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采用两步法制配了Co-H_2O纳米流体,研究了在不同磁场强度下的纳米流体光热转换特性以及直接吸收式太阳能集热器的集热效率。实验结果表明:磁场可强化Co-H_2O纳米流体的光吸收性能,且最佳磁场强度为3×10~(-3)T。在3×10~(-3)T磁场强度的作用下:质量分数为0.1%、0.04%Co-H_2O纳米流体,相对于去离子水其最高温度分别提升了42.86%和39.5%,质量分数为0.1%Co-H_2O纳米流体,相对于去离子水和未加磁场时最大集热效率分别提高了51.70%和13.24%。上述结果表明磁场在磁性纳米流体光热转换特性方面具有强化促进作用。
Co-H_2O nanofluids were prepared by a two-step method. The properties of nanofluids under different magnetic field intensities and the heat-collecting efficiencies of direct-absorbing solar collectors were studied. The experimental results show that the magnetic field can enhance the optical absorption of Co-H_2O nanofluids, and the optimum magnetic field strength is 3 × 10 -3 T. Under the magnetic field strength of 3 × 10 ~ (-3) T, the maximum concentration of 0.04% Co-H_2O nanofluids increased by 42.86% and 39.5%, respectively, compared with that of deionized water. The mass fraction of Compared with deionized water and without magnetic field, the maximum heat-collection efficiency of 0.1% Co-H_2O nanofluids increased by 51.70% and 13.24% respectively. The above results show that the magnetic field has an enhancement effect on the photothermal conversion properties of the magnetic nanofluid.