Numerical investigation of high efficiency radiator cooling with nanofluids

Energy efficiency becomes more critical with the depletion of fossil energy resources. Heat management is aimed to be improved in many systems e.g., nuclear power plants, chip industry, and automotive sector. To increase the cooling efficiency, the two main solutions are increasing cooling surface area and improving fluid characteristics. However, it is not always possible to increase the dimensions of the coolers. New generation fluids (nanofluids) can be used to improve cooling performance. Thanks to the nanoparticles added to base fluids e.g., water, which have low thermal conductivities, nanofluids have improved heat transfer properties. In this thesis, thermal efficiency of nanofluid in flat tube geometry for a radiator system was numerically investigated. In this context, firstly, the analysis of the 1% to 7% volumetric concentrations of Al2O3 and CuO nanoparticles in the reference study in the range of 250-1750 Reynolds numbers was recalculated using ANSYS Fluent and solver was verified. The maximum difference between the thesis study and the reference study was 7.6% for 1% Al2O3/water ata Reynolds number of 500. In this analyzes performed, heat transfer behaviour was investigated for four different concentrations ranging from 0.079% to 0.27% of carbon-based graphene nanoplatelets (GNP) for laminar flow in a flat tube geometry, considering temperature-dependent thermo-physical properties and figure of merit(FOM) were calculated. As a result of the analysis, 0.27% GNP/water nanofluid in comparison to water, showed a 28.76% improvement in the average heat transfer coefficient. The study concluded that even at low concentrations, significant thermal improvements can be obtained.