纳米流体在内置扭带管的流动和传热特性研究

发布时间：2018-05-15 21:36

本文选题：纳米流体 + 传热　；参考：《东北电力大学》2015年硕士论文

【摘要】：纳米流体强化传热以及管内插入扭带强化传热已经成为应用广泛，技术比较成熟的强化传热技术。纳米流体的研究主要集中在：纳米流体体系的选择、纳米流体的制备及稳定性研究、纳米流体热导率影响因素及模型研究、纳米流体强化传热机理研究、纳米流体粘度测量及影响因素研究。而对纳米流体应用在强化管中的研究较少，于是本文通过理论验证及实验来研究纳米流体在内置扭带管表面传热特性及流动特性，首先对内置扭带管的强化因素进行理论计算分析，然后研究纳米流体稳定性与分散剂的关系，制备出稳定性最好的纳米流体，并测量其热导率，接着设计并建立一套纳米流体表面传热实验系统，Reynolds数（Re）在2000～7000的范围内，分别对质量分数为0.1%，0.3%和0.5%的不同纳米流体在扭转比H/d为3.5-5.5的内置扭带管中的传热特性进行实验研究。结果表明：随着Re增加，纳米流体和去离子水的沿程阻力系数f均减少；水的沿程阻力系数f小于纳米流体，纳米流体的质量分数与沿程阻力f成正比，内置扭带管的沿程阻力f大于光管，且随着扭转比的增大而减少，，三种纳米流体的沿程阻力系数f十分相近；Nusselt数（Nu）随Re和纳米颗粒质量分数的增大而增大；纳米流体的Nu比水高，内置扭带管的努谢尔数Nu大于光管，且随着扭转比的增大而减少，三种纳米流体相比，Cu-水纳米流体的Nu最大。质量分数为0.5%的Cu-水纳米流体在Y=3.5与Y=5.5的内置扭带管的增强幅度分别为2.29与2.14。
[Abstract]:Nano-fluid heat transfer enhancement and heat transfer enhancement by inserting torsion strip into tube have been widely used and the technology is relatively mature. The research of nano-fluid mainly focuses on the selection of nano-fluid system, the preparation and stability of nano-fluid, the influence factors and models of thermal conductivity of nano-fluid, the mechanism of heat transfer enhancement of nano-fluid. Study on viscosity Measurement and influencing factors of Nanofluids. However, there is little research on the application of nano-fluid in the strengthened tube, so the heat transfer and flow characteristics of nano-fluid on the surface of the inner torsion tube are studied by theoretical verification and experiment. Firstly, the strengthening factors of the inner torsion tube were calculated and analyzed theoretically, then the relationship between the stability of nano-fluid and dispersant was studied, the best stability of nano-fluid was prepared, and its thermal conductivity was measured. Then, an experimental system for surface heat transfer of nanoscale fluids is designed and built. The heat transfer characteristics of different nano-fluids with 0.1% and 0.5% mass fraction in a torsional tube with a torsional ratio of 3.5-5.5 are investigated in the range of 2000 ~ 7000, respectively. The results show that with the increase of re, the drag coefficient f of both nano-fluid and deionized water decreases, and the resistance coefficient f of water is smaller than that of nano-fluid, and the mass fraction of nano-fluid is proportional to the resistance f. The side resistance f of the inner torsion tube is larger than that of the light tube, and decreases with the increase of the torsion ratio. The resistance coefficient f is very close to the Nusselt number and Nu) of the three kinds of nanofluids increases with the increase of re and the mass fraction of the nanoparticles. The Nu of nanofluids is higher than that of water. The Nu number of the inner torsion tube is larger than that of the light tube, and decreases with the increase of the torsion ratio. The Nu of the three nanofluids is the largest compared with the Cu-water nanofluids. The reinforcements of Cu-water nanofluids with 0.5% mass fraction are 2.29 and 2.14 in the inner torsion tube of Yi 3.5 and Y 5. 5, respectively.
【学位授予单位】：东北电力大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TK124

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