Electrical and Thermal Conductivities of 50/50 Water-ethylene Glycol Based TiO2 Nanofluids to be Used as Coolants in PEM Fuel Cells

Both thermal and electrical conductivities of nanofluids are the key parameters to be optimized for making nanofluids suitable for use as coolants in electrically active thermal applications such as fuel cells. Although nanofluids are considered to be the potential solutions as coolants for Proton Exchange Membrane (PEM) fuel cells, their high electrical conductivity is seen as a challenge in their applications. This study investigates theoretically and experimentally the electrical and thermal conductivities of 50/50 water-ethylene glycol based TiO2 nanofluids with nanoparticle concentrations in the range of 0.05-0.5 vol%. Though Maxwell model predicts decrease of electrical conductivity with increase of nanoparticle concentrations, an enormous increase of electrical conductivity (∼ 900% with 0.5 vol% at 70 °C) has been observed compared with that of the base fluid. This experimental result indicates that the Maxwell model is unable to predict the electrical conductivity of nanofluids. On the other hand, the thermal conductivity increases with the increase of concentration of nanoparticles. With 0.5 vol% nanoparticle concentration, the thermal conductivity increased by just over 10% compared to the base fluid.