Theoretical comparative assessment of single- and two-phase models for natural convection heat transfer of Fe3O4/ethylene glycol nanofluid in the presence of electric field

Natural convective heat transfer of Fe3O4/ethylene glycol nanofluids around the platinum wire as a heater in the absence and presence of the high electric field was investigated, numerically. The control volume finite element method was employed for the numerical simulation. Effects of the flow model, the volume fraction of nanoparticles, Rayleigh number, and the electric field intensity on the natural heat transfer coefficient (NHTC) of nanofluid were studied. Simulation results of single-phase and two-phase flow models showed that the two-phase model could better predict experimental data than the single-phase model due to take into account the velocity of each phase in the mixture. The two-phase model could predict a particular volume fraction of 0.02 vol%, which enhancement the volume fraction further that deteriorated heat transfer. Streamlines showed that, as the supplied voltage is increased, velocity vectors and buoyant force increase, and NHTC of nanofluid enhances. Isotherms also showed that the thickness of the thermal boundary layer decays for higher voltage of the electric field, and the natural heat transfer rate promotes. Local Nusselt number (Nu(theta)) changed as a function of angle around the hot wire. Nu(theta)increased with applying the electric field for all angles, and the highest Nu(theta)obtained at theta = 180 degrees (below the wire).

Automated summary

The natural convective heat transfer of Fe3O4/ethylene glycol nanofluids around a platinum wire heater was investigated numerically, with effects of various parameters and the influence of an electric field studied. Results showed that the two-phase flow model could better predict experimental data than the single-phase model, and increasing the volume fraction of nanoparticles beyond a certain point worsened heat transfer. Increasing voltage resulted in higher velocity vectors and buoyant force, enhancing the natural heat transfer coefficient of the nanofluid.