用于降低吸附床接触热阻的导热复合材料研究

发布时间：2018-08-27 12:51

【摘要】：面对如今严峻的能源问题和环境问题,将吸附式制冷技术作为蒸汽压缩制冷技术的补充和替代是一个良好的解决方案。近年来,国内外学者对吸附式制冷做了大量研究工作,为吸附式制冷的工程应用奠定了基础。关于吸附床强化传热传质也有大量的研究成果,但是目前为止,对于降低吸附床和吸附剂之间较大的接触热阻,从而进一步提高吸附床的换热能力还没有有效、易行的解决办法。本文研制了一种耐温高导热复合材料,可应用于吸附剂与吸附床之间,用来降低吸附剂与吸附床之间的接触热阻。具体内容如下：首先为评价导热复合材料的导热性能,搭建了基于稳态法的导热系数测试实验台。本文详细介绍了该实验台的工作原理,结构组成,测试步骤,并结合文献,采用304L不锈钢样品对测试实验台的精度进行了标定。结果显示实验台的最大误差为7.1%。之后从测试原理,计算模型和加工过程等方面分析了产生此误差的原因。然后以环氧树脂E-44为基体,二氨基二苯基甲烷(DDM)为固化剂,微米级A1203为导热填料制备了耐温高导热复合材料。随着导热填料用量的增大,复合材料的导热性能也随之增大。但是升高过程不是线性的,而是在导热网链形成之前处于缓慢上升状态,一旦导热网链形成导热性能迅速提高。关于填料粒径,本文选用了101μm和35μm的Al2O3粒子进行研究。实验结果表明,采用10μm粒子作导热填料的复合材料导热系数较高。采用Agari方程对实验结果进行拟合,从理论上解释了该现象产生的原因。将两种粒径粒子按不同比例混合可以获得比单独一种粒子都要高的导热能力,而且以1：1的比例混合两种粒子,获得的复合材料导热能力最好。为了改善填料与基体间的界面性能,将填料粒子用硅烷偶联剂KH-560处理。测试了经不同浓度偶联剂处理后的复合材料导热性能,当偶联剂KH-560的浓度为8%时,复合材料导热性能最好。由于经过偶联剂处理的填料粒子加入基体中之后,体系的粘度变大。为了降低体系粘度,提高填料粒子的分散性能,向体系中加入了一定浓度的稀释剂。加入稀释剂后可有效提高复合材料的导热能力,但是并不是越多越好,质量分数为40%时效果最好。由于影响复合材料导热性能的因素众多,为了找到合适的配比方案,同时研究各因素间的相互影响,本文制订了5因素5水平的正交实验表,对上述因素进行正交实验综合分析,并得出最佳实验配比方案。以此实验配比方案为基础,配制耐温高导热复合材料将其涂抹在模拟的吸附床和吸附剂之间,利用最小二乘法计算出涂抹复合材料后吸附床和吸附剂之间接触热阻的大小,并和文献中的接触热阻进行比较。结果显示使用本材料后,接触热阻至少可以降低52.6%。
[Abstract]:In the face of severe energy and environmental problems, it is a good solution to take adsorption refrigeration technology as the supplement and substitute of steam compression refrigeration technology. In recent years, scholars at home and abroad have done a lot of research on adsorption refrigeration, which lays a foundation for the engineering application of adsorption refrigeration. There have also been a lot of research results on enhanced heat and mass transfer in adsorption bed, but so far, it is not effective to reduce the contact thermal resistance between adsorption bed and adsorbent and further improve the heat transfer capacity of adsorption bed. An easy solution. In this paper, a high temperature and high thermal conductivity composite material has been developed, which can be used between adsorbent and adsorption bed to reduce the contact thermal resistance between adsorbent and adsorption bed. The main contents are as follows: firstly, in order to evaluate the thermal conductivity of the composites, a thermal conductivity test bench based on steady state method was set up. In this paper, the working principle, structure composition and test steps of the test bench are introduced in detail, and the precision of the test bench is calibrated by using 304L stainless steel sample. The results show that the maximum error is 7.1. Then, the causes of this error are analyzed from the aspects of test principle, calculation model and machining process. Then the high thermal conductivity composites were prepared with epoxy resin E-44 as matrix, diaminodiphenyl methane (DDM) as curing agent and micrometer A1203 as thermal conductive filler. The thermal conductivity of the composites increases with the increase of the filler content. However, the rising process is not linear, but is in a slowly rising state before the formation of the heat conduction network chain, and once the heat conduction network chain is formed, the thermal conductivity is improved rapidly. Regarding the particle size of filler, the Al2O3 particles of 101 渭 m and 35 渭 m were selected to study. The experimental results show that the thermal conductivity of composites with 10 渭 m particles as thermal conductive filler is higher. The experimental results were fitted by Agari equation, and the reason of the phenomenon was explained theoretically. The thermal conductivity of the composite is better than that of the single particle by mixing the two particles in different proportions, and when the two particles are mixed at 1:1, the thermal conductivity of the composite is the best. In order to improve the interfacial properties between filler and matrix, filler particles were treated with silane coupling agent KH-560. The thermal conductivity of the composite treated with different concentration of coupling agent was tested. When the concentration of coupling agent KH-560 was 8%, the thermal conductivity of the composite was the best. The viscosity of the system increases when the filler particles treated by coupling agent are added to the matrix. In order to reduce the viscosity of the system and improve the dispersion of filler particles, a certain concentration of diluent was added to the system. The addition of diluent can effectively improve the thermal conductivity of the composites, but not the more the better, the best effect is when the mass fraction is 40. Because there are many factors that affect the thermal conductivity of composite materials, in order to find out the appropriate proportion scheme and study the interaction among the factors, the orthogonal experiment table of 5 factors and 5 levels is developed. The above factors were analyzed comprehensively by orthogonal experiment, and the optimum experimental formula was obtained. On the basis of the experimental scheme, the thermal resistance between the adsorption bed and the adsorbent was calculated by least square method, and the thermal resistance between the adsorbent and the adsorption bed was calculated by using the least square method, and the thermal resistance between the adsorbent and the adsorbent was calculated by using the least square method. And compared with the contact thermal resistance in the literature. The results show that the contact thermal resistance can be reduced by 52.6%.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB332

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