【作者】 金漫丽；

【导师】 杨昆；

【作者基本信息】 华中科技大学 ， 工程热物理， 2011， 硕士

【摘要】 近年来,随着电子设备组装密度越来越高,散热问题越来越突出。微通道热沉具有比表面积大、换热效率高及结构紧凑等优点,成为国内外学者研究的热点。本文的设计要求是:在40mm×20mm散热面上,热流密度达到20W/cm2时,热沉壁面温度低于60℃。为了实现此目标,本文提出了一种高效叉排肋片结构的微小通道。采用FLUENT软件对叉排结构热沉和传统直列结构热沉进行了性能对比,结果表明叉排结构热沉较直列结构其换热能力提高了18%以上,但也带来了阻力增大的问题。此外,从场协同角度出发解释了叉排微小通道热沉传热强化和耗功增大的机理。根据数值研究结果对叉排热沉的肋片倒圆角,发现倒圆角对热沉性能的影响很小。因此,本文在不改变肋片形状的基础上,对影响叉排肋片微小通道热沉的结构参数做了深入的探讨,研究表明:叉排肋片存在一个最佳的肋片长度比值,最佳的肋片厚度比值,最佳的肋片高度比值,使得热沉的性能最优。分析有、无进出口管对热沉压降的影响,结果表明进出口管的压降占总压降的50%以上,这说明热沉主体的压降比总压降小很多。以优化的结果为基础,结合加工工艺,本文加工了四组叉排肋片微小通道,在不同加热功率、不同流量、不同设计尺寸情况下,对其进行了散热和流动测试实验,并对实验结果进行了分析和讨论。实验发现热沉壁面温度与热流密度呈线性关系,加热功率变化时,热沉的动态响应仅需1分钟;随着流量增加,热沉换热性能提高,压力损失也增大;实验结果表明设计尺寸为Y=1,Wc=2.1热沉的换热效果最好,这与数值计算结果一致。并且当流量为4.17ml/s时,在热流达到30W/cm2的情况下,热沉的壁面温度低于60℃,表明本文设计的热沉满足课题要求。实验热沉的数值模拟与实验结果吻合得较好,并且本文设计的热沉较层叠蜂窝状热沉的换热性能提高了1倍以上。本文的研究成果和结论对微小通道热沉的设计具有重要的指导意义。更多还原

【Abstract】 With the rapid development of the packing density of the electronic device,the heat dissipation of the electronic device becomes more and more obvious. Microchannel heat sinks have been a hot spot for domestically and abroad scholar now because of the advantages of high surface-to-volume ratio in limited space, strong cooling abilities and compact structures. The design requirements in this thesis were that the cooling system could remove a heat flux of 20 W/cm2 on a 40mm×20mm heat transfer surface, while the allowable wall temperature was 60℃.A high performance of a miniature channel with staggered fin was proposed to realize the aim. Numerical studies were conducted to compare the performances of staggered fin and conventional parallel heat sinks, the results showed that staggered fin structure can obtain better cooling performance, which increased the heat transfer coefficient up to 18%, and resulted a problem of larger pressure loss. The heat transfer enhancement and power consumption increase mechanism of the staggered fin was also analyzed from the field synergy point. The staggered fins were round off , a comparison of modified staggered fin miniature channel and normal staggered fin miniature channel were performed, it was showed that the modification had little impact on the performance. Therefore, the optimization of popular staggered fin miniature channel heat sink was made in this thesis. Through the study, It was found that there was an optimum fin length ratio, an optimum fin width and an optimum fin height for the staggered fin miniature channel heat sink. The numerical results indicated that inlet and outlet pipes had lager impact on the pressure lose of staggered fin miniature channel heat sinks, which accounted for more than 50%. It was found that the real pressure drop of heat sink could less than the whole pressure.According to the optimized results and processing technologies, four staggered fin miniature channel heat sinks were fabricated. Experimental investigation was conducted to determine the heat transfer and flow characteristics of the heat sinks. The cooling performance was investigated and analyzed under various operation situations, which concluded different input heating power, flow rate, structure parameters. The following conclusions were obtained: The average wall temperature of heat sink was linear to heat flux and the dynamic response time for heating power was only one minute; A larger flow rate resulted in a better heat transfer performance, but a greater pressure drop; When the parameter of the staggered fin miniature channel heat sink was Y=1, Wc=2.1mm , the performance was best. In addition, the cooling system could effectively remove a heat flux of 30W/cm2 under 4.17 ml/s flow rate, while the wall temperature was below 60℃, which fully meet the topic requests. Numerical results were also obtained based on the experimental conditions. A good match was found between the numerical and experimental temperatures. Compared with honeycomb structure, the cooling performance of staggered fin miniature channel heat sink was more than twice. The results and conclusions from this thesis could provided the important insights to the design of staggered fin miniature channel heat sink.更多还原