Improving Stability and Heat Transfer Performance of Nanofluids by Surface-Modifying Nanoparticles With β-Cyclodextrin

Nanofluids have attracted considerable interest for enhancing heat transfer efficiency; however, poor stability remains a challenge. In this study, β-cyclodextrin (β-CD) was grafted onto TiO 2 nanoparticles using nitrogen filling and vacuum drying methods to improve the stability of nanofluids. The modified nanoparticles were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. The stability and thermophysical properties of the nanofluids were evaluated in the temperature range of 20°C to 60°C. The results showed that the nitrogen filling method provided better grafting efficiency and stability, with a 36.62% reduction in settling velocity compared to the vacuum drying method. The β-TiO 2 /EG:DI nanofluid exhibited a peak thermal conductivity of 0.579 W/(m·K) at 60°C, a 12.46% increase over the pure base fluid. Thermoeconomic analysis indicated that the β-TiO 2 /EG:DI nanofluid has a maximum price-performance factor of 1.206 under laminar flow at 50°C, representing a 23.67% increase compared to the unmodified TiO 2 /EG:DI nanofluid. These findings suggest that β-TiO 2 /EG:DI nanofluid is suitable for industrial applications in the laminar flow regime.