导热油基纳米流体的制备与物理性能研究

发布时间：2018-04-06 20:24

本文选题：导热油　切入点：纳米流体　出处：《济南大学》2015年硕士论文

【摘要】：导热油作为太阳能光热发电系统的主要传热工质,越来越受到人们的关注,提高导热油的传热效率成为人们研究的重点。纳米流体的诞生,促进了传热工质传热效率的提高。将纳米颗粒添加到导热油中制备导热油基纳米流体,能够有效的改善导热油的传热性能。本文以导热油基的Al2O3纳米流体和SiO2纳米流体为研究对象,确定了制备Al2O3/导热油纳米流体和SiO2/导热油纳米流体的最佳制备工艺参数,在此基础上对所制备的纳米流体的物理性能进行测量和分析。本课题的研究不仅为进一步提高导热油基的传热效率提供一些实验数据,而且也进一步为纳米流体应用于太阳能光热发电系统提供参考依据,这在太阳能光热发电系统的工程应用和学术理论方面都有着一定的重大意义。论文的主要研究内容如下：1.为了解决纳米流体的悬浮稳定性,采用L9(34)正交试验进行分析,选取油酸用量、硬脂酸用量、磁力搅拌时间、超声振动时间为四个影响因素,每个因素选取三个水平,得出最佳制备工艺参数为：油酸用量为30%,硬脂酸用量为5%,磁力搅拌时间为45mm,超声振动时间为10min。采用最佳制备工艺参数制备了不同粒径、不同体积分数的Al2O3/导热油纳米流体和SiO2/导热油纳米流体。2.实验对所制备的Al2O3/导热油纳米流体和SiO2/导热油纳米流体的导热系数进行测量,分析了温度、体积分数以及纳米颗粒粒径对导热油基纳米流体导热系数的影响,并采用传统理论模型对导热油基纳米流体的导热系数比进行计算,结果发现,Al2O3/导热油纳米流体的导热系数最大增大率为19.49%,SiO2/导热油纳米流体的导热系数最大增大率为15.25%。3.对导热油基纳米流体的粘度进行了系统的分析,研究了颗粒体积浓度、颗粒粒径、温度对纳米流体粘度的影响,通过实验及理论分析得出,温度由25℃升高到65℃,体积分数为0.2%的Al2O3(30nm)/导热油、SiO2(30nm)/导热油纳米流体分别减小了74.96%、76.89%；在测量温度为25℃条件下,体积分数由0.1%增大到1.0%时,Al2O3/导热油和SiO2/导热油纳米流体的粘度最大增大了17.34%和25.37%;粒径对导热油基纳米流体的粘度均有不同程度的影响,但是规律不明显。4.对导热油基纳米流体的润湿性进行了实验与理论分析,通过表面张力和接触角两个方面对润湿性进行了分析研究,结果发现,所制备的Al2O3/导热油纳米流体和SiO2/导热油纳米流体的接触角均小于导热油的接触角,纳米流体的表面张力均大于导热油的表面张力,纳米流体的润湿性均优于导热油。5.建立了一套模拟光热实验所用的测试装置,对所制备的Al2O3/导热油纳米流体和SiO2/导热油纳米流体的光热特性进行了实验研究,此外,对导热油和纳米流体的辐射换热进行计算分析,进一步通过光吸收性能和光热转换效率对实验结果进行分析,结果显示,添加纳米颗粒可以明显提高光热性能,在本实验中体积分数为0.2%和0.5%的导热油基纳米流体的光热性能较好。
[Abstract]:The main oil as heat transfer medium in solar thermal power generation system, more and more attention, improve the heat transfer efficiency of heat transfer oil become the focus of the study. The birth of nanofluids, heat transfer is enhanced heat transfer efficiency. The nano particles are added to the preparation of oil based nano fluid for heat conducting oil, can improve the heat transfer performance of heat conducting oil effectively. The heat conducting oil based Al2O3 and SiO2 nanofluids as the research object, the preparation of Al2O3/ oil Nanofluids and SiO2/ oil nanofluids optimal preparation parameters, were measured and analyzed on the basis of the nanofluids prepared by physical performance. This research not only provides some experimental data to further improve the heat transfer efficiency of heat conducting oil based, but also for the further application of nano fluid in solar thermal power generation system Provide reference, in the solar thermal power generation system in engineering application and academic theory is of great significance. The main research contents of this paper are as follows: 1. in order to solve the suspension stability of nanofluids, using L9 (34) analysis of orthogonal test, selecting the amount of stearic acid, oleic acid dosage, stirring time, vibration the time of ultrasonic to the four factors, each factor selected from three levels, the optimum preparation process parameters: oleic acid 30%, stearic acid content is 5%, stirring time was 45mm, ultrasonic time is 10min. the best preparation process parameters were prepared with different particle size, thermal conductivity of different volume fraction Al2O3/ oil Nanofluids and SiO2/ oil nanofluids.2. experiment of the prepared Al2O3/ oil nanofluid and SiO2/ oil nanofluids were measured, analyzed the temperature, body Integral number and particle size effects on thermal oil nanofluids thermal conductivity, and thermal conductivity of heat conducting oil nanofluids ratio was calculated, using the traditional theoretical model results show that the Al2O3/ oil nanofluid thermal conductivity maximum increase rate of 19.49%, SiO2/ oil nanofluid thermal conductivity maximum increase rate systematic analysis for 15.25%.3. of oil based nano fluid viscosity, the particle volume concentration, particle size, influence of temperature on viscosity, through experiment and theoretical analysis shows that the temperature from 25 degrees rise to 65 DEG C, 0.2% volume fraction of Al2O3 (30nm) / oil SiO2 (30nm) / oil nanofluids were decreased by 74.96%, 76.89%; in the measurement of the temperature is 25 DEG C under the condition of volume fraction increases from 0.1% to 1%, Al2O3/ oil and SiO2/ oil nano fluid viscosity most A large increase by 17.34% and 25.37%; particle size on the thermal oil based nano fluid viscosity have different degrees of influence, but not obvious regularity of.4. wettability on thermal oil nanofluids by experiment and theoretical analysis, the surface tension and contact angle of the two aspects of the wettability were studied. The results showed that and the prepared Al2O3/ oil nanofluid and SiO2/ oil nanofluid contact angle is less than the thermal oil contact angle and surface tension of nanofluids were greater than the heat conducting oil wettability of nanofluids are better than that of.5. thermal oil testing device has been set up by a simulation experiment of the thermal, thermal the characteristics of the prepared Al2O3/ oil nanofluid and SiO2/ oil nanofluids were studied. In addition, the radiation of heat conducting oil and nano fluid heat transfer calculation and analysis, further through the light The absorption and photothermal conversion efficiency of the experimental results were analyzed. The results showed that nano particles can significantly improve the photothermal properties. In this experiment, the thermal conductivity of the heat conducting oil based nanofluids with volume fraction of 0.2% and 0.5% is better.

【学位授予单位】：济南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1

【相似文献】