Enhanced Photothermal Conversion Properties of Magnetic Nanofluids through Rotating Magnetic Field for Direct Absorption Solar Collector
writer：Debing Wang, Yanlin Jia, Yan He*, Lingling Wang, Jinghong Fan, Huaqing Xie, WeiYu*
keywords：Magnetic nanofluids, Photothermal conversion efficiency, External rotating magnetic field, Direct absorption solar collector
source：期刊
specific source：Journal of Colloid and Interface Science, Volume 557, 1 December 2019, Pages 266-275
Issue time：2019年
The direct absorption solar collector (DASCs) with nanofluids can remarkably improve the utilization efficiency of solar energy. However, in the actual applications, the temperature distribution of the receiver is extremely uneven when the concentration of nanofluids is high or the receiver is deep. This makes the temperature of upper layer much higher than that of the lower layer, resulting in much heat loss to the surrounding by convection. Here, we propose a magnetic forced convection nanofluids absorption system, where an external rotating magnetic field is used to change the heat transfer mechanism of working fluids from traditional heat conduction to the thermal convection. It is found that the photothermal conversion efficiency of FeNi/C-EG nanofluids is up to 58.1% in this system, which is 22.7% higher than non-external rotating magnetic field when the nanofluids concentration is 50 ppm. Furthermore, the agglomeration of nanofluids can be effectively reduced by an external rotating magnetic field.