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Study On High Thermal Conductivity Composites For Reducing Thermal Contact Resistance Of Adsorber

Posted on:2016-04-20Degree:MasterType:Thesis
Country:ChinaCandidate:G D XiongFull Text:PDF
GTID:2191330461987588Subject:Refrigeration and Cryogenic Engineering
Abstract/Summary:PDF Full Text Request
Faced with serious energy and environmental issues, the adsorption refrigeration technology as a complementary and alternative vapor compression refrigeration technology is a good solution. Recently, worldwide scholars have done a lot of work on the adsorption refrigeration, it laies the foundation for adsorption refrigeration engineering applications. There are a large number of research results about adsorber heat and mass transfer, but so far, we have not yet effective and easy way to reduce the thermal contact resistance between the bed and the adsorbent and improve heat transfer capacity of the adsorbent bed. This paper developed a temperature resistance and high thermal conductivity composite material, it can be applied between the adsorbent and the adsorbent bed, to reduce the thermal contact resistance between them. Details are as follows:First, we set up a thermal conductivity test bench based on steady-state method in order to measure the thermal conductivity of the composite. This paper describes the principles of the test bench, composition and procedures. Then, according to literature, the bench is calibrated by 304L stainless steel. The results show that the maximum error of bench is 7.1%. The reason for this error is analyzed from the test principle, model and process.Then, the temperature resistance and high thermal conductivity composite materials were prepared, matrix was epoxy resin E-44, curing agent was DDM, thermal conducting fillers were micron Al2O3. With increasing fillers loading thermal properties of the composites increases. But increased process is not linear, before the formation of thermal conductivity chain, the thermal conductivity increases slowly. Thermal performance is improved rapidly after the chain formed.About the fillers size, 10μm and 35μm are studied. The results show that composites with 10μm fillers have better thermal performance. The reasons for this phenomenon are explained by Agari equation. The two kinds of fillers are mixed in different proportion can be obtained conductivity higher than a single filler, and when the proportion is 1:1, thermal performance is best.In order to improve the interfacial properties between fillers and matrix, the fillers are treated by coupling agent KH-560. According to controlled trial, the best KH-560 concentration is 8%. After the fillers treated by KH-560 add in matrix, viscosity of the matrix becomes larger. Diluent is added in order to reduce the viscosity of the matrix and improve the dispersion of the fillers. The results show that the 40% diluent mass fraction is best.There are many factors affecting thermal conductivity of composite materials, in order to find the ratio of suitable solution and find mutual influence between various factors, this paper developed 5 factors and 5 levels orthogonal experiment table, a comprehensive analysis of orthogonal experiment to the above factors is presented. The best ratio is also got.The temperature resistance and high thermal conductivity composite material based on above best ratio is applied between adsorbent and simulation adsorber. Thermal contact resistance between them is calculated by least squares method. The resistance is compared with the one in literature, it can be reduced at least 52.6%.
Keywords/Search Tags:Adsorption refrigeration, Composite, Thermal contact resistance, Epoxy resin, Thermal conductivity
PDF Full Text Request
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