多孔介质金属泡沫传热热阻及等价导热系数的实验研究

发布时间：2018-06-06 03:13

本文选题：多孔介质金属泡沫 + 骨架导热热阻　；参考：《华东交通大学》2017年硕士论文

【摘要】：随着人类的发展,科技的进步,对能源的需求量日益增加,能源紧缺问题也受到愈发广泛的关注。提高能源利用效率能够绿色、经济的降低能源的消耗,是节约能源的首选方案。多孔介质金属泡沫作为一种新型材料,在航空航天、电子工业等领域受到广泛关注。其兼顾多孔性及金属刚性使其具有强化传热的特点。近年来,多孔介质传热的研究成为热点,对传热模型的描述也日趋成熟,但是在能量方程的描述中,对于多孔介质导热系数的选择仍有分歧。本文针对两能量模型中导热系数的定义,提出一个更符合实际的等价导热系数,并以泡沫铜为例对等价导热系数进行了计算。本文搭建了多孔介质金属泡沫传热热阻测定实验装置,并测得了泡沫铜的传热总热阻、骨架导热热阻以及表面接触热阻。分别对厚度、结构参数、加热功率、压紧力等不同因素对实验的影响进行了分析。实验结果表明:实验总热阻随压紧力的增大而减小,减小幅度最大可达50%以上。通过不同厚度试件数据的推导计算,得到了骨架导热热阻并进行了拟合回归。在孔隙率相近时,孔隙密度(PPI)越大,其骨架导热热阻越小。孔隙密度(PPI)一致时,孔隙率越大其热阻也越大。表面接触热阻对传热的影响很大,并通过计算将试件的表面接触热阻量化。提出并定义了更符合多孔介质传热机理的等价导热系数,基于热阻一致性原则,根据等价导热系数的定义分别计算得到了立方体细丝模型和十四面体模型的有效导热面积。通过骨架导热热阻的实验数据与上述模型参数相结合得出了相应模型的等价导热系数的值。
[Abstract]:With the development of human beings and the progress of science and technology, the demand for energy is increasing day by day. It is the first choice to save energy by improving energy efficiency and reducing energy consumption economically. As a new type of material, porous metal foam has attracted wide attention in aerospace, electronic industry and other fields. It has the characteristics of enhanced heat transfer due to both porosity and metal rigidity. In recent years, the study of heat transfer in porous media has become a hot topic, and the description of heat transfer model has become more and more mature. However, in the description of energy equation, the choice of thermal conductivity of porous media is still different. In this paper, according to the definition of thermal conductivity in two-energy model, a more practical equivalent thermal conductivity is proposed, and the equivalent thermal conductivity is calculated by taking copper foam as an example. In this paper, an experimental device for measuring heat transfer resistance of metal foam in porous media is set up, and the total heat transfer resistance, skeleton thermal conductivity resistance and surface contact thermal resistance of copper foam are measured. The effects of thickness, structural parameters, heating power and compaction force on the experiment are analyzed. The experimental results show that the total thermal resistance of the experiment decreases with the increase of the compression force, and the maximum reduction can be more than 50%. Through the derivation and calculation of the specimen data with different thickness, the thermal resistance of the skeleton is obtained and the fitting regression is carried out. When the porosity is close, the larger the pore density is, the smaller the thermal resistance of the skeleton is. The larger the porosity, the greater the thermal resistance when the pore density is the same. The surface contact thermal resistance has a great influence on heat transfer, and the surface contact thermal resistance of the specimen is quantified by calculation. Based on the principle of consistency of thermal resistance and the definition of equivalent thermal conductivity, the effective thermal conductivity of the cubic filament model and the ten-tetrahedron model are calculated, respectively. The equivalent thermal conductivity of the corresponding model is obtained by combining the experimental data of the thermal conductivity of the skeleton with the above model parameters.
【学位授予单位】：华东交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG139

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