The effect of particle volume fraction and temperature on the enhancement of thermal conductivity of maghemite (γ–Fe2O3) water-based nanofluids

Cold sintering to form bulk maghemite for characterization beyond magnetic properties

“…These conductivity measurements can mark as the first available data of maghemite in the literature. In the past, transport properties were measured only about maghemite composites: 10 −7 ‐10 −2 S/m for maghemite‐polyaniline nanocomposites with varying maghemite concentrations and 0.982 W/(mK) for maghemite‐water nanofluids with 2.5 vol% of maghemite …”

“…While their magnetic properties are well characterized, their nonmagnetic properties are not. Their thermal conductivities have only been measured in the nanofluid form . Their electrical properties have been measured in the composite form, especially with polyaniline (a conductive polymer) for electromagnetic absorbers, and chemical and biological sensor applications .…”

“…I G U R E 2 SEM images of fracture surfaces of the cold-sintered maghemite samples: A, 130°C and 380 MPa. B, 250°C and 380 MPa maghemite concentrations10,11 and 0.982 W/(mK) for maghemite-water nanofluids with 2.5 vol% of maghemite 8. …”

Experimental investigation, modelling, and order of magnitude analysis of oxygen mass transfer in pulsed plate column with α‐Fe2O3 nanofluid

“…[ 122 ] where D L is the diffusivity of O 2 in the base fluid (sodium sulphite solution without nanoparticles) which was found by using Wilke and Chang's technique [ 123 ] and ψ is the nanoparticle loading in volume fraction (v/v) and is calculated using the Equation (). [ 124 ] The values of ψ were found to be 3 × 10 −5 , 6 × 10 −5 , 9 × 10 −5 , 1.2 × 10 −4 , 1.5 × 10 −4 , and 1.9 × 10 −4 , corresponding to 017% w/v, 0.034% w/v, 0.051% w/v, 0.068% w/v, 0.085% w/v, and 0.102% w/v, respectively. where M np is the mass of the nanoparticles, ρ np is the density of the nanoparticles (5240 kg/m 3 for α‐Fe 2 O 3 nanoparticles and 4260 kg/m 3 for TiO 2 nanoparticles), M bf is the mass of the base fluid, and ρ bf is the density of the base fluid.…”

“…where D L is the diffusivity of O 2 in the base fluid (sodium sulphite solution without nanoparticles) which was found by using Wilke and Chang's technique [123] and ψ is the nanoparticle loading in volume fraction (v/v) and is calculated using the Equation ( 9). [124] The values of ψ were found to be 3 Â 10 À5 , 6 Â 10 À5 , 9 Â 10 À5 , 1.2 Â 10 À4 , 1.5 Â 10 À4 , and 1.9 Â 10 À4 , corresponding to 017% w/v, 0.034% w/v, 0.051% w/v, 0.068% w/v, 0.085% w/v, and 0.102% w/v, respectively.…”