碳化物光热转换纳米流体的制备及其性能研究

发布时间：2018-04-02 04:14

  本文选题：光热转换　切入点：纳米流体　出处：《青岛科技大学》2017年硕士论文

【摘要】：化石能源危机与环境污染是目前最严重的世界性难题,寻找可替代化石能源的清洁能源是当务之急。其中太阳能获取容易、总量大、清洁安全、对环境友好,从而成为研究的重点。纳米流体在太阳能光热利用方面有非常好的前景,光热转换纳米流体的制备与性能研究对太阳能光热利用具有重要意义。本文通过分散法制备了ZrC/水纳米流体,借助XRD和TEM对Zr C纳米颗粒的组成、形貌进行了表征,通过沉降法研究了ZrC/水纳米流体的稳定性,搭建了光热转换性能测试装置,改进了光热转换效率的计算方法,研究了其光吸收、光热转换性能。结果表明:纳米流体经超声30分钟,PVP分散剂加入量为碳化锆质量的8-10%时稳定性最好;纳米流体的透过率随固含量增加而降低;当光程为1cm、固含量为0.02 wt%时太阳光几乎全吸收,太阳加权吸收系数Am达到0.99;太阳光模拟条件下,0.02 wt%ZrC纳米流体的最大温升为38.2℃,光热转换效率为92%。这种效率计算方法考虑了热量的散失,因而能更合理的评价纳米流体光热转换性能。通过研磨法制备了WC/水纳米流体,研究了分散剂种类、加入量对纳米流体稳定性的影响,研究了纳米流体的光吸收、光热转换性能。结果表明:选择2 wt%的PVA作为分散剂可以得到稳定的纳米流体;WC纳米流体的光吸收随固含量增加而增强,当光程为1 cm时,0.3 wt%WC纳米流体的Am为0.99;太阳光模拟条件下,固含量为0.3 wt%的WC纳米流体最大温升为39.5℃,光热转换效率为97%,是理想的太阳能吸收体。以WC纳米流体为光热转换介质搭建了太阳能水蒸发试验装置,利用纳米流体局部加热水蒸发提高太阳能利用率,通过增加纳米流体浓度来提高蒸发效率。和纯水整体蒸发相比,蒸发量、蒸发速率显著增大,使用0.3 wt%的WC纳米流体蒸发速率为1.53 kg·m-2·h-1;与纯水空白对照组相比,使用0.3 wt%的WC纳米流体蒸发效率增加23%,这为纳米流体在太阳能水蒸发及海水淡化领域提供新的思路。碳化锆和碳化钨纳米流体均表现出宽波段吸收特性,可以显著增强对太阳辐射的吸收,这些工作对光热转换纳米流体在太阳能利用领域的应用具有重要意义。
[Abstract]:The crisis of fossil energy and environmental pollution are the most serious problems in the world at present. It is urgent to find clean energy that can replace fossil energy. Among them, solar energy is easy to obtain, large amount of energy, clean and safe, and friendly to the environment. This has become the focus of research. Nanofluids have a very good prospect in solar photothermal utilization. The preparation and properties of photothermal conversion nanofluids are of great significance to the photothermal utilization of solar energy. In this paper, ZrC/ water nanofluids were prepared by dispersion method. The composition and morphology of ZrC nanoparticles were characterized by XRD and TEM. The stability of ZrC/ water nanofluids was studied by sedimentation method, the photothermal conversion performance test device was built, the calculation method of photothermal conversion efficiency was improved, and its optical absorption was studied. The results showed that the stability of nano-fluid was the best when the amount of PVP dispersant was 8-10% of the mass of zirconium carbide, and the transmittance of nano-fluid decreased with the increase of solid content. When the light path is 1 cm and the solid content is 0.02 wt%, the solar light absorption coefficient am is 0.99.The maximum temperature rise of 0.02 wt%ZrC nanoscale fluid is 38.2 鈩，

本文编号：1698734