Stability appraisement of the alumina-brine nanofluid in the presence of ionic and non-ionic disparents on the alumina nanoparticles surface as heat transfer fluids: Quantum mechanical study and Taguchi-optimized experimental analysis

Nanofluids stability is a key factor that influences the properties of nanofluids, and it is necessary to study and analyze the influential factors affecting the dispersion stability of nanofluids. Although numerous methods have been developed to evaluate the stability of nanofluids, stability assessment through quantum mechanical study has been largely overlooked and theoretical behaviors behind this enhancement remain to be elucidated. The present work focuses on achieving stabilization of Al2O3/brine nanofluids by adding three surfactants, including Sodium Dodecyl Sulfate (SDS), Triton X-100(TRI), and Cetyl pyridinium chloride (CPC) into the suspension of alumina nanoparticles, which surrounds nanoparticles through the particle surface. Quantum mechanical calculations performed to understand the stability conferred by the surfactants on the surface and heat transfer capability studied using Taguchi-optimized experimental analysis. An experimental investigation to quantify the combined effect of pH, volume fraction, sodium chloride concentration, and temperature, on the dispersion and thermal conductivity of Al2O3/brine nanofluid, revealed that the optimum value for the thermal conductivity is obtained mainly by controlling all parameters as well as surfactant type. The SDS and TRI surfactants on the surface of the alumina nanoparticles (NP) increased the particle dispersion and heat transfer as chain-like nanofluids, while the CPC enhanced the particle aggregation and formed flake-like nanofluids to form nanofluids with lower thermal conductivity. The DFT calculations revealed that the interaction energy between NP and SDS molecules was stronger over other surfactants. Further, NP/SDS system was the most stable configuration and had the most negative binding energy. The QTAIM analysis indicated that hydrogen bridge interactions favor the stability of the fluid-surfactant mixture as NP/SDS > NP/TRI > NP/CPC. [Display omitted] •Using DFT studies to predict NP/surfactant stability to prepare stable nanofluids.•Significant negative binding energies show the stability of NP/surfactants systems.•NP/SDS system is the most stable configuration and has the most negative binding energy.•NP/SDS system shows higher thermal conductivity with chain-like morphology.•The QTAIM surface analysis indicates NP/SDS > NP/TRI > NP/CPC as the system stability.