SURFACE MODIFICATION OF Fe₃O₄ NANOPARTICLES FOR PREPARING STABLE WATER-BASED NANOFLUIDS

Nanofluids are known as suspension of nanoparticles in a base fluid having improved thermophysical properties, which can be used in different applications. Nanofluid stability has an important role in its thermophysical properties which can highly affect the performance of the energy systems. In the literature, thermal performances of nanofluids and heat transfer improvement studies are generally emphasized in heat exchangers and energy systems. However, the stability of nanofluids is critical for these systems. It is possible to prepare more stable nanofluids and extend the lifetime of nanofluids by performing surface modifications to nanoparticles. In this regard, the modification process method has been presented for Fe₃O₄ particles by examining effects of different modification processes on stability and thermophysical properties. The modified Fe₃O₄ nanoparticles are used to prepare water-based nanofluids with superior stability. Relevant analyses including FT-IR, XRD, EDX, TEM, and SEM analyses were performed to evaluate the properties of the synthesized nanoparticles and prepared nanofluids. Subsequently, the nanofluids with a volume concentration of 0.2% were prepared. The viscosity and thermal conductivity of samples were measured at temperatures between 20°C and 60°C to find out the effect of surface modification. Considering all performed analyses Fe₃O₄@SiO₂-mix-(CH₂)₃Cl@imidazole-water nanofluid has been proposed with superior stability.