Thermo-rheological characterizaton of vegetal dielectric nanofluids doped with TiO₂ nanoparticles for application in power transformers

Four series of composite dielectric nanofluids were developed using a vegetable-based dielectric oil matrix doped with titanium dioxide (TiO₂) nanoparticles at concentrations of 0.5, 1.0, 3.0, and 5.0 wt%. The objective was to investigate the effects of nanoparticle content on the rheological, thermal, and colloidal stability properties of the nanofluids for potental use in electrical transformers. Rheological characterizaton was performed using amplitude and frequency sweep tests to determine viscosity, linear viscoelastic range (LVER), storage modulus (G′), and loss modulus (G″). The nanofluids exhibited concentration-dependent changes in viscoelastic behavior, revealing the influence of nanoparticle loading on flow and structural properties.
Dynamic light scattering (DLS) analysis was conducted to evaluate the polydispersity index, zeta potential, and particle size distribution, providing insights into nanoparticle dispersion and stability within the oil phase. These parameters are critical for ensuring long-term homogeneity and reliable performance under operational conditons. Additonally, the glass transition temperature (Tg) and melting temperature (Tm) of each formulation were determined to assess the thermal behavior of the nanofluids.
The combined rheological, thermal, and colloidal analysis supports the viability of TiO₂-based nanofluids as advanced insulating and heat-dissipating materials, offering promising potential for enhancing the performance and efficiency of dielectric fluids in high-voltage transformer applications.