Cooling nanofluids based on graphene oxide for thermal engines

The article presents the results of experimental studies of the thermal conductivity, heat capacity, viscosity and density of cooling “nanofluids” which represent a two-phase mixture of aqueous solution of ethylene glycol and nanoparticles of graphene oxide. Graphene oxide, which is a multi-graphene laminate compound with covalently bound oxygen with a number of layers from 1 to 10, was obtained by ultrasonic exfoliation of graphite oxide. The known theoretical models for the thermal conductivity and viscosity of two-phase nanofluids may not coincide with the experimental data, which makes it difficult to use these models to predict the properties of the nanofluids being created. The effect of graphene oxide particles concentration and the nanofluids temperature on their thermal conductivity, heat capacity, viscosity and density is shown. When choosing among existing or while creating and investigating new cooling liquids, it is advisable to compare not only their individual physical properties (for example, thermal conductivity or viscosity), but the entire complex of their features (thermal conductivity, viscosity, heat capacity, density) that determines their “cooling” properties, called the cooling complex. A quantitative evaluation of the water and antifreeze cooling complex and the investigated nanofluid has been presented. Differences in nanoparticle obtaining technologies, in their sizes, shapes, concentrations, and physical properties of base liquids affected the thermal conductivity, heat capacity, viscosity and density of cooling nanofluids and, as a consequence, the heat transfer coefficient. The obtained results of the measurement of the thermal conductivity coefficient, viscosity, heat capacity, and density of the cooling nanofluid allowed us to reasonably approach experimental studies of the heat transfer between the heated wall of the part and the cooling fluid at different coolant velocities, pressures, temperatures and concentrations of nanoparticles.

cooling nanofluid, graphene oxide, heat conductivity, heat capacity, viscosity, density, cooling complex

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