Percolation theory at work – boosting the heat transfer performance of graphitic nanofluids

E.V. Timofeeva, D. Singh, W. Yu, D. France
Argonne National Laboratory, US

Keywords: nanofluids, nanosheet graphite, percolation theory, thermal conductivity, viscosity, heat transfer coefficient


A plethora of studies have reported high thermal conductivity of nanofluids with high aspect ratio carbon nanoparticles such as graphenes and carbon nanotubes. Although many repot thermal conductivity enhancements in carbonaceous nanofluids there is no agreement on the concentration effect of such nanomaterial additives. We have investigated the effects of nanoparticle morphology and surface treatment on the thermo-physical properties of nanofluids with graphitic nanomaterials in EG/H2O base fluid. The results have demonstrated that nanoparticle morphology along with surface treatment and concentration needs to be considered in formulation of graphitic nanofluids to achieve advanced heat transfer coefficients. Adjusting the nanoparticle concentration to the percolation threshold allows closing the gap between high thermal conductivity and advanced heat transfer in graphitic nanofluids. Using simple, low cost, and up-scalable surface modification method for graphitic nanoparticles we were able to formulate the nanofluid coolant with advanced combination of properties that allows 70+% improvement in heat transfer coefficient when used in laminar flow and 30+% enhancements in heat transfer coefficient when used in turbulent flow. The implementation of this technology in HEV’s and EV’s will result in reducing the size, weight and number of heat exchangers and improving overall vehicle efficiency.