Herein, a novel coalescence–jumping phase transition thermal diode using hybrid nanofluids, an emerging fluid with proven supreme properties, is first proposed and investigated. The rectification enhancement mechanism investigated by the evaporation performances of working fluid-filled superhydrophilic porous tank. Furthermore, developed mathematical model well-matched experimental results in t...

The VOx/γ-Al2O3 catalyst VA-200, which was introduced in a previous article, is further characterized by XPS and visible Raman spectroscopy. The reoxidation of highly dispersed VOx species with gas phase oxygen is investigated in detail and is described by an empirical kinetic model. It is observed that the reoxidation of reduced VOx/γ-Al2O3 catalyst is strongly affected by the presence of wate...

We report the structure and stability of ceria units deposited on the surface of γ-Al2O3 or incorporated in its cavities, as determined by periodic density functional calculations. Ceria species are modeled as CeO2 or Ce2O4 moieties or as a small nanoparticle, Ce13O26, on the (100) and (001) surfaces of a γ-Al2O3 slab. Among the studied structures the incorporation of Ce(4+) ions in cavities of...

In the recent years, great interest has been devoted to the unique properties of nanofluids. The dispersion process and the nanoparticle suspension stability have been found to be critical points in the development of these new fluids. For this reason, an experimental study on the stability of water-based dispersions containing different nanoparticles, i.e. single wall carbon nanohorns (SWCNHs)...

This study numerically investigates heat transfer augmentation using water-based Al₂O₃ and CuO nanofluids flowing in a triangular cross-sectional duct under constant heat flux in laminar flow conditions. The Al₂O₃/water nanofluids with different volume fractions (0.1%, 0.5%, 1%, 1.5%, and 2%) and CuO/water nanofluids with various volume fractions (0.05%, 0.16%, 0.36%, 0.5%, and 0.8%) are employ...

To understand the effect of different thermal conductivities on catalytic combustion characteristics, effect of thermal conductivity on micro-combustion characteristics of hydrogen-air mixtures in Pt/γ-Al2O3 catalytic micro-combustors were investigated numerically with detailed chemical kinetics mechanisms. Three kinds of wall materials (100, 7.5, and 0.5 W/m·K) were selected to investigate the...

In this study, the thermal conductivity of aqueous nanofluids containing clusters iron oxide (Fe3O4/γ-Fe2O3) nanoparticles has been investigated experimentally for first time, with aim assessing role a controlled aggregation in these final nanofluids. For that, different cluster size (46–240 nm diameter range) were synthesized by solvothermal method and fully characterized transmission electron...