Planing process of fin heat sinks

Based on analyzing the traditional process to manufacture fin heat sinks(FHS) ,the production of FHS by the planing process was proposed ,the mechanism of the fins curl was investigated and the fins surface finish was analyzed . Through controlling chip curl based on the continuous strip chips ,flat straight fins were processed . Compared with the traditional processes ,this process makes full use of material and the processed FHS has better heat transfer capacity ,higher heat transfer efficiency and more reliability . The tool geometrical parameters and pro- cessing performance affect the fins curl . The opti mumprocessing parameters are :a cutter edge inclination angle of 0°,a rake angle between 50°and 55°,and a planing depth from 0 .2 mmto 0 .3 mm. The planing speed has little effect on the fins curl .

Heat dissipation enhancement method for finned heat sink for AGV motor driver's IGBT module

With the widespread use of high-power and highly integrated insulated gate bipolar transistor(IGBT),their cooling methods have become challenging.This paper proposes a liquid cooling scheme for heavy-duty automated guided vehicle(AGV)motor driver in port environment,and improves heat dissipation by analyzing and optimizing the core component of finned heat sink.Firstly,the temperature distribution of the initial scheme is studied by using Fluent software,and the heat transfer characteristics of the finned heat sink are obtained through numerical analysis.Secondly,an orthogonal test is designed and combined with the response surface methodology to optimize the structural parameters of the finned heat sink,resulting in a 14.57%increase in the heat dissipation effect.Finally,the effectiveness of heat dissipation enhancement is verified.This work provides valuable insights into improving the heat dissipation of IGBT modules and heat sinks,and provides guidance for their future applications.

Evaluation on Heat Transferring Performance of Fabric Heat Sink by Finite Element Modeling

Considering the limitation in current manufacturing technology of commercial pin fin heat sinks,a new fabric heat sink has been designed. However,it is lack of an understanding of the heat transferring performance of this new kind of heat sink. In this study,the finite element method (FEM) was used to predict the heat transferring performance of fabric heat sink under the condition of natural convection and forced convection, and its heat transferring performance was compared with that of pin fin heat sink. The results showed that in the condition of natural convection the heat transferring performance of pin fin heat sink was better than that of fabric heat sink, and vice versa under the forced convection condition.

Evaluation on Heat Transferring Performance of Fabric Heat Sink by Finite Element Modeling

Considering current technology limitation in manufacturing present pin fin heat sinks, a new fabric heat sink has been previously designed. However, there is a lack of an understanding of the heat transferring performance of this new kind of heat sink. Nowadays, finite element analysis has been generally developed for determining heat transfer from in-line and staggered pin fin heat sinks used in electronic packaging applications. In this study, this method is used to predict the heat transfer performance of the new heat sink with woven fabric structure, called fabric pin fin heat sink. Effect of the fin length and the material types made of heat sink on the thermal-structure response of the pin fin was investigated under forced convection. The results show that the minimum temperature of heat sink decreases with an increase of pin fin length,but the decreasing amplitude has decreased. Moreover, the heat transfer performance of fabric heat sink made of continuous carbon Fibers/Polymer (PPS) is worse than that of copper and of aluminum.

Heat Transfer Characteristics of Square Micro Pin Fins under Natural Convection

In order to comply with the recent demand for downsizing of the electric equipment, the minia- turization and the improvement in heat transfer performance of a heat sink under natural air-cooling are increasingly required. This paper describes the experimental and numerical investigations of heat sinks with miniature/micro pins and the effect of the pin size, pin height and the number of pins on heat transfer characteristics of heat sinks. Five types of basic heat sink models are investigated in this study. The whole heat transfer area of heat sinks having the different pin size, pin height and the number of pins respectively is kept constant. From a series of experiments and numerical analyses, it has been clarified that the heat sink temperature rises with increase in the number of pins. That is, the heat sink with miniaturized fine pins showed almost no effect on the heat transfer enhancement. This is because of the choking phenomenon occurred in the air space among the pin fins. Reflecting these results, it is confirmed that the heat transfer coefficient reduces with miniaturization of pins. Concerning the effects of the heat transfer area on the heat sink performance, almost the same tendency has been observed in other three series of large surface area, that is, higher pin height. Furthermore as a result of studying non-dimensional convection heat transfer performance, it was found that the relation between the Nusselt number (Nu) and the Rayleight number (Ra) is given by Nu = 0.16 Ra0.52.

Air Cooling of Mini-Channel Heat Sink in Electronic Devices

Heat transfer experiments were conducted to investigate the thermal performance of air cooling through mini-channel heat sink with various configurations. Two types of channels have been used, one has a rectangular cross section area of 5 × 18 mm2 and the other is triangular with dimension of 5 × 9 mm2. Four channels of each configuration have been etched on copper block of 40 mm width,30 mm height, and 200 mm length. The measurements were performed in steady state with air flow rates of 0.002 - 0.005 m3/s, heating powers of 80 - 200 W and channel base temperatures of 48°C, 51°C, 55°C and 60°C. The results showed that the heat transfer to air stream is increased with increasing both of air mass flow rate and channel base temperature. The rectangular channels have better thermal performance than trian- gular ones at the same conditions. Analytical fin approach of 1-D and 2-D model were used to predict the heat transfer rate and outlet air temperature from channels heat sink. Theoretical results have been compared with experimental data. The predicted values for outlet air temperatures using the two models agree well with a deviation less than ±10%. But for the heat transfer data, the deviation is about +30% to –60% for 1-D model, and –5% to –80% for 2-D model. The global Nusselt number of the present experimental data is empirically correlated as with accuracy of ±20% for and compared with other literature correlations.

基于响应面的车用功率模块Pin-Fin优化设计

集成Pin-Fin散热器可以降低功率模块的结-流热阻,提升车用电机控制器的功率密度和可靠性,是车用功率模块先进热管理技术的发展趋势。然而,Pin-Fin散热器的设计面临电-热-流多物理场耦合的挑战,难于解析表征与定量优化,设计的周期长、成本高。基于响应面优化方法,该文提出一种集成Pin-Fin散热器的模型化设计方法,建立集成Pin-Fin形貌结构与阵列排布的数学描述,给出Pin-Fin散热器热-流性能的理论模型,建立Pin-Fin的多目标优化模型,获得Pin-Fin散热器结构的最优设计。为了验证理论模型和优化设计的可行性和有效性,搭建面对面变流器对拖实验平台,对标商业化车用功率模块的Pin-Fin设计,采用大量固定工况,以及实际车用工况实验结果,对比验证优化后的Pin-Fin能降低车用功率模块7.62%的结-流热阻,减小65%的功率模块损伤,提升车用电机控制器寿命1.8倍,为车用功率模块低热阻集成Pin-Fin散热器提供新的研究思路。

翅片结构对微型平板换热器换热性能的影响

平板换热器广泛应用于微电子领域的器件散热。为探究换热器的翅片形状和通道间隙对微型平板换热器换热性能的影响,设计平直型、间断型和波纹型3种不同翅片形状的平板换热器,分别包含0.5、1、2 mm这3种不同宽度的通道间隙。在不同的雷诺数下对平板换热器的性能进行实验研究。利用获得的努塞尔数、总传热系数和泵功耗等参数,对微型平板换热器的综合性能进行评价。结果表明:换热器的总传热系数和泵功耗随雷诺数变化越来越大,换热器的翅片形状对换热器的换热效果影响显著。波纹型翅片的总传热系数最高,间断型翅片的泵功耗损失最小,间断型和波纹型翅片的综合换热性能均远优于平直型翅片,且散热器的通道间隙越大,散热性能越好。

矩阵式微射流冲击圆柱肋热沉的换热特性

本文构建了一种新型矩阵式微射流圆柱肋热沉,热沉设计成三明治结构,具有紧凑、体积小等特点。上部为上气室,中间为射流孔板,射流孔板上设置有回流通道,降低了横向流对射流冲击换热的影响,底部为下气室,下气室设有圆柱肋板,阵列圆柱肋可增加传热面积同时增强流体扰动而加强换热。采用实验与数值模拟结合的方法,分别对射流雷诺数、热流密度、冲击高径比对热沉内换热特性影响进行研究。结果表明:当射流雷诺数为1596~2874,射流冲击高度为4、6、8 mm时,与无肋被冷却表面相比,有圆柱肋的被冷却表面温度更低,平均对流换热表面传热系数提高1%~3%。随射流雷诺数增加热沉换热性能也逐渐增强,在射流雷诺数为2874时,实验测得圆柱肋板被冷却表面的平均对流换热表面传热系数最大可达1036 W/(m^(2)·K)。

微小型毛细泵环热控制系统及其制造技术

针对当前微电子芯片高热流密度问题,设计一种微小型毛细泵吸环路(Capillary pumped loops,CPL)热控制系统。介绍制造该微小型CPL的方法:采用犁切—挤压成形微沟槽翅结构和刨削成形整体式翅片散热片,毛细吸液芯则采用商用多孔泡沫金属或丝网材料。该微小型CPL系统由蒸发器、冷凝器、蒸汽联管、液体联管以及液体工质组成。蒸发器中含有多尺度多维交错互通微沟槽翅强化沸腾结构,冷凝器为微沟槽翅结构与翅片散热片组成的复合结构,可有效提高系统蒸发冷凝效率。整个系统利用工质蒸发冷凝相变传热,通过毛细泵吸作用和蒸发气体压力保证循环,依靠饱和毛细芯对气体的阻碍作用保证工质的单向流动,无需机械泵和阀控制。

大功率LED平板型翅片散热器的优化设计

针对一款阵列型大功率LED投光灯的散热特点,使用计算流体力学软件Icepak,仿真模拟其关键散热部分,并应用中心组合设计及响应面分析法对平板型散热器进行了优化;选取翅片高度、翅片间距和翅片厚度为3个响应因子,散热器的温度为响应值;运用Design Expert 8.06软件对数据进行分析和优化计算,得到了三因子与散热器温度的回归方程以及三因子之间相互作用的三维响应面图.结果表明:三因子的最佳取值为翅片高度23.92 mm,翅片间距5.99 mm,翅片厚度1.03 mm,在此条件下散热器温度为45.182 2℃,与Icepak模拟仿真值相比,误差仅为+0.575%;说明使用此方法求得平板型散热器优化的数学模型是可行的.

LED板状肋片散热器性能的方向效应

为考察装配板状肋片散热器的多角度照射型LED灯的自然对流散热性能的方向效应,以一款LED投光灯的关键散热结构为研究对象,采用实验测量法验证数值模拟的计算精度,并将数值模拟的温度和流体数据用于分析3种驱动电流和7个出光倾角下最大温升和温度均匀性的散热机制。结果表明:不同倾角下的散热器肋间风道内的流速分布的较大差异,是导致最大温升和温度均匀性变化的根本原因;最高温度点的上、下游流速的差值可用于定量解释温度均匀性的变化规律。不同倾角下肋片间距对最大温升的影响趋势表明:最佳间距附近的散热器性能对倾角的敏感度最高,散热能力的方向效应不容忽视。

高热流密度器件水冷散热器结构性能的实验研究

与平行流水冷散热相比,现阶段对喷射流水冷散热的研究报道较少。为了研究喷射流结构的散热效果,本文设计了两种喷射流结构的水冷散热器,搭建了以去离子水为冷却介质的液冷散热器实验台,调节实验的热流密度及冷却水流量在不同条件下观察芯片温度及散热器底板温度的变化,得到了不同热流密度下芯片温度、散热器底板温度及热阻随冷却水流量的变化规律。散热器内部针翅结构和冷却水流动方式的改变可使芯片温度降低5~8℃,散热器底板平均温度也相应降低4℃左右,且底板温度梯度较小。同时,热阻的变化随流量增大逐渐变缓,散热器结构改进使热阻减小了7%~8%。实验结果表明,改进结构的散热器能有效加强边角区域流体的扰动,提升散热器整体的换热效率,表明喷射流水冷散热是一种高效的散热方式。

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。

大功率LED分段翅片散热器热设计

针对平板翅片式散热器存在的不足,提出一种分段翅片散热器。基于COMSOL Multiphysics平台,对不同分段数的分段翅片散热器的流动传热过程进行模拟。在此基础上,将Matlab模糊推理工具箱与Simulink相结合,对不同结构的散热器进行可靠性评估。最终得到分段数为4的散热器换热系数最大、可靠性最高、结构最佳,每段翅片长度、厚度、高度、翅片间距及分段间隔分别为29 mm,4 mm,40 mm,10 mm和3 mm。当入口风速由1 m/s增大到9 m/s,分段数为4翅片散热器的换热系数相对于平直翅片散热器提高了3.42%~5.47%,压降增大了31.60%~40.85%,可靠性提高了0.2。此研究为散热器结构的优化设计提供了理论依据和参考。

小型平行板散热器阵列的传热特性

利用计算流体力学（CFD）方法对超级计算机机箱中的128个小尺寸平行板散热器的集总散热特性进行模拟，对散热器齿间距、齿厚、材料等参数进行了优化和研究；利用空气动力学理论建立了散热器热阻模型；得到了平行板散热器的散热经验公式、热阻及对流换热系数表达式．结果表明：机箱温度对散热器齿间距和齿厚的关系曲线是散热器传导热阻和对流热阻共同作用的结果，传导热阻和对流热阻随齿间距和齿厚变化的非单调性是造成该关系曲线坩埚状极值现象的根本原因，并且齿间距等形状参数是影响散热器对流换热系数的重要因素；比奥准则适用于大尺寸平行板散热器，但不适用于对流换热系数随齿间距而变化的小型散热器；该型平行板散热器齿间距和齿厚的最优尺寸经验范围分别为1．2～2mm和0．1～1．2mm．

数据中心刀片式服务器不同冷却方式的模拟对比

本文以刀片式服务器的冷却为研究对象,应用6SigmaDC软件的电子热分析模块,构建了刀片式服务器模型,对不同参数下的翅片式散热器在刀片式服务器中的散热情况进行了数学模拟。得到翅片式散热器翅片高度、齿数、翅片厚度等多个参数对散热器散热性能的影响规律,通过对比分析得到翅片散热器的最优结构参数,及芯片风冷散热所能达到的最低温度。为优化芯片的散热,在相同服务器上构建冷水板水冷散热模型,与风冷散热时芯片的温度进行对比,得出芯片水冷散热性能是风冷散热的1.3倍。基于刀片式服务器内部温度分布分析,提出刀片式服务器采用风冷与水冷相结合的混合冷却为最佳散热方式,为数据中心服务器的散热设计提供了理论参考。

基于热阻模型的低雷诺数顺排圆形微针肋热沉多目标优化设计

利用离散方法建立了顺排圆形微针肋的离散热阻模型,根据文献结果选取适用于微尺度柱群绕流的压降控制函数,以减小热阻-压降为优化目标构建加权评价函数。通过MultiStart-Fmincon多目标优化算法,对层流状态下顺排圆形微针肋热沉的微柱间距、半径、宽度进行了优化设计,得到了不同权重下的尺寸优化结果,并用有限元分析软件对优化结果进行了模拟验证。结果表明,在选取的设计区间及工作环境下,本文提出的优化设计方法具有较好的合理性和精度。流场分析表明,柱间流速与过流截面积相关,迎水柱前后的流体压差较大且随微柱集度增加而增大,可通过二次设计提升迎水柱强度。

IGBT热管式整体翅片散热器优化分析

本文建立了IGBT热管散热器模型,并用实验数据验证所建立的三维热管散热器模型及基于有限体积法的数值模拟结果的可靠性,然后研究翅片厚度t和翅片间距s对散热器散热性能的影响。结果表明:数值模型可靠;当t由0.5 mm增至1 mm时整体翅片热管散热器的摩擦系数f增加45%,而传热因子j最大增加30%;当s由1.2 mm增至2 mm时散热器的摩擦系数f减小15%,而j的变化较小且s=1.2 mm时j的平均值最大。