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矩形微通道已广泛用于均热板中,并且已有大量研究对微通道进行优化.为了对矩形微通道的尺寸进行优化,选择微通道的温度分布标准偏差作为标准.首先,根据Navier–Stokes方程推导了矩形微通道的平均流速公式,然后,又推导了微通道的壁面温度分布公式,最后采用多项式拟合的方式对平均流速公式进行简化,得出微通道的温度分布标准偏差.数值研究表明,宽长比越大,温度分布越好.仅当宽度与深度的比率满足接触角的函数时,可以获得在微通道的纵向上的最佳温度分布.为均热板矩形微通道的尺寸优化提供了一定的理论计算依据,提出了以微通道的温度分布标准偏差最小作为优化的方向. 相似文献
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针对电子器件的散热问题,设计了6种渐缩型微通道,并通过合理布置圆形凹穴来削减截面几何尺寸突变导致的压力损失。旨在借助凹穴结构促进微通道冷却液混合提升换热性能,以及通过优化通道几何尺寸来改善微通道的流体流速分布,从而进一步提升微通道换热性能。在高热流密度条件下,对6种带凹穴渐缩微通道和普通矩形微通道的流动换热特性进行了对比数值分析,并以泵功和热阻为评价指标来评价通道综合传热性能。结果表明:通过设置渐缩微通道凹槽及通道截面的合理分布,改善了流速的分布,使温度分布更加均匀,并且增强了其散热能力。在实验组的最优结构下,渐缩微通道热阻比普通矩形微通道降低了18.4%,综合传热性能最高提升了15.2%。 相似文献
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应用FLUENT软件对旋转矩形通道内气流流场进行三维粘性数值模拟,分析了RNG k-ε湍流模型和RSM模型在模拟旋转矩形通道气流流场的差别,以及旋转直通管道在不同流量及不同转速下其气流流场的变化规律。结果表明:RSM模型比RNG模型能更好地模拟湍流驱动二次流;通道内的主流和二次流特性随流量和转速发生显著变化。 相似文献
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利用正交函数法对定热流密度加热、壁面温度在周向可任意变化条件下,气体在微矩形槽道内的热充分发展滑移流动的换热特性进行理论分析,获得相应条件下的Nu数计算方法及换热特性,并与大尺度槽道的换热特性进行比较,探讨了Kn数、槽道高宽比及不同加热条件对微矩形槽道内滑移流动换热性能的影响。结果表明,在任何加热条件下,微矩形槽道内的平均Nu数均低于相同加热条件下大尺度矩形槽道中的Nu数,且随Kn数的增加而减小。高宽比越小,平均Nu数下降越大。在相同的高宽比和Kn数下,单边加热条件下的换热性能相比相同加热条件的常规大槽道内的换热性能下降最小。 相似文献
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对4种微通道散热结构(平行结构、网格结构、螺旋结构和树型结构)在相等传热面积、相同边界条件下的流场与温度场进行数值研究。通过热流耦合场数值分析,得出了不同微通道散热结构的电子芯片温度分布和微通道内的速度场,分析了微通道拓扑结构对电子芯片散热效果的影响。使用平行微通道散热的芯片温度均低于80℃,其中有81%的面积在60℃以下;使用网格和螺旋散热结构的芯片最高温度均在90℃以上,其中温度在20~60℃之间所占比例分别约为62%和61%;使用树型微通道散热的电子芯片温度均低于70℃,其中有94%的面积在60℃以下,且温度分布最均匀。此外,芯片微通道内的流体平均流速大的微通道系统能带走更多的热量。 相似文献
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三维集成电路(3D IC)由于其高热密度,给其热管理带来了巨大挑战。微通道热沉因结构紧凑、散热能力突出,是解决三维集成电路散热问题的有效途径。本文以三维集成电路单层不同形状的横截面的微通道热沉为研究对象,利用计算流体动力学(CFD)方法对三维集成电路单层不同形状的横截面的微通道的热特性进行数值仿真分析。实验结果表明,不同形状的横截面的微通道,有着不同的散热性能,针对矩形横截面的微通道和圆形横截面的微通道进行比较,矩形横截面的微通道有着更好的散热性能。 相似文献
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国内外对燃气流道几何形状优化的研究还比较少,而生产企业一般通过尝试得到参数,缺乏理论依据.对燃气喷嘴出口处气体流动就是先采用二维模型进行的有限元模拟,给出出口处通道内流体的二维数学描述及数值处理方法,并采用四边形结构网格,考核了网格数和时间步长,对不同内部流道型线的喷嘴气体流动进行数值模拟.可以得到,对于窄矩形喷嘴,进口处的形状对流场运动的分布有较大的影响,轴对称收缩喷嘴的收缩角大小主要影响气流出口附近的流动,对流动具有不同的阻滞效果. 相似文献
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微通道中液氮的流动沸腾——换热特性分析 总被引:3,自引:0,他引:3
对微通道中液氮流动沸腾换热特性进行试验研究和分析。给出典型的沸腾曲线,分析壁温、干度和换热系数沿微通道管程的变化规律,考察热流密度、质量流量和压力对流动沸腾换热的影响。将126个试验数据点与四个换热关联式比较,并对微通道中流动沸腾换热机理进行分析。结果表明,在多数情况下干度和热流密度对沸腾换热系数的影响较小,换热系数主要决定于质量流量和压力,随两者增加而增加,换热以对流蒸发为主导机理。KLIMENKO关联式预测效果最好,TRAN微通道关联式次之,对常规管道得到广泛使用的CHEN关联式和SHAH关联式都远远高估了试验值。基于两相流压降和换热特性分析,推知微通道中的两相流流型不同于常规管道:在低干度情况下,流型以弥散泡状流为主;而在高干度情况下,流型以由雾状汽芯和不规则液膜组成的环状流为主。 相似文献
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Seong-Yeon Yoo Hwa-Kil Kwon Jin-Hyuk Kim 《Journal of Mechanical Science and Technology》2007,21(3):505-512
Cross-flow over tube banks is commonly encountered in practice in heat transfer equipments. The local and average heat transfer
characteristics for staggered tube banks are investigated in the present study. A naphthalene sublimation technique is employed
to obtain the local heat transfer coefficients, and experiments are performed for various tube spacings, tube locations and
Reynolds numbers. The variation of the local heat transfer coefficients is quite different from the first tube to the third
tube, but they are similar afterwards. The average Nusselt number increases more than 30% and 65% on the second and third
tubes, respectively, in comparison with that of the first tube. And the empirical correlations for average heat transfer coefficients
are compared with the conventional heat transfer correlations. 相似文献
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Kui-Soon Kim 《Journal of Mechanical Science and Technology》1993,7(3):258-271
The flow and heat transfer characteristics of an impinging jet is investigated in two major stages. The first stage is about the investigation of the three dimensional mean flow and the turbulent flow quantities in free jet, stagnation and wall jet region. After a complete documentation of the flow field, the convective heat transfer coefficient distributions on the impingement plate are presented, during the second stage of the study. Heat transfer experiments using the new hue-capturing technique result in high resolution wall heating rate distributions. The technique is fully automated using a true color image processing system. The present heat transfer results are discussed in detail in terms of the flow characteristics. The measurements from the new method are compared with conventional heat flux sensors located on the same model. These heat transfer distributions are also compared with other studies available from the literature. The new non-intrusive heat transfer method is highly effective in obtaining high resolution heat transfer maps with good accuracy. 相似文献
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Sang Hyuk Lee Nahmkeon Hur Seongwon Kang 《Journal of Mechanical Science and Technology》2014,28(1):145-155
A numerical method to efficiently predict heat transfer phenomena of a louver fin radiator was presented — multi-scale semimicroscopic heat exchange (SHE) method. This method consists of microscopic analysis and semimicroscopic analysis. To predict heat transfer characteristics of a louver fin element, the microscopic analysis employs modeling of the detailed geometry of a fin element. Numerical models for the heat transfer rate and flow friction derived from the microscopic analysis are then used for simulations of the full radiator model in semimicroscopic analysis. In the semimicroscopic analysis, conjugate heat transfer is analyzed for the domain with the radiator whose louver fin area is replaced by a porous media. The results with the proposed method show a good agreement with the experimental data. The proposed method can be used to predict flow and heat transfer characteristics of a realistic louver fin radiator with a reduced cost and sufficient accuracy. 相似文献
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Seok Hun Yoon Cheol Oh Jae Hyuk Choi 《Journal of Mechanical Science and Technology》2002,16(3):354-362
In this paper, the heat transfer characteristics of a self-oscillating heat pipe are experimentally investigated for the effect of various working fluid fill charge ratios and heat loads. The characteristics of temperature oscillations of the working fluid are also analysed based on chaotic dynamics. The heat pipe is composed of a heating section, a cooling section and an adiabatic section, and has a 0.002m internal diameter, a 0.34m length in each turn and consists of 19 turns. The heating and the cooling portion of each turn has a length of 70mm. A series of experiments was carried out to measure the temperature distributions and the pressure variations of the heat pipe. Furthermore, heat transfer performance, effective thermal conductivity, boiling heat transfer and condensation heat transfer coefficients are calculated for various operating conditions. Experimental results show the efficacy of this type of heat pipe. 相似文献
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Seong -Yeon Yoo Jong -Hark Park Young -Man Kwark 《Journal of Mechanical Science and Technology》1996,10(2):213-222
Naphthalene sublimation technique is employed to investigate three dimensional heat transfer characteristics of the simulated electronic chips. Experiments are performed for a single chip and chip arrays. In case of a single chip, local heat transfer coefficients on four surfaces of the chip are measured for various gap sizes and air velocities. Dramatic change of local heat transfer is seen on each surface of the chip, and gap size between chip and base plate is found to affect heat transfer significantly. In case of chip arrays, heat transfer characteristics from two-dimensional array of rectangular modules and three-dimensional array of hexahedral modules are investigated. Chip location, gap between chip and base plate and streamwise chip without gap. Fully developed behavior is found from the third row, but it slightly depends on flow conditions. Local and average heat transfer coefficients of three-dimensional modules are a little bit greater than those of two-dimensional modules. The differences in magnitude decrease as the longitudinal chip spacing decreases. 相似文献