Prediction of electrical conductivity of TiO2 water and ethylene glycol-based nanofluids for cooling application in low temperature PEM fuel cells

TiO2 nanofluids with water-ethylene glycol (EG) as base fluid can be used as coolants in proton exchange membrane (PEM) fuel cells. The high electrical conductivity of these nanofluids can potentially suppress the electrical performance of PEM fuel cells. Hence, it is important to accurately predict their electrical conductivity before considering them for use in fuel cells. TiO2 nanofluids with 0.05-0.5 vol% concentrations (as suggested by earlier studies) were selected to study their electrical conductivity experimentally in the range of 20-70 ˚C (i.e. operating condition of a PEM fuel cell). Increasing TiO2 nanoparticles concentration causes the electrical conductivity of the nanofluid to increase such that with 0.5 vol% concentration at 60 ˚C, the electrical conductivity was found to be over 9 times more than that for the base fluid. However, the existing models cannot predict this accurately. Moreover, while not supported by experimental data, standard correlations for the electrical conductivity of nanofluids are not temperature dependent. This data was then used to develop a new correlation for estimating the electrical conductivity of TiO2 nanofluids at different concentrations and temperatures in ranges suitable use as coolants in PEM fuel cells.