Experimental study of temperature and mass ratio on thermophysical properties of MWCNTs-TiO2/H2O nanofluids

Nanofluids (NFs) are considered advanced heat transfer fluids due to their enhanced thermal conductivity, improved heat transfer efficiency, energy-saving potential, and prospects for system miniaturization. However, the development of NFs faces challenges, as traditional single-component NFs often suffer from poor stability, limited thermal conductivity improvement, and high viscosity, which hinder their practical application. Herein, we prepared multi-walled carbon nanotubes (MWCNTs)-TiO 2 /H 2 O NFs via a two-step method and investigated the regulatory effects of temperature (20 °C-80 °C) and mass ratio (10:1-1:10) on their dispersion stability, thermal conductivity, and viscosity characteristics. It turned out that MWCNTs and TiO 2 nanoparticles formed an interfacial coupling structure through physical adsorption. This structure was mediated by the preferential anchoring of TiO 2 nanoparticles onto the surface-active sites of MWCNTs, which effectively suppressed particle agglomeration and ensured dispersion stability of the MWCNTs-TiO 2 /H 2 O NFs. The MWCNTs-TiO 2 /H 2 O NFs with a mass ratio of 1:2 demonstrated optimal performance enhancement ratios (PER) by reducing viscosity loss and significantly improving thermal conductivity within the temperature range. Comparative studies with single-component NFs revealed that this hybrid NFs exhibited significant advantages in both thermal conductivity and viscosity performance, further confirming the synergistic optimization effect between the MWCNTs and TiO 2 nanoparticles. Our work reveals the core role of the interface coupling mechanism between MWCNTs and TiO 2 nanoparticles in optimizing the thermal transport performance of NFs, providing a theoretical basis for the development of efficient heat transfer systems based on synergistic effects.