截断型双层微通道热沉设计与优化

发布时间：2017-12-28 02:10

本文关键词：截断型双层微通道热沉设计与优化　出处：《华北电力大学(北京)》2016年硕士论文　论文类型：学位论文

【摘要】：双层微通道热沉具有结构紧凑、单位体积散热效率高、对冷却剂要求低和操作成本低等突出优点,自提出以来便受到研究者广泛关注。随后,广大研究者分别利用理论、实验和数值模拟的方法研究双层热沉冷却性能。虽然经过了十几年的发展,但是,在传统双层热沉中,仍存在着上层冷却剂加热下层冷却剂的加热效应,该加热效应会显著抑制双层热沉冷却性能的进一步提升。为此,本文提出了截断型双层热沉设计,并利用多参数优化方法对截断型双层热沉进行优化。首先,采用单参数研究方法分析了通道数、通道宽度、底层通道高度和底层冷却剂入口流速对传统双层热沉性能的影响。研究表明,影响双层热沉的多个参数之间存在着强烈的耦合关系,因此,单参数优化无法获取最佳双层热沉性能,需开展多参数最佳化。随后,在单参数研究的基础上,本文以通道数、通道宽度、底层通道高度和底层冷却剂入口流速为优化变量,在总泵功不变的约束下开展传统双层热沉的多参数优化,对比了两个不同的单目标优化(一个以底壁面最大温差为目标函数,一个以热阻为目标函数)中双层热沉最佳几何结构的差异,并提出了多目标优化方法以同时降低热阻和底壁面最大温差。结果显示,即便通过多参数优化,传统双层热沉中仍存在上层冷却剂加热下层冷却剂的加热效应。因此,为减弱该加热效应,本文提出了截断型双层热沉设计。研究结果表明,截断型双层热沉中存在最佳截断位置,最佳截断位置存在于两层冷却剂温度相等的地方并取决于上层冷却剂加热效应和冷却效应的权衡。随后,本文研究了底通道长度、通道数、通道对肋条宽度比和总泵功对截断型双层热沉性能的影响。研究表明,当传统双层热沉具有较长的底通道,较大的通道数,较小的通道对肋条宽度比和较小的总泵功时,采用截断顶通道的设计可显著提高双层热沉冷却性能。最后,为进一步提高截断型双层热沉的冷却性能,寻找最佳截断位置,本文以通道数、通道宽度、通道高度和通道截断长度为优化变量,分别以总泵功不变和总流量不变为约束条件,以热阻为目标函数,从三组差异较大的初始设计出发来实施截断型双层热沉的多参数优化。结果表明,总泵功为0.05 W时,最佳热阻为0.102 K/W。与三组初始设计相比分别降低了60.3%,49.3%和56.2%；总流量为200ml/min时,最佳热阻为0.093 K/W。与三组初始设计相比分别降低了31.1%,32.6%和36.3%。
[Abstract]:The double-layer microchannel heat sink has many advantages, such as compact structure, high volume heat dissipation per unit volume, low requirement for coolant and low operation cost. Subsequently, the researchers used theoretical, experimental and numerical simulation methods to study the cooling performance of the double layer heat sink. Though more than ten years' development, the heating effect of the upper coolant heating lower layer coolant still exists in the traditional double-layer heat sink. The heating effect will significantly inhibit the further improvement of the cooling performance of the double-layer heat sink. In this paper, a truncated double layer heat sink is designed and the multi parameter optimization method is used to optimize the truncated double layer heat sink. First, the influence of channel number, channel width, bottom channel height and bottom coolant inlet velocity on the performance of traditional double-layer heat sink is analyzed by single parameter method. The research shows that there is a strong coupling relationship between multiple parameters that affect the double-layer heat sink. Therefore, single parameter optimization can not get the best double-layer heat sink performance, and multi parameter optimization is needed. Then, based on single parameter research, based on the channel number, channel width, channel bottom height and bottom coolant entrance velocity as optimization variables, multi parameter optimization of traditional double heat sink to carry out at the same total pump power constraints, comparing two different single objective optimization (one of the largest in the bottom the wall temperature difference as the objective function, a thermal resistance as the objective function) in the double heat sink difference of optimal geometric structure, and puts forward a multi-objective optimization method to reduce the thermal resistance and the bottom wall of the maximum temperature difference. The results show that, even through multi parameter optimization, the heating effect of the lower coolant heating in the upper layer of the upper layer coolant still exists in the traditional double layer heat sink. Therefore, in order to reduce the heating effect, a truncated double layer heat sink design is proposed in this paper. The results show that there is an optimal truncation location in the truncated double-layer heat sink. The optimal cut-off location is located at the same temperature as the two layers of coolant, and depends on the trade-off between the heating effect and cooling effect of the upper layer coolant. Then, this paper studies the effect of bottom channel length, channel number, channel of rib width ratio and the total pump power of truncated double heat sink performance. Research shows that when the traditional heat sink bottom channel has a longer, larger channel count, smaller channel total pump on the rib width ratio and low power, the design of the top truncation can significantly improve the double channel heat sink cooling performance. Finally, in order to further improve the cooling performance of the truncated double heat sink, to find the best cut-off position, taking the number of channels, channel width, channel height and channel truncation length as optimization variables, respectively with the total pump power and total flow rate unchanged unchanged as constraint conditions, the thermal resistance of an objective function of the implementation of multi parameter optimization truncated double heat sink from the initial design of large differences between the three groups. The results show that the optimum thermal resistance is 0.102 K/W when the total pump work is 0.05 W. Compared with the initial design of the three groups, it is 60.3%, 49.3% and 56.2% respectively. When the total flow rate is 200ml/min, the optimum thermal resistance is 0.093 K/W. Compared with the initial design of the three groups, the reduction was 31.1%, 32.6% and 36.3% respectively.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TK124;TN402

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