ABSTRACT This study examines the effects of nanoparticle concentration, magnetic field frequency, and carrier fluid viscosity on the induction heating response of nanofluids exposed to an alternating magnetic field. Uncapped iron-oxide nanoparticles with a mean diameter 14.42 nm were sonically dispersed into mixtures of deionized water and ethylene glycol (WEG) as well as highly viscous oil blends. The resulting nanofluids were exposed to an alternating magnetic field with a strength of 72.6 kA/m at frequencies of 217, 303, and 397 kHz with the heating response characterized calorimetrically through the specific absorption rate (SAR). Concentration and frequency effects mirror those found in literature with SAR reduction and enhancement, respectively. Additionally, SAR output is characterized across a wide range of viscosities showing a consistent decrease in heating output as viscosity increases through the WEG regime, however, the SAR was found to be relatively consistent across the oil blends. The effects of particle aggregation were measured through dynamic light scattering denoting particle clustering as a function of viscosity. Viscosity trends with SAR are accounted for by the viscous inhibition of particles reducing their Brownian heating, as well as clustering effects potentially inhibiting heat production in the low viscosity range where aggregation is pronounced. Lastly, a model predicting the Brownian contribution to heating as a function of frequency, concentration, and viscosity is proposed. This study provides a broad view of the effects on heating output for suspensions of commercially available iron oxide nanoparticles for several concentrations and field frequencies across an expansive range of viscosity.

中文翻译：

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氧化铁纳米粒子在不同粘性介质中的感应加热响应，并预测布朗加热贡献

摘要 本研究考察了纳米粒子浓度、磁场频率和载液粘度对暴露于交变磁场的纳米流体的感应加热响应的影响。平均直径为 14.42 nm 的未封端氧化铁纳米颗粒被声波分散到去离子水和乙二醇 (WEG) 的混合物以及高粘度油混合物中。所得纳米流体暴露于强度为 72.6 kA/m、频率为 217、303 和 397 kHz 的交变磁场中，其加热响应通过比吸收率 (SAR) 进行量热表征。浓度和频率效应分别反映了文献中发现的 SAR 降低和增强。此外，SAR 输出在很宽的粘度范围内具有特征，表明随着粘度在 WEG 范围内增加，加热输出持续降低，然而，发现 SAR 在整个油混合物中相对一致。通过动态光散射测量颗粒聚集的影响，将颗粒聚集表示为粘度的函数。SAR 的粘度趋势是由于颗粒的粘性抑制降低了它们的布朗加热，以及聚集效应可能抑制在聚集明显的低粘度范围内产生热量。最后，提出了一种预测布朗对加热的贡献作为频率、浓度和粘度的函数的模型。