Engineering study of continuous supercritical hydrothermal method using a T-shaped mixer: Experimental synthesis of NiO nanoparticles and CFD simulation

Modelling and simulation of counter-current and confined jet reactors for hydrothermal synthesis of nano-materials

“…The slurry containing nanoparticles then travelled upwards and left the reactor to enter a heat exchanger for rapid cooling before being collected as the product. In order to concentrate the study on fluid flow and heat transfer, the mixture stream from P2 and P3 ( Figure 2) was mimicked using deionised water during temperature profiling experiments and CFD modelling with the same approach being employed in the literature (Kawasaki et al, 2010) for the CFD simulations of continuous supercritical hydrothermal synthesis of NiO nanoparticles, though studies are being carried out to combine CFD with population balance (PB) modelling for the prediction of flow field, heat transfer phenomenon and particle size distribution. Typical solid concentration in the nanoparticle slurry under the current operating conditions is ~ 0.1 % w/w, indicating that the product slurry is very dilute.…”

“…Aimable et al (Aimable et al, 2009) simulated the mixing zone of a reactor with X-shaped geometry to predict the distributions of temperature and velocity, but the simulation was not validated experimentally. Kawasaki et al (Kawasaki et al, 2010) studied a Tshaped mixer for continuous supercritical hydrothermal synthesis of TiO 2 nano-particles. CFD simulations were performed to obtain velocity and temperature profiles under different operating conditions, but the results were not validated with experimental data.…”

Development of Novel Micro Swirl Mixer for Producing Fine Metal Oxide Nanoparticles by Continuous Supercritical Hydrothermal Method

“…The mesh number at the metal section was between 830,000 and 1,300,000, depending on the mixer shape. Other simulation details are as described, in detail, in our previous study 11 . The temperature contour diagrams of the mixed fl uid s y-z surface are shown in Fig.…”

“…Continuous supercritical hydrothermal synthesis was carried out using swirl mixers and the conventional T-shaped mixers having different inner diameters ID . The NiO nanoparticles synthesized from Ni NO 3 2 were assessed to discuss the effect of mixer type and ID on the particle size, because, in our previous work, we found that the effect of heating rate greatly influenced the particle size and size distribution of the nanoparticles 11 . In addition, a computational fl uid dynamics CFD simulation was carried out to compare the heating profi les of each mixer.…”

Hydrothermal and Supercritical Water Processing of Inorganic Substances

“…Lanthanum oxide nanoparticles [56], lithium iron phosphate (LiFePO 4 ) nanoparticles [57], NiO nanoparticles [58], zinc oxide nanoparticles [59], ZnO nanoparticles formation by reactions of bulk Zn with H 2 O and CO 2 [60], CFD simulation of ZnO nanoparticle synthesis [61], hafnium oxide nanoparticles [62], effect of cations and anions on properties of zinc oxide particles [63], metallic cobalt nanoparticles [64], Bi 2 Te 3 nanoparticles [65], g-Al 2 O 3 nanoparticles [66], Perovskite oxide Ca 0.8 Sr 0.2 Ti 1Àx Fe x O 3Àd (CTO) nanoparticles [67], anatase TiO 2 nanoparticles [68], nanoparticulate yttrium aluminum garnet [69], CoFe 2 O 4 nanoparticles [70], YVO 4 and rare earth-doped YVO 4 ultrafine particles [71], lithium iron phosphate (LiFePO 4 ) [72], YAG monodispersed particles [73], luminescent yttrium aluminum garnet (Y 3 Al 5 O 12 ) [74], copper manganese oxide nanocrystals [75], Zn 2 SiO 4 :Mn 2þ fine particles [76], iron nanoparticles [77], iron oxide (a-Fe 2 O 3 ) nanoparticles in activated carbon [78], high-temperature LiCoO 2 [78,90], KNbO 3 powders [79], MgFe 2 O 4 nanoparticles [80], Zn 2 SnO 4 anode material (synthesized in batch mode) [81], lithium iron phosphate particles [82], ZnGa 2 O 4 :Mn 2þ nanoparticles [83], magnetite particles [84], and lithium iron phosphate (LiFePO 4 ) nanoparticles [85], boehmite nanoparticles [89]. Formation of fine particles during hydrothermal and supercritical water synthesis of compounds is due to the extremely high hydrolysis reaction rate and the low solubility of produced compounds in supercritical water.…”