Preparation and characterization of tio2-mwcnt hybrid and tio2-fe2o3-mwcnt trihybrid nanofluids
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Date
2025
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University of the Western Cape
Abstract
Over the past few decades, numerous studies have been conducted by the research community on the investigation of the cooling properties of nanofluids compared to those of the conventional heat transfer fluids, such as mineral oil, water, engine oil, and ethylene glycol. The literature indicates that many studies have been conducted on mononanofluids and hybrid nanofluids, but studies on trihybrid nanofluids remain limited. Recently, trihybrid nanofluids have emerged as a new class of nanofluids with enhanced thermophysical properties relative to mono and hybrid nanofluids. The aim of this study was to formulate stable hybrid and trihybrid nanofluids and perform a comparative analysis of their stability and thermophysical properties. Prior to nanofluids preparation, the nanoparticles were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS) to study the structural properties, morphology, particle size distribution, and the elemental composition of nanoparticles. Ternary (TiO2-α-Fe2O3-MWCNT) and binary (TiO2-MWCNT) nanoparticles were suspended in deionized water (DIW) at a constant volume concentration of 0.1 vol.% with composition ratios of 15:80:5, 10:80:10, and 5:80:15 for trihybrid and 80:20 and 20:80 for hybrid nanofluids. The stability of THNFs and HNFs was improved by optimizing critical formulation parameters such as nanoparticle composition ratio, dispersion fraction, and sonication time. The stability of nanofluids was assessed via visual inspection, UV-Vis spectroscopy, and pH measurements. The thermophysical properties of THNFs and HNFs(thermal conductivity (κ), viscosity (µ), and electrical conductivity (λ)) were measured using standard instruments. THNFs exhibited enhanced colloidal stability compared to HNFs, indicating improved nanoparticle dispersion and reduced sedimentation. Among THNFs, sample C (TiO2α-Fe2O3-MWCNT) 5:80:15 demonstrated the highest performance, with κ enhanced by 8.97%, λ increased by a factor of 5.2, and µ increased by 37.7%. In the case of HNFs, sample E (TiO2-MWCNT) 20:80 showed the best results, with κ improved by 6.66%, λ enhanced by a factor of 4.83, and µ increased by 34.99%. Conclusively, the κ, λ, and µ values of THNFs were found to be elevated to those of HNFs, showing that hybridization of different nanoparticles enhances the thermophysical performance of nanofluids.
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Keywords
Nanofluids, Thermal conductivity, Viscosity, Stability, Heat transfer