Effect of particle concentration on the stability of water-based SiO2 nanofluid

As an unconventional fluid medium, nanofluid has outstanding advantages in thermal conductivity and stability, which can not only be applied in the frontier field of engineering, but also bring technological innovation to the traditional manufacturing and construction industries. However, the water-based nanofluid has the problem of poor stability, leading to nanofluid failure and severely limiting the development of nanofluid. In this paper, the ‘Two-step method’ was used to prepare SiO2 nanofluid with mass fractions of 0.5%, 1.0%, and 1.5%. The stability of the SiO2 nanofluid was determined by four characterization methods: visual observation, absorbance test, viscosity test andsurface tension test. Finally, the three-stage time-varying process on stability of the water-based SiO2 nanofluid was proposed. The results showed that the initial stability of the nanofluid was worse with increasing concentration. This conclusion was in good agreement with the theoretical derivation. Moreover, the stability of the nanofluid still exhibited this characteristic in the period of 0–8 days. This study can provide useful information for revealing the nanofluidic stability theory and support the further development of nanofluid technologies