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  本文關鍵詞： 細通道 納米流體 傳熱 綜合性能 實驗　出處：《廣西大學》2017年碩士論文　論文類型：學位論文

【摘要】：隨著集成技術的提高,化工、食品等行業(yè)的過程設備越來越趨于小型化。小型化設備會導致熱流密度的增加,因此必須配以尺寸合適、質量輕盈、效率高的傳熱裝置以滿足這一變化。彎曲微細通道內因流體流動會產生強化傳熱的二次流而廣泛應用于傳熱設備中。此外,采用高傳熱系數的納米流體替代傳統傳熱工質也是進一步增強微小型換熱器換熱性能的有效方法。本文采用實驗方法研究了 2種細通道夾套內不同流體工質的傳熱和流動特性。實驗工質為有無分散劑添加的質量濃度為0.05%和0.1%的Ti02—去離子水納米流體及基液工質。通過對比分析納米顆粒質量濃度和有無分散劑添加對彎曲細通道夾套傳熱和流動特性的影響。此外,在每種納米流體實驗后對實驗回路和夾套清洗前后分別采用去離子水進行重復性實驗得到相關數據與基液進行對比分析。結果表明:1)對于螺旋細通道夾套而言,表面摩擦系數f值隨著質量濃度的提高而增加,分散劑能有效提高摩擦系數;傳熱方面,質量濃度為0.05%有分散劑添加的納米流體的傳熱性能最好,而質量濃度為0.05%無分散劑添加的納米流體傳熱性能較差。但對濃度0.1%的2種納米流體而言,其平均Nu數差別不大;重復性實驗測得的平均Nu數與表面摩擦系數f均高于基液,且清洗后實驗測得的平均Nu數與表面摩擦系數f均高于清洗前。納米流體中質量濃度為0.05%有分散劑添加的納米流體的綜合性能最好,在質量濃度0.1%納米流體實驗后清洗實驗回路和夾套進行的重復性實驗的綜合性能最好。2)對于周向平行彎曲細通道夾套而言,分散劑會提高納米流體的進出口壓降和平均Nu數,但納米流體無論有無分散劑添加,實驗測得的平均Nu數均都不大于基液;重復性實驗測得的進出口壓降和平均Nu數均是清洗后大于清洗前,但是進出口壓降均大于基液,而Nu數均小于基液;質量濃度為0.05%有分散劑添加的納米流體的綜合性能最好,而在質量濃度0.05%納米流體實驗后清洗實驗回路和夾套進行的重復性實驗的綜合性能最好。根據實驗數據分別對2種細通道夾套的表面摩擦系數f、平均Nu數擬合了經驗公式。
[Abstract]:With the improvement of integration technology, process equipment in chemical, food and other industries is becoming more and more miniaturized. Miniaturization equipment will lead to an increase in heat flux, so it must be matched with appropriate size and light quality. Efficient heat transfer devices are widely used in heat transfer equipment due to the secondary flow of fluid flow, which enhances heat transfer, in curved microchannels. It is also an effective method to improve the heat transfer performance of micro heat exchanger by using nanometer fluid with high heat transfer coefficient instead of traditional heat transfer medium. In this paper, two kinds of fluid working fluids in the jacket of fine channel are studied experimentally. Heat transfer and flow characteristics. Experimental fluids for Ti02-deionized water Nanofluids with or without dispersants of 0.05% and 0.1% mass concentrations and working fluids for base solution. The bending effect of nano-particle mass concentration and dispersant added or not is analyzed by comparison and analysis. Effects of heat transfer and flow characteristics of fine channel jackets; in addition, After each kind of nanoscale fluid experiment, the experimental loop and jacket were tested with deionized water before and after cleaning, and the relative data were compared with the base solution. The results showed that: 1) for the spiral fine channel jacket, The surface friction coefficient f increases with the increase of mass concentration, and dispersant can effectively increase the friction coefficient. In heat transfer, the heat transfer performance of nano-fluid with mass concentration of 0.05% dispersant is the best. However, the average Nu number of the two nano-fluids with concentration 0.1% is not different, the average Nu number and the surface friction coefficient f measured by repetitive experiments are higher than those of the base solution, while the heat transfer performance of the nano-fluid with mass concentration of 0.05% dispersant is poor, but the average Nu number of the two kinds of nano-fluids with 0.1% concentration is not different from that of the base solution. After cleaning, the average Nu number and the surface friction coefficient f were higher than those before cleaning. The nano-fluid with 0.05% mass concentration and dispersant had the best comprehensive properties, and the average Nu number and the surface friction coefficient f were higher than those before cleaning. After the mass concentration 0.1% nanoscale fluid experiment, the comprehensive performance of the cleaning test loop and the jacket was the best. 2) for the circumferential parallel bending fine channel jacket, the dispersant could increase the pressure drop and the average Nu number of the nano-fluid inlet and outlet. However, the average number of Nu measured by experiments was not larger than that of base solution, and the pressure drop of inlet and outlet and the average number of Nu measured by repetitive experiments were higher than those before cleaning, but the pressure drop of inlet and outlet was larger than that of base liquid. The Nu number is smaller than the base solution, and the nano-fluid with dispersant 0.05% has the best comprehensive properties. The experimental loop and jacket have the best comprehensive performance after the mass concentration 0.05% nanoscale fluid experiment. According to the experimental data, the surface friction coefficient f and the average Nu number of the two kinds of fine channel jackets are fitted with the empirical formula.
【學位授予單位】：廣西大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TB383.1

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