设计了平板热管散热器来实现LED芯片的高效散热。通过Flotherm模拟软件,对大功率LED在自然对流条件下的散热情况进行了三维数值模拟。通过平板热管与常规铜、铝散热基板对比,发现平板热管有效降低了大功率功率LED的结温和热阻,使得LED温度分布更为均匀。此外,还研究了平板热管LED散热系统在不同芯片功率下的热性能,并对四种不同排布方式的LED平板热管散热系统进行了优化,发现阵列分布其温度分布最为均匀,结温最低,是较优的排布方式。     

大功率LED散热回路热管的实验研究

大功率LED热问题是制约大功率 LED的稳定性、可靠性和寿命的技术瓶颈之一,有效的低热阻封装LED热设计是提高LE D性能的关键。本文提 出一种应用于大功率LED散热的铜-水回路热管(LHP),研究了加热方 式、充液率、风压和倾角 等对LHP均温性、起动性和热阻等的影响。研究结果表明:在输入功率为30W时,LHP的启动时间约为 6.5min;热阻范围为0.48～1.62K/W;在热 负荷为30W时,蒸发器的温度可以稳定控制在75℃以下;蒸发器表 面均温差被控制在1.6℃以下;LHP的最佳的充液率为60%;冷凝器侧 风压在一定范围内(小于130Pa)时,冷凝器侧风压力越大,LED产 品的散热性能越好。     

大功率LED针翅式散热器散热性能数值模拟

发光二极管(LED)作为新一代光源,得到广泛应用.然而在工作过程中,大部分的电能会转变为热能,使LED的结温升高,可靠性降低.为了使LED芯片产生的热量能够及时有效地散发出去,通常采用翅片散热方法对其进行散热.采用数值模拟的方法对大功率LED针翅式散热器的散热性能进行了研究.为了验证模型的准确性,利用K型热电偶和安捷伦数据采集仪对散热器进行了实验测试.实验结果表明,该数值模型方程能够很好地模拟散热器的散热性能.此外,研究了大功率LED针翅式散热器的几何参数(翅片高度、半径、排数、列数)对LED散热性能(结温、对流换热系数和热阻)的影响,并且对翅片结构进行了优化分析.     

Thermal analysis of high power LED package with heat pipe heat sink

The goal of this study is to improve the thermal characteristics of high power LED (light-emitting diode) package using a flat heat pipe (FHP). The heat-release characteristics of high power LED package are analyzed and a novel flat heat pipe (FHP) cooling device for high power LED is developed. The thermal capabilities, including startup performance, temperature uniformity and thermal resistance of high power LED package with flat heat pipe heat sink have been investigated experimentally. The obtained results indicate that the junction temperature of LED is about 52 °C for the input power of 3 W, and correspondingly the total thermal resistance of LED system is 8.8 K/W. The impact of the different filling rates and inclination angles of the heat pipe to the heat transfer performance of the heat pipe should be evaluated before such a structure of heat pipe cooling system is used to cool high power LED system.     

Experimental investigation on the performance of CPU coolers: Effect of heat pipe inclination angle and the use of nanofluids

An experimental study of heat transfer performance of a CPU cooling heat pipe, examining the effects of inclination angle and nanofluids, has been conducted. It is shown that inclination angle of the unit has a significant effect on the cooling process, since it directly influences the operation of the evaporator. The effect is mainly due to the capillary effect and boiling limits of the heat pipe. The results demonstrate that for a given CPU temperature, there is a threshold angle at which the thermal resistance of the heat pipe increases dramatically. It is observed that as the CPU temperature increases, the threshold angle decreases from 60° to 30°. Introduction of 0.5 wt% Al₂O₃ nanoparticles to the water coolant of heat pipe has led to a decrease in thermal resistance. It is shown that at 10 W, the presence of nanofluid has reduced the thermal resistance by 15%, while at 25 W, the thermal resistance has dropped by 22%.     

Study on a cooling system based on thermoelectric cooler for thermal management of high-power LEDs

To improve the heat dissipation of high-power light-emitting diodes (LEDs), a cooling system with thermoelectric cooler (TEC) is investigated. In the experiment, the 6 × 3 W LEDs in two rows are used to compose the light source module and the environment temperature is 17 °C. The temperatures of heat dissipation substrate of LEDs and cooling fins of a radiator are measured by K type thermocouples to evaluate the cooling performance. Results show that the temperature of the substrate of LEDs reaches 26 °C without TEC. However, it is only 9 °C when the best refrigeration condition appears. The temperature of the substrate of LEDs decreases by 17 °C since the heat produced by LEDs is absorbed rapidly by TEC and dissipated through the radiator, and the junction temperature of LEDs reaches only 45 °C which is much lower than the absolute maximum temperature of LEDs (120 °C). The experiment demonstrates that the cooling system with TEC has good performance.     

适用于大功率光电芯片散热的一体化平板热管

为解决大功率光电芯片散热问题,构造了一种新结构一体化平板热管。利用超轻多孔泡沫金属作为毛细吸液芯,以水、丙酮和乙醇为工质,在不同充液比、加热功率和倾角条件下对新结构热管的热性能进行了研究,结果表明,这种新结构平板热管不仅消除了热管与散热片间的接触热阻,而且使整个散热翅片也处于均温状态,当功率达到380W、热流密度超过445 W/cm2时,热管仍具有较好的均温特性,且热阻较小,可达0.04℃/W。在3种工质中,水是最佳工质选择,且当充液比为30%时具有较好的效果。实验表明,以泡沫金属为吸液芯的新结构一体化平板热管具有很好的传热性能,并扩展了承载大热流密度的能力。     

Thermal Resistance Measurement of LED Package with Multichips

Thermal transient measurements of high power GaN-based light-emitting diodes (LEDs) with multichip designs are presented and discussed in the paper. Once transient cooling curve was obtained, the structure function theory was applied to determine the thermal resistance of packages. The total thermal resistance from junction to ambient considering optical power is 19.87 K/W, 10.78 K/W, 6.77 K/W for the one-chip, two-chip and four-chip packages, respectively. The contribution of each component to the total thermal resistance of the package can be determined from the cumulative structure function and differential structure function. The total thermal resistance of multichip packages is found to decrease with the number of chips due to parallel heat dissipation. However, the effect of the number of chips on thermal resistance of package strongly depends on the ratio of partial thermal resistance of chip and that of slug. Therefore, an important thermal design rule for packaging of high power multichip LEDs has been analogized.     

电子设备液冷散热的冷却液热学性能分析

从3个方面对液冷散热器中冷却液的热学性能进行分析对比,包括不同温度下的热物理参数变化、不同流态下的热传导系数和相同功耗下的冷却液温升。以65#冷却液和PAO冷却液为例,对比分析表明在-20~70 ℃区间内65#冷却液在热学性能上较PAO更强,但物理参数的稳定性较PAO差。在同一电子设备系统的液冷散热器中使用这两种不同冷却液介质后,通过实验测量电子设备内各芯片的平衡温度,结果表明,65#冷却液较PAO具有更好的散热效果,芯片温升约可降低10 ℃。