细通道夹套内纳米流体强化传热实验研究

发布时间：2018-02-12 21:03

本文关键词： 细通道纳米流体传热综合性能实验　出处：《广西大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着集成技术的提高,化工、食品等行业的过程设备越来越趋于小型化。小型化设备会导致热流密度的增加,因此必须配以尺寸合适、质量轻盈、效率高的传热装置以满足这一变化。弯曲微细通道内因流体流动会产生强化传热的二次流而广泛应用于传热设备中。此外,采用高传热系数的纳米流体替代传统传热工质也是进一步增强微小型换热器换热性能的有效方法。本文采用实验方法研究了 2种细通道夹套内不同流体工质的传热和流动特性。实验工质为有无分散剂添加的质量浓度为0.05%和0.1%的Ti02—去离子水纳米流体及基液工质。通过对比分析纳米颗粒质量浓度和有无分散剂添加对弯曲细通道夹套传热和流动特性的影响。此外,在每种纳米流体实验后对实验回路和夹套清洗前后分别采用去离子水进行重复性实验得到相关数据与基液进行对比分析。结果表明:1)对于螺旋细通道夹套而言,表面摩擦系数f值随着质量浓度的提高而增加,分散剂能有效提高摩擦系数;传热方面,质量浓度为0.05%有分散剂添加的纳米流体的传热性能最好,而质量浓度为0.05%无分散剂添加的纳米流体传热性能较差。但对浓度0.1%的2种纳米流体而言,其平均Nu数差别不大;重复性实验测得的平均Nu数与表面摩擦系数f均高于基液,且清洗后实验测得的平均Nu数与表面摩擦系数f均高于清洗前。纳米流体中质量浓度为0.05%有分散剂添加的纳米流体的综合性能最好,在质量浓度0.1%纳米流体实验后清洗实验回路和夹套进行的重复性实验的综合性能最好。2)对于周向平行弯曲细通道夹套而言,分散剂会提高纳米流体的进出口压降和平均Nu数,但纳米流体无论有无分散剂添加,实验测得的平均Nu数均都不大于基液;重复性实验测得的进出口压降和平均Nu数均是清洗后大于清洗前,但是进出口压降均大于基液,而Nu数均小于基液;质量浓度为0.05%有分散剂添加的纳米流体的综合性能最好,而在质量浓度0.05%纳米流体实验后清洗实验回路和夹套进行的重复性实验的综合性能最好。根据实验数据分别对2种细通道夹套的表面摩擦系数f、平均Nu数拟合了经验公式。
[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.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1

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