Zheng Yuanzhou, Shahsavar Amin, Afrand Masoud
Hubei Key Laboratory of Inland Shipping Technology, Wuhan University of Technology, 588 Youyi Avenue, Wuhan, China; School of Navigation, Wuhan University of Technology, 588 Youyi Avenue, Wuhan, China.
Department of Mechanical Engineering, Kermanshah University of Technology, Kermanshah, Iran.
Ultrason Sonochem. 2020 Jun;64:105004. doi: 10.1016/j.ultsonch.2020.105004. Epub 2020 Mar 3.
In this study, the duration of sonication efficacy on the thermal conductivity of FeO-liquid paraffin nanofluid is investigated. The nanofluid is produced at 0.005, 0.01, 0.015, 0.02, 0.025 and 0.03 vol concentrations by applying two-step method. The sonication process is performed in a temperature range of 20-90 °C. The duration of sonication seems to have two important effects: On the one hand, increasing the duration of sonication breaks the nanoparticles clusters, hence distributes the nanoparticles more uniformly which in turn rises thermal conductivity. On the other hand, an excessive increase in the duration of sonication can impair nanofluid stability. The results of experimental tests proved that the optimal duration of sonication is 3 h. The optimal duration of sonication is not dependent on the nanoparticles volume fraction (φ) and temperature. It was found that at the highest temperature and φ (90 °C,0.03), the greatest thermal conductivity enhancement (28.49%) is obtained. In contrast, at the lowest temperature and φ (20 °C,0.005) the lowest thermal conductivity enhancement was obtained (2.82%).
在本研究中，对超声处理对FeO-液体石蜡纳米流体热导率的有效时长进行了研究。采用两步法制备了体积浓度分别为0.005、0.01、0.015、0.02、0.025和0.03的纳米流体。超声处理过程在20-90°C的温度范围内进行。超声处理时长似乎有两个重要影响：一方面，延长超声处理时长会破坏纳米颗粒团簇，从而使纳米颗粒分布更均匀，进而提高热导率。另一方面，超声处理时长过度增加会损害纳米流体的稳定性。实验测试结果证明，超声处理的最佳时长为3小时。超声处理的最佳时长不依赖于纳米颗粒体积分数（φ）和温度。结果发现，在最高温度和φ（90°C，0.03）时，热导率提高幅度最大（28.49%）。相反，在最低温度和φ（20°C，0.005）时，热导率提高幅度最小（2.82%）。
