基于烟囱效应的通信基站热沉优化设计

利用数值模拟的方法，探究了烟囱效应对通信基站热沉自然对流散热的强化作用，对影响热沉散热性能的主要因素及其机理进行了分析，并以热沉热阻作为优化目标，通过优化翅片间距与隔板间隙的取值提升了热沉的散热性能。在优化设计过程中，通过模糊均值聚类对拉丁超立方抽样所得的样本点进行筛选，快速并有效的缩减了设计区间，使用Kriging模型对新设计区间内的均匀样本点进行拟合，构建了热沉热阻与设计变量间的代理模型，并结合遗传算法寻优，确定了最优设计参数取值。在最优参数布置下，相比于初始热沉，热沉的发热面温度降低了15.23 K,总热阻降低了34.29%。     

UV-LED风冷散热系统瞬态性能分析与测试

针对一款典型的UV-LED风冷翅片热管散热系统,建立了从LED阵列到散热器末端的热阻网络,应用MATLAB模拟了翅片热管散热器在设计工况和变工况下各点温度的瞬态变化性能,并选取部分点进行了实验测试。结果显示,该风冷翅片热管散热器具有较好的瞬态传热性能,其最大温差在散热器铜板处;瞬态温度响应具有滞后性;LED散热量突然急剧变化时,对芯片部分的影响较大,而环境温度或者外部的对流散热状况在短时间内的波动则对LED几乎没有影响。     

圆形热负荷作用面电器件散热器的结构参数对热阻的影响

用数值方法分析了圆形热负荷作用面电器件散热器的结构参数对热阻的影响。定义了无量纲坐标及无量纲热阻R，得到了在不同几何参数条件下毕渥数Bi与无量纲热阻R的关系。在大量数据基础上拟合获得了毕渥数Bi及散热器几何参数与无量纲热阻R的关联式，该关联式不仅可以获得热阻随参数变化的趋势，而且能够直接预测散热器的热阻，揭示了热负荷作用面为圆形的电器件散热器散热特性。研究结果为使用这类散热器的设计提供了理论和计算依据。     

用于电子元件散热的集成热管换热特性研究

本文对应用于电子元件散热的热管换热器在不同的加热功率、不同风量情况下的传热特性进行了实验研究，从而得出换热量、总热阻、翅片表面阻力系数、换热系数、总热阻与加热功率及风道内空气肫数的关系，并与市场上的SP-94型热管散热器及传统纯铜散热器进行了比较，发现该热管换热器无论是散热量、平均换热系数还是总热阻都有明显的优势。因此，这种散热器在实际工程应用中必将有着广泛的潜力。     

蒸汽喷射制冷原理在大型翅片散热上的应用

研究了一种利用喷射制冷原理的翅片散热器散热效率提高装置。创新性地将蒸汽喷射制冷原理应用于翅片散热器,可有效提高翅片散热器散热效率,解决因工况环境等因素导致的设备散热不及时等问题,符合绿色环保节能减排发展理念。     

1000MW直接空冷机组散热单元换热特性的数值模拟

以某1 000MW直接空冷机组为例,对机组散热器外部流场进行了数值模拟,分析了不同迎面风速、环境温度、翅片间距以及翅片厚度对散热器外部换热和流动特性的影响.结果表明:随着迎面风速的增大,散热器外部的传热系数和流动阻力均显著增大,环境温度对散热器外部换热和流动特性的影响并不明显,但对总散热量影响较大;较大的翅片间距能增大散热器外部的传热系数、减小流动阻力,但会使单位管长的换热面积减小,总散热量减小;对应于一定的迎面风速,存在较为合理的翅片间距和翅片厚度,迎面风速越大,合理的翅片间距越大,翅片厚度越小.     

电子元件散热器翅片自然对流散热性能研究

针对室外电子设备在自然对流条件下的散热问题,设计开发了一种新型散热器翅片结构——翅片开孔式涡流发生器,易于加工且直接与翅片连接,不存在焊接的问题。利用数值模拟的方法探究了涡流发生器的布置方式与攻角对散热器散热的影响。结果表明:翅片开设三角孔,在翅片间空气流动过程中起到了明显的作用,有效降低了三角形涡流发生器造成的流动阻力,增加了空气的扰动;当涡流发生器间距为40 mm、攻角为15°时,散热器翅片高温热源区域的散热效果最好。     

风电变流器电容部件散热分析及仿真优化

针对某1.5 MW Freqcon变流器的电容系统的散热问题,建立了几何结构模型,在热分析理论的基础上,采用ICEPAK软件,对存在问题的电容冷却系统的温度场、速度场进行了三维仿真分析。研究发现在柜体最上端和最下端存在涡流区域,导致电容系统散热性能降低。为解决问题,提出了两种优化方案,并进行了比较分析,最后将方案二应用到实际运行中,结果表明:方案一去掉产生涡流部分的风道,可以在一定程度上减少涡流区域产生。方案二在方案一的基础上,利用ICEPAK的优化功能,优化参数,得出优化的最小风量为0.408m3/s,并且在该风量下电容器表面传热系数较高。实际运行结果与方案二模拟结果基本一致,并为风电变流器实际运行中的风道优化和电容散热提供一定的参考。     

双通水道带翅片散热器的优化设计(Ⅱ)

本文以金属热强度为结构优化的目标函数,利用MATLAB对双通水道带翅片的散热器的散热量进行计算,通过对数值结果的分析,得出该种散热器的最佳结构型式。     

双通水道带翅片散热器的优化设计

本文以金属热强度为结构优化的目标函数,利用Matlab对双通水道带翅片的散热器的散热量进行计算,通过对数值结果的分析,得出该种散热器的最佳结构型式.     

数据中心服务器水冷散热器的数值模拟与实验验证

水冷散热器在数据中心服务器CPU芯片冷却技术中发挥着重要的作用。如何获得高性能的散热效率成为了该领域关注的重点。针对一种翅柱式水冷散热器,用数值模拟的方法,通过改变翅柱的结构参数来优化散热器的散热性能以及流动特性。在相同的翅柱间距下,改变翅柱的直径和高度,在不同的入口流量下,研究其温度,努塞尔数,压降,摩擦系数,分析比较其综合系数对散热性能的影响,并对结果进行了实验验证。结果表明翅柱高度3.9mm,直径为0.9mm的散热器其综合系数最大     

Thermal optimization of tapered pin fin exposed to nonuniform surface heat transfer coefficient

In the present work, thermal analysis and design optimization of tapered pin fin subjected to variable surface heat transfer coefficient have been numerically carried out. It is well known that heat is transferred through the fin by conduction along its length and dissipated from the fin surface via natural convection to the ambient. The thermal analysis and the optimum dimension were carried out using finite element (FE) modeling software ANSYS-17.2. The thermal performance of the tapered pin fin has been studied over a wide range of physical dimensions. In addition, the effect of base to tip surface heat transfer coefficient ratio (ε) on the fin performance is evaluated. It was found that the effect of variable heat transfer coefficient has a significant impact on the fin efficiency. The rate of increase of fin efficiency was lower in the low as well as in high range of ε, meanwhile, it was steeper in the intermediate range of ε. It was also observed that the optimal values of the heat dissipation were higher for lower values of ε at the same conditions.     

微槽群平板热管散热器传热性能的研究

分别选择不同的翅片间距和高度,对一种新型微槽群平板热管散热器的翅片结构进行优化,得到了热管散热器的最佳整体结构。结果表明:翅片的间距为14mm、高度为60mm时,平板热管散热器的传热性能最好。将热管、管脚以及翅片的温度与实验结果进行对比,结果吻合良好。     

Improvement of heat transfer through fins: A brief review of recent developments

Fins or extended surfaces are generally used in heat exchangers to enhance heat transfer between the main surface and ambient fluid. Various types of simple‐shaped fins, namely, rectangular, square, annular, cylindrical, and tapered, have been used with different geometrical combinations. To satisfy industrial demand, different trials have also been carried out for designing optimized fins. The optimization of fins can be performed either by enhancing heat dissipation at an exact fin weight or by diminishing the weight of the fin by precise heat dissipation. Recently a notable amount of work on some typical fins, like, porous fins and perforated fins, has also been carried out. This paper presents a brief review on heat transfer enhancement using fins of different types considering variable thermophysical and geometric parameters, which will also be useful for future use of geometrical modifications of extended surfaces, based on the cost and availability of space.     

Numerical study of the fin efficiency and a modified fin efficiency formula for flat tube bank fin heat exchanger

In this paper, a three-dimensional numerical heat transfer analysis has been performed in order to obtain the temperature distribution and the fin efficiency using the experimentally determined local heat transfer coefficients from the naphthalene sublimation technique and heat and mass transfer analogy. The influences of the fin material, fin thickness, and transversal tube pitch on the fin efficiency are studied for flat tube bank fin heat exchangers. The fin efficiency, obtained by a numerical method using the averaged heat transfer coefficient, is compared with that using the local heat transfer coefficient. The reliability of the generally used formula for fin efficiency is tested also, and then a modified fin efficiency formula with a new equivalent fin height is provided. The results show that the difference between the fin efficiency obtained by the numerical method using the local heat transfer coefficient and the fin efficiency using the averaged heat transfer coefficient is small, but the fin efficiency obtained by the generally used formula is lower than that obtained by the numerical method using the local heat transfer coefficient; the fin efficiency obtained by the modified formula matches very well with the fin efficiency obtained by the numerical method using the local heat transfer coefficient. The modified formula for the fin efficiency calculation is more reliable, and it can be applied directly to the design of a flat tube bank fin heat exchanger and also will be useful in engineering applications.     

带短肋翅片管的强化传热机理研究

同时对普通翅片管和带有两个短肋的翅片管在均匀流场中、不同雷诺数下进行了流场和传热的数值模拟,分析了带有短肋的翅片管强化传热的机理。结果表明,由于翅片上带有的短肋和短肋后面的开孔,减少了翅片管管后流动的死滞区,提高了局部地区流体的流速,增加了扰动,从而起到了强化传热的作用。取入口雷诺数为20000时,加装短肋后可使总传热量增加5.1%,平均表面传热系数增加23.56%。随着雷诺数的增加,总换热量增加,强化传热效果也增强。     

Prediction of heat transfer coefficient on the fin inside one-tube plate finned-tube heat exchangers

The finite difference method in conjunction with the least-squares scheme and the experimental temperature data is proposed to predict the average heat transfer coefficient and the fin efficiency on the fin inside one-tube plate finned-tube heat exchangers for various air speeds and the temperature difference between the ambient temperature and the tube temperature. Previous works showed that the heat transfer coefficient on this rectangular fin is very non-uniform. Thus the whole plate fin is divided into several sub-fin regions in order to predict the average heat transfer coefficient and the fin efficiency on the fin from the knowledge of the fin temperature recordings at several selected measurement locations. The results show that the surface heat flux and the heat transfer coefficient on the upstream region of the fin can be markedly higher than those on the downstream region. The fin temperature distributions depart from the ideal isothermal situation and the fin temperature decreases more rapidly away from the circular center, when the frontal air speed increases. The average heat transfer coefficient on the fin increases with the air speed and the temperature difference between the ambient temperature and the tube temperature. This implies that the effect of the temperature difference between the tube temperature and the ambient temperature is not negligent.     

Optimization of a space radiator with energy storage

A simple model for heat transfer from a space radiator with latent heat thermal energy storage has been developed. For a given heat storage and dissipation capability, analytical results have been obtained for the optimum geometry of a radiator panel/fin based on a minimum mass criterion. Numerical results for a typical configuration show that mass reductions of 20–25% or more can be achieved for pulsed heating loads of durations of the order of 1 h or less. At the same time, the radiator sizes can be reduced by a factor of 4 or more. The results also suggest that the benefits of energy storage will be higher for operating conditions with lower heat dissipation rates.