太阳集热管纳米流体的光热性能实验

摘要

采用两步法制备SiC-H2O、TiC-H2O、Al2O3-H2O（α和γ）4种纳米流体，通过闷晒实验研究了4种纳米流体的光热转换性能，分析了颗粒种类、质量分数、分散剂、pH值、颗粒形状对纳米流体光热转换性能的影响，并且对比了普通玻璃管内纳米流体与全玻璃真空管内水的集热性能。实验结果表明，纳米流体的光热转换性能优于去离子水和全玻璃真空管，其中TiC-H2O纳米流体的光热转换性能最好，最高温度比水高出21.76%；分散剂能增强纳米流体的光热转换性能，并且不同纳米流体最适合的分散剂也不同；纳米流体存在其最佳的质量分数和pH值，其中SiC-H2O最适宜的质量分数为0.1%，最佳pH值为9；粒子形状对光热转换性能有较大影响。在55℃以下，SiC-H2O纳米流体直接吸收式集热效率高于全玻璃真空管内水的间接吸收集热效率，两者效率的最高差值可达30%。但在更高温度下，纳米流体集热效率迅速下降。%In this article,SiC-H2O,TiC-H2O,and Al2O3-H2O (α andγ) nanofluid were prepared through a two-step method,and the photo-thermal properties of the four nanofluids were studied by an insolation experiment. The impacts of the types of the nanoparticle,mass fraction,dispersants,pH value and particle shapes on photo-thermal properties of nanofluid were investigated. This study also compared the photo-thermal properties of nanofluid in ordinary glass tube and water in all-glass vacuum tube. The results show that photo-thermal properties of nanofluid are better than those of deionized water and all-glass vacuum tube.Among the nanofulids,the performance of TiC-H2O nanofluid is the best,with the peak temperature of 21.76% higher than that of deionized water. Dispersants can enhance the photo-thermal properties of nanofluid,but,each nanofluid has its own suitable dispersants. The optimal mass fraction and pH value are found in this experiment,and those for SiC-H2O are 0.1%(mass fraction) and 9,respectively. The shape of particle also has a major impact on the photo-thermal properties of nanofluid.Under the 55℃,direct absorption collecting efficiency using SiC-H2O nanofluid is higher than that of traditional all-glass vacuum tube using water,the maximal efficiency difference between the two collectors can be up to 30%,but the efficiency for nanofulids decreases rapidly at higher temperature.