Chemically synthesized graphene nanofluids-infused propylene glycol-water mixtures for enhanced thermal energy transmission properties for high-temperature applications: Assessment and multiobjective optimisation using response surface methodology

The aim of the given study is to enhance the thermal energy transmission properties of propylene glycol (PG)-water mixture by adding chemically synthesized graphene nanopowder in concentrations of 0.25wt% and 0.50wt% into three ratios of the base fluids 100:0, 75:25 and 50:50. The aim of the research is to investigate the effect of graphene concentration and temperature to a maximum of 120°C on the thermal conductivity of the nanofluids and optimize the two variables through Response Surface Methodology (RSM). Ultrasonication was used to prepare nanofluids in order to provide good dispersion and thermal conductivity was measured experimentally through a KD2 Pro analyzer. The findings indicate that graphene can vastly increase thermal conductivity by 10-14% in all mixtures with the highest conductivity of 0.592W/mK in the mixture of 0.5wt percent graphene in 120°C water. The quadratic forms of RS models demonstrated a great predictive power with the R 2 of 0.9963, 0.9975, and 0.9916 of the three mixtures. The thermal conductivity values at 120°C and 0.5wt% graphene had been optimized as 0.551W/mK of PG (100:0), 0.569W/mK of PG-water (75:25) and 0.592W/mK of PG-water (50:50). These results affirm that the graphene-enriched PG-water nanofluids have better thermal characteristics and have significant possibilities of high temperature cooling and heat transfer use.