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采用两步法配制Cu-H2O纳米流体,对不同质量分数、粒径的Cu-H2O纳米流体和水作为平板太阳热水器的集热工质,测试其导热系数,并在相同太阳辐照下进行集热性能实验,研究平板集热器的集热效率、水箱中的水温与得热量。实验结果表明:纳米流体可明显提高水的导热性能。粒径为25 nm,质量分数为0.10%的Cu-H2O纳米流体集热效率比水的提高了23.83%,质量分数为0.20%的Cu-H2O纳米流体的集热效率反而低于0.10%的。粒径为50 nm的Cu-H2O纳米流体集热效率低于粒径为25 nm的。粒径为25 nm、质量分数为0.10%的纳米流体循环系统中最高水温与最高得热量相对于水作为工质分别提高了12.24%和24.52%。
Cu-H2O nanofluids were prepared by a two-step method. The Cu-H2O nanofluids with different mass fractions and particle sizes were used as the heat collecting medium for flat-panel solar water heaters. The thermal conductivities of Cu-H2O nanofluids were tested and tested under the same solar irradiation Thermal performance experiment, research collector heat collector efficiency, the water temperature in the tank and have calories. The experimental results show that nanofluids can significantly improve the thermal conductivity of water. The Cu-H2O nanofluid with particle size of 25 nm and mass fraction of 0.10% has a heat-gathering efficiency 23.83% higher than that of water and the Cu-H2O nanofluid with mass fraction of 0.20% has a heat-collection efficiency of less than 0.10%. The Cu-H2O nanofluids with a particle size of 50 nm have lower thermal efficiency than those with a particle size of 25 nm. The maximum water temperature and the highest calorific value of nanofluid circulation system with particle size of 25 nm and mass fraction of 0.10% increase by 12.24% and 24.52% respectively compared with that of water.