基于水基SiO_2纳米流体PV/T系统辐射性能研究

Study on radiation characteristics of PV/T system based on water-based SiO_2 nanofluids

为研究辐射在水基SiO_2纳米流体PV/T系统的传递特性,用两步法制备不同的水基SiO_2纳米流体。利用分光分度仪测试不同工质在不同光程和体积分数下的透射率,结合Mie和Rayleigh散射理论建立系统的辐射传递模型,同时对该系统进行了实验测试。结果表明:水基SiO_2纳米流体对光电可用辐射有高透过性,对低频辐射有高吸收性,与Si-PV光伏响应曲线基本匹配;当流体体积分数小于0.5%时,透射率实验值与理论值吻合度好;当光程大于10 mm时,90%的低频辐射被工质吸收,低于80%的光电可利用辐射传递到Si-PV表面;以水基SiO_2纳米流体作为PV/T辐射分频工质,可有效降低Si-PV的温升速率,且其光热总效率可达75%以上。

In order to study the transmission characteristics of radiation in water-based SiO_2 nanofluids PV/T system, various water-based SiO_2 nanofluids were prepared by two-step method.The transmittance of different nanofluids under various optical spacing was measured by spectrophotometer. The radiation transfer model of the system was established by combining Mie and Rayleigh scattering theory. Results show that the water-based SiO_2 nanofluids are highly permeable to the available radiation of the photo-electricity, and the low-frequency radiation is highly absorbed, which is perfectly matched with the Si-PV Spectral response curve. When the volume fraction is less than 0.5%, the transmittance is in good agreement with the theoretical value. When the optical path is more than 10 mm, 90% of the low frequency radiation is absorbed by the nanofluids, and less than 80% of the photoelectric radiation can be transmitted to Si-PV surface.The water-based SiO_2 nanofluids are used as PV/T radiation splitting filter. it is useful to reduce the temperature of Si-PV, and its total thermal efficiency is more than 75%.