均匀热源条件下类叶状微通道矩形热沉的构形设计

针对均匀背景热流条件下的散热问题,构建了类叶状微通道矩形热沉模型,基于构形理论,在给定热沉体积与液冷通道总体积的约束条件下,以热沉最高温度和压降最小化为 目标,以微通道单元数、主通道与分支通道的夹角、主通道与分支通道的管径比为设计变量进行了优化设计.结果表明:通过增加微通道单元数、减小主通道与分支通道的夹角、采用较小的主通道与分支通道之管径比,可以降低热沉的最高温度,但是会增大压降损失.     

高光束质量大功率半导体激光阵列的微通道热沉

针对现有高光束质量大功率半导体激光阵列内部发光单元条宽、填充因子不断减小,腔长不断增加的发展趋势所带来的热源分布及长度变化影响器件热阻的问题,利用分离热源边界条件结合商用计算流体力学(CFD)软件FLUENT进行数值计算,获得微通道热沉热阻随阵列器件发光单元条宽、空间位置变化关系以及不同阵列腔长对应的微通道优化长度.根据优化参数制备获得尢氧铜微通道热沉,并对宽1 cm,腔长1 mm,条宽100μm,填充因子为25%的半导体激光阵列进行散热能力测试,冷却器外形尺寸27 mm×11 mm×1.5 mm.微通道热沉热阻0.34 K/W,能够满足半导体激光阵列器件高功率集成输出的散热需求.     

单层与双层高效微小通道换热器的数值研究及优化

单层微通道热沉解决了高热流密度器件冷却问题,但被冷却器件表面存在温差大的缺点,双层微通道热沉由于其独特的结构设计,提高了被冷却表面的温度均匀性。建立了双层热沉的三维流固耦合模型,以恒定泵功为约束条件,热阻为热沉性能评价指标,比较了单层、双层逆向与双层同向热沉性能,结果表明,在泵功0.05 W和热流密度100 W/cm~2时,三种不同形式热沉热阻分别为0.1677k/W、0.1535k/W、0.1895k/W,热沉被冷却表面的最大温差分别为9.76 K、6.06 K、12.34 K,通过比较双层逆向热沉显著改善被冷器件温度均匀性,降低热阻。双层热沉上下通道泵功分配对热沉性能有较大影响,通过优化,分别使双层同向热沉、逆向热沉热阻减小15.83%、9.84%。     

复合型微通道热沉设计与制作技术研究

从大功率半导体激光器可靠性封装和应用考虑,利用商用有限元软件Abaqus与CFdesign对微通道热沉材料、结构进行优化设计,结合相应的制造工艺流程制备实用化复合型微通道热沉。微通道热沉尺寸为27 mm×10.8 mm×1.5 mm,并利用大功率半导体激光阵列器件对所制备热沉进行散热能力、封装产生的"微笑效应"进行了测试,复合微通道热沉热阻约0.3 K/W,"微笑"值远小于无氧铜微通道封装线阵列,可以控制在1μm以下。复合型微通道热沉能满足半导体激光阵列器件高功率集成输出的散热需求与硬焊料封装的可靠性要求。     

基于微通道热沉的片状激光放大器散热模拟及优化

为实现片状结构高重复频率大能量激光放大器的高效热管理，采用有限元分析(FEA)方法，充分考虑增益介质内部非均匀热分布、微通道热沉中的流速、对流扩散等影响因素，引入流-热-固多物理场耦合数值分析模型，对激光放大器热沉进行分析优化，并基于优化结果探讨了不同流速下微通道热沉的散热冷却能力。模拟结果表明：当基底厚度H_b=2 mm、单个微通道高度H_c=4 mm和宽度W_c=0.4 mm、两微通道的间距W_w=0.3 mm时，微通道热沉冷却能力最强，热阻最小；微通道内冷却液流速过大会导致较大的流动压力损失；微通道热沉的平均等效换热系数可达50000 W/(m²·K)。     

高热流密度热沉散热能力数值仿真分析

固体激光器增益介质的热效应问题严重制约了高功率固体激光器的发展。本文从实际应用角度出发,通过数值仿真实验对比散热热沉的主要几何参数(包括热沉基底厚度、肋片高度、肋片宽度、肋片间距)对散热效果的影响;同时也分析了不同的外部流量条件下热沉的散热性能。计算结果表明:优化热沉几何参数,选取适宜的流量,热沉散热效果会有一定提升。     

CCEPS激光器水冷设计的流固耦合传热数值研究

用计算流体力学(CFD)方法对传导冷却端面抽运板条(CCEPS)激光器的多种水冷设计方案分别进行了流固耦合传热数值模拟,比较了流固耦合传热模拟和单纯的导热模拟结果的差别,对各种水冷设计方案进行综合比较,研究了冷却通道的尺寸、数量以及冷却水流量等因素对激光板条温度分布以及对热沉的流动阻力特性的影响。一般情况下,减小通道的特征尺寸,增加通道数目和冷却水的流量可以降低固液耦合界面的传热热阻,因此,微通道冷却方式比常规的空腔冷却和小通道冷却显著提高了总传热系数,降低了总热阻,可将发热部分的温度明显降低,但是微通道冷却方式必然造成较大的流动压力损失。     

3D堆叠芯片硅通孔的电-热-力耦合构形设计

建立了3D堆叠芯片硅通孔(TSV)单元体模型,在单元体总体积和TSV体积占比给定时,考虑电-热-力耦合效应,以最高温度、(火积)耗散率、最大应力和最大形变为性能指标,对TSV横截面长宽比和单元体横截面长宽比进行双自由度构形设计优化.结果表明,存在最佳的TSV横截面长宽比使得单元体的最高温度、(火积)耗散率和最大应力取得极小值,但对应不同优化目标的最优构形各有不同,且TSV两端电压和芯片发热功率越大,其横截面长宽比对各性能指标的影响越大.铜、铝、钨3种材料中,钨填充TSV的热学和力学性能最优,但其电阻率较大.铜填充时,4个指标中最大应力最敏感,优先考虑最大应力最小化设计需求以确定TSV几何参数,可以较好兼顾其他性能指标.     

两相冲击强化换热激光二极管用单片热沉

针对大功率激光二极管(LD)的冷却需求,基于沸腾-空化耦合效应,以及场协同理论,研制了一种微通道两相冲击强化相变热沉,封装腔长1.5 mm的LD线阵。实验测试了连续功率LD输出0~100 W时的电-光转换效率以及电流-输出功率等特性,冷却工质采用R134a,磁驱齿轮泵电机转速23 Hz时热沉热阻为0.211℃/W。结果显示微通道相变热沉具有良好的取热能力,能够满足大功率LD的散热要求。与改进前的热沉相比,基于场协同理论优化了的两相冲击热沉,热阻明显下降。     

金刚石复合热沉面发射激光器面阵热特性研究

通过设计基于金刚石微槽结构的复合热沉,利用不同材料的热导率差异改变热流传导方向,以优化垂直腔面发射半导体激光器(VCSEL)面阵由于温度分布不均匀导致的中心热量堆积的问题,从而改善激光器面阵整体的输出功率,提高可靠性。基于有限元分析法建立三维热电耦合模型,研究了VCSEL面阵单元排布方式对激光器热串扰效应的影响,同时还研究分析了金刚石复合热沉中微槽形状和位置的变化对半导体激光器内部温度的影响,设计最优结构对激光器的出光性能做进一步优化。采用金刚石复合热沉后的垂直腔面发射激光器面阵,与传统金刚石热沉的封装结构相比,激光器发光单元的温度差值降低了29%,为大面积半导体激光器面阵的输出功率优化提供了新思路。     

Optimal design methodology of plate-fin heat sinks for electronic cooling using entropy generation strategy

This paper presents a formal systematic optimization process to plate-fins heat sink design for dissipating the maximum heat generation from electronic component by applying the entropy generation rate to obtain the highest heat transfer efficiency. The design investigations demonstrate the thermal performance with horizontal inlet cooling stream is slightly superior to that with vertical inlet cooling stream. However, the design of vertical inlet stream model can yield to a less structural mass (volume) required than that of horizontal inlet stream model under the same amount of heat dissipation. In this paper, the constrained optimization of plate-fins heat sink design with vertical inlet stream model is developed to achieve enhanced thermal performance. The number of fins and the aspect ratio are the most responsive factors for influencing thermal performances. The heat sink used on AMD Thunderbird 1-GHz processor has been examined and redesigned by presenting optimization methodology. The optimal thermal analysis has a very good agreement to the both of vendors' announced information and using simulation of parabolic hyperbolic or elliptic numerical integration code series (PHOENICS). The optimum design that minimizes entropy generation rate in this paper primarily applied three criteria for plate-fins heat sink optimal design: formal constrained nonlinear programming to obtain the maximum heat dissipation; prescribed heat dissipation; prescribed surface temperature. As a result, the thermal performance can be notably improved; both the sink size and structural mass can apparently be reduced through the presented design method and process. This analysis and design methodology can be further applied to other finned type heat sink designs.     

Performance Analysis of Pin-Fin Heat Sinks With Confined Impingement Cooling

This work assesses the performance of pin-fin heat sinks with confined impingement cooling using numerical simulation. The extent to which the Reynolds number, the height and the width of the fins, the nozzle-to-heat sink distance, the thermal conductivity, the upper confining plate and the fin number affect the thermal resistance are considered. The work shows that increasing the Reynolds number reduces the thermal resistance, but the effect decreases slowly as the Reynolds number increases. Although increasing the fin height can reduce the thermal resistance, reduction decreases. The fin width that is associated with the minimum thermal resistance increases with the Reynolds number. The optimal nozzle-to-heat sink distance increases with the Reynolds number. The thermal resistance decreases with an increasing thermal conductivity; however, the drop in the thermal resistance becomes smaller. The presence of the upper confining plate increases the thermal resistance. Additionally, the thermal resistance initially decreases and then increases slowly as the fin number increases.     

Design and Optimization of Single-Phase Liquid Cooled Microchannel Heat Sink

Semiconductor devices for demanding automotive applications generate a large amount of heat $({≫}{rm 100}~{rm W}/{rm cm}^{2})$. These high power devices can be cooled off very effectively by liquid coolant flowing through the microchannel heat sink. Microchannel heat sinks are very attractive because of their compactness, light weight, and large surface-to-volume ratio. Higher surface-to-volume ratio results in enhanced cooling performance. In this paper, a systematic robust analytical method is presented for design and optimization of single-phase liquid cooled microchannel heat sink. Effects of various design parameters such as eccentricity and footprint of heat source or device, thickness of the heat sink base, channel aspect ratio, number of microchannels or fins, coolant flow rate, and thermal conductivity of heat sink material on heat sink thermal resistances and pressure drop are delineated. Finally, analytical results are compared with experimental data and good agreement is obtained. The analytical method helps to reduce the design cycle time and time-to-market significantly.      

Optimization study of stacked micro-channel heat sinks for micro-electronic cooling

With smaller inlet flow velocity, a micro-channel stack requires less pumping power to remove a certain rate of heat than a single-layered micro-channel, because it provides a larger heat transfer area. A simple thermal resistance network model was developed to evaluate the overall thermal performance of a stacked micro-channel heat sink. Based on this simple model, in this study, a single objective minimization of overall thermal resistance is carried out using genetic algorithms. The aspect ratio, fin thickness and the ratio of channel width to fin thickness are the variables to be optimized, subject to constraints of maximum pressure drop (4 bar) and maximum volumetric flow rate (1000 ml/min). During the optimization, the overall dimensions, number of layers and pumping power (product of pressure drop and flow rate) are fixed. The study indicates that reduction in thermal resistance can be achieved by optimizing the channel configuration. The effects of number of layers in the stack, pumping power per unit area, and the channel length are also investigated.     

Geometrical Design of Plate-Fin Heat Sinks Using Hybridization of MOEA and RSM

The work in this paper is aimed at demonstrating the practical multiobjective optimization of plate-fin heat sinks and the superiority of using a combined response surface method and multiobjective evolutionary optimizer over solely using the evolutionary optimizer. The design problem assigned is to minimize a heat sink junction temperature and fan pumping power. Design variables determine a heat sink geometry and inlet air velocity. Design constraints are given in such a way that the maximum and minimum fin heights are properly limited. Function evaluation is carried out by using finite volume analysis software. Two multiobjective evolutionary optimization strategies, real-code strength Pareto evolutionary algorithm with and without the use of a response surface technique, are implemented to explore the Pareto optimal front. The optimum results obtained from both design approaches are compared and discussed. It is illustrated that the multiobjective evolutionary technique is a powerful tool for the multiobjective design of electronic air-cooled heat sinks. With the same design conditions and an equal number of function evaluations, the multiobjective optimizer in association with the response surface technique totally outperforms the other. The design parameters affecting the diversity of the Pareto front include fin thickness, fin height distribution, and inlet air velocity while the plate base thickness and the total number of fins of the non-dominated solutions tend to approach certain values.     

LED筒灯复合结构热管散热器的数值模拟

为解决LED筒灯使用单纯自然对流散热扩散热阻过大、温度分布不均的问题,提出一种基于平板热管和热虹吸管的复合结构热管散热器,并用数值模拟的方法研究了热功率、翅片高度、翅片数目、辐射换热对该散热器性能的影响。模拟结果表明应用于LED筒灯的复合结构热管散热器的热阻随着热功率的增加而减小,翅片高度和翅片数目存在一个最优值,使得散热器温度和热阻最小,自然对流情况下不可忽视辐射换热的作用。     

微针鳍散热器结构参数模拟及优化

通过数值模拟研究了交错式微针鳍散热器的散热效应,分析了针鳍阵列间距和高度对散热器壁温和压降的影响。结果表明,压降随针鳍间距和针鳍高度的减小而呈非线性增加；壁温随针鳍间距的增大而上升,随针鳍高度的增加则呈现出波动趋势。基于上述研究,进一步利用响应表面近似法对微针鳍的横向间距、纵向间距和高度进行了优化,优化后压降最大可降低61.11%。     

Extreme Two‐Phase Cooling from Laser‐Etched Diamond and Conformal,Template‐Fabricated Microporous Copper

This paper reports the first integration of laser‐etched polycrystalline diamond microchannels with template‐fabricated microporous copper for extreme convective boiling in a composite heat sink for power electronics and energy conversion. Diamond offers the highest thermal conductivity near room temperature, and enables aggressive heat spreading along triangular channel walls with 1:1 aspect ratio. Conformally coated porous copper with thickness 25 µm and 5 µm pore size optimizes fluid and heat transport for convective boiling within the diamond channels. Data reported here include 1280 W cm^?2 of heat removal from 0.7 cm² surface area with temperature rise beyond fluid saturation less than 21 K, corresponding to 6.3 × 10⁵ W m^?2 K^?1. This heat sink has the potential to dissipate much larger localized heat loads with small temperature nonuniformity (5 kW cm^?2 over 200 µm × 200 µm with <3 K temperature difference). A microfluidic manifold assures uniform distribution of liquid over the heat sink surface with negligible pumping power requirements (e.g., <1.4 × 10^?4 of the thermal power dissipated). This breakthrough integration of functional materials and the resulting experimental data set a very high bar for microfluidic heat removal.     

Optimization of convectively cooled heat sinks

Many factors of heat sink, such as its size and mass, component locations, number of fins, and fan power affect heat transfer. Owing to the opposite effects of these factors on heat sink maximum temperature, we have now a multi-objective optimization problem. A typical optimization case consists of hundreds of heat sink temperature field evaluations, which would be impractical to do with CFD. Instead, we propose to combine analytical results of convection and numerical solution of conduction to address these so-called conjugated heat transfer problems. We solve heat conduction in a solid numerically using the finite volume method and tackle convection with the analytical equation of forced convection in a parallel plate channel.This model is suitable for forced and natural convection heat sinks, and we have verified its validity by comparing its results to measured data and CFD calculations. We use the model to improve two industrial examples, using a multi-objective version of the particle swarm optimization (PSO) algorithm. The first example is a forced convection heat sink composed of nine heat generating components at the base plate, and the other is a natural convection case with two components. In both cases, mass is minimized; the other criterion is maximum temperature for the forced convection case and heat sink outer volume for the natural convection case. Our method is many orders of magnitude faster than CFD. Additionally, we provide some LES results of pin fins with natural convection for further use in similar optimizations.     

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。