基于场协同理论的电子元件散热CFD数值模拟

针对电子元件的散热问题,以电子元件为研究对象,采用CFD技术对以空气为冷却流体的电子元件的6种散热方案进行了数值模拟。采用流体固体共轭传热技术,获得电子元件散热小空间的温度场及速度场。基于场协同原理对其温度场和速度场的协同效果进行分析和比较,获得电子元件散热的优化方案,为进一步提高电子元件的散热效果及热设计水平提供理论依据。     

电力电子器件封装模块的散热特性

以传统电力电子器件封装模型为基础,介绍了大功率电力电子器件热量传递机理、失效原因。阐述了电力电子器件的主要外部散热方式及发展现状。最后基于有限元软件ANSYS为平台,通过改变电力电子器件内部结构,包括芯片间距、衬板厚度、铜底板厚度,分析了内部结构芯片散热的影响。通过测试发现,当芯片分布均匀时,散热效果最好,导热系数较高的材质,芯片散热效果较为理想。在小范围内,芯片结温随底铜板厚度增加而下降,之后芯片结温随厚度增加而升高。     

栅格式方孔翅片自然对流换热的数值模拟

为改善电子器件的散热情况,提出了一种新型结构的栅格式方孔翅片,并对其在自然对流条件下的散热特性进行了研究。利用正交试验法和Fluent数值模拟,模拟了102种不同翅片高度与间距比H/S、不同孔边长与翅片厚度比b/δ的散热情况。研究得到:大空间自散热条件下,H/S=2、b/δ=0～4时的Gr-Nu的关系图;有限空间散热条件下,b/δ=1.5、H/S=1～16/3时的Gr-Nu的关系图。结果表明,格栅式方孔翅片可以改善电子器件的散热,并为LED照明等电子器件散热设计提供新的思路和理论依据。     

电子设备散热技术研究

随着微电子技术的发展,使得电子器件的热流密度不断增加,这样势必对电子器件有更高的散热要求,因此有效地解决散热问题已成为电子设备必须解决的关键技术.针对现代电子设备所面临的散热问题,就自然对流散、强制风冷散热、液体冷却、热管、微槽道冷却、集成热路、热电致冷等常用的电子设备散热技术及某些前沿的研究现状、发展趋势及存在问题分别予以阐述,希望对同行能有所帮助.     

纳米冷却技术

随着电子集成技术的迅速发展,电子器件的热流密度不断增加,对微尺度下电子冷却技术的要求也在不断提高。微电子领域是最早提出微尺度流动和传热问题的工程领域。在具有微尺度的微电子领域中,当空间和时间尺度微细化后,出现了很多与常规尺度下不同的物理现象。而随着微电子技术的发展,电子器件的热流密度不断增加,这势必对电子器件有更高的散热要求,因此有效地解决散热问题已成为电子设备必须解决的关键技术。鉴于纳米冷却技术的先进性和优越性,本文从微尺度下电子冷却技术的发展背景出发,重点介绍了纳米冷却技术的应用、现状及发展前景。     

电子元器件散热方法研究

随着电子器件的高频、高速以及集成电路技术的迅速发展和MEMS（Micro Electro-Mechanical Systern）技术的进步,电子元器件的总功率密度大幅度增长而物理尺寸却越来越小,热流密度也随之增加,所以高温的温度环境势必会影响电子元器件的性能,这就要求对其进行更加高效的热控制。因此,有效解决电子元器件的散热问题已成为当前电子元器件和电子设备制造的关键技术。本文针对电子元器件的散热与冷却问题,综述了当前应用研究中不同的散热和冷却方法,并进行了适当的分析。     

铜-硼/金刚石复合材料翅片热沉散热研究

采用气压浸渗法制备了热导率为850 W ? m-1 ? K-1的铜-硼/金刚石复合材料翅片热沉,测试了其在自然冷却、强迫风冷和强迫水冷三种冷却模式下的散热效果.结果表明,热源功率越高,铜-硼/金刚石复合材料的散热效果越显著.在强迫水冷模式下,当加热片的输入功率为80 W时,使用铜-硼/金刚石复合材料翅片热沉时加热片的最高温度比使用铜翅片热沉时低14℃,比使用铝翅片热沉时低23℃.Icepak热模拟发现,在强迫水冷模式下输入功率为80 W时,与铜和铝翅片热沉相比,铜-硼/金刚石复合材料翅片热沉的整体温度更低且温度分布更均匀.研究结果证实,铜-硼/金刚石复合材料是一种高效的散热材料,在大功率电子器件散热中具有广阔的应用前景.     

实现电子器件散热的微小型平板LHP蒸发器传热特性研究

提出了微小型平板LHP来实现高热流密度电子器件的散热,分析了LHP的工作原理以及运用于电子器件散热的优点.建立了蒸发器多孔芯,金属壁面以及工质汽、液空间区域的耦合数学模型,并运用SIMPLE算法进行求解.数值结果表明,微小型平板LHP蒸发器具有较高热流的散热能力,加热表面的温度水平较低,均温性较好,有利于电子器件的散热.提出微小型平板LHP存在侧壁效应传热极限,由于该极限的存在,系统传热能力在17.5×104 W·m-2左右.     

大功率电子器件蒸发冷却电极温度场的计算

阳极或收集极的散热问题是大功率电子器件的基本问题之一。近廿年来虽发展了高效率的蒸发冷却散热结构;但其设计仍停留在模拟和经验设计阶段。本文给出了蒸发冷却电极的数学模型及其求解方法;讨论了这种数学物理方程的非线性和多值解性质;并以典型的大功率电子管蒸发冷却阳极为例,用数字计算机求解出内部温度场的分布;为蒸发冷却电极的设计提供了分析根据。据此可进行结构设计,估价给定结构的散热能力。     

喷雾冷却技术及其在电子冷却领域的应用

喷雾冷却作为一种新型的冷却方式,在电子器件散热方面具有广阔的应用前景。本文介绍了喷雾特性、换热工质、喷射角度及高度、强化表面和纳米添加剂对喷雾冷却换热性能的影响。简述了常见的电子冷却技术以及喷雾冷却技术在电子冷却方面的应用前景。     

Assessment of high-heat-flux thermal management schemes

This paper explores the recent research developments in high-heat-flux thermal management. Cooling schemes such as pool boiling, detachable heat sinks, channel flow boiling, microchannel and mini-channel heat sinks, jet-impingement, and sprays, are discussed and compared relative to heat dissipation potential, reliability, and packaging concerns. It is demonstrated that, while different cooling options can be tailored to the specific needs of individual applications, system considerations always play a paramount role in determining the most suitable cooling scheme. It is also shown that extensive fundamental electronic cooling knowledge has been amassed over the past two decades. Yet there is now a growing need for hardware innovations rather than perturbations to those fundamental studies. An example of these innovations is the cooling of military avionics, where research findings from the electronic cooling literature have made possible the development of a new generation of cooling hardware which promise order of magnitude increases in heat dissipation compared to today's cutting edge avionics cooling schemes     

基于退火算法的PCB电子元件散热布局优化分析

本文采用模拟退火算法对空气强迫流动下PCB电子元件的散热布局进行优化设计，进而提高电子设备散热效率，并利用CFD（流体动力学）软件对结果进行验证。验证结果表明模拟退化算法可有效解决PCB电子元件散热布局的优化问题，避免了传统算法的大规模计算量，在电子元件散热领域中有着良好的应用前景．     

基于CFD的电子模块散热优化的场协同分析

采用CFD技术对电子模块的散热情况进行数值模拟,获得电子模块以及周围空气的温度场和速度场,基于传热场协同理论分析了电子模块及其周围空气的速度场和温度场的协同程度,并根据电子模块的温度水平以及电子模块的散热量为评价指标,通过对电子模块的散热方案进行优化比选,获得电子模块冷却的优化方案,为探究电子模块高效散热机理打下坚实的...     

Experimental study on the performance of miniature heat pipes withwoven-wire wick

The thermal density of electronic system has been increased continuously because high speed and high density are required for them. The heat dissipation of CPU for a notebook PC has been recently increased to be more than 10 W, but, on the other hand, the available packaging space has been decreased. Therefore, it has become inevitable to perform cooling by using miniature heat pipes (MHPs). In the present study, a new woven-wire-type wick for the MHP is developed, which has a large capillary limit and a high productivity. These MHPs with diameters of 3 mm or 4 mm are applicable to small-sized electronic parts such as CPU of a notebook PC. Because the operational characteristics of MHPs with the diameters of 3 mm or 4 mm are different from those of general medium-size heat pipes, performance tests have been conducted in order to review heat-transfer characteristics and effects of various factors on the performance of MHPs. The design factors under consideration are fill ratio of working fluid, length of heat pipe, length of evaporator and condenser, inclination angle of installation, number of wick strand and thermal load     

基于大功率电子器件的冷控系统设计

随着电子元器件的集成化程度越来越高,散热问题已经成为制约电子技术发展的主要因素之一.有效解决电子元器件的散热问题已经成为当前研究的热点问题.传统的风冷系统已经很难满足其散热要求.为此,以电子设备的水冷系统为研究对象,以ATmega 1280微处理器作为基础,设计了一款低成本、高效率的大功率电子器件的水冷控制系统,对系统各关键硬件模块做了详细的介绍,并采用模块化的方法给出了系统的软件架构.综合实验结果表明该系统操作方便、可靠性好、电磁兼容性强,具有较高的实用价值.     

Evaporation-condensation cooling systems for electronic equipment

The paper shows that heat pipes with metal-fibrous capillary structures and evaporation-condensation cooling system based on heat pipes are highly efficient means of providing optimal thermal conditions for different electronic instruments and devices. Such cooling system combining the functions of effective heating conduit (equivalent heat conductivity is much higher than the heat conductivity of the best heat-conducting materials) and effective radiator with the possibility of passive heat dissipation is characterized by a high heat transport ability, low thermal resistance, relatively small size and weight, reliable performance at different orientation in space under exposure to mass forces action. The paper presents examples of developed designs and investigations of heat pipes and evaporation-condensation systems with metal-fibrous capillary structures aimed at cooling the different heat generating items of electronic equipment. In this case, special types and designs of systems are discussed. These systems operate under different conditions of heat removal to absorbing medium and feature both a high heat transport ability and specific dielectric properties. In addition, the thermotechnical characteristics of proposed cooling systems are also presented.     

Combined effects of sub-cooling and operating pressure on theperformance of a two-chamber thermosyphon

The heat dissipation rates at the chip level are projected to reach the 50-100 W/cm² mark for some future high performance electronic systems. Liquid cooling with phase change has been demonstrated to be a very efficient technique for thermal management of such high heat dissipation rates. Past work on liquid immersion cooling using fluorocarbons has shown the advantage of using enhanced structures to reduce boiling incipience excursion and raise the critical heat flux (CHF). Thermosyphons, employing these enhanced structures are an alternative to liquid immersion and are suitable for point cooling applications, where very compact evaporators are needed. This study investigates the combined effect of sub-cooling and pressure on the performance of an enhanced microstructure based thermosyphon, which has shown very high heat transfer rates (up to 100 W/cm² with a wall superheat of 27.8°C). The pressure levels tested were partial vacuum (40-101.3 kPa), atmospheric pressure (101.3 kPa) and high pressure (101.3-370 kPa). The experiments were initiated at room temperature, and hence the sub-cooling corresponded to the difference in the liquid saturation temperature at the starting system pressure and room temperature. The results show a reduction in wall superheat values at higher pressures, at a given heat flux. The performance of the system was evaluated by defining a surface-to-ambient resistance. Results show that a partial vacuum at all heat fluxes results in better performance compared to higher pressures. The combined effect of pressure and sub-cooling was also tested for a compact evaporator and the results obtained were similar to the baseline case (larger evaporator)     

电子器件热电制冷温度条件的优化

基于热电制冷热力学循环分析了热电制冷器正常工作的温度条件,以及两种极限工况性能受工作温度条件的制约关系。优值系数是热电制冷器性能的内在制约,散热和温度条件则是热电制冷性能的外在制约,热电制冷元件工作的温度特性与电子元件工作的理想温度条件是非常适应的。基于热电制冷的主动冷却技术对高热流密度电子集成部件的封装散热具有重大意义。     

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.