Cu-H_2O纳米流体平板太阳集热器集热性能研究

EXPERIMENTAL INVESTIGATION ON EFFICIENCY OF FLAT-PLATE SOLAR COLLECTORS WITH Cu-H_2O NANOFLUIDS

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%。

In this study, Cu-H2O nanofluids with different mass fraction and size were prepared through two-step method. Its thermal conductivities and the effect of Cu-HzO nanofluids on the efficiency of a flat-plate solar collector was investigated experimentally. Meanwhile, the water temperature and heat gain of the fiat-plate solar water heater were also investigated. The experimental results show that the thermal conductivities can enhanced observably. The efficiency of solar collector enhanced by 23.83% with using Cu-H2O nanofluids （25 nm, 0.10% ） as the absorbing medium. The effi ciency of Cu-H2O nanofluids （25 nm, 0.20% ） is lower than that of Cu-H2O nanofluids （25 nm, 0.10% ）. The instantaneous efficiency of solar collector decreas with increasing nanoparticle size. The highest temperature and highest heat gain of water in the nanofiuid（25 nm, 0.10% ） tank can increased up to 12.24% and 24.52% compared with water, respectively.