Usefulness of adding magnetic nano-powders to water: Introducing novel criteria for assessing heat transfer applications

Wang, Haiyang; Liang, Miaomiao; He, Zemin; Kang, Xiaoxi; Zhao, Yang; Zhao, Yuzhen

Usefulness of adding magnetic nano-powders to water: Introducing novel criteria for assessing heat transfer applications

2021

In this study, the usefulness of adding Fe₃O₄ nanoparticles to water was considered, taking into account the energy demand management. Based on experimental measurements, an increase of 90% and 130% in thermal conductivity and viscosity has been experienced owing to loading Fe₃O₄. The nanofluid advantage over base fluid is assessed by evaluating the figure of merit (FOM) proposed by various researchers. Taking into account the Prasher, Garj, Lee and Timofeeva criterion, the use of Fe₃O₄/water nanofluid is acceptable. According to Tesfai criterion, up to 1 vol%, utilizing Fe₃O₄/water nanofluid has priority over the base fluid. A novel criterion was derived for assessing the heat transfer potential in a smooth tube subjected to constant surface temperature. It was found that the heat transfer potential depends on the number of transfer units (NTU). For NTU > 5, loading nanoparticles decreased the heat transfer potential up to 11% owing to a decrease in specific heat.

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