Experimental and molecular dynamic insights on the thermophysical properties for MWCNT-Phosphonium based eutectic thermal media

Abstract

In this study, a thermal media is synthesized by mixing hydrogen bond acceptor (HBA) [Methyltriphenylphosphonium bromide (MTPB)] salt with hydrogen bond donor (HBD) [ethylene glycol] at a molar ratio of 1:4. Thereafter the corresponding nanofluid was prepared by dispersing 0.02 wt% Multi-Walled Carbon Nanotube (MWCNT) having a diameter 10–30 nm in the base fluid. Prior to dispersion, the shape and morphology of the MWCNT were ascertained using both Field Emission Scanning Electron Microscope (FESEM) and Field Emission Transmission Electron Microscope (FETEM). The crystallinity and functional groups were investigated by X-ray Powder Diffraction meter (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). The stability of the prepared nanofluid was initially performed using visual observation followed by zeta potential measurements. Thermogravimetric analysis (TGA) was performed to check the stability of nanofluid at a temperature close to 500 °C at a heating rate of 10 °C/min under nitrogen environment. Thermophysical properties such as density, viscosity, thermal conductivity, and specific heat of nanofluid were measured in the temperature range 25–85 °C. It is evident from the experimental data that viscosity and density decrease with an increase in temperature. On the contrary, the specific heat and thermal conductivity of the nanofluid were found to increase with temperature. This is due to the induced Brownian motion of the nanoparticle, which results in higher kinetic energy at high temperature. In the penultimate section, Molecular Dynamic (MD) simulations were performed to compare and validate the results of thermal conductivity of nanofluid.