Experimental analysis of the thermohydraulic performance of graphene and silver nanofluids in automotive cooling systems

This paper presents an experimental investigation of the thermohydraulic performance of nanofluids, composed of graphene and silver nanoparticles with a binary mixture of equal parts of water and ethylene glycol (50:50 vol%) as a base fluid, in automotive radiators. The nanofluids were prepared by high pressure homogenization method with volumetric concentrations of 0.01%, 0.05% and 0.1%. The thermophysical properties were measured experimentally and compared with correlations and others results of similar research found in the literature. The nanofluids were tested in an automotive radiator installed in a wind tunnel, simulating the operation of an automotive cooling system. The experiments were conducted at mass flow rates between 0.08 and 0.11 kg/s, with coolant inlet temperatures between 55 and 85 degrees C. The air velocity on the radiator was kept constant at 2.1 m/s. The heat transfer rate and the pumping power of the fluids tested were determined under the test conditions stipulated. With regard to the pumping power at high temperatures and mass flow rates, the nanofluids showed increases up to 4.1%. The silver nanofluids produced an increase up to 4.4% in the heat transfer rate, while the graphene samples demonstrated a decrease in thermohydraulic performance when compared with the base fluid. (C) 2018 Elsevier Ltd. All rights reserved.